Impact of invasive insects on native insect communities

Genotypic Variation and Potential Mechanisms of Resistance against Multiple Insect Herbivores in Cranberries

Plant genotypes often exhibit varying resistance levels to herbivores. However, the impact of this genotypic variation on resistance against multiple herbivores remains poorly understood, especially in crops undergoing recent process of domestication. To address this gap, we studied the magnitude and mechanism of resistance in 12 cranberry (Vaccinium macrocarpon) genotypes to three leaf-chewing herbivores - Sparganothis fruitworm (Sparganothis sulfureana), spotted fireworm (Choristoneura parallela), and spongy moth (Lymantria dispar) - along a domestication gradient (native 'wild' genotypes, 'early hybrid' genotypes, and 'modern hybrid' genotypes). Like cranberries, S. sulfureana and C. parallela are native to the United Sates, while L. dispar is an invasive pest. We measured the survival and growth of larvae on each genotype, as well as variation in plant performance (height and biomass) and leaf defensive chemical traits (C/N ratio, total phenolics, total proanthocyanidins, and flavonols levels) in these genotypes to elucidate potential resistance mechanisms. We found differences in C. parallela and L. dispar larval performance across genotypes, with larvae performing better on the modern hybrid genotypes, while S. sulfureana showed no differences. Morphological and chemical traits varied among genotypes, with total phenolics being the only trait correlated with C. parallela and L. dispar larval performance. Notably, the wild genotypes 'McFarlin' and 'Potter' had higher total phenolics and were more resistant to both herbivores than the modern hybrids 'Demoranville' and 'Mullica Queen.' This research contributes to a comprehensive understanding of the impact of crop domestication on multiple insect herbivores, offering insights for future breeding efforts to enhance host-plant resistance against agricultural pests.

Geographic Location, Population Dynamics, and Fruit Damage of an Invasive Citrus Mealybug: The Case of Delottococcus aberiae De Lotto in Eastern Spain

The invasive mealybug Delottococcus aberiae De Lotto (Hemiptera: Pseudococcidae) has rapidly spread in the Mediterranean basin since its detection in 2009 in the Valencia Community in eastern Spain. The use of sticky traps baited with its sex pheromone, (4,5,5-trimethyl-3-methylenecyclopent-1-en-1-yl)methyl acetate, has allowed to determine the geographical distribution of D. aberiae by means of the surveillance network described in the present work. The population monitoring of the pest over a five-year period (2019-2023) has revealed an increase from 31% to 70% of the affected citrus-growing area. The monitoring network has also allowed a better understanding of the pests' biological cycle throughout the year. The populations start growing from March to June and reach their maximum in July-August. During autumn, there is a gradual decline in the population. Although the highest annual populations were detected in 2022 and 2023, the greatest crop losses were recorded in 2020 and 2021, with mean values near 18%. Data suggest that the damage responsible for fruit deformation, and thus the economic losses, are related to the population levels in spring (April-May) rather than those in summer (July-August). The findings of this study can be valuable for future research and development of effective pest control strategies.

Competitive interactions between invasive fall armyworm and Asian corn borer at intraspecific and interspecific level on the same feeding guild

Interspecific competition is an important factor in the population dynamics and geographical distribution of insect populations. Fall armyworm (FAW), Spodoptera frugiperda, an invasive species, and the Asian corn borer (ACB), Ostrinia furnacalis, a native pest species are major pests on maize in China, posing a threat to maize yield and grain quality. A series of laboratory, greenhouse, and field experiments were conducted to elucidate the competitive interactions between FAW and ACB. In the laboratory experiments, FAW exhibited aggressive behaviors more frequently when compared with ACB, while the latter species exhibited defense behaviors more frequently. Higher intraspecific competition was recorded in the FAW conspecific rather than in ACB, particularly in the 6th larval stage. FAW had a higher interspecific competitive advantage through intraguild predation over ACB, resulting in partial or complete displacement ACB when initially the ratio of the 2 species was 1 : 1. The interspecific competition also had significantly influenced on the population parameters, defensive enzymes, and nutrient of these 2 species. Competitive interaction proved that the response of superoxide, catalase, and soluble protein in FAW were significantly increased, whereas the total sugar content in both species was substantially decreased. Survival rate, and the plant damage that co-infested by both species varied significantly among the sequential combinations under greenhouse and field conditions. FAW consistently exhibited stronger intraspecific aggression than ACB under laboratory and field conditions when co-existing on the same feeding guild. These findings contribute to efforts toward the improvement of integrated pest management programs for FAW, in decision making for invasive and native pests' management strategies to reduce the high risks of FAW and ACB outbreaks.

The neglect of nonnative orthopterans as potential invaders: A call for awareness

Despite the potential ecological and economic impacts of invasive species, there is a dearth of data on the presence, impacts, and management implications of potentially invasive Orthoptera species. This lack of research and inconsistent data, including risk screenings and impact assessments, is especially evident in Europe. Consequently, assessing the status, distribution, and potential threats of nonnative Orthoptera in Europe remains challenging, impeding the development of effective management strategies. To address this gap, we call for increased efforts to collect and curate data on non-native and possibly invasive Orthoptera in Europe. Such efforts will improve our understanding of this order's invasion dynamics, facilitate the identification of priority areas for conservation, and support the development of effective management policies and preventive measures.

Evaluation of farmers friendly IPM modules for the management of fall armyworm, Spodoptera frugiperda (JE Smith) in maize in the hot semiarid region of India

Invasive alien species (IAS) pose a severe threat to global agriculture, with their impact projected to escalate due to climate change and expanding international trade. The fall armyworm (FAW), Spodoptera frugiperda (J. E. Smith), a native of the Americas, has rapidly spread across various continents, causing significant damage to several food crops, especially maize. Integrated pest management (IPM) programs are vital for sustainable FAW control, combining multiple strategies for sustainable results. Over three consecutive years, 2019-20, 2020-21 and 2021-22, the field demonstrations were conducted in semiarid regions of India, testing a four-component IPM approach viz., pheromone traps, microbial, botanicals and ETL based applications of insecticides against farmers' practices (sole insecticide application). IPM implementation led to substantial reductions in FAW infestation. Furthermore, egg mass and larvae infestations were significantly lower in IPM-adopted villages compared to conventional practices. Pheromone-based monitoring demonstrated a consistent reduction in adult moth populations. The lowest technology gap (10.42), extension gap (8.33) and technology index (12.25) was recorded during 2020-21. The adoption of IPM led to increased maize yields (17.49, 12.62 and 24.87% over control), higher net returns (919, 906.20 and 992.93 USD), and favourable benefit-cost ratios (2.74, 2.39 and 2.33) compared to conventional practices respectively during 2019-20, 2020-21 and 2021-22. The economic viability of IPM strategies was evident across three consecutive years, confirming their potential for sustainable FAW management in the semiarid region of India. These strategies hold promise for adoption in other parts of the world sharing similar climatic conditions.

Unveiling the Genetic Symphony: Harnessing CRISPR-Cas Genome Editing for Effective Insect Pest Management

Phytophagous insects pose a significant threat to global crop yield and food security. The need for increased agricultural output while reducing dependence on harmful synthetic insecticides necessitates the implementation of innovative methods. The utilization of CRISPR-Cas (Clustered regularly interspaced short palindromic repeats) technology to develop insect pest-resistant plants is believed to be a highly effective approach in reducing production expenses and enhancing the profitability of farms. Insect genome research provides vital insights into gene functions, allowing for a better knowledge of insect biology, adaptability, and the development of targeted pest management and disease prevention measures. The CRISPR-Cas gene editing technique has the capability to modify the DNA of insects, either to trigger a gene drive or to overcome their resistance to specific insecticides. The advancements in CRISPR technology and its various applications have shown potential in developing insect-resistant varieties of plants and other strategies for effective pest management through a sustainable approach. This could have significant consequences for ensuring food security. This approach involves using genome editing to create modified insects or crop plants. The article critically analyzed and discussed the potential and challenges associated with exploring and utilizing CRISPR-Cas technology for reducing insect pest pressure in crop plants.

Large-scale production of house fly, Musca domestica (Diptera: Muscidae), larvae fed 3 manure types

House flies, Musca domestica, L., (Diptera: Muscidae) are well-known pests at animal facilities; however, they can be used for manure biodegradation. Utilizing house flies to process animal manure offers a means to recycle nutrients and reduce contaminants (e.g., pathogens and heavy metals), while also producing multiple revenue streams (e.g., protein for feed, fat for biodiesel, frass as a soil amendment). This study determined house fly larval performance on a larger scale (kilogram of wastes; thousands of larvae; single feeding) as a follow-up to a previous experiment performed at a bench-top scale (g of wastes; hundreds of larvae; incremental feeding). Four thousand larvae were fed 1 kg of swine, dairy, or poultry manure, or a control (Gainesville diet: 50% wheat bran, 30% alfalfa meal, and 20% corn meal). Peak larval weight occurred 4 days after inoculation and no significant difference in development time to first pupariation occurred across diets. However, percent survivorship to pupariation varied, with the highest occurring in Gainesville (74%), swine (73%), and poultry (67%) manure, whereas 50% survived when fed dairy manure. The highest pupal weight was found for those fed Gainesville (27 mg), and similar weights were found for those fed swine (21 mg), dairy (24 mg), and poultry (25 mg) manure. Although using house flies to manage manure has received little consideration in Western countries, other regions have this practice in place. Results may provide insight on differences between small- and large-scale studies, which is valuable for industrialization of this species for waste management and creating a more circular economy.

Invasive alien insects represent a clear but variable threat to biodiversity

Invasive alien insects are an important yet understudied component of the general threat that biological invasions pose to biodiversity. We quantified the breadth and level of this threat by performing environmental impact assessments using a modified version of the Environmental Impact Assessment for Alien Taxa (EICAT) framework. This represents the largest effort to date on quantify the environmental impacts of invasive alien insects. Using a relatively large and taxonomically representative set of insect species that have established non-native populations around the globe, we tested hypotheses on: (1) socioeconomic and (2) taxonomic biases, (3) relationship between range size and impact severity and (4) island susceptibility. Socioeconomic pests had marginally more environmental impact information than non-pests and, as expected, impact information was geographically and taxonomically skewed. Species with larger introduced ranges were more likely, on average, to have the most severe local environmental impacts (i.e. a global maximum impact severity of 'Major'). The island susceptibility hypothesis found no support, and both island and mainland systems experience similar numbers of high severity impacts. These results demonstrate the high variability, both within and across species, in the ways and extents to which invasive insects impact biodiversity, even within the highest profile invaders. However, the environmental impact knowledge base requires greater taxonomic and geographic coverage, so that hypotheses about invasion impact can be developed towards identifying generalities in the biogeography of invasion impacts.

Phenotypic divergence in an island bee population: Applying geometric morphometrics to discriminate population-level variation in wing venation

Phenotypic divergence is an important consequence of restricted gene flow in insular populations. This divergence can be challenging to detect when it occurs through subtle shifts in morphological traits, particularly in traits with complex geometries, like insect wing venation. Here, we employed geometric morphometrics to assess the extent of variation in wing venation patterns across reproductively isolated populations of the social sweat bee, Halictus tripartitus. We examined wing morphology of specimens sampled from a reproductively isolated population of H. tripartitus on Santa Cruz Island (Channel Islands, Southern California). Our analysis revealed significant differentiation in wing venation in this island population relative to conspecific mainland populations. We additionally found that this population-level variation was less pronounced than the species-level variation in wing venation among three sympatric congeners native to the region, Halictus tripartitus, Halictus ligatus, and Halictus farinosus. Together, these results provide evidence for subtle phenotypic divergence in an island bee population. More broadly, these results emphasize the utility and potential of wing morphometrics for large-scale assessment of insect population structure.

Rapid adaptation in a fast-changing world: Emerging insights from insect genomics

Many researchers have questioned the ability of biota to adapt to rapid anthropogenic environmental shifts. Here, we synthesize emerging genomic evidence for rapid insect evolution in response to human pressure. These new data reveal diverse genomic mechanisms (single locus, polygenic, structural shifts; introgression) underpinning rapid adaptive responses to a variety of anthropogenic selective pressures. While the effects of some human impacts (e.g. pollution; pesticides) have been previously documented, here we highlight startling new evidence for rapid evolutionary responses to additional anthropogenic processes such as deforestation. These recent findings indicate that diverse insect assemblages can indeed respond dynamically to major anthropogenic evolutionary challenges. Our synthesis also emphasizes the critical roles of genomic architecture, standing variation and gene flow in maintaining future adaptive potential. Broadly, it is clear that genomic approaches are essential for predicting, monitoring and responding to ongoing anthropogenic biodiversity shifts in a fast-changing world.