Testing the Effects of Prey Type on the Life History and Population-Level Parameters of Chrysoperla externa (Neuroptera: Chrysopidae)

Green lacewings are valuable predators, utilized in augmentative biological control against various agricultural pests. However, further studies are required to comprehend the performance of these predators when consuming natural prey. We investigated the capacity of Chrysoperla externa (Hagen) to utilize the following three distinct prey types: the pupae of the coffee leaf miner Leucoptera coffeella (Guérin-Mèneville & Perrottet), the eggs of the sugarcane borer Diatraea saccharalis (F.), and the eggs of the Mediterranean flour moth Ephestia kuehniella (Zeller). The first two of these species are naturally occurring prey found in field crops, while the last serves as a factitious prey species for the mass rearing of natural enemies. We hypothesized that the type of prey would differentially affect the life history and population-level parameters of C. externa. Laboratory experiments were conducted to compare the pre-imaginal survival and developmental times, adult longevity and reproduction, and population growth of C. externa when larvae were provided with each of the three prey items. Results indicated that C. externa utilized the two natural prey items, L. coffeella pupae and D. saccharalis eggs, for its development, reproduction, and population growth. However, larvae developed significantly faster and females exhibited higher reproductive parameters, including fecundity and daily oviposition, when consuming the factitious prey, E. kuehniella eggs. This resulted in a higher intrinsic rate of population increase, as well as shorter times for the population to double in size. Understanding the population dynamics of C. externa when consuming different prey items is crucial for optimizing their utilization in augmentative biological control programs.

Evaluation of Black Soldier Fly Hermetia illucens as Food for Pink-Spotted Lady Beetle Coleomegilla maculata

The discovery of new and improved factitious and artificial diets is necessary for cost-effective rearing of predatory arthropods. This study evaluated Hermetia illucens black soldier fly (BSF) as a suitable alternative food source for rearing the predatory coccinellid Coleomegilla maculata (Cmac). The hypothesis that BSF larval powder was suitable food to support the growth, development, and reproduction of Cmac was tested in the laboratory. When compared to a standard in-house diet containing brine shrimp egg powder plus Chlorella vulgaris green algae and myristic acid (BSE+CM), the BSF and BSF+CM diets reduced immature growth and development. Immatures successfully reared to teneral adults were smaller when fed BSF or BSF+CM rather than BSE+CM. Combining BSF with a powdered artificial diet (AD), i.e., BSF+AD, did not improve predator growth or development, compared to Cmac reared on BSE+CM. Cmac oviposition responses, i.e., egg clutch production, to BSF vs. BSE+CM or BSF+AD vs. BSE+CM did not differ significantly. In conclusion, BSF has the potential to be food that supports Cmac oviposition behavior. Future research is necessary to discover an ideal mixture of BSF, BSE+CM, or AD that supports Cmac growth, development, and reproduction over multiple generations.

Feeding preference and intraguild interactions between the parasitoid Trichogramma achaeae and the predator Macrolophus pygmaeus, two biological agents of Tuta absoluta

BACKGROUND

Tuta absoluta is an exotic species and a major pest of tomato crops in Europe. Macrolophus pygmaeus and Trichogramma achaeae are two biocontrol agents widely used in integrated pest management programs of the South American tomato pinworm Tuta absoluta. In this study, we evaluated under laboratory conditions the (i) voracity of M. pygmaeus females fed on single diets of Tuta absoluta eggs parasitized or unparasitized by Trichogramma achaeae, (ii) voracity and feeding preference of M. pygmaeus females provided with mixed diets of Tuta absoluta eggs unparasitized and parasitized by Trichogramma achaeae and (iii) effect of competitive and intraguild interactions between M. pygmaeus and Trichogramma achaeae on the number of Tuta absoluta eggs consumed and/or parasitized. Lastly, we assessed under field conditions the effect of interspecific and intraspecific interactions between natural enemies on the number of Tuta absoluta eggs consumed and/or parasitized.

RESULTS

Macrolophus pygmaeus consumed more unparasitized than parasitized eggs of Tuta absoluta. Under mixed diet regimes, Manly indices revealed a feeding preference for unparasitized eggs, and a decrease in the total number of eggs consumed, as the proportion of available parasitized eggs increased, whereas the unparasitized eggs were consumed in direct proportion to their availability. Conspecific interactions between M. pygmaeus, in contrast to Trichogramma achaeae, revealed the possible occurrence of intraspecific competition. For intraguild heterospecific interactions, the number of Tuta absoluta eggs consumed by M. pygmaeus and parasitized by Trichogramma achaeae was lower than that predicted for additive and non-interactive scenarios. Under field conditions, a significant difference between the conspecific treatment and heterospecific treatments revealed a slightly higher success rate in controlling Tuta absoluta when both M. pygmaeus and Trichogramma achaeae were used simultaneously.

CONCLUSION

Macrolophus pygmaeus prefers unparasitized eggs of Tuta absoluta but inflicts intraguild predation on Trichogramma achaeae. In conspecific experiments, mutual interference between M. pygmaeus predators intensifies as the number of individuals increases, but for Trichogramma achaeae, it occurs in an unpredictable manner. Adding Trichogramma achaeae could significantly increase the level of control of Tuta absoluta compared to what could be achieved when only M. pygmaeus is present in glasshouse tomatoes. © 2023 Society of Chemical Industry.

Natural Enemies and Biological Control of Stink Bugs (Hemiptera: Heteroptera) in North America

Stink bugs comprise a significant and costly pest complex for numerous crops in the US, including row crops, vegetables, and tree fruits and nuts. Most management relies on the use of broad-spectrum and disruptive insecticides with high human and environmental risks associated with them. Growing concerns about pesticide resistance in stink bugs are forcing pest managers to explore safer and more sustainable options. Here, we review the diverse suite of natural enemies of stink bugs in the US, noting that the egg and the late nymphal and adult stages of stink bugs are the most commonly attacked by parasitoids, whereas eggs and young nymphs are the stages most commonly attacked by predators. The effectiveness of stink bugs' natural enemies varies widely with stink bug species and habitats, influencing the biological control of stink bugs across crops. Historically, biological control of stink bugs has focused on introduction of exotic natural enemies against exotic stink bugs. Conservation and augmentation methods of biological control have received less attention in the US, although there may be good opportunities to utilize these approaches. We identify some considerations for the current and future use of biological control for stink bugs, including the potential for area-wide management approaches.

Evaluating the Impact of Two Generalist Predators on the Leafhopper Erasmoneura vulnerata Population Density

Simple Summary

Erasmoneura vulnerata, a grapevine leafhopper native to North America, was detected in Europe (North-eastern Italy) in the early 2000s. Although it is considered a minor pest in its native range, outbreaks of this species have been reported in North-eastern Italy. In this study, we investigated the potential of two generalist predators, i.e., Chrysoperla carnea and Oriusmajusculus, in suppressing E. vulnerata in laboratory and semi-field experiments. Both species significantly reduced nymph numbers in laboratory and semi-field conditions. For this reason, field trials were performed. Predator releases in vineyards reduced E. vulnerata abundance by about 30%. Since naturally occurring E. vulnerata antagonists exert a moderate impact and the effectiveness of natural insecticides is limited, the augmentative release of generalist predators can be considered a complementary tool in controlling E. vulnerata populations in vineyards, particularly in organic farms.

Abstract

Outbreaks of the Nearctic leafhopper Erasmoneura vulnerata represent a threat to vinegrowers in Southern Europe, in particular in North-eastern Italy. The pest outbreaks are frequent in organic vineyards because insecticides labeled for organic viticulture show limited effectiveness towards leafhoppers. On the other hand, the naturally occurring predators and parasitoids of E. vulnerata in vineyards are often not able to keep leafhopper densities at acceptable levels for vine-growers. In this study, we evaluated the potential of two generalist, commercially available predators, Chrysoperla carnea and Orius majusculus, in suppressing E. vulnerata. Laboratory and semi-field experiments were carried out to evaluate both species’ predation capacity on E. vulnerata nymphs. The experiments were conducted on grapevine leaves inside Petri dishes (laboratory) and on potted and caged grapevines (semi-field); in both experiments, the leaves or potted plants were infested with E. vulnerata nymphs prior to predator releases. Both predator species exhibited a remarkable voracity and significantly reduced leafhopper densities in laboratory and semi-field experiments. Therefore, field studies were carried out over two growing seasons in two vineyards. We released 4 O. majusculus adults and 30 C. carnea larvae per m² of canopy. Predator releases in vineyards reduced leafhopper densities by about 30% compared to the control plots. Results obtained in this study showed that the two predators have a potential to suppress the pest density, but more research is required to define appropriate predator–prey release ratios and release timing. Studies on intraguild interactions and competition with naturally occurring predators are also suggested.

Wolbachia influence on the fitness of Anagyrus vladimiri (Hymenoptera: Encyrtidae), a bio-control agent of mealybugs

BACKGROUND

Like numerous other animals, biocontrol agents (BCAs) of arthropod pests carry various microorganisms that may have diverse effects on the biology of their eukaryote hosts. We postulated that it is possible to improve the efficacy of BCAs by manipulating the composition of their associated microbiota. The parasitoid wasp Anagyrus vladimiri (Hymenoptera: Encyrtidae) from a mass-rearing facility was chosen for testing this hypothesis.

RESULTS

High-throughput sequencing analysis indicated that fungal abundance in A. vladimiri was low and variable, whereas the bacterial community was dominated by the endosymbiont Wolbachia. Wolbachia was fixed in the mass-rearing population, whereas in field-collected A. vladimiri Wolbachia's prevalence was only approximately 20%. Identification of Wolbachia strains from the two populations by Multi Locus Sequence Typing, revealed two closely related but unique strains. A series of bioassays with the mass-rearing Wolbachia-fixed (W⁺ ) and a derived antibiotic-treated Wolbachia-free (W^- ) lines revealed that: (i) Wolbachia does not induce reproductive manipulations; (ii) W^- females have higher fecundity when reared individually, but not when reared with conspecifics; (iii) W⁺ females outcompete W^- when they share hosts for oviposition; (iv) longevity and developmental time were similar in both lines.

CONCLUSIONS

The findings suggest that W⁺ A. vladimiri have no clear fitness benefit under mass-rearing conditions and may be disadvantageous under lab-controlled conditions. In a broader view, the results suggest that augmentative biological control can benefit from manipulation of the microbiome of natural enemies.

Biological Control of Tephritid Fruit Flies in the Americas and Hawaii: A Review of the Use of Parasitoids and Predators

Simple Summary

Biological control has been the most commonly researched control tactic within fruit fly management programs, and parasitoids have been the main natural enemies used against pestiferous fruit fly species. In view of this fact, it is important to highlight and compile the data on parasitoids with a certain frequency, aiming to facilitate the knowledge of all the researchers. Information regarding the activities of parasitoids and predators on pestiferous fruit flies in the Americas is limited; therefore, this study aimed to compile the diversity of parasitoids and predators associated with tephritid fruit flies, as well as providing the scientific evidence about the use of parasitoids and predators as biological control agents for fruit flies im the Americas and Hawaii.

Abstract

Biological control has been the most commonly researched control tactic within fruit fly management programs. For the first time, a review is carried out covering parasitoids and predators of fruit flies (Tephritidae) from the Americas and Hawaii, presenting the main biological control programs in this region. In this work, 31 species of fruit flies of economic importance are considered in the genera Anastrepha (11), Rhagoletis (14), Bactrocera (4), Ceratitis (1), and Zeugodacus (1). In this study, a total of 79 parasitoid species of fruit flies of economic importance are listed and, from these, 50 are native and 29 are introduced. A total of 56 species of fruit fly predators occur in the Americas and Hawaii.

Augmentative releases of the soil predatory mite Gaeolaelaps aculeifer reduce fruit damage caused by an invasive thrips in Mediterranean citrus

BACKGROUND

Soil-dwelling predatory mites of the family Laelapidae are augmentatively released for the biological control of several pests with an edaphic phase in numerous greenhouse crops. Yet, there is no information about the potential of releasing these predators to control pests in open field crops. We tested, during two consecutive years, the potential of augmentative releases of Gaeolaelaps aculeifer, alone or in combination with coco fiber discs as mulch, to reduce the damage caused on citrus fruits by the invasive thrips Pezothrips kellyanus in Mediterranean citrus. In a separate trial, we also compared different mulch types (coco fiber discs, rice husks or a mixture of sawdust and wheat bran) for their potential to support the establishment and population development of the predatory mites after their release.

RESULTS

The percentage of unmarketable fruits caused by P. kellyanus was significantly reduced in the plots where G. aculeifer was released. The addition of coco fiber discs did not reduce further the percentage of unmarketable fruits. Sawdust + bran mulch was the most effective in preserving immature and adult predatory mite population after their release.

CONCLUSION

Augmentative releases of G. aculeifer have the potential to reduce fruit damage caused by P. kellyanus in citrus. © 2020 Society of Chemical Industry.

Supplemental Foods Affect Energetic Reserves, Survival, and Spring Reproduction in Overwintering Adult Hippodamia convergens (Coleoptera: Coccinellidae)

For insects that overwinter as adults, winter food resources may affect subsequent spring reproduction and abundance. We tested if provision of food supplements to overwintering adult Hippodamia convergens (Guerin) increased energy reserves, winter survival, and spring reproduction. During 2015-2016, H. convergens adults were placed in field cages in December; adults in each cage received water, Acyrthosiphon pisum (Harris) (Hemiptera: Aphididae), Ephestia kuehniella (Zeller) (Lepidoptera: Pyralidae) eggs, bee pollen, wheast protein, sugar, honey, or no food (control). In 2016-2017, treatments were reduced to sugar, bee pollen, A. pisum with E. kuehniella eggs, and no food (control). Adults were sampled to quantify weight, lipid, carbohydrate, and protein content. In 2015-2016, A. pisum and E. kuehniella eggs increased adult weight and protein content, but adult carbohydrate content was reduced by A. pisum and wheast protein treatments. Adults receiving honey and sugar supplementation had higher lipid and carbohydrate content relative to controls. The number of live individuals at the end of the experiment in March 2016 did not differ among treatments. In 2016-2017, winter prey supplements had the greatest effect on protein content, weight, and number of live adults recovered, whereas sugar supplementation increased lipid and carbohydrate content, and number of live adults recovered. Spring reproduction of surviving pairs was evaluated among treatments in March 2017. Prey supplementation in 2016-2017 increased the number of eggs laid and decreased preoviposition period, and food treatment did not affect fertility. Our results indicate that prey and sugar resources improve the overwintering success and spring reproduction of H. convergens.

The Fitness and Economic Benefits of Rearing the Parasitoid Telenomus podisi Under Fluctuating Temperature Regime

Successful biological control requires detailed knowledge about the mass rearing conditions of the control agents in order to ensure higher quality of field-released insects. Thus, we investigated whether rearing fluctuating thermal condition would affect the fitness and costs of the parasitoid wasp Telenomus podisi Ashmead (a biocontrol agent used for controlling the Neotropical brown stink bug Euschistus heros (Fabricius)) when compared with parasitoid reared at constant temperature condition, which is commonly used in insect facilities. Parasitoids were reared under either constant (continuous exposure at 25 ± 2°C) or fluctuating temperature conditions (i.e., 30 ± 2°C during day and 20 ± 2°C at night) during four consecutive generations. Our results indicated that tested fluctuating temperature is more suitable for rearing of T. podisi as such temperature condition not only resulted in fitness benefits (e.g., shorter developmental time, longer female longevity, higher fecundity/fertility) but also reduced (approximately 23.5%) the estimated costs for producing the parasitoids. Furthermore, rearing T. podisi under fluctuating temperatures improved tolerance to low constant temperatures (i.e., 20°C) without changing the tolerance to constant high temperatures (30°C) in the fourth generation. Surprisingly, even parasitoids that developed under fluctuating thermal conditions performed better than those reared at constant temperature of 25°C. Collectively, our findings suggest that T. podisi reared under fluctuating thermal condition can tolerate better fluctuating temperatures that normally occur both during long periods of transport and in agricultural ecosystems, which will increase the quality and productivity of mass-reared T. podisi for inundative releases.

Identification of the Klambothrips myopori (Thysanoptera: Phlaeothripidae) Predator Complex in California

To identify the predator complex of the invasive thrips, Klambothrips myopori, on its ornamental host plant Myoporum laetum, field surveys were conducted at three sites in southern California over the period of 1 y. Five insect orders and five spider families were represented in the survey. Although the most abundant groups differed among collection sites, syrphid larvae, anthocorids, Chrysoperla spp., Franklinothrips orizabensis Johansen (Thysanoptera: Aeolothripidae), and one spider family (Salticidae) were all collected at each site. Based on the field surveys, Orius spp. and Chrysoperla spp. were identified as possible key natural enemies of K. myopori. Laboratory studies were then conducted to determine the consumption rates of Orius insidiosus Say (Hemiptera: Anthocoridae) and Chrysoperla rufilabris Burmeister (Neuroptera: Chrysopidae) at constant densities of K. myopori and to define the functional responses of the predators. Both predators consumed more second-instar larvae than other prey stages. Orius insidious displayed a type II functional response, while C. rufilabris displayed both type II and type III depending on prey stage. Generally speaking, O. insidiosus and C. rufilabris consumed a higher proportion of prey at lower pest densities, implying that in an augmentative control program using these commercially available natural enemies, predators could be released early in the year when host plants begin to flush and thrips populations are low to suppress population growth.

Whitefly Control Strategies against Tomato Leaf Curl New Delhi Virus in Greenhouse Zucchini

(1) Background: Tomato leaf curl New Delhi virus (ToLCNDV), transmitted by tobacco whitefly (Bemisia tabaci Gennadius) (Hemiptera: Aleyrodidae), is of major concern in the cultivation of zucchini. The threat of this virus motivates reliance on chemical vector control but European consumers’ demands for vegetables grown free of pesticides provides an important incentive for alternative pest management; (2) Methods: Different whitefly management strategies and ToLCNDV incidences were surveyed in commercial zucchini greenhouses in south-east Spain. In an experimental greenhouse, three different whitefly control strategies, biological, chemical, and integrated (IPM), were evaluated in a replicated trial to determine the most effective strategy for virus suppression (3) Results: Whitefly was present in all commercial zucchini crops surveyed, whereas fewer crops had Amblyseius swirskii or other natural enemies. During three consecutive years, pest management was increasingly based on chemical treatments. Yet, ToLCNDV was widespread in zucchini greenhouses. Experimental results showed that the order of best strategy for virus suppressing was integrated management (73%) > biological control (58%) > chemical control (44%); and (4) Conclusions: IPM was the best strategy for virus suppression. The results can assist in the design of appropriate control strategies for chemical pesticide reduction and decision-making in pest management.

Optimizing aphid biocontrol with the predator Aphidoletes aphidimyza, based on biology and ecology

Aphidoletes aphidimyza is one of the most important predators used in the augmentative biological control of aphids, key pests of many crops worldwide. Adult females are very efficient in locating aphid infestations over a relatively long range, up to 45 m, and deposit eggs near or within aphid colonies. The predatory larvae are aphid generalists preying on several agriculturally important aphid species. The successful use of this biocontrol agent in agricultural systems depends on several biotic and abiotic factors. Among biotic factors, aphid species, plant structure, interspecific competition and intraguild predation may significantly impact the predator´s population dynamics. Key abiotic conditions include day lengths (above a critical threshold to prevent diapause), availability of mating sites in the crop, temperature (above 15 °C to enable egg laying), air relative humidity (above 70%) and availability of pupation sites. Although several successes have been reported in open field crops with naturally occurring or released populations, commercial releases are primarily used in protected crops. Optimized emergence boxes combining provisioning of food sources for the adults, integration with the technological advances that occurred in the greenhouse environment lately, insights into the nutritional ecology in open field crops and exploration of the genetic variability are proposed as future directions to improve adoption and efficacy of A. aphidimyza in crop protection. © 2018 Society of Chemical Industry.

Host availability affects the interaction between pupal parasitoid Coptera haywardi (Hymenoptera: Diiapridae) and larval-pupal parasitoid Diachasmimorpha longicaudata (Hymenoptera: Braconidae)

The use of multiple species in biological control programmes is controversial when interactions among them are not fully understood. We determined the response of the pupal parasitoid Coptera haywardi (Oglobin) to different availability of Anastrepha ludens (Loew) pupae previously parasitized or not by larval-pupal Diachasmimorpha longicaudata (Ashmead). The two types of pupae were exposed at different ages and proportions to different numbers of C. haywardi females for 48 h. The performance of C. haywardi adults emerging from parasitized and unparasitized pupae was measured. Coptera haywardi prefers to attack unparasitized A. ludens pupae rather than pupae parasitized by D. longicaudata. However, when the availability of unparasitized pupae was low or the number of foraging females was high, C. haywardi competed against early immature stages of the D. longicaudata, or hyperparasitized, feeding directly on the advanced-immature developmental stages of the early acting species. Adults of C. haywardi emerging as hyperparasitoids were no different in size, fecundity and longevity from those emerging as primary parasitoids. Our data suggest that simultaneous use of these species in augmentative biological control projects may be feasible but should be carefully planned in order to avoid any detrimental effect of its interaction.

Mass rearing and augmentative biological control evaluation of Rhynocoris fuscipes (Hemiptera: Reduviidae) against multiple pests of cotton

BACKGROUND

Rhynocoris fuscipes (Fab.) (Hemiptera: Reduviidae) is a generalist predator of cotton pests and is commonly found inhabiting cotton-growing regions in southern India. With the goal of integrating this predator in standard management practices used against cotton pests on a commercial scale, (1) we developed a protocol for adult group rearing of this predator inside micro-environmental cages (MECs), and (2) we evaluated the biocontrol potential of mass-produced predators against cotton pests under potted and field conditions.

RESULTS

Higher fecundity and adult longevity of R. fuscipes was recorded in the MECs than under natural growing conditions. The reduviid predator preferred stones and fallen leaves as hiding places in the MECs. The predator showed a higher biocontrol potential during the night hours against two pests, Phenacoccus solenopsis Tinsley and Dysdercus cingulatus (Fab.), than during the day under potted conditions. Under field conditions, R. fuscipes significantly reduced the population of Aphis gossypii Glover, P. solenopsis, D. cingulatus and Helicoverpa armigera (Hübner) by 28, 70, 29 and 50%, respectively. No negative impact of R. fuscipes was reported on other natural enemies present in the cotton agroecosystem.

CONCLUSION

Significantly higher crop yield and cost benefit ratio were observed in R. fuscipes-released plots than in the control plots. The results suggest that R. fuscipes can be mass produced efficiently under controlled conditions in MECs, and used in an integrated management program for multiple cotton pests. © 2017 Society of Chemical Industry.

Economic value of biological control in integrated pest management of managed plant systems

Biological control is an underlying pillar of integrated pest management, yet little focus has been placed on assigning economic value to this key ecosystem service. Setting biological control on a firm economic foundation would help to broaden its utility and adoption for sustainable crop protection. Here we discuss approaches and methods available for valuation of biological control of arthropod pests by arthropod natural enemies and summarize economic evaluations in classical, augmentative, and conservation biological control. Emphasis is placed on valuation of conservation biological control, which has received little attention. We identify some of the challenges of and opportunities for applying economics to biological control to advance integrated pest management. Interaction among diverse scientists and stakeholders will be required to measure the direct and indirect costs and benefits of biological control that will allow farmers and others to internalize the benefits that incentivize and accelerate adoption for private and public good.

The multicolored Asian lady beetle, Harmonia axyridis: a review of its biology, uses in biological control, and non-target impacts

Throughout the last century, the multicolored Asian lady beetle, Harmonia axyridis (Pallas) has been studied quite extensively, with topics ranging from genetics and evolution to population dynamics and applied biological control being covered. Much of the early work on H. axyridis was conducted in the native Asian range. From the 1980's to the present, numerous European and North American studies have added to the body of literature on H. axyridis. H. axyridis has recently gained attention in North America both as a biological control agent and as a pest. This literature review was compiled for two reasons. First, to assist other researchers as a reference, summarizing most of the voluminous body of literature on H. axyridis pertaining to its biology, life history, uses in biological control, and potential non-target impacts. Secondly, to be a case study on the impacts of an exotic generalist predator.