Arthropod Predators Research Articles

Vinegaroons (Uropygi: Mastigoproctus tohono) in a multi-predator/multi-prey system: Prey, predators, and cannibalism

Vinegaroons are members of a guild of apex arthropod predators in the high desert grasslands of southeastern Arizona. Despite their importance as major predators in the ecosystem, almost nothing is known about their potential prey, predators, or competitors. We evaluated predator-prey relationships of vinegaroons and 30 species of potential prey, 27 species of potential predators, and the detailed interactions among three taxa of their apex predator guild. With few exceptions, vinegaroons overpowered and preyed on most potential prey within a suitable size range, were almost immune to predation, and appeared to be the dominant species in interactions with other predator guild members. Their most vulnerable life stages were the first two free-living instar stages, whereas adults and fourth instar individuals were not preyed on by any predators active in the same areas and times as vinegaroons. Third instar individuals were a crucial transition stage in which they had a few predators but also were large enough that they required capturing many prey items to grow sufficiently to molt to the fourth instar. In interactions among arthropod predators, the general observation was that when predation occurred, the larger individual usually prevailed irrespective of taxon. Cannibalism among adult and fourth instar vinegaroons does not occur under natural conditions in contrast to when they are placed together in artificial stressful situations. Cannibalism of the three smallest instars appears likely and might partially explain why they are solitary and spend minimal time foraging.

Effect of Transgenic Cotton Expressing Bt Cry1Ac or Cry1Ab/Ac Toxins on Lacewing Larvae Mediated by Herbivorous Insect Pests.

A simple food chain (plant, insect pests, and predatory arthropods) in an agro-ecosystem was set up here as a model system to elucidate the potential effect of transgenic Bacillus thuringiensis (Bt) cotton on non-target organisms. The system included transgenic/non-transgenic cotton, neonate larvae of three herbivorous insects (Spodoptera exigua, Helicoverpa armigera, and S. litura), and predatory lacewing larvae (Chrysopa spp.), which represent the first, second, and third trophic levels, respectively. The results showed that transgenic treatments and different densities of prey had significant effects on both body-weight gain of neonate herbivorous larvae and the number of prey captured by lacewing larvae, respectively. It was found that Bt toxin could persist at the third trophic level in lacewing larvae. The diet mixture bioassay showed that body-weight gain of lacewing larvae was significantly affected by various treatments, especially at lower concentrations of plant-expressed Bt toxin in the diet mixture, which caused significant decreases in body-weight gain. In contrast, synthetic Bt toxin at higher concentrations in the diet did not show this effect. Thus, we inferred that Bt toxin indirectly affected the growth of the lacewings and the lacewings may not be susceptible to Bt toxin or are able to metabolize it.

Conservation Biological Control of Codling Moth (Cydia pomonella): Effects of Two Aromatic Plants, Basil (Ocimum basilicum) and French Marigolds (Tagetes patula).

Simple SummaryIntercropping apple trees with aromatic plants is a way to attract natural enemies and strengthen biological control services. However, the effects of aromatic plants are still unclear under field conditions. Here, we studied the potential of two aromatic plant species to promote codling moth natural enemies in a full factorial experiment. Ocimum basilicum increases codling moth parasitism. Tagetes patula has a general negative effect on both the codling moth and its natural enemies. We do not find a reduction in codling moth density or damaged apples on trees associated with aromatic plants.The addition of flowering companion plants within or around crop fields is a promising strategy to strengthen pest regulation by their natural enemies. Aromatic plants are frequently used as companion plants, but their effects on natural enemies remain unclear under field conditions. Here, we evaluated the effects of two aromatic plant species on the parasitism of the codling moth (Cydia pomonella) and the recruitment of predatory arthropods (spiders, earwigs) in a factorial field experiment. Apple trees were intercropped with basil (Ocimum basilicum), French marigolds (Tagetes patula), or ryegrass (Lolium perenne). The association between apple trees and O. basilicum increases codling moth parasitism, but does not affect arthropod predator abundances. Furthermore, we find a general negative effect of T. patula on arthropod diversities and abundances, including the pest and its natural enemies. Finally, changes in the parasitism rate and arthropod community structure due to the aromatic plants do not reduce codling moth density or associated apple damage. Further experiments are needed to determine the mechanisms involved in aromatic plant effects on pest repellence and on natural enemy recruitment (volatile organic compound composition, floral resource supply, or pest density dependence).

The Biology and Ecology of Parasitoid Wasps of Predatory Arthropods.

Parasitoid wasps are important components of insect food chains and have played a central role in biological control programs for over a century. Although the vast majority of parasitoids exploit insect herbivores as hosts, others parasitize predatory insects and arthropods, such as ladybird beetles, hoverflies, lacewings, ground beetles, and spiders, or are hyperparasitoids. Much of the research on the biology and ecology of parasitoids of predators has focused on ladybird beetles, whose parasitoids may interfere with the control of insect pests like aphids by reducing ladybird abundance. Alternatively, parasitoids of the invasive ladybird Harmonia axyridis may reduce its harmful impact on native ladybird populations. Different life stages of predatory insects and spiders are susceptible to parasitism to different degrees. Many parasitoids of predators exhibit intricate physiological interrelationships with their hosts, adaptively manipulating host behavior, biology, and ecology in ways that increase parasitoid survival and fitness.

Pest mites and their interaction with Phytoseiidae and other arthropod predators in an almond orchard in South-West Spain

The almond crop in Spain has increased in importance in recent years and consequently there is a need to improve knowledge about pests, diseases, and weeds. The present study was conducted from 2017 to 2020, with the objective of determining the fauna of spider mites and their natural enemies, with a special emphasis on phytoseiids. The main spider mite species was Tetranychus urticae Koch, and secondary species were Bryobia rubrioculus (Scheuten) and Eutetranychus banksii (McGregor). Phytoseiidae were the most abundant group of natural enemies, with 59% of the individuals observed; Euseius stipulatus (Athias-Henriot) was the predominant species, accounting for 96% of adult females identified, Typhlodromus (Anthoseius) athenas Swirski & Ragusa accounted for the remaining 4%. Other (potential) natural enemies were Chrysopidae, Scolothrips longicornis Priesner, and Stethorus sp. with 36, 2, and 3%, respectively, of the natural enemy individuals. The seasonal pattern of T. urticae indicated population peaks from July to September, and its control was based on miticides in most seasons. Euseius stipulatus and T. athenas appeared mainly in May–June and did not show interaction with the spider mite population. Chrysopidae were present throughout the season, from May to October in the 4 years, but no direct relationship with the spider mite population was observed. In contrast, the seasonal pattern of both S. longicornis and Stethorus sp. coincided with the most important peaks of spider mites and these predators were seen in the spider mite colonies, although in very low numbers. The importance of these latter specialized spider mite predators and ways to strengthen them are discussed.

Influence of Turfgrass Parameters on the Abundance of Arthropods in Sod Farms.

Sod farms, where turfgrass is commercially produced, have a unique system, in which sod is harvested within 2 yr after planting. Understanding the turfgrass factors that influence the abundance of predators, herbivores, detritivores, and parasitoids that inhabit turfgrass paves the foundation for developing effective pest management programs. However, little is known about those factors in sod farms. The objective of the study was to determine the influence of turfgrass height, density, and thatch thickness on abundance of arthropod taxa in sod farms. The study was conducted at 18 and 10 sod field sites in 2019 and 2020, respectively. Four pitfall traps were deployed at each site. In 2019, each site was sampled in May, June, and July, whereas in 2020, each site was sampled in June and August. In 2019, the numbers of predatory heteropterans were two times greater in bermudagrass (Cynodon dactylon L.) than in zoysiagrass (Zoysia spp.). The numbers of predatory mirids, Spanogonicus albofasciatus (Reuter), and carabids significantly decreased with increases in turfgrass height. In 2020, the abundance of staphylinids increased as the thatch thickness increased. The abundance of Sphenophorus spp. adults were significantly greater in bermudagrass than in zoysiagrass in 2020 and were more abundant in the denser turfgrasses in both years. The predatory arthropods were positively correlated with increased densities of cicadellids, whereas predatory mirids were positively associated with cicadellids, delphacids, and chrysomelids. These results have implications on management of arthropod pests in sod farms as abundance of beneficial arthropods are influenced by turfgrass factors.

A roadmap for ladybird conservation and recovery.

Ladybirds (Coleoptera: Coccinellidae) provide services that are critical to food production, and they fulfill an ecological role as a food source for predators. The richness, abundance, and distribution of ladybirds, however, are compromised by many anthropogenic threats. Meanwhile, a lack of knowledge of the conservation status of most species and the factors driving their population dynamics hinders the development and implementation of conservation strategies for ladybirds. We conducted a review of the literature on the ecology, diversity, and conservation of ladybirds to identify their key ecological threats. Ladybird populations are most affected by climate factors, landscape composition, and biological invasions. We suggest mitigating actions for ladybird conservation and recovery. Short-term actions include citizen science programs and education, protective measures for habitat recovery and threatened species, prevention of the introduction of non-native species, and the maintenance and restoration of natural areas and landscape heterogeneity. Mid-term actions involve the analysis of data from monitoring programs and insect collections to disentangle the effect of different threats to ladybird populations, understand habitat use by taxa on which there is limited knowledge, and quantify temporal trends of abundance, diversity, and biomass along a management-intensity gradient. Long-term actions include the development of a worldwide monitoring program based on standardized sampling to fill data gaps, increase explanatory power, streamline analyses, and facilitate global collaborations.

Effect of Cosmos, Crotalaria, Foeniculum, and Canavalia species, single-cropped or mixes, on the community of predatory arthropods.

Some plants can attract natural enemy by offering resources such as alternative food and refuge. However, studies need to be conducted before agricultural landscape diversification is implement. Our objective was to determine the best floristic compositions of cosmos (Cosmos sulphureus—Asteraceae), showy rattlepod (Crotalaria spectabilis—Fabaceae), fennel (Foeniculum vulgare—Apiaceae), and jack bean (Canavalia ensiformis—Fabaceae) to attract and maintain predatory arthropods, and know the potential of these treatments for future use in diversifying agricultural systems. The experimental design consisted in seven treatments of four species in single-crop, intercrops in three densities called mix1, mix2, and mix3, and the control (weeds). For the arthropod families classified as very frequent and constant, population dynamics in intercropping treatments was plotted according to the plant phenology. We conclude that all plants cultivated in single-cropping and intercropping treatments showed high predator richness and can potentially be used to diversify cultivated areas. Sulfur cosmos as a single crop and three mixes attracts higher numbers and greater family richness. Spider families—Oxyopidae, Araneidae and Thomisidae—and insects—Chrysopidae and Coccinellidae are more frequents. The dynamics of the predator populations varied according to the mixes treatment.

Predation efficiency of the green lacewings Chrysoperla agilis and C. mutata against aphids and mealybugs in sweet pepper.

Chrysoperla species include well-known predators of aphids and other soft-bodied arthropods. As such, they are considered important biological control agents of herbivorous pests in agroecosystems where many of green lacewings species occur. Despite the high number of species of the genus Chrysoperla, only a few have been assessed for the predation efficiency of their larvae against pests infesting plants, and even fewer are currently marketed for use in biocontrol practice. Difficulties in species identification within the Chrysoperla carnea complex species in particular has been related to varying success of commercial C. carnea s.l. releases in the field. In this study, we assessed the ability of two Chrysoperla species, Chrysoperla agilis a member of the carnea cryptic species group, and Chrysoperla mutata of the pudica group to consume aphid and mealybug individuals and suppress their populations in sweet pepper plants. We found that third-instar larvae of both species were able to consume a high number of aphids (approximately 120 nymphs per larva) and mealybugs (approximately 105 nymphs per larva) within 24 h. Furthermore, the release of second-instar larvae of both C. agilis and C. mutata was shown to be remarkably efficient in suppressing the pest populations in long-term greenhouse experiments. Aphid populations were suppressed by approximately 98% and mealybugs by 78% as compared to control plants. Our results highlight the predation efficiency and the biocontrol potential of two widespread Chrysoperla species for their use in pest control.

Epigaeic spider response to sagebrush steppe restoration treatments

Epigaeic (ground-active) spiders are dominant predators of arthropods and are important prey for vertebrates in sagebrush steppe systems. As part of the Sagebrush Steppe Treatment Evaluation Project (SageSTEP), the response of epigaeic spiders to sagebrush steppe restoration treatments was evaluated. Spiders were pitfall trapped pre-treatment and for up to 7 years post-treatment at 20 sites in the interior western United States. Spider species, functional groups, and communities were analyzed as regards site conditions and in response to treatments (prescribed fire, mechanical, and herbicide) designed to restore sagebrush steppe lands encroached by piñon–juniper woodlands (Pinus and Juniperus spp.) and invaded by cheatgrass (Bromus tectorum). A total of 10,149 epigaeic spiders were caught during the 8-year sampling period (2006–2014), comprising 18 families, 51 genera, and 109 species. Ten species are currently undescribed, including two species of jumping spiders (Salticidae), two species of funnel spiders (Agelenidae), and a species of trapdoor spider (Euctenizidae). Nearly 70% of adult catch comprised the 10 most commonly collected species; 50 species were caught fewer than five times. Spiders of the family Gnaphosidae (ground spiders) dominated the collection (65% of adults), followed by wolf spiders (Lycosidae; 12%), jumping spiders (8%), and crab spiders (Thomisidae; 4%). Fewer gnaphosids were caught in plots with higher tree cover, and this pattern was reversed by tree removal. There was no significant epigaeic spider response to the broadleaf herbicide tebuthiuron, nor to mowing or clear-cutting. Mastication caused a subtle increase in epigaeic spider richness at Utah juniper sites. Prescribed fire decreased abundance and richness of epigaeic spiders in the short term (1 year post-treatment), with catch at most sites converging to control levels by Year 2 post-treatment; application of the annual herbicide imazapic at treeless sites may have amplified this effect slightly in the short term. In general, gnaphosid catch and richness closely paralleled litter and bunchgrass cover. These patterns suggest that while gnaphosid spiders are not sagebrush-obligate species per se, these spiders prefer habitat conditions that provide more hiding cover, in the form of litter and vegetation, found more often in treeless sagebrush steppe plant communities and in woodland communities that have relatively lower tree cover.

Toxicity and risk assessment of nine pesticides on nontarget natural predator Harmonia axyridis (Coleoptera: Coccinellidae).

Harmonia axyridis (Coleoptera: Coccinellidae) is a beneficial predatory arthropod in the agricultural ecosystem. For the success and development of integrated pest management strategies, it is essential to assess the toxicity risks of commonly used pesticides to nontarget arthropods. The glass tube residue method was used to determine the risk of nine pesticides to H. axyridis after second-instar exposure. To assess the potential risk of the selected pesticides, the pre-adult LR50 values were calculated by the hazard quotient (HQ) method. The LR50 (application rate causing 50% mortality) values of imidacloprid, dinotefuran, thiamethoxam, acetamiprid, bifenthrin, and dimethoate were 0.44, 0.82, 0.10, 0.05, 0.04, and 0.21 g a.i.ha-1 , respectively, showing unacceptable risk to H. axyridis after exposure to in and off field. However, emamectin benzoate and two fungicides, tebuconazole and myclobutanil, posed a low risk to H. axyridis and their HQ values were less than the trigger value of 5. The four neonicotinoid insecticides (imidacloprid, dinotefuran, thiamethoxam, and acetamiprid), pyrethroid bifenthrin, and organophosphorus dimethoate showed a high risk to H. axyridis. Emamectin benzoate, tebuconazole, and myclobutanil showed a low risk to H. axyridis under both exposure scenarios. The results provide critical scientific evidence to guide future regulation of pesticide management practices and protection of nontarget arthropods like H. axyridis. © 2022 Society of Chemical Industry.

Response of Natural Enemies toward Selective Chemical Insecticides; Used for the Integrated Management of Insect Pests in Cotton Field Plots

Sucking pests of cotton (Gossypium hirsutum L.), such as thrips, or Thrips tabaci Lindeman, and jassid, or Amrasca biguttula Ishida, are among the most threatening insect pests to young cotton plants in Pakistan. New chemical insecticides have been trialed to control their damage in commercial fields. Formulations that show good suppression of these pest’s populations, while sparing bio-controlling agents, are always preferred for obtaining better crop yield. Six different commercially available insecticides, namely Fountain® (fipronil and imidacloprid), Movento Energy® (spirotetramat and imidacloprid), Oshin® (dinotefuran), Concept Plus® (pyriproxyfen, fenpyroximate, and acephate), Maximal® (nitenpyram), and Radiant® (spinetoram) were evaluated in the present study to shortlist the best available insecticide against targeted pests. Harmful impacts of selected insecticides were also evaluated against naturally occurring predators, such as spiders and green lacewings (Chrysoperla carnea). Radiant® (spinetoram) and Movento Energy®, respectively, were best at controlling thrips (with 61% and 56% mortality, respectively) and jassid (62% and 57% mortality, respectively) populations during 2018 and 2019. Radiant® proved itself as the best option and showed minimal harmful effects on both major arthropod predators of cotton fields i.e., spiders (with 8–9% mortality) and green lacewings (with 12–16% mortality). Movento Energy® also showed comparatively less harmful effects (with 15–18% mortality) towards natural predatory fauna of cotton crops, as compared to other selective insecticides used in the study. The findings of current study suggest that the judicious use of target-oriented insecticides can be an efficient and predator-friendly management module in cotton fields. However, the impact of these chemicals is also depended on their timely application, keeping in consideration the ETL of pests and the population of beneficial arthropods.

Rainforest conversion to rubber and oil palm reduces abundance, biomass and diversity of canopy spiders.

Rainforest canopies, home to one of the most complex and diverse terrestrial arthropod communities, are threatened by conversion of rainforest into agricultural production systems. However, little is known about how predatory arthropod communities respond to such conversion. To address this, we compared canopy spider (Araneae) communities from lowland rainforest with those from three agricultural systems in Jambi Province, Sumatra, Indonesia, i.e., jungle rubber (rubber agroforest) and monoculture plantations of rubber and oil palm. Using canopy fogging, we collected 10,676 spider specimens belonging to 36 families and 445 morphospecies. The four most abundant families (Salticidae N = 2,043, Oonopidae N = 1,878, Theridiidae N = 1,533 and Clubionidae N = 1,188) together comprised 62.2% of total individuals, while the four most speciose families, Salticidae (S = 87), Theridiidae (S = 83), Araneidae (S = 48) and Thomisidae (S = 39), contained 57.8% of all morphospecies identified. In lowland rainforest, average abundance, biomass and species richness of canopy spiders was at least twice as high as in rubber or oil palm plantations, with jungle rubber showing similar abundances as rainforest, and intermediate biomass and richness. Community composition of spiders was similar in rainforest and jungle rubber, but differed from rubber and oil palm, which also differed from each other. Canonical Correspondence Analysis showed that canopy openness, aboveground tree biomass and tree density together explained 18.2% of the variation in spider communities at family level. On a morphospecies level, vascular plant species richness and tree density significantly affected the community composition but explained only 6.8% of the variance. While abundance, biomass and diversity of spiders declined strongly with the conversion of rainforest into monoculture plantations of rubber and oil palm, we also found that a large proportion of the rainforest spider community can thrive in extensive agroforestry systems such as jungle rubber. Despite being very different from rainforest, the canopy spider communities in rubber and oil palm plantations may still play a vital role in the biological control of canopy herbivore species, thus contributing important ecosystem services. The components of tree and palm canopy structure identified as major determinants of canopy spider communities may aid in decision-making processes toward establishing cash-crop plantation management systems which foster herbivore control by spiders.

Big, bad, and red: Giant velvet mite defenses and life strategies (Trombidiformes: Trombidiidae: Dinothrombium)

Giant velvet mites, the largest living mites, are a familiar sight when they are present above ground, usually after the first summer rains, in warm arid areas. Despite their often-conspicuous presence in enormous numbers, little is known about their basic biology, life history strategies, or predators. The emergence of Dinothrombium magnificum (LeConte, 1852) in southern Arizona, USA usually occurs after the first summer rain that exceeds 1 cm. Of the 17 species of vertebrate predators offered velvet mites, only those that quickly engulf their prey intact (horned lizards and toads) successfully preyed upon the mites. Even those ate only one or few before rejecting subsequent mites. Of the 12 species of insect predators and 11 species of other arthropod predators offered mites, only the larvae of antlions were possibly meaningful predators. Nevertheless, antlion larvae only rarely succeeded in puncturing the rubbery integument of a mite and killing it. When sampled by an author, a velvet mite produced an exceedingly bitter, astringent, and spicy taste that endured in the mouth for about an hour. Overall, velvet mites appear to have no meaningful predators, likely because of their enormous suite of highly effective defensives: red aposematic coloration, aposematic odor, a tough puncture-resistant integument, unpleasant tasting chemicals on the integument, and exceedingly distasteful internal compounds.

Do prey shape, time of day, and plant trichomes affect the predation rate on plasticine prey in tropical rainforests?

AbstractPredation can effectively limit insect herbivores with cascading effects on plant community composition and diversity of tropical rainforests. Assessing variation in predation is therefore important to understand the mechanisms structuring complex rainforest ecosystems. Variation in predation with time of day may provide herbivores with temporal enemy‐free space. Trichomes (plant hairs) may provide spatial enemy‐free space by increasing climbing resistance for walking arthropod predators and by scattering bat echolocation calls. Artificial model prey is commonly used to measure predation pressure on insect herbivores. Whether model prey shape is sufficient to deceive predators and whether attacks represent actual predation however remain unresolved. We used artificial, plasticine prey to assess temporal and spatial variation in predation in two Panamanian rainforests and tested whether model prey shape is as important for prey recognition by predators as often assumed. We assessed the effect of prey shape and size, time of day, and trichomes on predation by comparing attacks on caterpillar‐ and humanoid‐shaped figurines. We find higher nocturnal than diurnal predation in one but not the other forest, suggesting that herbivores may benefit from enemy‐free space during the day in some forests. We find no evidence for an effect of trichomes on predation in the two plant species tested. Equal attack numbers on caterpillar‐ and humanoid‐shaped objects challenge the idea that the visual resemblance of model prey alone is sufficient to deceive predators. We conclude that attacks on model prey represent a variety of responses to novel objects (e.g. exploration, aggression, possibly predation) and urge caution when interpreting their results.Abstract in Spanish is available with online material.

Evolution of visual system specialization in predatory arthropods.

Under strong selective pressure for survival, image-forming vision set off an ongoing predatory arms race 500 million years ago. Since then, and particularly so in the arthropods, predatory behavior has driven a myriad of eye adaptations that increase visual performance. In this review, we provide examples of how different arthropod predators have achieved improvements in key visual features such as spatial and temporal resolution of their retina. We then describe morphological, neural and behavioral strategies used by animals in this group to gather crucial information about the prey, such as its distance, velocity and size. We also highlight the importance of head and body tracking movements to aid in categorizing the potential prey, and briefly mention the ongoing work on the sensorimotor transformations necessary for target interception.

Field Evaluation of Organophosphorus Insecticides, Chlorpyrifos and Fungal Bio-Pesticides, Beauveria bassiana Towards the Sugar Beet Moth Scrobipalpa ocellatella (Lepidoptera: Gelechiidae) and Studying their Effect on the Population Size of the Associated Arthropod Predators in the Egyptian Sugar Beet Fields.

Field Evaluation of Organophosphorus Insecticides, Chlorpyrifos and Fungal Bio-Pesticides, Beauveria bassiana Towards the Sugar Beet Moth Scrobipalpa ocellatella (Lepidoptera: Gelechiidae) and Studying their Effect on the Population Size of the Associated Arthropod Predators in the Egyptian Sugar Beet Fields.

Winter activity of Clubiona spiders and their potential for pest control

Winter-active arthropod predators (like vegetation-dwelling spiders) significantly suppress pest populations during winter in pome fruit orchards in Central Europe. Clubiona spiders are very abundant in orchards and have been observed to be active during winter. Here, we performed laboratory experiments to assess the movement and predation activity of clubionids at low temperatures. In addition, we also assessed prey survival (psyllids and crickets). We revealed that Clubiona spiders actively moved even at a temperature below 0 °C. Pest prey (Cacopsylla sp.) was able to survive at low temperatures, but crickets died at 3 and -1 °C. Overall Clubiona activity was very low but present during the whole observation period of five days. The predation activity of Clubiona declined with lower temperatures for both cricket and pest (Cacopsylla sp.) prey. Nevertheless, 44% and 25% of Clubiona individuals captured and consumed psyllid and cricket prey, respectively, even at the lowest temperature of −1 °C. Our results show that Clubiona spiders are active predators at low temperatures and, therefore, should contribute to the suppression of overwintering pest populations.

Adana İlinde pamukta zararlı Çiğit emici böceği, Oxycarenus hyalinipennis (Costa) (Hemiptera: Lygaeidae) ile birlikte saptanan avcı arthropoda türleri ve popülasyon değişimleri

Bu çalışma ile Adana ili Balcalı yöresinde pamuk tarlasında 2017 ve 2018 yıllarında Çiğit emici böceği, Oxycarenus hyalinipennis (Costa) (Hemiptera: Lygaeidae) birlikte bulunan avcı arthropoda türleri ve popülasyon değişimleri incelenmiştir. Tarla denemeleri, Çukurova Üniversitesi Ziraat Fakültesi Bitki Koruma Bölümü Araştırma ve Uygulama Alanında yürütülmüştür. Bu çalışmada; Coleoptera takımından 9 tür, Hemiptera takımından 3 tür ve 2 cins, Neuroptera takımından bir cins ve Araneae (örümcekler) takımından 4 tür olmak üzere toplam 16 tür ve cins düzeyinde 3 avcı tür saptanmıştır. Avcı arthropoda popülasyon yoğunluğu O. hyalinipennis’e göre daha düşük olmuş, zararlı tür ile bulunan avcı arthropoda türlerinin popülasyon yoğunlukları arasında dikkate alınabilir spesifik ilişkiler görülmemiştir.

Impact of Cover Crop Planting and Termination Dates on Arthropod Activity in the Following Corn.

Relative to fallow-cash crop rotations, the addition of a cover crop can contribute to greater plant diversity and has the potential to conserve predatory arthropods. The transition of arthropods from a cover crop to a subsequent cash crop depends on several factors, such as cover crop biomass production and weather conditions. Information about the effect of cover crop planting and termination dates on arthropods in a subsequent corn system is limited. A two-year field study was conducted in Nebraska in 2018/2019 and 2019/2020 to evaluate the impact of cover crop planting and termination dates as a source for arthropods in the subsequent corn. A total of 38,074 and 50,626 arthropods were collected in the first and second year, respectively. In both years, adding a grass cover crop increased predatory arthropods but reduced yield in follow corn crop. Of the arthropods collected, Carabidae and Araneae had greater activity with cover crop biomass increments, whereas Collembola and Acari activity only increased in treatments with little or no cover crop biomass. Insect pest pressure was not significant in any treatment for either year. A cover crop planted in mid- or late-September and terminated at corn planting was identified as the best management strategy to maximize cover crop biomass, increase predator activity, and modify predator-prey dynamics. The results of this study provide growers with a cover crop management strategy to maximize cover crop biomass, beneficial arthropod activity, and potentially minimize insect pest problems; however, corn Zea Mays (L.) grain yield was reduced as cover crop biomass increased.