Parasitoid Community Research Articles

Bottom-up effect of host protective symbionts on parasitoid diversity: Limited evidence from two field experiments.

Protective symbionts can provide effective and specific protection to their hosts. This protection can differ between different symbiont strains with each strain providing protection against certain components of the parasite and pathogen community their host faces. Protective symbionts are especially well known from aphids where, among other functions, they provide protection against different parasitoid wasps. However, most of the evidence for this protection comes from laboratory experiments.Our aim was to understand how consistent protection is across different symbiont strains under natural field conditions and whether symbiont diversity enhanced the species diversity of colonizing parasitoids, as could be expected from the specificity of their protection.We used experimental colonies of the black bean aphid Aphis fabae to investigate symbiont‐conferred protection under natural field conditions over two seasons. Colonies differed only in their symbiont composition, carrying either no symbionts, a single strain of the protective symbiont Hamiltonella defensa, or a mixture of three H. defensa strains. These aphid colonies were exposed to natural parasitoid communities in the field. Subsequently, we determined the parasitoids hatched from each aphid colony.The evidence for a protective effect of H. defensa was limited and inconsistent between years, and aphid colonies harbouring multiple symbiont strains did not support a more diverse parasitoid community. Instead, parasitoid diversity tended to be highest in the absence of H. defensa.Symbiont‐conferred protection, although a strong and repeatable effect under laboratory conditions may not always cause the predicted bottom‐up effects under natural conditions in the field.

Parasitoid Wasp Community Dynamics in Vineyards Following Insecticide Application

In order to integrate parasitoid wasps in agroecosystems as biological control agents, we need to understand how insecticides affect the parasitoids in the crops and their surroundings. We investigated the non-target effect of Indoxacarb, an insecticide commonly used against European grapevine moth, on parasitoid wasp communities in vineyards. We focused on characterizing: 1. The dynamics of common wasp species, and 2. Wasp abundance and species richness in the vineyard center, edge, and nearby natural area. Seven vineyards, with neighboring natural areas, were sampled before, and up to 2 weeks after, Indoxacarb applications over 2 years. We expected initial negative effects of spraying in the vineyard with some effect of Indoxacarb drift into the natural habitat, followed by wasp recovery, first in natural areas, then at the vineyard edge and finally in the center. Sticky traps were hung at the vineyard edge and center to evaluate migration into and out of the vineyard. Vacuum sampling was used to obtain parasitoid total abundance and species richness, and the abundances of four common species (43% of the wasps collected). From the vacuum samples we found that total wasp abundance and richness declined after spraying in the vineyards’ margins and center but rose over time in the natural area. Vineyard wasp abundance was restored to pre-spraying levels within 2 weeks. Among the abundant species, Trichogramma sp. and Telenomus sp., which parasitize lepidopteran hosts, declined after spraying, and Trichogramma sp. recovered more quickly than Telenomus sp. Two other abundant species, Lymaenon litoralis and Oligosita sp., did not decline after spraying. In the sticky traps, wasp abundance increased at the vineyard edge but not center after spraying, suggesting that there was migration of wasps at the vineyard edge, into or out of the crop. The results indicate an effect of Indoxacarb on the parasitoid wasp community, particularly on parasitoids of lepidopterans, the target group of Indoxacarb. The results also indicate a potential for recovery of the parasitoid community through migration from neighboring natural vegetation.

The parasitoid complex of diamondback moth, Plutella xylostella (Linnaeus) (Lepidoptera: Plutellidae), in Canada: impact and status

Abstract Diamondback moth, Plutella xylostella (Linnaeus) (Lepidoptera: Plutellidae), a globally important pest of Brassicaceae crops, migrates into all provinces of Canada annually. Life tables were used to determine the mortality levels contributed by the parasitoid complexes associated with diamondback moth in British Columbia, Ontario, Prince Edward Island, and insular Newfoundland. Overall, diamondback moth populations showed high generational mortality (> 90%) in all provinces, although parasitism levels were generally low. The net reproductive rate of increase in diamondback moth was less than 1.0 (populations declined) in both years in British Columbia and in each of two years in Newfoundland and Ontario, but it was greater than 1.0 in all three years in Prince Edward Island. Lower parasitism levels were found in Prince Edward Island (3.0–6.3%) compared with other provinces (8.4–17.6%, except one year in British Columbia). Diadegma insulare was the main larval parasitoid found; it was present in all provinces. Microplitis plutellae was present in all provinces except British Columbia. Oomyzus sokolowskii was found in British Columbia and Ontario. The parasitoid community documented from sentinel sampling was less diverse than that found through destructive sampling. Hypotheses are provided to explain the presence of major parasitoids. Increasing larval parasitism would have the largest effect on diamondback moth population growth in Canada.

The diversity of aphid parasitoids in East Africa and implications for biological control.

Hymenopteran parasitoids provide key natural pest regulation services and are reared commercially as biological control agents. Therefore, understanding parasitoid community composition in natural populations is important to enable better management for optimized natural pest regulation. We carried out a field study to understand the parasitoid community associated with Aphis fabae on East African smallholder farms. Either common bean (Phaseolus vulgaris) or lablab (Lablab purpureus) sentinel plants were infested with Aphis fabae and deployed in 96 fields across Kenya, Tanzania, and Malawi. A total of 463 parasitoids emerged from sentinel plants of which 424 were identified by mitochondrial cytochrome oxidase I (COI) barcoding. Aphidius colemani was abundant in Kenya, Tanzania and Malawi, while Lysiphlebus testaceipes was only present in Malawi. The identity of Aphidius colemani specimens were confirmed by sequencing LWRh and 16S genes and was selected for further genetic and population analyses. A total of 12 Aphidius colemani haplotypes were identified. Of these, nine were from our East African specimens and three from the Barcode of Life Database (BOLD). Aphidius colemani and Lysiphlebus testaceipes are potential targets for conservation biological control in tropical smallholder agro-ecosystems. We hypothesize that high genetic diversity in East African populations of Aphidius colemani suggests that this species originated in East Africa and has spread globally due to its use as a biological control agent. These East African populations could have potential for use as strains in commercial biological control or to improve existing Aphidius colemani strains by selective breeding.

The open bar is closed: restructuration of a native parasitoid community following successful control of an invasive pest

The open bar is closed: restructuration of a native parasitoid community following successful control of an invasive pest

Integrated Pest Management for Stored Grain: Potential Natural Biological Control by a Parasitoid Wasp Community.

Simple SummaryParasitoid wasps are well-known biological control agents for arthropod pests in agricultural and forest ecosystems. The stored food product environment is generally also favourable for the parasitoid wasps of the insect pests that infest those food products. Nevertheless, most studies suggest that biological control can reduce pest populations sufficiently only when combined with additional pest-management tools. Combining natural enemies and synthetic chemical pesticides is one of the main challenges in integrated pest management (IPM). We estimated, for the first time, the naturally occurring parasitoid community in grain stores before and after use of synthetic chemical pesticides. There is strong evidence that despite the immediate effect of the pesticides on the parasitoid community, over time, the community can recover. Undoubtedly, a lot of research, particularly of the nature of parasitoid wasps’ recovery in grain-storage facilities, is still required. This will reduce chemical use and implement biological control as a successful and important component of stored-product IPM.Insect contamination of stored grain is a major concern for the grain industry. Phosphine is currently the standard fumigant used to control insect pests in stored grain. However, some species and populations of insects that infest stored grain exhibit resistance to this fumigant and consumers are concerned about pesticide residues. Therefore, alternative methods of effective pest control are needed to partially or completely replace the use of phosphine. There is growing interest in biological control via parasitoid wasps. However, there is evidence that biological control will succeed only if used alongside other pest-management measures. Integrating biological control with the use of chemical insecticide is challenging and may lead to severe reductions in parasitoid survival and success. The main aim of the current study is to shed light on a greatly overlooked issue: the parasitoid community found in stored grain before and after phosphine treatment. The current study results indicate that there is a high level of parasitoid biodiversity within grain stores. We found common parasitoids at both semi-arid and Mediterranean sites, suggesting that those parasitoids can be active across a wide range of abiotic conditions. This research indicates that the community may recover even though phosphine has an immediate negative effect on a parasitoid community. Nevertheless, the parasitoid wasps seem to reduce the host population insufficiently. In light of the findings presented here, those interested in implementing pest-management strategies that include both phosphine treatment and biological control should consider conservation and augmentation of the naturally occurring parasitoid population. These studies should take into account interactions between and within parasitoid populations and phosphine distribution within the grain storage. To limit the effect of phosphine on the parasitoids, pest-management strategies should also reflect careful consideration of the timing of phosphine treatment and the need for sufficient refuge for the parasitoids.

Third and fourth trophic level composition shift in an aphid–parasitoid–hyperparasitoid food web limits aphid control in an intercropping system

Abstract Understanding how resource diversification affects ecological interactions, food web structure and ecosystem functioning is essential in both fundamental and applied ecology. While plant diversification strategies (either in‐field or around‐field) are often proposed in agricultural landscapes as practices to improve the biological control of herbivores by natural enemies, results remain variable and unsure. Here, we studied the effect of an in‐field diversification practice (the intercropping of leguminous crops within cereal fields, an increasingly common practice but with inconsistent results on biological control) on cereal aphid control and the structure of a cereal aphid–parasitoid–hyperparasitoid food web for 2 years. We report that aphid control was not increased in mixed fields, nor was cereal parasitoid diversity and food web complexity. Nevertheless, the provision of alternative hosts in mixed fields led to a functional community composition shift, favouring generalist parasitoid species over specialist ones. Moreover, we observed a higher hyperparasitism rate in mixed fields, suggesting that secondary parasitoids were favoured by alternative resources, which may have disrupted aphid control by primary parasitoids. Synthesis and applications. This study demonstrates that parasitoid community composition shift and increased top‐down control by the fourth trophic level can impact parasitoid efficiency to control herbivores. These results highlight the necessity to study fine‐scale mechanisms within food webs to be able to set up efficient methods to support biodiversity and associated ecosystem services in agricultural landscapes.

The complex trophic community of Disholcaspis eldoradensis, a sucrose‐secreting cynipid gall wasp of Quercus lobata

1. Galls of some species of cynipid wasps produce a sugary secretion that attracts ants, which are thought to defend gall‐inducers against natural enemies, although evidence in support of this hypothesis is mixed. Some discrepancies may be explained by the complexity of the multitrophic interactions, which involve multiple ant and parasitoid species, and which are influenced by gall size and aggregation. The gall exudate also affects these relationships, although secretion patterns and possible host plant impacts appear to be unstudied.2. We studied Disholcaspis eldoradensis Beutenmuller (Hymenoptera:Cynipidae) galls on Quercus lobata Née (Fagaceae) and its interactions with ants and parasitoids. We used exclusion experiments to test the defensive benefits of ants and timing of parasitoid oviposition, and we measured how gall size, aggregation, and ant visitation influence these interactions. In addition, we measured variation in sucrose secreted by galls during larval development.3. Ants benefited gall inducers in 2018, but not 2019. Over 80% of visits observed were from invasive ants. Gall aggregation was not associated with parasitism, gall inducer success, or visitation by ants. During 2018, gall size was inversely correlated with the chance of parasitism and positively correlated with gall inducer biomass, whereas in 2019, parasitoid community composition varied with gall size. Sucrose secretion varied widely among galls and through time.4. Facultative mutualisms between ants and sugar‐secreting galls are complex and likely vary through time depending on local ecological circumstances. Gall secretions warrant increased attention and may impose a substantial burden on some host plant photosynthetic budgets.

Extrinsic Inter- and Intraspecific Competition in Parasitoid Wasps

The diverse ecology of parasitoids is shaped by extrinsic competition, i.e., exploitative or interference competition among adult females and males for hosts and mates. Adult females use an array of morphological, chemical, and behavioral mechanisms to engage in competition that may be either intra- or interspecific. Weaker competitors are often excluded or, if they persist, use alternate host habitats, host developmental stages, or host species. Competition among adult males for mates is almost exclusively intraspecific and involves visual displays, chemical signals, and even physical combat. Extrinsic competition influences community structure through its role in competitive displacement and apparent competition. Finally, anthropogenic changes such as habitat loss and fragmentation, invasive species, pollutants, and climate change result in phenological mismatches and range expansions within host-parasitoid communities with consequent changes to the strength of competitive interactions. Such changes have important ramifications not only for the success of managed agroecosystems, but also for natural ecosystem functioning.

Transgenic Cry1Ac + CpTI cotton does not compromise parasitoid-mediated biological control: An eight-year case study.

The on-farm deployment of genetically modified crops may negatively affect nontarget arthropods, potentially disrupting food web structure and ecosystem functions. Aphid-parasitoid interactions are well-suited to study these potential impacts in agro-ecosystems. Over the span of 8 years, we systematically compared infestation levels of the aphid Aphis gossypii, its associated parasitoid community and overall parasitism rate between transgenic Cry1Ac + CpTI cotton and nontransgenic cotton. Furthermore, we measured the impact of transgenic Cry1Ac + CpTI cotton on structural traits and interspecies interactions within quantitative aphid-parasitoid food webs. Transgenic Cry1Ac + CpTI cotton did not affect the abundance of aphids and parasitoids, or in-field parasitism rates. Despite weak interannual variability, transgenic Cry1Ac + CpTI cotton also did not alter food web architecture or biological control services. Our work not only elucidates the impact of transgenic Cry1Ac + CpTI cotton on different nontarget arthropods (i.e. aphids, parasitoids, hyperparasitoids) and their associated ecosystem services or disservices, but also diversifies the ecological risk assessment toolbox for transgenic insecticidal crops. © 2021 Society of Chemical Industry.

Landscape-scale population connectivity in two parasitoid species associated with the spruce budworm: Testing the birdfeeder effect using genetic data.

Periodic and spatially synchronous outbreaks of insect pests have dramatic consequences for boreal and sub-boreal forests. Within these multitrophic systems, parasitoids can be stabilizing agents by dispersing toward patches containing higher host density (the so-called birdfeeder effect). However, we know little about the dispersal abilities of parasitoids in continuous forested landscapes, limiting our understanding of the spatiotemporal dynamics of host-parasitoid systems, and constraining our ability to predict forest resilience in the context of global changes. In this study, we investigate the spatial genetic structure and spatial variation in genetic diversity of two important species of spruce budworm larval parasitoids during outbreaks: Apanteles fumiferanae Viereck (Braconidae) and Glypta fumiferanae (Viereck) (Ichneumonidae). Using parasitoids sampled in 2014 from 26 and 29locations across a study area of 350,000km2 , we identified 1,012 and 992 neutral SNP loci for A. fumiferanae (N=279 individuals) and G.fumiferanae (N=382), respectively. Using DAPC, PCA, AMOVA, and IBD analyses, we found evidence for panmixia and high genetic connectivity for both species, matching the previously described genetic structure of the spruce budworm within the same context, suggesting similar effective dispersal during outbreaks and high parasitoid population densities between outbreaks. We also found a significant negative relationship between genetic diversity and latitude for A. fumiferanae but not for G. fumiferanae, suggesting that northern range limits may vary by species within the spruce budworm parasitoid community. These spatial dynamics should be considered when predicting future insect outbreak severities in boreal landscapes.

Short Communication: Silba adipata (Diptera: Lonchaeidae) parasitoids on cayenne pepper (Capsicum frutescens) in Bali, Indonesia

Abstract. Yuliadhi KA, Supartha IW, Darmiati NN, Bangun A, Yudha IKW, Utama IWEK, Wiradana PA. 2021. Silba adipata (Diptera: Lonchaeidae) parasitoids on cayenne pepper (Capsicum frutescens) in Bali, Indonesia. Biodiversitas 22: 3929-3935. The black fig fly (Silba adipata) is newly emerging pests that attack cayenne pepper (Capsicum frutescens L.) plants in Bali Province, Indonesia. This study aimed to determine the parasitoid type, community structure, distribution, and parasitization rate of the parasitoids of S. adipata on cayenne pepper in Bali. The sampling method employed in this study involves purposive sampling techniques on 100-150 pieces of cayenne pepper infested with S. adipata at each location point, with the emerging parasitoids identified morphologically. Three types of parasitoid species were associated with S. adipata, which include Asobara japonica Belokobylskij, Fopius arisanus (Sonan), and Diachasmimorpha longicaudata (Ashmead). The parasitoid community structure associated with S. adipata had a low abundance index, low diversity index, and a moderate dominance index. Based on the distribution of the three parasitoids, D. longicaudata is distributed evenly in Bali, whereas F. arisanus was not found in Jembrana . Conversely, A. japonica was only found in Badung, Bangli, Gianyar, and Klungkung. As summary, D. laungicaudata had the highest parasitization rate compared to the F. arisanus and A. japonica. D. longicaudata is a potential parasitoid, which can be studied for the future biological control of S. adipata.

Fruit fly parasitoids (Hymenoptera: Braconidae) in south‐east Queensland, Australia

AbstractOpiine braconids include natural enemies of tephritid fruit flies, and interest in their greater utilisation for fruit fly control is growing. However, there is a lack of basic data on the prevalence and impact of these wasps for most regions of Australia. We sampled fruit fly host fruits from urbanised and peri‐urban locations of south‐east Queensland and reared out parasitoids and their host flies to determine the regional parasitoid community and how parasitism varied across time and habitat type. A total of 4969 fruits were collected from which 21 277 tephritid puparia were obtained. Of 12 601 fruit flies that emerged, the Queensland fruit fly, Bactrocera tryoni, was the dominant species. A total of 5736 parasitoids, representing four species, were recovered from both suburban and peri‐urban sites. For all samples combined, the average parasitism rate was 30%. The exotic, egg–larval–pupal parasitoid Fopius arisanus represented 81% of the parasitoids collected and was recovered from all of the 13 host fruit species sampled. The second most common species, the native larval–pupal parasitoid, Diachasmimorpha kraussii, represented 15% of recovered parasitoids and was collected from a smaller range of host fruit species. The remaining two parasitoids, Diachasmimorpha tryoni and Psyttalia fijiensis, were rare in samples. Parasitoid infestation was highly variable across samples, with higher rates of parasitism observed from October to May. A targeted field experiment to measure differences in parasitism by D. kraussii between urban and peri‐urban habitats detected no variation in the abundance of D. kraussii across habitats, a result consistent with the general survey. The data show that for south‐east Queensland, parasitoids are a significant fruit fly mortality factor in both peri‐urban and urban landscapes. Any manipulation of parasitoids for regional pest management should focus on conservation of F. arisanus.

Species diversity and food web structure jointly shape natural biological control in agricultural landscapes

Land-use change and agricultural intensification concurrently impact natural enemy (e.g., parasitoid) communities and their associated ecosystem services (ESs), i.e., biological pest control. However, the extent to which (on-farm) parasitoid diversity and food webs mediate landscape-level influences on biological control remains poorly understood. Here, drawing upon a 3-year study of quantitative parasitoid-hyperparasitoid trophic networks from 25 different agro-landscapes, we assess the cascading effects of landscape composition, species diversity and trophic network structure on ecosystem functionality (i.e., parasitism, hyperparasitism). Path analysis further reveals cascaded effects leading to biological control of a resident crop pest, i.e., Aphis gossypii. Functionality is dictated by (hyper)parasitoid diversity, with its effects modulated by food web generality and vulnerability. Non-crop habitat cover directly benefits biological control, whereas secondary crop cover indirectly lowers hyperparasitism. Our work underscores a need to simultaneously account for on-farm biodiversity and trophic interactions when investigating ESs within dynamic agro-landscapes.

Disentangling the effects of the invasive pest, Dryocosmus kuriphilus, and the introduction of the biocontrol agent, Torymus sinensis, on native parasitoids in an isolated insular chestnut-growing area

Dryocosmus kuriphilus Yasumatsu (Hymenoptera Cynipidae) was first recorded in Sardinia (Italy) in 2007. Two years later a biological control program started with the introduction of its non-native parasitoid, Torymus sinensis Kamijo (Hymenoptera Torymidae). Over a nine-year period (2009–2017), data on the relative abundance of D. kuriphilus, its native parasitoids and T. sinensis were collected. Native parasitoids reacted quickly to the large availability of hosts. However, a dramatic change in the abundance of each native species was recorded from year to year. In the first few years, the native parasitoid community and pest abundance did not fluctuate much. The turning point was 2014, when, at the same time, the native parasitoid populations increased and the T. sinensis populations also began to increase. In the following year, both the D. kuriphilus and native parasitoid populations decreased considerably, whereas the T. sinensis populations reached over 50% parasitism. The univoltine D. kuriphilus acted as an asynchronous resource for native bivoltine parasitoids. An asynchronous host-parasitoid interaction produces wide fluctuations in their populations. In this case, D. kuriphilus strongly altered the local community, which was subjected to a chaotic change in composition and species abundance. When T. sinensis became established, it monopolized the pest, making this resource unavailable to native parasitoids that returned to attack almost exclusively the native oak cynipids. In fact, the successful control of D. kuriphilus by the introduction of T. sinensis rebalanced the situation that had been altered by the arrival of the invasive pest.

Parasitoid Communities in the Variable Agricultural Environments of Blueberry Production in the Southeastern United States.

In blueberry crops, there are multiple pest species, and some of those can be suppressed by natural enemies including parasitoid wasps and predators. Parasitoid wasps occur within the environment often tracking pest species for food resources to complete their lifecycle. These small wasps are also sensitive to agricultural environments including agrichemicals, habitat availability, and climate. We investigated how the structure of parasitoid communities varied between organic and conventional blueberry systems, and how the communities of these parasitoids varied within field spatial scales (forested border vs edge vs interior). With the lower intensity of agricultural interventions occurring in organic systems and forested borders, we predicted more stable parasitoid numbers that would be insulated from predicted climate variability. In our study, parasitoids were observed in low abundance in each cropping system, with community structure dependent on both management practice and field position. Unmanaged blueberry fields and forested field borders contained more parasitoid families, and in conventional systems, we saw fewer families present in the field interior as compared to field borders. In this first study to characterize Southern parasitoid communities in blueberry production systems, we observed over 50 genera of parasitoids, with a few dominant families (Braconidae and Ichneumonidae) that would contribute to biological control in blueberry systems. Overall, we captured few parasitoids, which indicates a potential vulnerability in biological control, and the need for further research using other sampling techniques to better understand these parasitoid communities.

Opposing Effects of Ceanothus velutinus Phytochemistry on Herbivore Communities at Multiple Scales.

Identifying the interactions of functional, biotic, and abiotic factors that define plant–insect communities has long been a goal of community ecologists. Metabolomics approaches facilitate a broader understanding of how phytochemistry mediates the functional interactions among ecological factors. Ceanothus velutinus communities are a relatively unstudied system for investigating chemically mediated interactions. Ceanothus are nitrogen-fixing, fire-adapted plants that establish early post-fire, and produce antimicrobial cyclic peptides, linear peptides, and flavonoids. This study takes a metabolomic approach to understanding how the diversity and variation of C. velutinus phytochemistry influences associated herbivore and parasitoid communities at multiple spatiotemporal scales. Herbivores and foliar samples were collected over three collection times at two sites on the east slope of the Sierra Nevada Mountain range. Foliar tissue was subjected to LC-MS metabolomic analysis, and several novel statistical analyses were applied to summarize, quantify, and annotate variation in the C. velutinus metabolome. We found that phytochemistry played an important role in plant–insect community structure across an elevational gradient. Flavonoids were found to mediate biotic and abiotic influences on herbivores and associated parasitoids, while foliar oligopeptides played a significant positive role in herbivore abundance, even more than abundance of host plants and leaf abundance. The importance of nutritional and defense chemistry in mediating ecological interactions in C. velutinus plant–herbivore communities was established, justifying larger scale studies of this plant system that incorporate other mediators of phytochemistry such as genetic and metageomic contributions.

Impact of an Exotic Invasive Pest, Spodoptera frugiperda (Lepidoptera: Noctuidae), on Resident Communities of Pest and Natural Enemies in Maize Fields in Kenya

The interactions among insect communities influence the composition of pest complexes that attack crops and, in parallel, their natural enemies, which regulate their abundance. The lepidopteran stemborers have been the major maize pests in Kenya. Their population has been regulated by natural enemies, mostly parasitoids, some of which have been used for biological control. It is not known how a new exotic invasive species, such as the fall armyworm (FAW), Spodoptera frugiperda (Lepidoptera, Noctuidae), may affect the abundance and parasitism of the resident stemborers. For this reason, pest and parasitism surveys have been conducted, before and after the FAW invaded Kenya, in maize fields in 40 localities across 6 agroecological zones (AEZs) during the maize-growing season, as well as at 3 different plant growth stages (pre-tasseling, reproductive, and senescence stages) in 2 elevations at mid-altitude, where all maize stemborer species used to occur together. Results indicated that the introduction of the FAW significantly correlated with the reduction of the abundance of the resident communities of maize stemborers and parasitoids in maize fields; moreover, the decrease of stemborer density after the arrival of FAW occurred mostly at both reproductive and senescent maize stages. It also suggests a possible displacement of stemborers by FAW elsewhere; for example, to other cereals. However, since this study was conducted only three years after the introduction of the FAW, further studies will need to be conducted to confirm such displacements.

Seasonal Abundance and Diversity of Egg Parasitoids of Halyomorpha halys in Kiwifruit Orchards in China.

Simple SummarySurveys of egg parasitoids of the brown marmorated stink bug, Halyomorpha halys, were conducted in 2018 and 2019 in green-fleshed ‘Hayward’ kiwifruit orchards in Mei County, Shaanxi Province, China, to assess the abundance and diversity of parasitoid communities under two different management systems. Parasitism occurred from June to August and from May to August across the two survey seasons, respectively. Five parasitoid species were recovered from successfully parasitized H. halys egg masses, where Trissolcus japonicus and Trissolcus cultratus were the predominant species. The abundance of T. japonicus varied throughout the season in both orchards in both survey seasons. Monthly T. japonicus abundance showed a unimodal distribution in 2018, peaking in July. There were two peaks (May–June and August) in the 2019 season. This study provides valuable information on the season-long abundance and diversity of egg parasitoids of H. halys in kiwifruit, and most importantly on the abundance and effectiveness, relative to other parasitoids, of T. japonicus in kiwifruit orchards.To develop effective and targeted biocontrol tactics for the brown marmorated stink bug, Halyomorpha halys, in crop habitats, a good understanding is essential of the abundance and diversity of its parasitoids in different crop habitats in its native range. To obtain information on the egg parasitoid communities of H. halys in kiwifruit, surveys using sentinel egg masses were conducted in 2018 and 2019. These assessed the species composition of egg parasitoids of H. halys in green-fleshed ‘Hayward’ kiwifruit orchards, and quantified their season-long abundances in orchards under two different management systems. Parasitism was observed from June to August 2018 (mean parasitism: 48%) and from May to August 2019 (mean parasitism: 29%) across the experimental orchards. In total, five different parasitoid species were found across the two surveys seasons in the kiwifruit orchards, Trissolcus japonicus, T. cultratus, T. plautiae, Anastatus japonicus, and Acroclisoides sp., where T. japonicus and T. cultratus were the predominant species. Monthly T. japonicus abundance data had a unimodal distribution in 2018, peaking in July. There were two peaks (May–June and August) in the 2019 season. Overall, T. japonicus was significantly more abundant in the organic orchard than the conventionally managed orchard only in 2018, and its monthly abundance differed significantly in the two orchards in the two survey seasons. Results and their implications for future classical biological control for H. halys in kiwifruit are discussed.

The abundance and diversity of fruit flies and their parasitoids change with elevation in guava orchards in a tropical Andean forest of Peru, independent of seasonality.

Lower elevations are generally thought to contain a greater abundance and diversity of insect communities and their natural enemies than higher elevations. It is less clear, however, how changes in seasons influence this pattern. We conducted a 2-year study (2013‒2014) in guava orchards located in a tropical Andean forest of Peru to investigate differences in fruit flies (Diptera: Tephritidae) and their parasitoid communities at two elevations and over two seasons. Fruit fly traps were installed, monitored, and guava fruits were sampled from eight orchards at low (800–950 m above sea level) and high (1,700–1,900 m above sea level) elevations and during the dry and rainy seasons. At each orchard, adult fruit fly trap captures and emergence of fruit flies and their parasitoids from guava fruit were quantified to determine their abundance and species composition. There was a greater abundance and species richness of fruit flies captured in traps at lower elevations, as well as higher abundance and species evenness of fruit flies that emerged from fruit, indicating that lower elevations are associated with larger fruit fly populations. The abundance, species richness and diversity of parasitoids were also greater at lower elevations. Consequently, guava fruit infestation and fruit fly parasitism rates were also greater at lower elevations. Seasonality also influenced fruit fly populations with a greater number of flies emerging from guava fruit and more fruit infested in the rainy season. However, seasonality had no effect on parasitoid population parameters or rate of parasitism, nor did it interact with elevation as an influence of populations of fruit flies or their parasitoids in guava orchards. This study highlights the importance of examining both elevation and seasonality for a better understanding of the population dynamics of fruit flies and their parasitoids in tropical agroecosystems.