Hyperparasitoid Species Research Articles

Benefits of remating of a hyperparasitoid acting as a biocontrol agent

Encarsia sophia is the dominant parasitoid of invasive whitefly pest such as Bemisia tabaci. This heteronomous hyperparasitoid species lays fertilised diploid eggs in whitefly nymphs, which serve as primary hosts. Larvae develop as female progeny by consuming whitefly hosts, providing direct biocontrol benefits. However, male progeny originate from unfertilised eggs laid on secondary hosts (primary parasitoids within whitefly nymphs) and develop by consuming primary parasitoid larvae rather than whitefly hosts. Therefore, it is crucial for indoor rearing and field release of the hyperparasitoid to determine whether a female with single-mating experience can parasitise primary hosts and produce female progeny for a whole lifetime and, if not, whether it is remating events and prolong the period of female production, thereby increasing the amount of parasitism on whiteflies. Our fecundity experiments of females with single-mating experience, equally provided with primary and secondary hosts, showed that single mating was insufficient for E. sophia females to lay fertilised eggs in whitefly nymphs for their whole lifetime. In multiple mating experiments, 76.7 % of male adults completed their second mating 2 h after the first, whereas female adults accepted the second mating only if primary hosts were available thereafter. Remating was beneficial for female adults as it prolonged the ovipositional period of fertilised eggs (from 13.3 ± 0.6 days for single to 17.1 ± 0.7 days for twice mating) and increased parasitism on B. tabaci primary host (from 53.1 ± 3.8 for single to 76.4 ± 5.9 for twice mating respectively). The mating experience of males increased their copulation success, whereas that of females decreased it. In conclusion, recommendations are provided for large-scale indoor rearing and field release of E. sophia. Firstly, sufficient time for providing males can be shortened to within 2 h, and a single male can engage in 2–3 mating sessions. Following the 15-day peak oviposition period, the addition of newly emerged males is advised. Secondly, for field release of adult parasitoids, it is recommended to concentrate on releasing females after completing mating indoors. For the release of pupae cards, ensure a balanced ratio of males and females on each card to facilitate mating upon emergence. Additionally, release extra males and females 2 weeks after the initial batch of releases.

A molecular approach to unravel trophic interactions between parasitoids and hyperparasitoids associated with pecan aphids.

Advances in molecular ecology can overcome many challenges in understanding host-parasitoid interactions. Genetic characterization of the key-players in systems helps to confirm species and identify trophic linkages essential for ecological service delivery by biological control agents; however, relatively few agroecosystems have been explored using this approach. Pecan production consists of a large tree perennial system containing an assortment of seasonal pests and natural enemies. As a first step to characterizing host-parasitoid associations in pecan food webs, we focus on aphid species and their parasitoids. Based on DNA barcoding of field-collected and reared specimens, we confirmed the presence of 3 species of aphid, one family of primary parasitoids, and 5 species of hyperparasitoids. By applying metabarcoding to field-collected aphid mummies, we were able to identify multiple species within each aphid mummy to unravel a complex food web of 3 aphids, 2 primary parasitoids, and upward of 8 hyperparasitoid species. The results of this study demonstrate that multiple hyperparasitoid species attack a single primary parasitoid of pecan aphids, which may have negative consequences for successful aphid biological control. Although further research is needed on a broader spatial scale, our results suggest multiple species exist in this system and may suggest a complex set of interactions between parasitoids, hyperparasitoids, and the 3 aphid species. This was the first time that many of these species have been characterized and demonstrates the application of novel approaches to analyze the aphid-parasitoid food webs in pecans and other tree crop systems.

Does This Look Infected? Hidden Host Plant Infection by the Pathogen Botrytis cinerea Alters Interactions between Plants, Aphids and Their Natural Enemies in the Field.

Few studies have considered whether hidden (asymptomatic) plant pathogen infection alters ecological interactions at the higher trophic levels, even though such infection still affects plant physiology. We explored this question in two field experiments, where two varieties of lettuce (Little Gem, Tom Thumb) infected with Botrytis cinerea were either (1) naturally colonised by aphids or (2) placed in the field with an established aphid colony. We then recorded plant traits and the numbers and species of aphids, their predators, parasitoids and hyperparasitoids. Infection significantly affected plant quality. In the first experiment, symptomatically infected plants had the fewest aphids and natural enemies of aphids. The diversity and abundance of aphids did not differ between asymptomatically infected and uninfected Little Gem plants, but infection affected the aphid assemblage for Tom Thumb plants. Aphids on asymptomatically infected plants were less attractive to predators and parasitoids than those on uninfected plants, while hyperparasitoids were not affected. In the second experiment, when we excluded natural enemies, aphid numbers were lower on asymptomatically and symptomatically infected plants, but when aphid natural enemies were present, this difference was removed, most likely because aphids on uninfected plants attracted more insect natural enemies. This suggests that hidden pathogen infection may have important consequences for multitrophic interactions.

A Taxonomic Study of Some Species of Hyperparasitoids Attacking the Primary Parasitoid Microterys nietneri of the Citricola Scale Insect, Coccus pseudomagnoliarum in Syria

Saleh, A.T. and A.M. Basheer. 2023. A Taxonomic Study of Some Species of Hyperparasitoids Attacking the Primary Parasitoid Microterys nietneri of the Citricola Scale Insect, Coccus pseudomagnoliarum in Syria. Arab Journal of Plant Protection, 41(3): 292-305. https://doi.org/10.22268/AJPP-41.3.292305 The citricola scale insect, Coccus pseudomagnoliarum, (Kuwana) (Hemiptera: Coccomorpha: Coccidae) is an economically important pest that occurs on citrus trees along the Syrian coast. The samples of host insects and infested plant parts were collected from April to June during 2016 and 2017 from two locations (Al-Sanobar, Dabba) in Lattakia Province and brought to the Biological Control Studies and Research Center (BCSRC), Faculty of Agriculture, Damascus University. Based on the information gathered, Microterys nietneri (Motschulsky) (Hymenoptera: Encyrtidae) may play an important role as a biological control agent of citricola scale insect, but high hyperparasitoids levels reduced M. nietneri efficiency as a citricola scale parasitoid. The objective of this study was to describe and identify naturally occurring hyperparasitoids. The following parasitoids were identified and reported for the first time in Syria: Cheiloneurus claviger (Thomson), Pachyneuron muscarum (Linnaeus), and Marietta leopardine (Motschulsky). Microscopic images were provided to illustrate the morphological and morphometric characteristics of these species. Keywords: Hyperparasitoids, Citricola scale, Microterys, Syria

Behavior of higher trophic levels associated with an invasive plant varies among populations.

Invasive plants from their native and introduced ranges differ in their interactions with herbivores but it is not known whether they also vary in their interactions with herbivore natural enemies. Here, we used olfactometer bioassays and cage experiments to investigate how foraging behaviors of 2 parasitoid and 1 hyperparasitoid species depended on plant population origin. Triadica sebifera (Euphorbiaceae) is native to China but invasive in the United States. In China, it is fed on by a specialist noctuid Gadirtha fusca (Lepidoptera: Nolidae), which hosts a parasitoid Apanteles sp. (Hymenoptera: Microgastinae) and hyperparasitoid (Hymenoptera: Eurytomidae) plus a generalist aphid Toxoptera odinae (Homoptera: Aphidiidae) parasitized by Lysiphlebus confusus (Hymenoptera: Aphidiinae). Both parasitoids preferred plants infested by their host over herbivore-free plants in olfactometer bioassays. Apanteles sp. and Eurytomid wasps preferred G. fusca infested plants from China populations over those from US populations in olfactometer bioassays but L. confusus wasps did not discriminate between T. odinae infested plants from China vs. US populations. Similarly, G. fusca caterpillars on China population plants were more likely to be parasitized than ones on US population plants when they were in the same cage but odds of parasitism for T. odinae did not differ for those on China vs. US population plants. These results suggest that populations from the native and introduced ranges may differ in traits that impact higher trophic levels. This may have implications for successful control of invasive plants as biocontrol agents are introduced or herbivores begin to feed on them in their introduced ranges.

Parasitoid and predator species of Coccidae (Hemiptera: Coccoidea) species in fruit orchards of Diyarbakır and Elazığ Provinces, Türkiye

This study was carried out in order to determine the predator and parasitoid species that feed on soft scale insect (Hemiptera: Coccidae) species in orchards of Diyarbakır and Elazığ Provinces in Turkiye in 2017 and 2018. Visual identification and rearing methods were used. Eight predatorory species belonging to the families Coccinellidae (4) and Cybocephalidae (1) (Coleoptera), Forficulidae (2) (Dermaptera), and Chrysopidae (1) (Neuroptera), were detected. In addition, 14 parasitoid and 2 hyperparasitoid species from the families Encyrtidae (14), Aphelenidae (1) and 2 Pteromalidae (1) (Hymenoptera) were collected. Among the parasitoid species, Metaphycus ater, M. luteolus, M. chermis and M. unicolor (Hymenoptera: Encyrtidae) are first records for the insect fauna of Türkiye.

Bacterial volatiles elicit differential olfactory responses in insect species from the same and different trophic levels.

Insect communities consist of species from several trophic levels that have to forage for suitable resources among and within larger patches of nonresources. To locate their resources, insects use diverse stimuli, including olfactory, visual, acoustic, tactile and gustatory cues. While most research has focused on cues derived from plants and other insects, there is mounting evidence that insects also respond to volatile organic compounds (VOCs) emitted by microorganisms. However, to date little is known about how the olfactory response of insects within and across different trophic levels is affected by bacterial VOCs. In this study, we used Y-tube bioassays and chemical analysis of VOCs to assess how VOCs emitted by bacteria affect the olfactory response of insects of the same and different trophic levels. Experiments were performed using two aphid species (Amphorophora idaei Börner and Myzus persicae var. nicotianae Blackman), three primary parasitoid species (Aphidius colemani Viereck, A. ervi Haliday, and A. matricariae Viereck), and two hyperparasitoid species (Asaphes suspensus Nees and Dendrocerus aphidum Rondani). Olfactory responses were evaluated for three bacterial strains (Bacillus pumilus ST18.16/133, Curtobacterium sp. ST18.16/085, and Staphylococcus saprophyticus ST18.16/160) that were isolated from the habitat of the insects. Results revealed that insects from all trophic levels responded to bacterial volatiles, but olfactory responses varied between and within trophic levels. All bacteria produced the same set of volatile compounds, but often in different relative concentrations. For 11 of these volatiles we found contrasting correlations between their concentration and the behavior of the primary parasitoids and hyperparasitoids. Furthermore, olfactometer experiments on three of these compounds confirmed the contrasting olfactory responses of primary parasitoids and hyperparasitoids. The potential of these findings for the development of novel semiochemical-based strategies to improve biological aphid control has been discussed.

Cereal Aphid Parasitoids in Europe (Hymenoptera: Braconidae: Aphidiinae): Taxonomy, Biodiversity, and Ecology.

Cereals are very common and widespread crops in Europe. Aphids are a diverse group of herbivorous pests on cereals and one of the most important limiting factors of cereal production. Here, we present an overview of knowledge about the taxonomy, biodiversity, and ecology of cereal aphid parasitoids in Europe, an important group of natural enemies contributing to cereal aphid control. We review the knowledge obtained from the integrative taxonomy of 26 cereal aphid primary parasitoid species, including two allochthonous species (Lysiphlebus testaceipes and Trioxys sunnysidensis) and two recently described species (Lipolexis labialis and Paralipsis brachycaudi). We further review 28 hyperparasitoid species belonging to three hymenopteran superfamilies and four families (Ceraphronoidea: Megaspillidae; Chalcidoidea: Pteromalidae, Encyrtidae; Cynipoidea: Figitidae). We also compile knowledge on the presence of secondary endosymbionts in cereal aphids, as these are expected to influence the community composition and biocontrol efficiency of cereal aphid parasitoids. To study aphid-parasitoid-hyperparasitoid food webs more effectively, we present two kinds of DNA-based approach: (i) diagnostic PCR (mainly multiplex PCR), and (ii) DNA sequence-based methods. Finally, we also review the effects of landscape complexity on the different trophic levels in the food webs of cereal aphids and their associated parasitoids, as well as the impacts of agricultural practices and environmental variation.

Composition and structure of winter aphid-parasitoid food webs along a latitudinal gradient in Chile.

All species interact in complex antagonistic or mutualistic networks that may be driven by turnover in species composition due to spatiotemporal environmental filtering. Therefore, studying differences in insect communities along environmental gradients may improve our understanding of the abiotic and biotic factors that shape the structure of trophic networks. Parasitoids are interesting models to do so, due to their intimate eco-evolutionary relationship with their hosts. We explored the differences in cereal aphid-parasitoid food webs during the winter among nine localities in Chilean central-south valley, along a gradient of 1200km from north (29° S) to south (40° S). We hypothesized that diapause incidence would increase in the coldest areas, resulting in a lower number of parasitoid species active during the winter. Consequently, network specialization, generality, and vulnerability indexes should increase with decreasing latitude, which implies fewer and more weakly connected links per parasitoid species through an increased fraction of basal host species. Based on the severity of winter, three areas along the explored gradient were distinguished, but clustering did not follow a clear north-south latitudinal gradient. Instead, few differences were observed in overwintering strategies, with very low levels of diapause in all localities, and no major differences in food-web composition. The major differences along the gradient were the relative abundances of the different aphid, parasitoid and hyperparasitoid species, with higher levels of spatial and temporal variation observed for the less abundant species. Our results provide a better understanding of the activity and abundance of aphid parasitoids during winter in relation to climatic conditions.

Hyperparasitoids of polysphinctine Darwin wasps (Hymenoptera: Ichneumonidae) in South America

AbstractThis study provides contributions to the knowledge on diversity and natural history of hyperparasitoids (Hymenoptera) associated with host–parasitoid interactions between spiders (Araneae) and polysphinctine Darwin wasps (Pimplinae) in the Atlantic Forest, Brazil, South America. All hyperparasitoids emerged in the laboratory from polysphinctine cocoons that were collected in cocoon webs in the field. A total of 27 hyperparasitoid wasps emerged from polysphinctine cocoons belonging to six genera, three families and two superfamilies: Ceyxia Girault, 1911 and Conura Spinola, 1837 (Chalcidoidea: Chalcididae); Palmistichus Delvare & LaSalle, 1993 (Chalcidoidea: Eulophidae); and Lymeon Förster, 1869, Mesochorus Gravenhorst, 1829, and Neotheronia Krieger, 1899 (Ichneumonoidea: Ichneumonidae). We add new biological information on nine species of hyperparasitoids, emerging from pupae of at least seven species of polysphinctine wasps, which were collected in seven different types of cocoon webs. In addition, a new species is described, Conura capixaba Tavares, sp. nov. (Chalcididae), and digital images of all hyperparasitoids are presented.

Natural History of Plutella armoraciae Busck, 1912, A Sympatric Congener of the Diamondback Moth, Plutella xylostella (L., 1758), in Southwestern Canada

The basic biology, seasonal ecology, and hymenopteran parasitoid community of Plutella armoraciae Busck, 1912 (Lepidoptera: Plutellidae) was investigated. The study area was a dry grasslands region of interior British Columbia, Canada, where P. armoraciae feeds on the introduced mustard Sisymbrium loeselii L., 1755 (Brassicaceae) in partial sympatry with its congener, the diamondback moth Plutella xylostella (L., 1758) (Lepidoptera: Plutellidae). Sampling was conducted over five years, including one year of repeated, intensive sampling over a large region. The two Plutella species can be differentiated with morphology alone and we provide comparisons of features of the eggs, larvae, pupae and adults of each species. Plutella armoraciae was found to overwinter as eggs or early-instar larvae in S. loeselii rosettes, with adults emerging in April and May, and the first full generation each year taking place in May and June. Larvae fed within webbed flowers and buds of S. loeselii plants, giving rise to a second autumn generation of adults that laid eggs of the overwintering generation. The early summer generation of P. armoraciae larvae peaked earlier than, but partially overlapped with, the peak occurrence of P. xylostella larvae. Both Plutella species were relatively common across all surveyed sites, but not highly abundant at any site. At least two species of larval parasitoids, Diadegma insulare (Cresson) (Hymenoptera: Ichneumonidae) and Diolcogaster claritibia (Papp) (Hymenoptera: Braconidae), were shared between the two Plutella species, and a community of eight other species of parasitoids and hyperparasitoids were reared from the pupae of one or both Plutella species. The observations of D. claritibia emerging from P. armoraciae are the first records of this parasitoid from a host species other than P. xylostella. It was also discovered that one of the most important parasitoids of P. xylostella worldwide, D. insulare, appears to use P. armoraciae as an overwintering host. We hypothesize that in areas where P. xylostella is a seasonal migrant, year-round resident Plutella species such as P. armoraciae could provide important overwintering hosts and reservoirs for shared parasitoids that help to reduce populations of P. xylostella.

Assessing adverse impact of the native biological control disruptors in the colonies of the recent invasive pest Phenacoccus manihoti Matile-Ferrero (Hemiptera: Pseudococcidae) in India

New challenges appear with every biological invasion and presses need to probe their ecological interactions. In the comprehensive yet complicated food web associated with the niche of the recently invaded cassava mealybug (CMB) Phenacoccus manihoti Matile-Ferrero (Hemiptera: Pseudococcidae), there was a multitrophic interaction structured vertically as well as horizontally. Altogether 45 species: thirty four species of insects from six orders (Coleoptera, Diptera, Hemiptera, Hymenoptera, Lepidoptera, and Neuroptera) and eleven species of spiders (Araneae) were grouped under four trophic levels into 11 guilds. The analysis of trophic guild structure and interaction indicated that many indigenous parasitoid species, which qualified to be placed under the fourth trophic level, actively parasitized the potential native predators of cassava mealybug (CMB) and thereby negatively impacted the natural biological control of CMB. Most of these resident hyperparasitoid species were recorded for the first time, to be associated directly or indirectly with CMB. The species diversity at fourth trophic level could be viewed as a bioindicator and one of the most important determinant factors on the success rate of any biological control program. No indigenous primary parasitoids were documented on CMB from any of the sites sampled. In the absence of any indigenous parasitoids and high level of parasitization of the potential CMB predators, the long-term and indirect ecosystem risks will be significant until the introduction and establishment of the proven classical biological control agent, Anagyrus lopezi (De Santis) (Encyrtidae: Hymenoptera) from other countries. • First comprehensive study involving multitrophic interactions in the niche of invasive pest Phenacoccus manihoti. • Many indigenous parasitoid species actively parasitized the potential native predators of CMB. • Negatively impact on the natural biological control of CMB. • No indigenous primary parasitoids documented. • We assess the long-term and indirect ecosystem risks due to CMB and spread to other countries.

The effects of allelochemical transfer on the dynamics of hosts, parasitoids, and competing hyperparasitoids

AbstractAllelochemicals produced by plants may be ingested by herbivorous insects and transferred to higher trophic levels with potentially deleterious effects. We develop a system of differential equations to investigate the effect of the transfer of allelochemicals, such as nicotine, on the population dynamics of a system of hosts, parasitoids, and two competing hyperparasitoids that attack different life stages of the parasitoids. We find both somewhat deleterious effects of nicotine on the larvae‐attacking hyperparasitoids and increased attack rates for the pupae‐attacking hyperparasitoids can promote coexistence. We also use an evolutionary game‐theoretic approach to determine the optimal distribution of hyperparasitoid attacks among nicotine‐producing and nicotine‐free plants. With strong deleterious effects of nicotine and increased attack rates for the pupae‐attacking hyperparasitoid, we find both species attack parasitoids on the nicotine‐free plant but only pupae‐attacking hyperparasitoids attack parasitoids on the nicotine‐producing plant.Recommendations for Resource Managers: In the absence of nicotine and with equal attack rates, the larvae‐attacking hyperparasitoids will exclude pupae‐attacking hyperparasitoids due to the advantage of attacking an earlier life‐stage of the parasitoid. Coexistence of larvae‐ and pupae‐attacking hyperparasitoid species can occur when the pupae‐attacking species has the advantage of a higher oviposition rate and/or when the larvae‐attacking species suffers increased mortality due to nicotine. If mortality rates of larvae‐attacking hyperparasitoids due to nicotine become too large, they are unable to persist. The population dynamics of systems incorporating multiple trophic levels are complex and intertwined. The presence of allelochemicals such as nicotine in the first trophic level may impact the observed diversity of hyperparasitoid species in the fourth trophic level.

A survey of aphid parasitoids and hyperparasitoids (Hymenoptera) on six crops in the Kurdistan Region of Iraq

In this study, we surveyed aphids and associated parasitoid wasps from six important crop species (wheat, sweet pepper, eggplant, broad bean, watermelon and sorghum), collected at 12 locations in the Kurdistan region of Iraq. A total of eight species of aphids were recorded which were parasitised by eleven species of primary parasitoids belonging to the families Braconidae and Aphelinidae. In addition, four species of hyperparasitoids (in families Encyrtidae, Figitidae, Pteromalidae and Signiphoridae) were recorded. Aphelinus albipodus (Hayat & Fatima, 1992), A. flaviventris (Kurdjumov, 1913), A. varipes (Förster, 1841) (Aphelinidae), Aphidius rhopalosiphi (De Stefani, 1902), A. uzbekistanicus (Luzhetzki, 1960), (Braconidae) and Alloxysta arcuata (Kieffer, 1902) (Figitidae) were recorded in Iraq for the first time. The results represent the first survey of these interactions in this region and form the basis for understanding crop-aphid-parasitoid-hyperparasitoid networks and for future biological control actions.

Parasitoid Species Associated with Immature Stages <i>pieris rapae</i> (L.) Inhabiting Cabbage Plantations in Assiut Governorate, Upper Egypt

This work was initiated for the first time to identify parasitoid species associated with the immature stages of <i>Pieris rapae</i> (L.) inhabiting cabbage plantations in Assiut governorate, Upper Egypt during the 2018 and 2019 cabbage growing seasons. Attacking periods and parasitism percentages (PPs) of the identified parasitoid species were calculated. One solitary parasitoid species, <i>Hyposoter ebeninus</i> was found to attack <i>P. rapae</i> larvae in the field 110 days after transplantation. However, one hyperparasitoid species <i>Baryscapus galactopus</i> was recorded as an internal gregarious hyperparasitoid of <i>H. ebeninus</i>. The solitary larval parasitoid <i>H. ebeninus</i> strikes were recorded throughout the last five weeks of the season with a marked decline before harvesting. Although <i>H. ebeninus</i> revealed 42.00% abundance, it presented 21.69% PP on <i>P. rapae</i> larvae during the entire period of study. One solitary, <i>Brachymeria femorata</i> and two gregarious parasitoid species [<i>Pteromalus puparum</i> (L) and <i>Tetrastichus</i> sp. (Haliday) were recorded as <i>P. rapae</i> pupae parasitoids on October, 2^nd. Parasitism peak was recorded on October, 16^th with an average of 56.25%. The first appearance of the gregarious pupal parasitoid <i>P. puparum</i> was recorded on October, 9^th. Four weeks later, the second gregarious parasitoid (<i>Tetrastichus</i> sp.) was recorded on November, 6^th. Both pupal gregarious parasitoid species were found to be active until harvesting. The gregarious parasitoid <i>P. puparum</i> presented high PP (23.73%) as compared with <i>Tetrastichus</i> sp. which exhibited 6.96% PP during the entire period of study. In conclusion, two solitaries, one hyperparasitoid, and two gregarious parasitoid species were identified. Pupal gregarious parasitoid species together reduced <i>P. rapae</i> pupae populations by 30.69%. These parasitoids could be used in the IPM programs for this pest in the future. At the same time, the effect of hyperparsitoides must be taken into consideration.

DNA-Based Identification of Larvae Offers Insights into the Elusive Lifestyles of Native Olive Seed Wasps in South Africa

Wild and cultivated olives in the Western Cape of South Africa are direct or indirect hosts to a high diversity of Braconidae and Chalcidoidea wasps. Olive-associated Braconidae are known to parasitise the larvae of Bactrocera oleae (Rossi), and probably also Bactrocera biguttula (Bezzi). The lifestyle of olive-associated Chalcidoidea is not fully understood, and may include phytophagous, parasitoid and hyperparasitoid species. Some chalcids could represent olive seed wasps (OSW), a generic term that designates the seed feeders responsible for losses in commercial olive production. In order to obtain direct DNA-based evidence for the lifestyle of four putative OSW – Eupelmus spermophilus Silvestri, Eurytoma oleae Silvestri, Eurytoma varicolor Silvestri, Sycophila aethiopica (Silvestri); and the parasitoid Neochrysocharis formosus (Westwood) – we developed a multiplex PCR assay comprising species-specific primers for each species. The assay was used to survey larvae collected from the seeds of wild and cultivated olives. Eupelmus spermophilus was the most abundant species in wild and cultivated olives, and may represent a threat to the local olive industry. Eurytoma oleae was found only within the seeds of wild olives, and may also represent an OSW. We found direct evidence supporting the potential agricultural relevance of S. aethiopica and E. varicolor as parasitoids of E. spermophilus. These results may inform strategies for the management and control of OSW in the Western Cape.

Shared enemies exert differential mortality on two competing parasitic wasps

Abstracta Classical biological control programs introduce primary parasitoids into new geographic regions, often exposing them to existing populations of hyperparasitoids. Hyperparasitoids are frequently implicated in the failure of parasitoid biological control agents to establish and provide control of insect pests. The outcome of competition among two or more parasitoid species may be altered if the parasitoids are differentially attacked by the same hyperparasitoids. A reliable assessment of the hyperparasitoid community is needed to understand how top-down trophic interactions influence the effectiveness of introduced parasitoids. We examined the diversity of hyperparasitoids attacking Cotesia glomerata in Colorado (USA), where the congener C. rubecula is absent. We compared this diversity with the hyperparasitoid community of C. glomerata and C. rubecula from Maryland (USA) where both wasps co-occur and use the imported cabbageworm (Pieris rapae) as their main host. Field collected C. glomerata broods were analyzed to examine the relationship between brood sizes and the adult sex ratio and the likelihood of attack by different hyperparasitoid species. A total of nine hyperparasitoid species were found in Colorado, of which four species also occurred in Maryland. While larger C. glomerata broods experienced increased odds of hyperparasitism, C. glomerata developing in larger broods had higher per capita survivorship than those developing in smaller broods. The proportion of adult male C. glomerata in a brood increased with brood size in both non-hyperparasitized and hyperparasitized broods, suggesting that female C. glomerata were not preferentially hyperparasitized. Hyperparasitoids inflicted greater mortality on C. rubecula than on C. glomerata. This differential hyperparasitism may enable the coexistence of C. glomerata with its congener C. rubecula, which usually outcompetes and displaces C. glomerata.

A molecular detection approach for a cotton aphid-parasitoid complex in northern China

Aphid-parasitoid interactions have been widely used as a model system in research studies on the structure and functions of arthropod food web. Research on aphid-parasitoid food webs is hindered by their micromorphological characteristics and the high amount of labor associated with their development. Species-specific primers for cotton aphids and their parasitoids were designed and integrated into two multiplex PCRs and six singleplex PCRs, and all PCRs were optimized to achieve high specificity and sensitivity (100–10,000 DNA copies). One cotton aphid (Aphis gossypii) as well as three primary parasitoid and seven hyperparasitoid species or genera were detected using this molecular approach. This group comprises all the primary parasitoids and 97.2–99.6% of the hyperparasitoids reported in cotton fields in northern China. A tritrophic aphid-primary parasitoid-hyperparasitoid food web was then established. The described method constitutes an efficient tool for quantitatively describing the aphid-primary parasitoid-hyperparasitoid food webs and assessing the efficiency of the biological control of parasitoids in cotton fields in northern China.

Simulated heatwave conditions associated with global warming affect development and competition between hyperparasitoids

Anthropogenic global warming and attendant effects like heatwaves affect the biology and ecology of both individuals and species within and across different trophic levels. Here, we examined the effects of a simulated heatwave on development of and competition between two hyperparasitoid wasps, Lysibia nana and Acrolyta nens when attacking the same host, cocoons of the primary parasitoid, Cotesia glomerata. Parasitized hosts were exposed to three different day and night temperature regimes (low, medium and high) that reflect cool, normal and heatwave conditions in the Netherlands. We found that higher temperatures decreased survival to eclosion more strongly in the hyperparasitoids than in their host. Heatwave conditions also shortened development time and led to the production of smaller adult wasps of both hyperparasitoid species in singly parasitized hosts. In multiparasitized hosts, L. nana won most of the contests when it oviposited first, irrespective of the time interval between the first and second parasitism, whereas A. nens only dominated when it had a 24 h head start or longer. Most importantly, our results show that L. nana in particular benefited in competition at higher temperatures, perhaps due to an increase in the metabolic rate and more rapid egg and/or larval development. This may potentially reduce opportunities for coexistence following heat waves. Our results suggest that heatwaves associated with global warming will enhance the rate of development, but negatively affect survival and other fitness‐related traits in (hyper)parasitoids. Moreover, the outcome of larval competition may be determined via physiological responses that are species‐specific and thus influence phenology.

The impact of climate on the winter strategies of insects

The impact of climate on the winter strategies of insects