Insect Predators Research Articles

Climatic Niche Differentiation between the Invasive Hornet Vespa velutina nigrithorax and Two Native Hornets in Europe, Vespa crabro and Vespa orientalis

The introduction and expansion of the Asian yellow-legged hornet (Vespa velutina nigrithorax) in Europe poses concern for multiple reasons, including biodiversity conservation. In addition to the predation of native insects (e.g., bees and wasps), this species may compete with native hornets due to an overlap of their climatic and trophic niches. The aim of this study is to investigate the realised climatic niche of V. v. nigrithorax and its response to climatic conditions and to evaluate the degree of overlap with the niches of the two native Vespa species present in Europe, Vespa crabro and Vespa orientalis. The niches of both native species partially overlap with the niche of the invasive species (Schoener’s D, 0.43 for V. crabro and 0.28 for V. orientalis), although some differences can be detected. V. crabro appears to be more adapted to cold and dry conditions than the invasive species, and V. orientalis is more adapted to arid climates. These differences may provide a competitive advantage to both native species in areas with a lower environmental suitability for V. v. nigrithorax, in the probable event that this species continues to spread, reaching all areas predicted to be suitable in Europe and in the Mediterranean basin.

Using The Refugia Plant as an Alternative Habitat for Predatory Insects On Potato Plants

One of the technological innovations that is very relevant for the implementation of IPM is habitat manipulation using refugia plants to conserve predatory insect. The aim of this study was to determine the effect of different species of Refugia plants on the diversity and species richness of predator on potato plants and their production yields. The research method used was a field experimental method with a randomized block design with 5 treatments of Refugia plant species repeated 3 times. The data were analyzed using analysis of variance (ANOVA) and are further tested by Honest Significant Difference (BNJ) analysis at a significance level of 5 percent. The results showed that nine predatory species were found in refugia and potato plants, namely Crytoleamus montrouzieri, Cocinella transversalis, Coleophora inaequalis, Monocielus sexmaculatus, Axion plagiatum, Coleophora reniplagiata, Illeis koebelei, Mantidae and Formicidae. The insect diversity index (H') of the predators found was rated as moderate for all treatments, ranging from 1.2 to 1.9.

They mostly come at night: Predation on sleeping insects by introduced candy-striped spiders in North America.

They mostly come at night: Predation on sleeping insects by introduced candy-striped spiders in North America.

Impact of No-Tillage on Soil Invertebrate Communities in the Southern Forest Steppe of West Siberia: Preliminary Research

The aim of our study is to assess changes in soil macroinvertebrate biodiversity when conventional tillage (CT) is replaced by no-tillage (NT) in agroecosystems of the southern part of the West Siberian forest steppe. The research was conducted in the Novosibirsk region at the end of May 2017, May 2018, and in June 2018. The agricultural plots with CT and NT were located close to each other on identical soils, at a distance of about 200 m from the nearest forest shelterbelts. NT technology has been applied on the experimental plot since 2007. Sampling of invertebrates was conducted in two ways, namely soil sampling and pitfall trapping. The majority of basic physicochemical properties of soil were the same or similar between the CT and NT plots. However, depending on the type of tillage, different soil invertebrate communities had already developed in the control (CT) and experimental (NT) plots during this time. The community of the CT plot includes a large number of flying predatory Carabidae species typical of early successional stages (such as Bembidion properans and B. quadrimaculatum, Poecilus spp.) and phytophages, i.e., larvae of Elateridae. The NT plot has significantly higher density and species richness of earthworms (Eisenia nordenskioldi and synanthropic E. fetida in the NT plot versus one individual of E. nordenskioldi in the CT plot). The NT plot has a significantly richer and more abundant assemblage of spiders (especially in spring) and a poor assemblage of insect predators (except for the superdominant ground beetle Poecilus cupreus and the subdominant P. versicolor in summer 2018). Large numbers of larvae of some carabids (e.g., Amara consularis) were found in the NT soil, suggesting that they complete a full life cycle in this habitat.

Predatory stink bug, Eocanthecona furcellata (Wolff) responses to oral exposure route of λ-cyhalothrin via sex-specific modulation manner

The toxic effects of insecticides on predatory arthropods have closely related to their exposure routes. However, little is known about the effects of insecticide on reproductive parameters when the route of exposure occurs at a trophic level via prey intake. We therefore conducted current studies assessing whether Eocanthecona furcellata adults would be affected by feeding with λ-cyhalothrin-contaminated prey. Reproductive parameters, i.e. prolonged premating and preoviposition durations, reduced number of egg batches and egg amount, disturbed ovarian development, and suppressed expression of reproductive related genes were observed in E. furcellata females by feeding with treated prey. Moreover, reduced survival rate and altered carbohydrate metabolism parameters were detected in male bugs. Biochemical parameters, including MDA content, the activities of three antioxidant enzymes and three detoxification enzymes exhibited sex-specific responses after oral-exposure to λ-cyhalothrin in E. furcellata. The results indicate that the insecticide affects the fitness and leads to impairing reproductive potential via sex-specific modulation manner in predator insects. Taken together, our results provide a comprehensive assessment about detrimental impacts of λ-cyhalothrin-exposure on predators via prey intake, as well as a solid basis for further research to protect the predators from hazardous impacts of insecticides.

A narrow host-range and lack of persistence in two non-target insect species of a bacterial symbiont exploited to deliver insecticidal RNAi in Western Flower Thrips.

Insecticidal RNAi is a targeted pest insect population control measure. The specificity of insecticidal RNAi can theoretically be enhanced by using symbiotic bacteria with a narrow host range to deliver RNAi, an approach termed symbiont-mediated RNAi (SMR), a technology we have previously demonstrated in the globally-invasive pest species Western Flower Thrips (WFT). Here we examine distribution of the two predominant bacterial symbionts of WFT, BFo1 and BFo2, among genome-sequenced insects. Moreover, we have challenged two non-target insect species with both bacterial species, namely the pollinating European bumblebee, Bombus terrestris, and an insect predator of WFT, the pirate bug Orius laevigatus. Our data indicate a very limited distribution of either symbiont among insects other than WFT. Moreover, whereas BFo1 could establish itself in both bees and pirate bugs, albeit with no significant effects on insect fitness, BFo2 was unable to persist in either species. In terms of biosafety, these data, together with its more specific growth requirements, vindicate the choice of BFo2 for delivery of RNAi and precision pest management of WFT.

High Sensitivity of the Tiger Beetle, Cicindela circumpicta, to Toxicity from Pyrethroids and Neonicotinoids, and Implications for Ecosystem Function and Species Extinctions

Risks to non-target species from pesticides have been a concern since the 1960s, but non-target arthropods have never received the attention as have non-target vertebrate species. Pesticide exposure could be a contributing factor in the decline of the endangered Cicindela nevadica lincolniana, as well as declines in predaceous and pollinating insects. Consequently, we examined susceptibility to three common pesticides (glyphosate, bifenthrin, and imidacloprid) of larvae of Cicindela circumpicta, a co-occurring species with Cicindela nevadica lincolniana and a potential model species for insect predators generally. Toxicity was tested by direct, 24-h exposure by contact to larvae. No toxicity from glyphosate was observed at any of the doses tested, nor was death in any controls observed. In contrast, C. circumpicta showed alarmingly high sensitivity to small amounts of both imidacloprid and bifenthrin, two of the most widely used insecticides worldwide. This level of toxicity shows a 3-fold higher sensitivity than reported for insect pollinators. The high sensitivity of tiger beetles to neonicotinoids, and the wide and continual use of this pesticide, strongly indicates the potential for declines in larval insect predators generally, and with the decline of C. n. lincolniana specifically. Results suggest that the focus of the concern for non-target impacts from neonicotinoids should be expanded for insect natural enemies.

Struktur Komunitas Artropoda di Pembibitan Kelapa Sawit

Nurseries are one of the essential agronomic activities in oil palm cultivation. Oil palm seedlings are cultivated on a large scale, different from nurseries for other plantation commodities. The nursery expanse comprises various biotic components, one of which is Arthropods. This study aims to determine the Artropod community and its function in oil palm nurseries. The research was carried out at two nurseries, Nagari Gunung Medan and Nagari Kurnia Selatan, Dharmasraya Regency, West Sumatra Province. Sampling using the pitfall trap, yellow pan trap, insect nets, and direct collection methods. The results showed that the Arthropods that make up the oil palm nursery ecosystem were insects and spiders. Arthropods in oil palm nurseries act as phytophages, predators, parasitoids, and detrivores. Phytophage insects found in oil palm nurseries were 700 individuals consisting of 4 orders, nine families, and 14 genera/species. Predatory insects, parasitoids, and detritivores were found in as many as 466 individuals consisting of 5 orders, 14 families, and 16 genera/species. There are two species of spiders in oil palm nurseries: Pardosa sp and Oxyopes javanus. Valanga sp was the species with the highest number of individuals in oil palm nurseries.

Quantitative Study of Aphid Natural Enemies in Central Oklahoma Canola Fields

Winter canola (Brassica napus L.) is planted in late September through October in central Oklahoma and harvested in June. Three aphid species typically infest canola fields in central Oklahoma: cabbage aphid, Brevicoryne brassicae L.; green peach aphid, Myzus persicae (Sulzer); and turnip aphid, Lipaphis pseudobrassicae (Davis). Predatory insects and spiders and hymenopteran parasitoids that prey on aphids are present in canola fields in central Oklahoma. We used a D-vac suction device to sample aphids and natural enemies in a total of 23 canola fields in central Oklahoma in early November and mid-March of three growing seasons. During the three growing seasons, 2.4 to 50.9 aphids were collected per 120 placements of the D-vac sampler per canola field. Diaeretiella rapae (McIntosh) was the most abundant parasitoid, with 0.04 to 5.1 individuals per 120 placements, while Araneae (spiders) were the most abundant predators ranging from 0.35 to 4.9 per 120 placements. Other predators were Chrysopidae, Hemerobiidae, Nabidae, and Syrphidae, with relative density of most taxa increasing from November to March. Correlations of relative density of D. rapae and larval Coccinellidae to aphid relative density were positive and significant suggesting the taxa had a reproductive and/or aggregative numerical response to aphids in canola. D. rapae, Coccinellidae, and perhaps spiders killed the most aphids in central Oklahoma canola fields.

Hoverfly (Eristalis tenax) pursuit of artificial targets.

The ability to visualize small moving objects is vital for the survival of many animals, as these could represent predators or prey. For example, predatory insects, including dragonflies, robber flies and killer flies, perform elegant, high-speed pursuits of both biological and artificial targets. Many non-predatory insects, including male hoverflies and blowflies, also pursue targets during territorial or courtship interactions. To date, most hoverfly pursuits have been studied outdoors. To investigate hoverfly (Eristalis tenax) pursuits under more controlled settings, we constructed an indoor arena that was large enough to encourage naturalistic behavior. We presented artificial beads of different sizes, moving at different speeds, and filmed pursuits with two cameras, allowing subsequent 3D reconstruction of the hoverfly and bead position as a function of time. We show that male E. tenax hoverflies are unlikely to use strict heuristic rules based on angular size or speed to determine when to start pursuit, at least in our indoor setting. We found that hoverflies pursued faster beads when the trajectory involved flying downwards towards the bead. Furthermore, we show that target pursuit behavior can be broken down into two stages. In the first stage, the hoverfly attempts to rapidly decreases the distance to the target by intercepting it at high speed. During the second stage, the hoverfly's forward speed is correlated with the speed of the bead, so that the hoverfly remains close, but without catching it. This may be similar to dragonfly shadowing behavior, previously coined 'motion camouflage'.

Land‐use change in the Amazon decreases ant diversity but increases ant‐mediated predation

Abstract Food production in Amazonian traditional societies often occurs through shifting cultivation that uses few pesticides and relies on ecosystem services provided by natural enemies. However, these sustainable agricultural practices are being threatened by increasing livestock and mechanised agriculture. This study aimed to evaluate the effects of the conversion from Amazon Forest to anthropogenic land uses (shifting cultivation and pasture) on α‐ and β‐diversity, functional groups, and ant‐mediated predation. Three types of habitats were sampled: forest (eight sites), shifting cultivation (five sites) and pasture (seven sites). The ant assembly of each site was sampled using pitfall traps in the epigeic and hypogeic strata. Beetle larvae were used to evaluate the predation function. Negative effects on epigeic ants and functional groups were found to be greater in sites where anthropogenic land use was more intensive (pasture) than in those where it was less intensive (shifting cultivation). Furthermore, this change increased the predation of insects in shifting cultivation and pasture compared to that in forest. This increase in insect predation was due to high activity of Ectatomma brunneum Smith, 1858, an environmental indicator for shifting cultivation and pasture. The increase in the number of predations in shifting cultivation and pasture may be beneficial from the perspective of biological pest control. However, this relationship needs to be better understood because the high presence and predatory activity of Ectatomma brunneum in these environments may be one mechanism by which α‐ and β‐diversity decrease through antagonistic interactions and dominance.

Spiders’ digestive system as a source of trypsin inhibitors: functional activity of a member of atracotoxin structural family

Spiders are important predators of insects and their venoms play an essential role in prey capture. Spider venoms have several potential applications as pharmaceutical compounds and insecticides. However, transcriptomic and proteomic analyses of the digestive system (DS) of spiders show that DS is also a rich source of new peptidase inhibitor molecules. Biochemical, transcriptomic and proteomic data of crude DS extracts show the presence of molecules with peptidase inhibitor potential in the spider Nephilingis cruentata. Therefore, the aims of this work were to isolate and characterize molecules with trypsin inhibitory activity. The DS of fasting adult females was homogenized under acidic conditions and subjected to heat treatment. After that, samples were submitted to ion exchange batch and high-performance reverse-phase chromatography. The fractions with trypsin inhibitory activity were confirmed by mass spectrometry, identifying six molecules with inhibitory potential. The inhibitor NcTI (Nephilingis cruentata trypsin inhibitor) was kinetically characterized, showing a KD value of 30.25 nM ± 8.13. Analysis of the tertiary structure by molecular modeling using Alpha-Fold2 indicates that the inhibitor NcTI structurally belongs to the MIT1-like atracotoxin family. This is the first time that a serine peptidase inhibitory function is attributed to this structural family and the inhibitor reactive site residue is identified. Sequence analysis indicates that these molecules may be present in the DS of other spiders and could be associated to the inactivation of prey trypsin (serine peptidase) ingested by the spiders.

Population Abundance of The Two-Spotted Spider Mite, Tetranychus urticae Koch and Its Predators and Some Insect Predators Infesting Cotton Plants at Mansoura District

Population Abundance of The Two-Spotted Spider Mite, Tetranychus urticae Koch and Its Predators and Some Insect Predators Infesting Cotton Plants at Mansoura District

Asymmetric inter-specific competition between invasive Phytolacca americana and its native congener

Interspecific competition determines the invasive capability of alien plants. Phytolacca americana, one of the most destructive invasive plants in China, was first discovered and recorded in China in 1935. Since its arrival, the rapid expansion of the species has driven out a native congener, Phytolacca acinosa. In this study, we assessed the competitive interaction of the invasive P. americana the native P. acinosa in a pot experiment at Yunnan University. Our results indicate that P. americana severely inhibits the growth and reproduction of P. acinosa. Furthermore, P. americana demonstrated a superior resistance against both insect predation and bacterial infection. We suggest that this improved tolerance against herbivory and potentional pathogen damage may be a cornerstone to the invasive success of Phytolacca americana.

Insect predator of spodoptera frugiperda J. E. Smith in Sleman and Gunungkidul regency, Indonesia

This research was conducted to identify and found the abundance of predatory insect species of S. frugiperda in Sleman and Gunungkidul Regencies, Yogyakarta Province, Indonesia. This research was conducted in June 2021 - March 2022 on corn plantations in Sleman and Gunungkidul Regencies. Determination of the sampling location was determined by stratified random sampling. Corn land used in sampling was determined by purposive. Insect predator caught by using sweeping net and hand picking. The results showed that there are 3 orders, 8 families, and 16 species of insect predators. 3 orders of the insect predators that found in the Sleman and Gunungkidul Regencies were Coleoptera, Hymenoptera, and Hemiptera. Insect predator families that found in Sleman dan Guungkidul Regencies were Coccinellidae, Carabidae, Staphylinidae, Formicidae, Vespidae, Pentatomidae and Reduviidae. Insect predators species that was most commonly found was Menochilus sexmaculatus with 467 individuals and the least was Sycanus sp. with 1 individual. The conclusion of this study is that there were 16 species of predators from S. frugiperda in Sleman and Gunungkidul Regencies. Practical implications of this research were the insect predators that found in Sleman and Gunungkidul Regencies can be used to maintain the population of Spodoptera frugiperda in two regencies.

The suppressive potential of a gene drive in populations of invasive social wasps is currently limited

Social insects are very successful invasive species, and the continued increase of global trade and transportation has exacerbated this problem. The yellow-legged hornet, Vespa velutina nigrithorax (henceforth Asian hornet), is drastically expanding its range in Western Europe. As an apex insect predator, this hornet poses a serious threat to the honey bee industry and endemic pollinators. Current suppression methods have proven too inefficient and expensive to limit its spread. Gene drives might be an effective tool to control this species, but their use has not yet been thoroughly investigated in social insects. Here, we built a model that matches the hornet’s life history and modelled the effect of different gene drive scenarios on an established invasive population. To test the broader applicability and sensitivity of the model, we also incorporated the invasive European paper wasp Polistes dominula. We find that, due to the haplodiploidy of social hymenopterans, only a gene drive targeting female fertility is promising for population control. Our results show that although a gene drive can suppress a social wasp population, it can only do so under fairly stringent gene drive-specific conditions. This is due to a combination of two factors: first, the large number of surviving offspring that social wasp colonies produce make it possible that, even with very limited formation of resistance alleles, such alleles can quickly spread and rescue the population. Second, due to social wasp life history, infertile individuals do not compete with fertile ones, allowing fertile individuals to maintain a large population size even when drive alleles are widespread. Nevertheless, continued improvements in gene drive technology may make it a promising method for the control of invasive social insects in the future.

Horizontally transferred genes as RNA interference targets for aphid and whitefly control.

RNA interference (RNAi)-based technologies are starting to be commercialized as a new approach for agricultural pest control. Horizontally transferred genes (HTGs), which have been transferred into insect genomes from viruses, bacteria, fungi or plants, are attractive targets for RNAi-mediated pest control. HTGs are often unique to a specific insect family or even genus, making it unlikely that RNAi constructs targeting such genes will have negative effects on ladybugs, lacewings and other beneficial predatory insect species. In this study, we sequenced the genome of a red, tobacco-adapted isolate of Myzus persicae (green peach aphid) and bioinformatically identified 30 HTGs. We then used plant-mediated virus-induced gene silencing (VIGS) to show that several HTGs of bacterial and plant origin are important for aphid growth and/or survival. Silencing the expression of fungal-origin HTGs did not affect aphid survivorship but decreased aphid reproduction. Importantly, although there was uptake of plant-expressed RNA by Coccinella septempunctata (seven-spotted ladybugs) via the aphids that they consumed, we did not observe negative effects on ladybugs from aphid-targeted VIGS constructs. To demonstrate that this approach is more broadly applicable, we also targeted five Bemisia tabaci (whitefly) HTGs using VIGS and demonstrated that knockdown of some of these genes affected whitefly survival. As functional HTGs have been identified in the genomes of numerous pest species, we propose that these HTGs should be explored further as efficient and safe targets for control of insect pests using plant-mediated RNA interference.

Side Effects of Kaolin and Bunch-Zone Leaf Removal on Generalist Predators in Vineyards.

In vineyards, kaolin application and bunch-zone leaf removal (LR) were effective in the control of leafhoppers and Lobesia botrana, but their side effects on generalist predators are still poorly understood. In north-eastern Italian vineyards, the impact of kaolin and LR on species and functional diversity of spiders, as well as the abundance of spiders and generalist predatory insects, was assessed in one vineyard for two consecutive years and in two vineyards for one year. The ecological indices of the spider community were never influenced by kaolin and only in one case were they influenced by LR. At the spider family level, kaolin reduced the abundance of Araneidae, Oxypidae and Salticidae, but only in single cases. In single cases, kaolin reduced the amount of Orius sp. anthocorids and increased that of Scymninae coccinellids, whereas LR increased the amount of Aeolothrips sp. The moderate use of kaolin and the application of LR had negligible and inconsistent impacts on generalist predatory arthropods in vineyards and were therefore, compatible with IPM strategies.

Impact of Post-Harvest Management Practices in Corn (Zea mays L.) Fields on Arthropods in Subsequent Soybean (Glycine max [L.] Merr.) Plantings.

There is increased adoption of cover cropping and conservation tillage in the USA. Many farmers view these practices as methods for improving their soils. However, different cover cropping and tillage practices conducted post-harvest can have a disparate impact on arthropods within the subsequent cash crop. Field experiments were conducted during 2017 and 2018 at two experimental sites to examine the influences of different post-harvest practices following corn (Zea mays L.) harvest on pests and beneficials in subsequent soybean [Glycine max (L.) Merr.] plantings. Experimental treatments included: (1) tillage via chisel plow (CP), (2) no-tillage in which corn residue/stubble remained on the soil surface (CS), and (3) planting a cover crop into corn residue (CC) following corn harvest. Overall, insect herbivore abundance was greater in the CP treatment. Foliar predator numbers were similar among treatments or of greater abundance in CP. The activity density of epigeal insect predators varied according to site and feeding guild. However, spider activity density was greatest in CP. Stink bug egg mortality due to predation and parasitism varied among treatments. However, the percentage of stink bug eggs that hatched was greatest in the CC during both years. Findings suggest that post-harvest practices investigated during this study will have a similar influence on most epigeal and foliar arthropods in soybean.

Weeds Enhance Insect Diversity and Abundance and May Improve Soil Conditions in Mango Cultivation of South Florida.

This study examined if weeds could serve as insectary plants to increase beneficial insect abundance and diversity in mango cultivation in southern Florida. Additionally, we examined how weed presence affects mango tree soil health. We found that weeds significantly increased pollinating and parasitoid insect abundance and diversity. Eight insect orders and eighteen families were significantly more abundant on mango trees with weeds growing beneath them than those where weeds were removed. There was no difference in predatory insects between treatments, and slightly more herbivorous insects on weedy mango trees. Pollinating insects visiting mango flowers in the weed treatment were significantly greater, as well as spiders on weedy mango trees. However, there were more lacewings (Neuroptera) observed on the mango trees without weeds, and leaf chlorophyll in the old and new mango leaves was significantly greater, in the weed-free treatment. Soil conditions, however, significantly improved in soil carbon and a greater pH reduction in the presence of weeds, though weeds affected neither soil nitrogen, phosphorous, nor chlorophyll in productive green leaves. These results show that a tolerable level of selective weed species' presence may benefit insect, plant, and soil biodiversity in farms. This is important in increasing production, sustainability, and biodiversity in agriculture, which otherwise may be deficient in non-crop life.