Global threat to agriculture from invasive species

Estimating the Global Geographical Distribution Patterns of the Invasive Crop Pest Diuraphis noxia Kurdjumov under Current and Future Climatic Scenarios

Invasive crop pests (ICPs) are a major cause of crop losses and adversely affect global food security. Diuraphis noxia Kurdjumov is a significant ICP that feeds on the sap of crops, reducing crop yield and quality. Although estimating the geographical distribution patterns of D. noxia under climate change is critical for its management and global food security, such information remains unclear. Based on 533 global occurrence records and 9 bioclimatic variables, an optimized MaxEnt model was used to predict the potential global geographical distribution of D. noxia. The results showed that Bio1, Bio2, Bio7, and Bio12 were significant bioclimatic variables that influenced the potential geographical distribution of D. noxia. Under current climatic conditions, D. noxia was mainly distributed in west-central Asia, most of Europe, central North America, southern South America, southern and northern Africa, and southern Oceania. Under the SSP 1-2.6, SSP 2-4.5, and SSP 5-8.5 scenarios for the 2030s and 2050s, the potential suitable areas increased, and the centroid migrated to higher latitudes. The early warning of D. noxia in northwestern Asia, western Europe, and North America should be attended to further. Our results provide a theoretical basis for early monitoring and warning of D. noxia worldwide.

Tracking Adaptive Pathways of Invasive Insects: Novel Insight from Genomics

Despite the huge human and economic costs of invasive insects, which are the main group of invasive species, their environmental impacts through various mechanisms remain inadequately explained in databases and much of the invasion biology literature. High-throughput sequencing technology, especially whole-genome sequencing, has been used as a powerful method to study the mechanisms through which insects achieve invasion. In this study, we reviewed whole-genome sequencing-based advances in revealing several important invasion mechanisms of invasive insects, including (1) the rapid genetic variation and evolution of invasive populations, (2) invasion history and dispersal paths, (3) rapid adaptation to different host plant ranges, (4) strong environmental adaptation, (5) the development of insecticide resistance, and (6) the synergistic damage caused by invasive insects and endosymbiotic bacteria. We also discussed prevention and control technologies based on whole-genome sequencing and their prospects.

Climate change impacts on the potential worldwide distribution of the soybean pest, Piezodorus guildinii (Hemiptera: Pentatomidae)

The redbanded stink bug, Piezodorus guildinii (Westwood, 1837), is a highly destructive soybean pest native to the Neotropical Region. In the past 60 yr, P. guildinii has been observed to expand its distribution in North and South America, causing significant soybean yield losses. In order to predict the future distribution direction of P. guildinii and create an effective pest control strategy, we projected the potential global distribution of P. guildinii using 2 different emission scenarios, Shared Socioeconomic Pathways 126 and 585, and 3 Earth system models, with the maximum entropy niche model (MaxEnt). Then, the predicted distribution areas of P. guildinii were jointly analyzed with the main soybean-producing areas to assess the impact for different soybean region. Our results showed that temperature is the main environmental factor limiting the distribution of P. guildinii. Under present climate conditions, all continents except Antarctica have suitable habitat for P. guildinii. These suitable habitats overlap with approximately 45.11% of the total global cultivated soybean areas. Moreover, P. guildinii was predicted to expand its range in the future, particularly into higher latitudes in the Northern hemisphere. Countries, in particular the United States, where soybean is widely available, would face a management challenge under global warming. In addition, China and India are also high-risk countries that may be invaded and should take strict quarantine measures. The maps of projected distribution produced in this study may prove useful in the future management of P. guildinii and the containment of its disruptive effects.

Citizen Science Meet South American Tachinids: New Records of Feather-Legged Fly Trichopoda (Galactomyia) pictipennis Bigot (Diptera: Tachinidae) from Chile

The species of Gymnosomatini (Diptera: Tachinidae) are specialized to attack stink bugs (Hemiptera: Pentatomidae). Some of these flies, such as those in the genus Trichopoda Berthold, are conspicuous and represent target species to study with citizen science. Here we report for the first time the distribution range of T. (Galactomyia) pictipennis Bigot, a newly introduced biological control species of tachinid for use against stink bugs in Chile using data obtained through the citizen science method. Additionally, we update the distribution of T. arcuata (Bigot), a native biological control species of tachinid, and assess the grade of overlap between the flies and their main stink bug hosts. We obtained data regarding the occurrence of flies and stink bugs from the citizen science program "Moscas Florícolas de Chile," from Facebook groups, and from iNaturalist. We standardized our data to avoid temporal, spatial, and geographic biases. We report the extent of occurrence (EOO) and area of occupancy (AOO) for each fly and stink bug species. The EOOs for T. pictipennis and T. arcuata are 85,474 km² and 20,647 km² through central Chile ecosystems, respectively. The EOO of T. arcuata is overlapped by 53% with the introduced species. Trichopoda pictipennis has a high percentage of overlap with the EOO of Nezara viridula Linnaeus (61%), whereas T. arcuata has low percentages of overlap with different native Acledra species and with N. viridula. We discuss the potential of citizen science to detect (1) areas with higher diversity or gaps of occurrences, (2) new biological control agents, (3) prey records, (4) negative impacts on non-target species, (5) changes in composition at long-term, and (6) areas to promote conservation biological control in agricultural landscapes.

Ecology, invasion history and biodiversity-driven management of the coconut black-headed caterpillar Opisina arenosella in Asia

The coconut black-headed caterpillar (BHC), Opisina arenosella Walker (Lepidoptera: Xyloryctidae) is an important herbivore of palm trees that originates in South Asia. Over the past decades, O. arenosella has spread to several countries in Eastern and Southeast Asia. BHC larval feeding can cause severe defoliation and occasional plant death, resulting in direct production losses (e.g., for coconut) while degrading the aesthetic value of urban and rural landscapes. In this review paper, we systematically cover taxonomy, bio-ecology, invasion history and current management of O. arenosella throughout Asia. Given that O. arenosella is routinely controlled with insecticides, we equally explore options for more sustainable management through agroecological and biodiversity-based tactics e.g., cultural control or biological control. Also, recent advances in chemical ecology have unlocked lucrative opportunities for volatile-mediated monitoring, mating disruption and mass-trapping. Substantial progress has been made in augmentation biological control, with scheduled releases of laboratory-reared parasitoids lowering BHC infestation pressure up to 95%. Equally, resident ants provide 75-98% mortality of BHC egg masses within the palm canopy. Biological control has been effectively paired with sanitary measures and good agronomy (i.e., proper fertilization, irrigation), and promoted through participatory farmer training programs. Our comprehensive listing of non-chemical preventative and curative tactics offer bright prospects for a more environmentally-sound, biodiversity-driven mitigation of a palm pest of regional allure.

Current and future potential distribution of the invasive scale Ceroplastes rusci (L., 1758) (Hemiptera: Coccidae) under climate niche

BACKGROUND

The fig wax scale, Ceroplastes rusci is an invasive pest that feeds on more than 94 genera from 52 families that is spread across 60 countries, causing negative impacts to agriculture and forestry. Understanding the potential distribution of invasive species under climate change is crucial for the management and monitoring purposes. Thus, we predicted the potential distribution areas of C. rusci using Maximum Entropy (MaxEnt) based on the occurrence data and environmental variables under current and future climatic scenarios.

RESULTS

Our results showed that the temperature annual range (Bio 7) and mean temperature of the warmest quarter (Bio 10) attributed to a higher contribution to the current model of the distribution of C. rusci. The potential distribution maps illustrated the main concentrated areas of C. rusci which included South America, Africa, Asia, and Oceania. In addition, potential range expansions or reductions were predicted under different future climate change scenarios, which showed that the total suitable areas of the fig wax scale presented an increasing trend until 2100.

CONCLUSION

Our study provides significant data to understand the potential distribution of C. rusci around the world. It also serves as an early warning for the highly suitable habitat areas that even offers a platform to the currently non-infested regions or countries who are yet to develop monitoring strategies in response to the possible C. rusci outbreak. © 2022 Society of Chemical Industry.

The applicability of species sensitivity distributions to the development of generic doses for phytosanitary irradiation

Ionizing radiation is used as a phytosanitary treatment to prevent the introduction of pests through trade. Generic doses are a valuable means to increase the number of pest-commodity combinations that can be treated using phytosanitary irradiation. Generic doses allow for the treatment of the entire taxa for which the dose has been approved, allowing for the treatment of untested species. As such, the approval of a generic dose requires substantial supporting data and careful consideration of the risks involved. We adopt the Species Sensitivity Distribution (SSD) framework, already in widespread use in the field of ecotoxicology and environmental risk assessment, to evaluate generic doses for phytosanitary irradiation treatments. Parametric SSDs for Curculionidae and Tephritidae were developed using existing data on efficacious phytosanitary irradiation treatments. The resulting SSDs provided estimates of the taxa coverage expected by the generic dose, along with the margin of uncertainty. The SSD analysis lends support to the existing 150 Gy generic dose for Tephritidae and a proposed 175 Gy generic dose for Curculionidae. The quantitative estimates of risk produced by the SSD approach can be a valuable tool for phytosanitary rule making, improving the process for generic dose development and approval.

Honey bee introductions displace native bees and decrease pollination of a native wildflower

Introduced species can have cascading effects on ecological communities, but indirect effects of species introductions are rarely the focus of ecological studies. For example, managed honey bees (Apis mellifera) have been widely introduced outside their native range and are increasingly dominant floral visitors. Multiple studies have documented how honey bees impact native bee communities through floral resource competition, but few have quantified how these competitive interactions indirectly affect pollination and plant reproduction. Such indirect effects are hard to detect because honey bees are themselves pollinators and may directly impact pollination through their own floral visits. The potentially huge but poorly understood impacts that non-native honey bees have on native plant populations combined with increased pressure from beekeepers to place hives in U.S. National Parks and Forests makes exploring impacts of honey bee introductions on native plant pollination of pressing concern. In this study, we used experimental hive additions, field observations, as well as single-visit and multiple-visit pollination effectiveness trials across multiple years to untangle the direct and indirect impacts of increasing honey bee abundance on the pollination of an ecologically important wildflower, Camassia quamash. We found compelling evidence that honey bee introductions indirectly decrease pollination by reducing nectar and pollen availability and competitively excluding visits from more effective native bees. In contrast, the direct impact of honey bee visits on pollination was negligible, and, if anything, negative. Honey bees were ineffective pollinators, and increasing visit quantity could not compensate for inferior visit quality. Indeed, although the effect was not statistically significant, increased honey bee visits had a marginally negative impact on seed production. Thus, honey bee introductions may erode longstanding plant-pollinator mutualisms, with negative consequences for plant reproduction. Our study calls for a more thorough understanding of the indirect effects of species introductions and more careful coordination of hive placements.

Aliens on Boats? The Eastern and Western Expansion of the African House Gecko

Invasive species disrupt relations between endemics and their ecosystem and are an increasing biodiversity conservation problem. The Hemidactylus genus comprises the most successful invasive reptile species, including the worldwide-distributed Hemidactylus mabouia. In this study, we used 12S and ND2 sequences to taxonomically identify and tentatively determine the diversity and origin of these invaders in Cabo Verde while also clarifying this for several Western Indian Ocean (WIO) populations. By comparing our sequences to recently published ones, we showed, for the first time, that Cabo Verde individuals belong to the H. mabouia sensu stricto lineage and that both of its sublineages (a and b) occur there. Both haplotypes are also in Madeira, which indicates a connection between these archipelagos, possibly related to the past Portuguese trading routes. Across the WIO, results clarified the identity of many island and coastal populations, showing that this likely invasive H. mabouia lineage is widespread in the region, including northern Madagascar, with important conservation implications. Colonisation origins were difficult to access due to the wide geographical spread of these haplotypes; thus, several possible scenarios were outlined. The introduction of this species throughout western and eastern Africa may threaten endemic taxa and needs to be closely monitored.

Predicting the invasion risk of rugose spiraling whitefly, Aleurodicus rugioperculatus, in India based on CMIP6 projections by MaxEnt

BACKGROUND

Rugose spiraling whitefly (RSW), Aleurodicus rugioperculatus Martin, is a highly polyphagous invasive pest native to Central America. The occurrence of A. rugioperculatus in the Oriental region was first reported from Pollachi, Tamil Nadu, India in 2017. This pest is widely distributed in India, causing severe economic damage to coconut and other horticultural crops. It is a recent invasion in India and information on its potential distribution is lacking. Thus, in the present study we used the latest Coupled Model Intercomparison Project phase 6 (CMIP6) dataset through Maximum Entropy species distribution modelling (version 3.4.1, MaxEnt) to determine the potential distribution of RSW in present and future climate change scenarios in 2050 and 2070 under Shared Socioeconomic Pathway (SSP) 126 and SSP585 emission scenarios. The performance of the model was evaluated using the area under the curve (AUC), true skill statistics (TSS) and the continuous Boyce index (CBI).

RESULTS

The MaxEnt model performed well and predicted the potential distribution of A. rugioperculatus with high-accuracy AUC values of 0.991 and 0.989, TSS values of 0.891 and 0.842, and CBI values of 0.972 and 0.934 for training and testing, respectively. Jackknife analysis revealed that A. rugioperculatus distribution was mostly influenced by temperature-based bioclimatic variables contributing 62.1% of the suitability, with precipitation variables contributing the remainder. The most important bioclimatic variables for RSW distribution were annual mean temperature (Bio 1, 28.9%) followed by mean diurnal range (Bio 2, 19.5%) and annual precipitation (Bio 12, 19.1). Potential suitable areas for RSW establishment were mostly found in all coastal and southern states of India. A. rugioperculatus prefers a warm and humid climate, indicating that the tropics, subtropics and temperate regions are ideal for its spread and invasion. Our results highlighted that the suitable habitat area for A. rugioperculatus is predicted to increase and highest probability of invasion and spread in 2050 and 2070 under future climate change scenarios of SSP126 and SSP585 compared to present climatic conditions.

CONCLUSIONS

This is the first study to use the latest CMIP6 models and it predicts the potential distribution of RSW in India under present and future climate change scenarios. The implementation of strict domestic quarantine measures may prevent the spread and damage of RSW to noncoastal regions of India. The results of the current study should help in timely monitoring and surveillance of RSW and to formulate integrated pest management strategies at the national level to restrict its spread, invasion and damage to new areas. © 2022 Society of Chemical Industry.

Alien insect dispersal mediated by the global movement of commodities

Globalization and economic growth are recognized as key drivers of biological invasions. Alien species have become a feature of almost every biological community worldwide, and rates of new introductions continue to rise as the movement of people and goods accelerates. Insects are among the most numerous and problematic alien organisms, and are mainly introduced unintentionally with imported cargo or arriving passengers. However, the processes occurring prior to insect introductions remain poorly understood. We used a unique dataset of 1,902,392 border interception records from inspections at air, land, and maritime ports in Australia, New Zealand, Europe, Japan, USA, and Canada to identify key commodities associated with insect movement through trade and travel. In total, 8939 species were intercepted, and commodity association data were available for 1242 species recorded between 1960 and 2019. We used rarefaction and extrapolation methods to estimate the total species richness and diversity associated with different commodity types. Plant and wood products were the main commodities associated with insect movement across cargo, passenger baggage, and international mail. Furthermore, certain species were mainly associated with specific commodities within these, and other broad categories. More closely related species tended to share similar commodity associations, but this occurred largely at the genus level rather than within orders or families. These similarities within genera can potentially inform pathway management of new alien species. Combining interception records across regions provides a unique window into the unintentional movement of insects, and provides valuable information on establishment risks associated with different commodity types and pathways.

A mini-review on the impact of common gorse in its introduced ranges

It is indisputable that invasive plant species strongly impact the ecosystems they invade. Many of such impacts can be negative and threaten the local species through competition, environmental change, or habitat loss. However, introduced plants may also have positive roles in the ecosystems they invade. This review extracted information from reports on common gorse (Ulex europaeus), one of the top 100 invasive plants on the earth, including its detrimental effects and potential beneficial roles in invaded ecosystems. The reduction of native fauna and flora are the main harmful effects of common gorse identified by the literature review. Soil impoverishment and fire hazards are other negative impacts reported for common gorse that could affect agricultural systems and local economies. Despite the negative impacts, reports of positive ecological services provided by common gorse also exist, e.g., as a nursery plant or habitat for endangered native animals. We also reviewed the known human uses of this plant that could support management strategies through harvest and benefit the local communities, including its use as biofuel, raw matter for xylan extraction, medicine, and food. Finally, our review identified the gaps in the literature regarding the understanding of the beneficial role of common gorse on native ecosystems and potential human uses, especially in the tropics.

Identification of sex chromosomes and primary sex ratio in the small hive beetle, a worldwide parasite of honey bees

BACKGROUND

The small hive beetle (SHB), Aethina tumida, has emerged as a worldwide threat to honey bees in the past two decades. These beetles harvest nest resources, feed on larval bees, and ultimately spoil nest resources with gelatinous slime together with the fungal symbiont Kodamaea ohmeri.

RESULTS

Here, we present the first chromosome-level genome assembly for the SHB. With a 99.1% representation of conserved (BUSCO) arthropod genes, this resource enables the study of chemosensory, digestive, and detoxification traits critical for SHB success and possible control. We use this annotated assembly to characterize features of SHB sex chromosomes and a female-skewed primary sex ratio. We also found chromosome fusion and a lower recombination rate in sex chromosomes than in autosomes.

CONCLUSIONS

Genome-enabled insights will clarify the traits that allowed this beetle to exploit hive resources successfully and will be critical for determining the causes of observed sex ratio asymmetries.

The economic costs, management and regulation of biological invasions in the Nordic countries

A collective understanding of economic impacts and in particular of monetary costs of biological invasions is lacking for the Nordic region. This paper synthesizes findings from the literature on costs of invasions in the Nordic countries together with expert elicitation. The analysis of cost data has been made possible through the InvaCost database, a globally open repository of monetary costs that allows for the use of temporal, spatial, and taxonomic descriptors facilitating a better understanding of how costs are distributed. The total reported costs of invasive species across the Nordic countries were estimated at $8.35 billion (in 2017 US$ values) with damage costs significantly outweighing management costs. Norway incurred the highest costs ($3.23 billion), followed by Denmark ($2.20 billion), Sweden ($1.45 billion), Finland ($1.11 billion) and Iceland ($25.45 million). Costs from invasions in the Nordics appear to be largely underestimated. We conclude by highlighting such knowledge gaps, including gaps in policies and regulation stemming from expert judgment as well as avenues for an improved understanding of invasion costs and needs for future research.

The evolutionary process of invasion in the fall armyworm (Spodoptera frugiperda)

The fall armyworm (FAW; Spodoptera frugiperda) is one of the major agricultural pest insects. FAW is native to the Americas, and its invasion was first reported in West Africa in 2016. Then it quickly spread through Africa, Asia, and Oceania, becoming one of the main threats to corn production. We analyzed whole genome sequences of 177 FAW individuals from 12 locations on four continents to infer evolutionary processes of invasion. Principal component analysis from the TPI gene and whole genome sequences shows that invasive FAW populations originated from the corn strain. Ancestry coefficient and phylogenetic analyses from the nuclear genome indicate that invasive populations are derived from a single ancestry, distinct from native populations, while the mitochondrial phylogenetic tree supports the hypothesis of multiple introductions. Adaptive evolution specific to invasive populations was observed in detoxification, chemosensory, and digestion genes. We concluded that extant invasive FAW populations originated from the corn strain with potential contributions of adaptive evolution.

Both Adaptability and Endophytic Bacteria Are Linked to the Functional Traits in the Invasive Clonal Plant Wedelia trilobata

The role of the interactions between endophytes and host plants is unclear in invasive plants from different geographical latitudes. In this study, we aimed to explore the relationship between endophytic microbes and the functional traits of the invasive plant Wedelia trilobata. We explored the relationship between endophytes and the clonal growth traits of the invasive clonal plant Wedelia trilobata from different geographical latitudes using high-throughput sequencing technology and a common garden-planting experiment. We found that: (1) Different W. trilobata populations had similar endophytic fungi but different endophytic bacteria. However, no latitudinal variation pattern of the overall microbial community was found; (2) plant clonal growth performance (i.e., spacer length) was significantly correlated with endophytic bacterial diversity but not fungal diversity; and (3) the latitudinal variation pattern of the plant clonal growth performance of W. trilobata populations was found in pre-cultivated (i.e., wild) individuals but disappeared in post-cultivated W. trilobata. Our results suggest both environmental adaptability and the endophytic bacterial community are linked to the functional traits of the invasive clonal plant W. trilobata, and these functional traits tend to increase its invasiveness, which may enhance its invasion success.

Native generalist natural enemies and an introduced specialist parasitoid together control an invasive forest insect

Specialized natural enemies have long been used to implement the biological control of invasive insects. Although research tracking populations following biological control introductions has traditionally focused on the impact of the introduced agent, recent studies and reviews have reflected an appreciation of the complex interactions of the introduced specialist agents with native generalist natural enemies. These interactions can be neutral, antagonistic, or complementary. Here we studied the invasive defoliator winter moth (Operophtera brumata) in the Northeast USA to investigate the role of native, generalist pupal predators along with the introduced, host-specific parasitoid Cyzenis albicans. Prior research in Canada has shown that predation of winter moth pupae from native generalists increased after C. albicans was established as a biological control agent. To explain this phenomenon, the following hypotheses were suggested: (H₁ ) parasitoids suppress the winter moth population to a density that can be maintained by generalist predators, (H₂ ) unparasitized pupae are preferred by predators and therefore experience higher mortality rates, or (H₃ ) C. albicans sustains higher predator populations throughout the year more effectively than winter moth alone. We tested these hypotheses by deploying winter moth pupae over 6 years spanning 2005 to 2017 and by modeling pupal predation rates as a function of winter moth density and C. albicans establishment. We also compared predation rates of unparasitized and parasitized pupae and considered additional mortality by a native pupal parasitoid. We found support for the first hypothesis; we detected both temporal and spatial density dependence, but only in the latter years of the study when winter moth densities were low. We found no evidence for the latter two hypotheses. Our findings suggest that pupal predators have a regulatory effect on winter moth populations only after populations have been reduced, presumably by the introduction of the host-specific parasitoid C. albicans.

Effect of Life-History Traits and Habitat Condition on Genetic Diversity between Invasive and Native Plant Populations

Plant invasions have a huge impact on the health of ecosystems and human well-being. The invasion risk varies with the introduction pathway, the propagule pressure, and the genetic diversity of the founding population. We performed a systematic review and meta-analysis of 30 studies reporting the genetic diversity of 31 plant species in their invasive and native ranges. We evaluated if patterns of genetic diversity differ between ranges and whether these responses are influenced by life-history traits, hybridization, polyploidization, and habitat condition. We found that invasive populations had significantly lower genetic diversity and higher inbreeding than native populations. In fragmented and degraded habitats, the genetic diversity of invaders was lower, but inbreeding was not affected. Polyploid invaders with hybrid capacity also showed lower genetic diversity. Invasive herbs with vegetative propagation were more sensitive to the loss of genetic diversity and had higher levels of inbreeding. Our synthesis showed that the genetic response in the invaded range could result from historical processes, such as founder and bottleneck events. Traits such as selfing are more likely to preserve the signatures of founder events and influence the genetic diversity in invasive populations. Additionally, clonality seems to be the predominant reproduction system in the invaded range.

Genomic and ecological evidence shed light on the recent demographic history of two related invasive insects

Hypogeococcus pungens is a species complex native to southern South America that is composed of at least five putative species, each one specialized in the use of different host plants. Two of these undescribed species were registered as invasive in Central and North America: Hyp-C is a cactophagous mealybug that became an important pest that threatens endemic cactus species in Puerto Rico, and Hyp-AP feeds on Amaranthaceae and Portulacaceae hosts, but does not produce severe damage to the host plants. We quantified genomic variation and investigated the demographic history of both invasive species by means of coalescent-based simulations using high throughput sequencing data. We also evaluated the incidence of host plant infestation produced by both species and used an ecological niche modeling approach to assess potential distribution under current and future climatic scenarios. Our genetic survey evinced the footprints of strong effective population size reduction and signals of genetic differentiation among populations within each species. Incidence of plant attacks varied between species and among populations within species, with some host plant species preferred over others. Ecological niche modeling suggested that under future climatic scenarios both species would expand their distribution ranges in Puerto Rico. These results provide valuable information for the design of efficient management and control strategies of the Puerto Rican cactus pest and shed light on the evolutionary pathways of biological invasions.

Leveraging a natural murine meiotic drive to suppress invasive populations

Invasive rodents are a major cause of environmental damage and biodiversity loss, particularly on islands. Unlike insects, genetic biocontrol strategies including population-suppressing gene drives with biased inheritance have not been developed in mice. Here, we demonstrate a gene drive strategy (t_CRISPR) that leverages super-Mendelian transmission of the t haplotype to spread inactivating mutations in a haplosufficient female fertility gene (Prl). Using spatially explicit individual-based in silico modeling, we show that t_CRISPR can eradicate island populations under a range of realistic field-based parameter values. We also engineer transgenic t_CRISPR mice that, crucially, exhibit biased transmission of the modified t haplotype and Prl mutations at levels our modeling predicts would be sufficient for eradication. This is an example of a feasible gene drive system for invasive alien rodent population control.

The spread of Carpophilus truncatus is on the razor's edge between an outbreak and a pest invasion

In 2019, in southern Italy (Campania) there was an outbreak of a sap beetle infesting stored walnut fruits. A monitoring activity started to assess the spread and impact of the pest in walnut orchards and in warehouses, and an integrative characterization led to identify the beetle as Carpophilus truncatus. This species has been in Europe for a long time, rare and harmless until recently. We show also that this species is the same recently recorded in other two continents, Latin America and Australia, where it is causing massive damage on walnut and almond fruits. The sharing of a mitochondrial haplotype among populations recorded on three continents suggests that a worldwide invasion might be ongoing. A Geographic Profiling approach has determined that the more virulent population was first introduced in Italy, and the climate conditions of areas where C. truncatus is currently widespread and harmful indicate that the entire walnuts world production is in jeopardy as this species could adapt to any of the main walnut and almond production areas.

Amine-functionalized magnetic biochars derived from invasive plants Alternanthera philoxeroides for enhanced efficient removal of Cr(VI): performance, kinetics and mechanism studies

In this study, novel magnetic biochars derived from Alternanthera philoxeroides and modified by different amines (hexanediamine, melamine, and L-glutathione) were successfully prepared by hydrothermal carbonization and employed as an efficient adsorbent for Cr(VI). When pH = 2.0, T = 25 °C, c₀ = 100 mg/L, and the dosage of biochars is 0.05 g, the maximum adsorption capacity of Cr(VI) by pristine biochar (BAP) was 42.47 mg/g and modified biochars (MFBAP, MEBAP, LBAP) was 80.58, 62.26, and 55.66 mg/g, respectively. It was found that hexanediamine and melamine could enhance the S_BET of biochars, while L-glutathione could reduce its S_BET, which could be supported by BET measurement and SEM images. Adsorption kinetics and isotherm studies showed that the Cr(VI) adsorption process of MFBAP followed Elovich kinetic model and Langmuir isotherm, respectively, which means that it was mainly a chemical adsorption process. The characterization results proved that -NH₂ derived from amines plays a significant role in removing Cr(VI), which is mainly degraded by complexation reaction, electrostatic interaction, and reduction. In sum, the biochar modified by amines has excellent Cr(VI) adsorption performance, highly enhanced S_BET, and excellent recyclability, which is a promising candidate for solving the problem of invasive plants and wastewater treatment.

Defining invasive species and demonstrating impacts of biological invasions: a scientometric analysis of studies on invasive alien plants in Brazil over the past 20 years

Despite biological invasions being widely recognised as an important driver of environmental change, lack of consensus regarding the definition of invasive alien species (IAS) and vagueness around the demonstration of their impacts limits knowledge and research in this field. In this study, a scientometric approach was used to analyse academic documents published between 2002 and 2021 in three databases with reference to invasive alien plants in Brazil. Despite the growing body of scientific literature in the area, only 10% of the publications provided some definition of invasive species. Of the 398 publications analysed, 23.6% found some type of damage caused by the invader and, of these, only 5% addressed economic or social damage. Only 17% of the publications proposed a method for controlling and/or mitigating biological invasions. The absence of clear terminology and the lack of focus on impacts limits understanding of IAS of plants in Brazil. Based on the present findings, future studies on IAS of plants should move towards a consensus on the definition of biological invasion, as well as understand the impact caused by these species. In addition, it is recommended that further scientometric studies should guide future efforts to support objective measures for management and decision-making.

Modulation of plant nitrogen remobilization and postflowering nitrogen uptake under environmental stresses

Plants are sessile organisms that take up nitrogen (N) from the soil for growth and development. At the postflowering stage, N that plants require for seed growth and filling derives from either root uptake or shoot remobilization. The balance between N uptake and N remobilization determines the final carbon (C) and N composition of the seed. The N uptake and N remobilization mechanisms are regulated by endogenous signals, including hormones, developmental stage, and carbon/nitrogen ratio, and by environmental factors. The cellular responses to the environment are relatively well known. However, the effects of environmental stresses on the balance between N uptake and N remobilization are still poorly understood. Thus, this study aims to analyze the impact of environmental stresses (drought, heat, darkness, triggered defense, and low nitrate) on N fluxes within plants during seed filling. Using publicly available Arabidopsis transcriptome data, expression of several marker genes involved in N assimilation, transport, and recycling was analyzed in relation to stress. Results showed that the responses of genes encoding inorganic N transporters, N assimilation, and N recycling are mainly regulated by N limitation, the genes encoding housekeeping proteases are principally sensitive to C limitation, and the response of genes involved in the transport of organic N is controlled by both C and N limitations. In addition, ¹⁵N data were used to examine the effects of severe environmental stresses on N remobilization and N uptake, and a schematic representation of the major factors that regulate the balance between N remobilization and N uptake under the stress and control conditions was provided.

Potential for invasion of traded birds under climate and land-cover change

Humans have moved species away from their native ranges since the Neolithic, but globalization accelerated the rate at which species are being moved. We fitted more than half million distribution models for 610 traded bird species on the CITES list to examine the separate and joint effects of global climate and land-cover change on their potential end-of-century distributions. We found that climate-induced suitability for modelled invasive species increases with latitude, because traded birds are mainly of tropical origin and much of the temperate region is 'tropicalizing.' Conversely, the tropics are becoming more arid, thus limiting the potential from cross-continental invasion by tropical species. This trend is compounded by forest loss around the tropics since most traded birds are forest dwellers. In contrast, net gains in forest area across the temperate region could compound climate change effects and increase the potential for colonization of low-latitude birds. Climate change has always led to regional redistributions of species, but the combination of human transportation, climate, and land-cover changes will likely accelerate the redistribution of species globally, increasing chances of alien species successfully invading non-native lands. Such process of biodiversity homogenization can lead to emergence of non-analogue communities with unknown environmental and socioeconomic consequences.

Prolonged phloem feeding by the spotted lanternfly, an invasive planthopper, alters resource allocation and inhibits gas exchange in grapevines

Spotted lanternfly (Lycorma delicatula White; SLF) is a phloem-feeding planthopper invasive to the Eastern United States that can feed on a range of wild and cultivated plant species. Since its 2014 introduction in the United States, large infestations and subsequent economic damage have been reported in cultivated grapevines, but no studies have detailed grapevine physiological responses to SLF phloem feeding. This study investigated grapevine-SLF interactions, detailing how different infestation densities affect leaf gas exchange and end-season concentrations of nonstructural carbohydrates and nitrogen in vegetative and perennial tissues of two Vitis species. Effects on fruit ripeness parameters and dormant bud freeze tolerance were examined, in addition to other year-after effects. Phloem feeding by low densities (≤4 SLF shoot-1) had minimal effects, whereas greater densities (5-15 SLF shoot-1) increasingly affected carbohydrate and nitrogen dynamics in both Vitis species. Phloem feeding substantially affected starch and, to a lesser extent, total nitrogen concentrations of woody roots. Prolonged exposure strongly reduced leaf gas exchange. We conclude that intensive late-season phloem feeding by large adult SLF population densities (≥8 SLF shoot-1) can induce carbon limitation, with the potential for negative year-after effects in cases of severe belowground carbon depletion. This work presents novel insights into SLF-grapevine interactions, identifies avenues of future SLF-plant research, and assists the development of action thresholds for SLF management in vineyards.

Molecular epidemiology of the citrus bacterial pathogen Xanthomonas citri pv. citri from the Arabian Peninsula reveals a complex structure of specialist and generalist strains

Molecular epidemiology studies are essential to refine our understanding of migrations of phytopathogenic bacteria, the major determining factor in their emergence, and to understand the factors that shape their population structure. Microsatellite and minisatellite typing are useful techniques for deciphering the population structure of Xanthomonas citri pv. citri, the causal agent of Asiatic citrus canker. This paper presents a molecular epidemiology study, which has improved our understanding of the history of the pathogen's introductions into the Arabian Peninsula, since it was first reported in the 1980s. An unexpectedly high genetic diversity of the pathogen was revealed. The four distinct genetic lineages within X. citri pv. citri, which have been reported throughout the world, were identified in the Arabian Peninsula, most likely as the result of multiple introductions. No copper-resistant X. citri pv. citri strains were identified. The pathogen's population structure on Mexican lime (their shared host species) was closely examined in two countries, Saudi Arabia and Yemen. We highlighted the marked prevalence of specialist pathotype A* strains in both countries, which suggests that specialist strains of X. citri pv. citri may perform better than generalist strains when they occur concomitantly in this environment. Subclade 4.2 was the prevailing lineage identified. Several analyses (genetic structure deciphered by discriminant analysis of principal components, RST-based genetic differentiation, geographic structure) congruently suggested the role of human activities in the pathogen's spread. We discuss the implications of these results on the management of Asiatic citrus canker in the region.

An efficient method of evaluating multiple concurrent management actions on invasive populations

Evaluating the efficacy of management actions to control invasive species is crucial for maintaining funding and to provide feedback for the continual improvement of management efforts. However, it is often difficult to assess the efficacy of control methods due to limited resources for monitoring. Managers may view effort on monitoring as effort taken away from performing management actions. We developed a method to estimate invasive species abundance, evaluate management effectiveness, and evaluate population growth over time from a combination of removal activities (e.g., trapping, ground shooting) using only data collected during removal efforts (method of removal, date, location, number of animals removed, and effort). This dynamic approach allows for abundance estimation at discrete time points and the estimation of population growth between removal periods. To test this approach, we simulated over 1 million conditions, including varying the length of the study, the size of the area examined, the number of removal events, the capture rates, and the area impacted by removal efforts. Our estimates were unbiased (within 10% of truth) 81% of the time and were correlated with truth 91% of the time. This method performs well overall and, in particular, at monitoring trends in abundances over time. We applied this method to removal data from Mingo National Wildlife Refuge in Missouri from December 2015 to September 2019, where the management objective is elimination. Populations of feral swine on Mingo NWR have fluctuated over time but showed marked declines in the last 3-6 months of the time series corresponding to increased removal pressure. Our approach allows for the estimation of population growth across time (from both births and immigration) and therefore, provides a target removal rate (above that of the population growth) to ensure the population will decline. In Mingo NWR, the target monthly removal rate is 18% to cause a population decline. Our method provides advancement over traditional removal modeling approaches because it can be applied to evaluate management programs that use a broad range of removal techniques concurrently and whose management effort and spatial coverage vary across time.

The magnitude, diversity, and distribution of the economic costs of invasive terrestrial invertebrates worldwide

Invasive alien species (IAS) are a major driver of global biodiversity loss, hampering conservation efforts and disrupting ecosystem functions and services. While accumulating evidence documented ecological impacts of IAS across major geographic regions, habitat types and taxonomic groups, appraisals for economic costs remained relatively sparse. This has hindered effective cost-benefit analyses that inform expenditure on management interventions to prevent, control, and eradicate IAS. Terrestrial invertebrates are a particularly pervasive and damaging group of invaders, with many species compromising primary economic sectors such as forestry, agriculture and health. The present study provides synthesised quantifications of economic costs caused by invasive terrestrial invertebrates on the global scale and across a range of descriptors, using the InvaCost database. Invasive terrestrial invertebrates cost the global economy US$ 712.44 billion over the investigated period (up to 2020), considering only high-reliability source reports. Overall, costs were not equally distributed geographically, with North America (73%) reporting the greatest costs, with far lower costs reported in Europe (7%), Oceania (6%), Africa (5%), Asia (3%), and South America (< 1%). These costs were mostly due to invasive insects (88%) and mostly resulted from direct resource damages and losses (75%), particularly in agriculture and forestry; relatively little (8%) was invested in management. A minority of monetary costs was directly observed (17%). Economic costs displayed an increasing trend with time, with an average annual cost of US$ 11.40 billion since 1960, but as much as US$ 165.01 billion in 2020, but reporting lags reduced costs in recent years. The massive global economic costs of invasive terrestrial invertebrates require urgent consideration and investment by policymakers and managers, in order to prevent and remediate the economic and ecological impacts of these and other IAS groups.

Loss and fixation of strongly favoured new variants: Understanding and extending Haldane's result via the Wright-Fisher model

The implications of Haldane's analysis for the fixation of beneficial alleles lies at the heart of much of 'population genetic thinking' and underlies many approaches that have been tailored to the detection of positive selection. Within the framework of a branching process, Haldane gave an approximation for the probability that fixation ultimately occurs when the selective advantage of a beneficial allele is small (≪1). Here, we make no use of branching processes. Rather, we work solely within a finite-population Wright-Fisher framework. We use this framework to analyse where Haldane's result applies, and extend Haldane's analysis. In particular, we present results for: (i) the domain of applicability of Haldane's analysis; (ii) the probability that loss occurs up to a given time; (iii) the probabilities that loss and fixation ultimately occur; (iv) an analytic approximation associated with the probability of loss and fixation ultimately occurring; (v) quantification of the crossover from weak to strong selection; (vi) determination of the number of invasive alleles that have a significant probability (>0.95) of invading a novel population. We note that the results obtained for (ii), (iii) and (iv) hold for an arbitrary initial number of mutations, and for selection that can be arbitrarily strong. Our results have fundamental implications for population and conservation genetics, and open up new avenues to identify traces of historically beneficial alleles through comparative genomics.

Building a synthesis of economic costs of biological invasions in New Zealand

Biological invasions are a major component of anthropogenic environmental change, incurring substantial economic costs across all sectors of society and ecosystems. There have been recent syntheses of costs for a number of countries using the newly compiled InvaCost database, but New Zealand-a country renowned for its approach to invasive species management-has so far not been examined. Here we analyse reported economic damage and management costs incurred by biological invasions in New Zealand from 1968 to 2020. In total, US$69 billion (NZ$97 billion) is currently reported over this ∼50-year period, with approximately US$9 billion of this considered highly reliable, observed (c.f. projected) costs. Most (82%) of these observed economic costs are associated with damage, with comparatively little invested in management (18%). Reported costs are increasing over time, with damage averaging US$120 million per year and exceeding management expenditure in all decades. Where specified, most reported costs are from terrestrial plants and animals, with damages principally borne by primary industries such as agriculture and forestry. Management costs are more often associated with interventions by authorities and stakeholders. Relative to other countries present in the InvaCost database, New Zealand was found to spend considerably more than expected from its Gross Domestic Product on pre- and post-invasion management costs. However, some known ecologically (c.f. economically) impactful invasive species are notably absent from estimated damage costs, and management costs are not reported for a number of game animals and agricultural pathogens. Given these gaps for known and potentially damaging invaders, we urge improved cost reporting at the national scale, including improving public accessibility through increased access and digitisation of records, particularly in overlooked socioeconomic sectors and habitats. This also further highlights the importance of investment in management to curtail future damages across all sectors.

Global economic costs of herpetofauna invasions

Biological invasions by amphibian and reptile species (i.e. herpetofauna) are numerous and widespread, having caused severe impacts on ecosystems, the economy and human health. However, there remains no synthesised assessment of the economic costs of these invasions. Therefore, using the most comprehensive database on the economic costs of invasive alien species worldwide (InvaCost), we analyse the costs caused by invasive alien herpetofauna according to taxonomic, geographic, sectoral and temporal dimensions, as well as the types of these costs. The cost of invasive herpetofauna totaled at 17.0 billion US$ between 1986 and 2020, divided split into 6.3 billion US$ for amphibians, 10.4 billion US$ for reptiles and 334 million US$ for mixed classes. However, these costs were associated predominantly with only two species (brown tree snake Boiga irregularis and American bullfrog Lithobates catesbeianus), with 10.3 and 6.0 billion US$ in costs, respectively. Costs for the remaining 19 reported species were relatively minor (< 0.6 billion US$), and they were entirely unavailable for over 94% of known invasive herpetofauna worldwide. Also, costs were positively correlated with research effort, suggesting research biases towards well-known taxa. So far, costs have been dominated by predictions and extrapolations (79%), and thus empirical observations for impact were relatively scarce. The activity sector most affected by amphibians was authorities-stakeholders through management (> 99%), while for reptiles, impacts were reported mostly through damages to mixed sectors (65%). Geographically, Oceania and Pacific Islands recorded 63% of total costs, followed by Europe (35%) and North America (2%). Cost reports have generally increased over time but peaked between 2011 and 2015 for amphibians and 2006 to 2010 for reptiles. A greater effort in studying the costs of invasive herpetofauna is necessary for a more complete understanding of invasion impacts of these species. We emphasise the need for greater control and prevention policies concerning the spread of current and future invasive herpetofauna.

Biological control interventions and botanical pesticides for insect pests of crops in sub-Saharan Africa: A mapping review

Agricultural productivity can be increased sustainably in sub-Saharan Africa (SSA) by reducing crop losses due to insect pest damage. As an alternative to environmentally-damaging chemical pesticides, biological control interventions and botanical pesticides show potential to achieve both high yields and profits. However, synthesized information of their performance and understanding of their adoption among smallholder farmers is limited. Here, 173 studies of biological control interventions and botanical pesticides of insect pests for 35 crops from 20 sub-Saharan countries from 2005 to 2021 were systematically reviewed. Drawing on published datasets, we found that cereals, particularly maize, were the most studied crop (59%). Research on botanical pesticides constituted 32% of the studies, followed by augmentation/introduction biocontrol (29%), and push-pull (21%). Studies evaluating the technical performance of biocontrol interventions dominated (73%), with a regional clustering of push-pull studies in Kenya. Few studies investigated each intervention on each crop type, across different farming contexts and scales, highlighting an urgent need for landscape-scale studies to elucidate land-use impacts on biocontrol effectiveness. Limited evidence also exists on the synergistic effects of biocontrol on multiple ecosystem services and on non-target/beneficial organisms. We found an absence of interdisciplinary studies that addressed the wider indirect benefits of not using chemical pesticides, the social-economic outcomes, and barriers to adoption by farmers, which we argue are necessary to identify pathways to greater adoption and to support policy advocacy of biocontrol interventions in SSA.

Capacity of countries to reduce biological invasions

The extent and impacts of biological invasions on biodiversity are largely shaped by an array of socio-economic and environmental factors, which exhibit high variation among countries. Yet, a global analysis of how these factors vary across countries is currently lacking. Here, we investigate how five broad, country-specific socio-economic and environmental indices (Governance, Trade, Environmental Performance, Lifestyle and Education, Innovation) explain country-level (1) established alien species (EAS) richness of eight taxonomic groups, and (2) proactive or reactive capacity to prevent and manage biological invasions and their impacts. These indices underpin many aspects of the invasion process, including the introduction, establishment, spread and management of alien species. They are also general enough to enable a global comparison across countries, and are therefore essential for defining future scenarios for biological invasions. Models including Trade, Governance, Lifestyle and Education, or a combination of these, best explained EAS richness across taxonomic groups and national proactive or reactive capacity. Historical (1996 or averaged over 1996-2015) levels of Governance and Trade better explained both EAS richness and the capacity of countries to manage invasions than more recent (2015) levels, revealing a historical legacy with important implications for the future of biological invasions. Using Governance and Trade to define a two-dimensional socio-economic space in which the position of a country captures its capacity to address issues of biological invasions, we identified four main clusters of countries in 2015. Most countries had an increase in Trade over the past 25 years, but trajectories were more geographically heterogeneous for Governance. Declines in levels of Governance are concerning as they may be responsible for larger levels of invasions in the future. By identifying the factors influencing EAS richness and the regions most susceptible to changes in these factors, our results provide novel insights to integrate biological invasions into scenarios of biodiversity change to better inform decision-making for policy and the management of biological invasions.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s11625-022-01166-3.

Different Responses of Invasive Weed Alternanthera philoxeroides and Oryza sativa to Plant Growth Regulators

Invasive plants cause a global loss of biodiversity, pose a major threat to the environment and economy, and also significantly affect agricultural production and food security. Plant growth regulators (PGRs) are widely used in agricultural production and might also affect invasive weeds distributed around crops in various ways. At present, there are few studies concerning whether there are significant effects of PGRs on invasive weeds. In this study, two widely used PGRs in paddy fields, gibberellic acid (GA) and paclobutrazol (PAC), were applied on Oryza sativa and a noxious weed Alternanthera philoxeroides, which is frequently distributed in paddy fields. The purpose of this study was to investigate if there are different responses of rice and weeds to these two plant regulators and the significant effects of PGRs on invasive weeds. The results showed that GA significantly promotes the total biomass of A. philoxeroides by 52.00%, but does not significantly affect that of O. sativa. GA significantly increases the growth of aboveground and belowground A. philoxeroides, but not that of O. sativa. On the other hand, PAC extremely inhibited the aboveground and belowground biomass of A. philoxeroides by more than 90%, but did not significantly inhibit the belowground biomass of O. sativa. PAC also enhanced the leaf nitrogen content and chlorophyll content of A. philoxeroides, but not the traits of O. sativa. Therefore, the effects of PGRs are significantly different between rice and the invasive weed. The potential promotion effects of PGRs on weeds that are frequently distributed in farmland warrant sufficient attention. This is probably one of the important reasons why invasive weeds can successfully invade the agricultural ecosystem with large human disturbance. This study might sound an alarm for weed control in paddy fields.

Unveiling biogeographic patterns in the worldwide distributed Ceratitis capitata (medfly) using populations genomics and microbiome composition

Invasive species are among the most important, growing threats to food security and agricultural systems. The Mediterranean medfly, Ceratitis capitata, is one of the most damaging representatives of a group of rapidly expanding species in the Tephritidae family, due to their wide host range and high invasiveness potential. Here, we used restriction site-associated DNA sequencing (RADseq) to investigate the population genomic structure and phylogeographic history of medflies collected from six sampling sites, including Africa (South Africa), the Mediterranean (Spain, Greece), Latin America (Guatemala, Brazil) and Australia. A total of 1,907 single nucleotide polymorphisms (SNPs) were used to identify two genetic clusters separating native and introduced ranges, consistent with previous findings. In the introduced range, all individuals were assigned to one genetic cluster except for those in Brazil, which showed introgression of an additional genetic cluster that also appeared in South Africa, and which could not be previously identified using microsatellite markers. Moreover, we assessed the microbial composition variations in medfly populations from selected sampling sites using amplicon sequencing of the 16S ribosomal RNA (V4 region). Microbiome composition and structure were highly similar across geographic regions and host plants, and only the Brazilian specimens showed increased diversity levels and a unique composition of its microbiome compared to other sampling sites. The unique SNP patterns and microbiome features in the Brazilian specimens could point to a direct migration route from Africa with subsequent adaptation of the microbiota to the specific conditions present in Brazil. These findings significantly improve our understanding of the evolutionary history of the global medfly invasions and their adaptation to newly colonised environments.

Overwinter survival of Corbicula fluminea in a central Minnesota lake

Although Corbicula fluminea has been one of the more prolific freshwater invasive species in the world, previous studies have suggested a low probability for overwinter survival in northern latitudes without an artificially created thermal refuge. The discovery of live C. fluminea in a central Minnesota lake absent any known thermal refuge in 2020 presented an opportunity to further evaluate the overwinter survival and population structure of C. fluminea at the presumed edge of their potential range. The population was monitored from December 2020 through September 2021 alongside water temperature to better understand at which temperatures C. fluminea survived and if the population structure suggested reproduction occurring in the lake. We documented live C. fluminea in temperatures as low as 0.3°C. Shell size of recovered individuals suggested multiple cohorts, and the appearance of a new cohort at the end of the study, indicating active reproduction in the lake and suggesting the population had likely been present in the lake for at least two winters by the conclusion of the study period. Our findings provide evidence of the survival below historically documented lower lethal temperature limits and suggests adaptations to modeling predicting suitable habitat, both present and in a changing climate, are necessary to better assess risk of invasion by this species.

Conceptualisation of multiple impacts interacting in the marine environment using marine infrastructure as an example

The human population is increasingly reliant on the marine environment for food, trade, tourism, transport, communication and other vital ecosystem services. These services require extensive marine infrastructure, all of which have direct or indirect ecological impacts on marine environments. The rise in global marine infrastructure has led to light, noise and chemical pollution, as well as facilitation of biological invasions. As a result, marine systems and associated species are under increased pressure from habitat loss and degradation, formation of ecological traps and increased mortality, all of which can lead to reduced resilience and consequently increased invasive species establishment. Whereas the cumulative bearings of collective human impacts on marine populations have previously been demonstrated, the multiple impacts associated with marine infrastructure have not been well explored. Here, building on ecological literature, we explore the impacts that are associated with marine infrastructure, conceptualising the notion of correlative, interactive and cumulative effects of anthropogenic activities on the marine environment. By reviewing the range of mitigation approaches that are currently available, we consider the role that eco-engineering, marine spatial planning and agent-based modelling plays in complementing the design and placement of marine structures to incorporate the existing connectivity pathways, ecological principles and complexity of the environment. Because the effect of human-induced, rapid environmental change is predicted to increase in response to the growth of the human population, this study demonstrates that the development and implementation of legislative framework, innovative technologies and nature-informed solutions are vital, preventative measures to mitigate the multiple impacts associated with marine infrastructure.

The Bugs in the Bags: The Risk Associated with the Introduction of Small Quantities of Fruit and Plants by Airline Passengers

Simple Summary

This study was carried out with the aim of emphasizing the importance of checking the plant material that can be imported in the baggage of airline passengers. Travelers are often unaware of the regulations in place and of the risks connected with such importation. The risk of the introduction of harmful organisms correlated with this pathway is yet not well studied and its frequency is underestimated. The results of the research underline the need for continuous checks at entry points and the establishment of a specialized position for inspections.

Abstract

Among European countries, Italy is the most exposed to the risk of biological invasions, principally for its numerous entry points (ports and airports) and for climatic conditions favorable for the acclimatization of several invasive species. Here it was assessed that the greatest threats to our agro-ecosystems come mainly from the passenger baggage in which a variety of fruits and vegetables are carried. From 2016 to 2021, large quantities of plant products were found in the luggage of passengers travelling from outside the EU and seized at the BCPs (border control posts) in the Campania region. Inspections and the following laboratory analyses were conducted on the plant material to assess the presence of exotic pests. Inspections led to several non-native species being recorded, and among the intercepted organisms, some should be considered “alarming”, such as Bactrocera dorsalis, Anastrepha obliqua, and Leucinodes africensis. Despite a well-organized border inspection system, travelers transporting infested material unknowingly contribute to increasing the risk of the introduction of exotic species. Given the current situation, it is necessary to impose stricter controls and greater attention, ensuring compliance with the requirements of the new phytosanitary regulations by the actors involved in the transport of plant material. Finally, it is essential to improve awareness through a phytosanitary campaign on plant health risks, especially for people wishing to transport fruits and vegetables in their luggage.

Potential Distribution of and Sensitivity Analysis for Urochloa panicoides Weed Using Modeling: An Implication of Invasion Risk Analysis for China and Europe

Urochloapanicoides P. Beauv. is considered one of the most harmful weeds in the United States and Australia. It is invasive in Pakistan, Mexico, and Brazil, but its occurrence is hardly reported in China and European countries. Species distribution models enable the measurement of the impact of climate change on plant growth, allowing for risk analysis, effective management, and invasion prevention. The objective of this study was to develop current and future climate models of suitable locations for U. panicoides and to determine the most influential climatic parameters. Occurrence data and biological information on U. panicoides were collected, and climatic parameters were used to generate the Ecoclimatic Index (EI) and to perform sensitivity analysis. The future projections for 2050, 2080, and 2100 were modeled under the A2 SRES scenario using the Global Climate Model, CSIRO-Mk3.0 (CS). The potential distribution of U. panicoides coincided with the data collected, and the reliability of the final model was demonstrated. The generated model identified regions where the occurrence was favorable, despite few records of the species. Sensitivity analysis showed that the most sensitive parameters of the model were related to temperature, humidity, and cold stress. Future projections predict reductions in climate suitability for U. panicoides in Brazil, Australia, India, and Africa, and an increase in suitability in Mexico, the United States, European countries, and China. The rise in suitability of China and Europe is attributed to predicted climate change, including reduction in cold stress. From the results obtained, preventive management strategies can be formulated against the spread of U. panicoides, avoiding economic and biodiversity losses.

Cucurbit[7]uril-Mediated Supramolecular Bactericidal Nanoparticles: Their Assembly Process, Controlled Release, and Safe Treatment of Intractable Plant Bacterial Diseases

A safe, biocompatible, and stimuli-responsive cucurbit[7]uril-mediated supramolecular bactericidal nanoparticle was fabricated by encapsulating a highly bioactive carbazole-decorated imidazolium salt (A₁, EC₅₀ = 0.647 μg/mL against phytopathogen Xanthomonas oryzae pv oryzae) into the host cucurbit[7]uril (CB[7]), thereby leading to self-assembled topographies from microsheets (A₁) to nanospheroidal architectures (A₁@CB[7]). The assembly behaviors were elucidated by acquired single-crystal structures, ¹H NMR, ITC, and X-ray powder diffraction experiments. Complex A₁@CB[7] displayed lower phytotoxicity and could efficiently switch on its potent antibacterial ability via introducing a simple competitor 1-adamantanamine hydrochloride (AD). In vivo antibacterial trials against rice bacterial blight revealed that A₁@CB[7] could relieve the disease symptoms after being triggered by AD and provide a workable control efficiency of 42.6% at 100 μg/mL, which was superior to bismerthiazol (33.4%). These materials can provide a viable platform for fabricating diverse stimuli-responsive supramolecular bactericides for managing bacterial infections with improved safety.

Seasonal and Year-Round Distributions of Bactrocera dorsalis (Hendel) and Its Risk to Temperate Fruits under Climate Change

Simple Summary

The oriental fruit fly Bactrocera dorsalis (Hendel) is a pest species in the Tephritidae family that damages many fruits and vegetables. Dispersal of B. dorsalis is mediated by human activities (e.g., trade) and climate change, and it can cause serious damage to crops in newly invaded regions. Previous studies mainly focused on the areas potentially suitable for year-round reproduction, but it is unclear where the seasonal and year-round suitable areas are in the world. We used ecological niche models to predict the potential seasonal and year-round distribution areas of B. dorsalis. Bioclimate factors contributed differently to these two kinds of distributions. In the future, the areas suitable for B. dorsalis will increase, and the range will likely expand northward from existing locations. The spread of B. dorsalis in the seasonally suitable areas could threaten the production of some temperate fruits, including apples, peaches, pears, and oranges.

Abstract

Bactrocera dorsalis (Hendel) is an important pest to fruits and vegetables. It can damage more than 300 plant species. The distribution of B. dorsalis has been expanding owing to international trade and other human activities. B. dorsalis occurrence is strongly related to suitable overwintering conditions and distribution areas, but it is unclear where these seasonal and year-round suitable areas are. We used maximum entropy (MaxEnt) to predict the potential seasonal and year-round distribution areas of B. dorsalis. We also projected suitable habitat areas in 2040 and 2060 under global warming scenarios, such as SSP126 and SSP585. These models achieved AUC values of 0.860 and 0.956 for the seasonal and year-round scenarios, respectively, indicating their good prediction capabilities. The precipitation of the wettest month (Bio13) and the mean diurnal temperature range (Bio2) contributed 83.9% to the seasonal distribution prediction model. Bio2 and the minimum temperature of the coldest month (Bio6) provided important information related to the year-round distribution prediction. In future scenarios, the suitable area of B. dorsalis will increase and the range will expand northward. Four important temperate fruits, namely, apples, peaches, pears, and oranges, will be seriously threatened. The information from this study provides a useful reference for implementing improved population management strategies for B. dorsalis.

Contrasting National Plant Protection Needs, Perceptions and Techno-Scientific Capabilities in the Asia-Pacific Region

Pests and pathogens inflict considerable losses in global agri-food production and regularly trigger the (indiscriminate) use of synthetic pesticides. In the Asia-Pacific, endemic and invasive organisms compromise crop yields, degrade farm profitability and cause undesirable social-environmental impacts. In this study, we systematically assess the thematic foci, coherence and inclusiveness of plant protection programs of 11 Asia-Pacific countries. Among 23 economically important diseases and 55 pests, survey respondents identified rice blast, rice brown planthopper, citrus greening disease, Tephritid fruit flies and fall armyworm as threats of regional allure. These organisms are thought to lower crop yields by 20–35% and cause management expenditures up to US$2,250 per hectare and year. Though decision-makers are familiar with integrated pest management (IPM), national programs are invariably skewed toward curative pesticide-intensive control. Pesticide reductions up to 50–100% are felt to be feasible and potentially can be attained through full-fledged IPM campaigns and amended policies. To rationalize farmers' pesticide use, decision criteria (e.g., economic thresholds) wait to be defined for multiple crop x pest systems and (participatory) training needs to be conducted e.g., on (pest, disease) symptom recognition or field-level scouting. Efforts are equally needed to amend stakeholder perceptions on ecologically based measures e.g., biological control. Given that several Asia–Pacific countries possess robust techno-scientific capacities in various IPM domains (e.g., taxonomy, molecular diagnostics, socioeconomics), they can take on an active role in regionally coordinated campaigns. As such, one can reinvigorate IPM and ensure that preventative, non-chemical pest management ultimately becomes the norm instead of the exception throughout the Asia–Pacific.

The distribution of covert microbial natural enemies of a globally invasive crop pest, fall armyworm, in Africa: Enemy release and spillover events

Invasive species pose a significant threat to biodiversity and agriculture world‐wide. Natural enemies play an important part in controlling pest populations, yet we understand very little about the presence and prevalence of natural enemies during the early invasion stages.

Microbial natural enemies of fall armyworm Spodoptera frugiperda are known in its native region, however, they have not yet been identified in Africa where fall armyworm has been an invasive crop pest since 2016. Larval samples were screened from Malawi, Rwanda, Kenya, Zambia, Sudan and Ghana for the presence of four different microbial natural enemies; two nucleopolyhedroviruses, Spodoptera frugiperda NPV (SfMNPV) and Spodoptera exempta NPV (SpexNPV); the fungal pathogen Metarhizium rileyi; and the bacterium Wolbachia. This study aimed to identify which microbial pathogens are present in invasive fall armyworm, and determine the geographical, meteorological and temporal variables that influence prevalence.

Within 3 years of arrival, fall armyworm was exposed to all four microbial natural enemies. SfMNPV probably arrived with fall armyworm from the Americas, but this is the first putative evidence of host spillover from Spodoptera exempta (African armyworm) to fall armyworm for the endemic pathogen SpexNPV and for Wolbachia. It is also the first confirmed incidence of M. rileyi infecting fall armyworm in Africa.

Natural enemies were localised, with variation being observed both nationally and temporally. The prevalence of SfMNPV (the most common natural enemy) was predominantly explained by variables associated with the weather; declining with increasing rainfall and increasing with temperature. However, virus prevalence also increased as the growing season progressed.

The infection of an invasive species with a natural enemy from its native range and novel pathogens specific to its new range has important consequences for understanding the population ecology of invasive species and insect–pathogen interactions. Additionally, while it is widely known that temporal and geographic factors affect insect populations, this study reveals that these are important in understanding the distribution of microbial natural enemies associated with invasive pests during the early stages of invasion, and provide baseline data for future studies.