Beneficial Predators Research Articles

Exploring the effects of entomopathogenic nematode symbiotic bacteria and their cell free filtrates on the tomato leafminer Tuta absoluta and its predator Nesidiocoris tenuis

The use of biocontrol agents, such as predators and entomopathogenic nematodes, is a promising approach for the effective control of the tomato leafminer Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidaean), an oligophagous insect feeding mainly on Solanaceae species and a major pest of field- and greenhouse-grown tomatoes globally. In this context, the effects of two entomopathogenic nematode species Steinernema carpocapsae (Weiser) (Rhabditida: Steinernematidae) and Heterorhabditis bacteriophora (Poinar) (Rhabditida: Heterorhabditidae), as well as their respective bacterial symbionts, Xenorhabdus nematophila and Photorhabdus luminescens (Enterobacterales: Morganelaceae), which were applied as bacterial cell suspensions and as crude cell-free liquid filtrates on T. absoluta larvae, were investigated. The results showed that of all treatments, the nematodes S. carpocapsae and H. bacteriophora were the most effective, causing up to 98 % mortality of T. absoluta larvae. Regarding bacteria and their filtrates, the bacterium X. nematophila was the most effective (69 % mortality in young larvae), while P. luminescens and both bacterial filtrates showed similar potency (ca. 48–55 % mortality in young larvae). To achieve a holistic approach of controlling this important pest, the impact of these factors on the beneficial predator Nesidiocoris tenuis (Reuter) (Hemiptera: Miridae) was also studied. The results demonstrated that although nematodes and especially S. carpocapsae, caused significant mortality on N. tenuis (87 %), the bacterial cell suspensions of X. nematophila and P. luminescens and crude cell-free liquid filtrates had minimum impact on this beneficial predator (∼11–30 % mortality).

Impact of seed dressing insecticides on natural enemies of Bt cotton ecosystem

Investigations were carried out on the effect of seed dressing chemicals on the beneficial predators in the Bt cotton ecosystem during 2021-22. All seed dressing insecticides were found safer to the natural enemies as the population of Chrysoperla and ladybird beetle were found comparable to population of untreated control treatment up to 37 days of seed treatment. Similarly, the spider population was also not affected up to 17 days of seed treatment. Thereafter, the population of natural enemies was found higher with the higher prey (sucking pests) populations in the untreated check compared to treatments of seed dressing chemicals and in later treatments, there was no significant difference. The maximum population of spiders (0.52/plant), Chrysoperla (0.42/plant) and ladybird beetle (0.42/plant) was observed in the untreated control. Yield data indicated that the treatment with imidacloprid 70 WG @ 3 g kg-1 obtained highest seed cotton yield (21.69 q ha-1) and it was found superior over the other seed treatments.

Emergence of the aphid Hysteroneura setariae (Thomas, 1878) and ladybird predators Coccinella septempunctata L., 1758 (Coleoptera: Coccinellidae) on the grass Muhlenbergia capillaris (Lamark) Trinius in central Japan

Pink muhly grass Muhlenbergia capillaris (Lamark) Trinius is a perennial, tussock-forming grass that is native to North and Central America. The reddish-purple coloration of the spikes of this species has resulted in this grass becoming popular as an ornamental plant around the world. Interestingly, very few insects have been reported to be associated with this grass. I therefore examined arthropod assemblages on M. capillaris in two urban parks in central Japan in autumn and found that the aphid Hysteroneura setariae (Thomas, 1878) (Hemiptera: Aphididae) and its natural ladybird predator Coccinella septempunctata L., 1758 (Coleoptera: Coccinellidae) occurred at high densities at one of the parks (ca. 9000 vs 3.4 individuals/m2). Other insect pests, such as the moth Helicoverpa armigera (Hübner, 1808) (Lepidoptera: Noctuidae) and mirid bugs were also present, but at markedly lower densities. Since H. setariae is not a pest in Japan and C. septempunctata is a beneficial predator, M. capillaris could be used as a banker plant in agricultural fields as well as in urban green spaces.

Identification of metabolizing enzyme genes associated with xenobiotics and odorants in the predatory stink bug Arma custos based on transcriptome analysis

The predatory stink bug, Arma custos, is a highly effective beneficial predator of crop pests. The lack of gene information related to xenobiotic detoxification and odorant degrading enzymes in the predator stink bugs to date has limited our ability for more in-depth studies of biological control. Hence, we conducted de novo assembly of the A. custos transcriptome from guts, antennae, and other tiussue samples of 5th instar larvae using Illumina sequencing technology. A total of 91, 50 and 23 genes of cytochrome P450 monooxygenases (CYPs), carboxyl/choline esterases (CCEs) and glutathione S-transferases (GSTs) genes were identified, respectively. Gene expansions of CYP3 and CYP4 clans and the hormone and pheromone processing CCE class were found in A. custos. Analysis of tissue-specific expression patterns showed that 37 CYPs, 14 CCEs and 8 GSTs were enriched in guts, and 6 CYPs, 5 CCEs and 2 GSTs were up-regulated in antennae, suggesting their potential roles on xenobiotics detoxification and ordorant degradation. Gene information data presented here could be useful for a deeper understanding of the ecology, physiology and behavior of this beneficial species and could be helpful to improve their bio-control efficiency.

Comparing Insect Predation by Birds and Insects in an Apple Orchard and Neighboring Unmanaged Habitat: Implications for Ecosystem Services.

Preserving ecosystem services, such as natural enemies that can provide pest control, can positively impact crops without compromising agricultural yield. Even though controlling pests by natural enemies has been suggested to reduce pests in agriculture, growers continue using conventional pesticides that kill beneficial predators. Here we studied whether the predation of avian and insect-beneficial predators varies in an apple orchard with conventional insecticide use compared to a bordering tree stand without insecticides. We studied the predation rates of mealworm pupae as a proxy to coddling moth pupae at 42 stations in both an apple orchard and a Eucalyptus stand at three distances (0 m, 50 m, and 100 m) from the border. Half of the stations were netted to prevent bird predation but were accessible to insects. The other half were non-netted and accessible to birds. We conducted six trials, each lasting two weeks, during which we recorded the predation of 504 stations with 5040 pupae. To validate which species predated the pupae, we added video cameras that took RGB videos during the day and IR videos at night in 45 stations and found that in net-free stations, birds preyed in 94.1% of stations in the orchard and 81.8% in the Eucalyptus stand. However, ants predated 70% of the pupae in stations with nets in the orchards and 100% in stations in the Eucalyptus strands. In addition, we found a significant rise in predation by birds as the distance into the orchard increased. Conversely, insect predation declined within the orchard but escalated in the adjacent unmanaged area. These findings suggest that the orchard's environment negatively affects beneficial insect activity, specifically predatory ants. This study demonstrates that birds can play an essential role in predating insect pests inside the orchard. In addition, we believe that the decreased predation of ants within the orchard was due to intense insecticide use.

Deleterious Effects of Cymbopogon nardus (L.) Essential Oil on Life Cycle and Midgut of the Natural Predator Ceraeochrysa claveri (Navás, 1911) (Neuroptera: Chrysopidae).

Cymbopogon nardus (citronella) essential oil (EO) has been widely used in the cosmetic and food industry due to its repellent and fumigant properties. The aim of this study was to evaluate its effects on the life cycle and midgut morphology of the natural predator Ceraeochrysa claveri. Larvae were fed on sugarcane borer eggs (Diatraea saccharalis) pretreated with citronella EO solutions (1-100 µg/mL in methanol, 5 s) or solvent and air-dried at room temperature for 30 min. Larval and pupal stage duration, the percentage of emergence of the insect, and malformed insects were recorded. One day after adults emerged from their cocoons, adult insects were used to obtain their midgut and analyzed using light microscopy. The chemical composition of C. nardus EO revealed that citronellal (25.3%), citronellol (17.9%), geraniol (11.6%), elemol (6.5%), δ-cadinone (3.6%), and germacrene D (3.4%) were the predominant compounds. Exposure to the EO produced a significant change in development duration for third instar and prepupa of the insect. The observed alterations in the lifecycle included prepupae with no cocoon formation, dead pupa inside the cocoon, and malformed adults. Several injuries in the midgut epithelium of exposed adults were registered, such as detachment of columnar cells leaving only swollen regenerative cells fixed on the basement membrane, and the formation of epithelial folds. In summary, these data suggest that C. nardus oil has adverse effects on the life cycle and midgut morphology of a beneficial predator.

A new species of Chrysotus Meigen (Diptera, Dolichopodidae) from soybean fields in South Dakota, USA.

A new long-legged fly species, Chrysotussoya sp. nov. (Diptera: Dolichopodidae), is described and illustrated from specimens collected in soybean fields near Brookings, South Dakota, USA. The abundance of this species in soybeans suggests it plays an important role as a beneficial predator.

A full-length transcriptome and gene expression analysis of three detoxification gene families in a predatory stink bug, Picromerus lewisi.

The predatory stink bug P. Lewisi shows potential for Integrated Pest Management programs for controlling Lepidoptera pest insects in crops and forests. The importance of this insect for biological control has stimulated several studies into its biology and ecology. However, P. lewisi has little genetic information available. In the present study, PacBio single-molecule real-time (SMRT) sequencing and Illumina RNA-seq sequencing technologies were used to reveal the full-length transcriptome profiling and tissue-specific expression patterns of P. lewisi. A total of 12,997 high-quality transcripts with an average length of 2,292 bp were obtained from different stages of P. lewisi using SMRT sequencing. Among these, 12,101 were successfully annotated in seven public databases. A total of 67 genes of cytochrome P450 monooxygenases, 43 carboxylesterase genes, and 18 glutathione S-transferase genes were identified, most of which were obtained with full-length ORFs. Then, tissue-specific expression patterns of 5th instar nymphs were analyzed using Illumina sequencing. Several candidate genes related to detoxification of insecticides and other xenobiotics as well as the degradation of odors, were identified in the guts and antennae of P. lewisi. The current study offered in-depth knowledge to understand the biology and ecology of this beneficial predator and related species.

Comparative Transcriptome Analysis to Reveal Differentially Expressed Cytochrome P450 in Response to Imidacloprid in the Aphid Lion, Chrysoperla zastrowi sillemi (Esben-Petersen).

Simple SummaryChrysoperla zastrowi sillemi (CZS) is a generalist predator of arthropod pests in different crops and is distributed in wide geographical regions. Being a natural predator, CZS shares an ecological niche with the pests and is exposed to several groups of pesticides including imidacloprid. Due to continuous exposure, it has developed resistance to several insecticides. Transcriptomes of imidacloprid-resistant and susceptible strains have been generated and compared for expression differences. From the transcriptome, sequences belonging to the CYP gene family have been mined for their nomenclature and classification into the four CYP clans. Putative functions of the CYP families in CZS have been identified by phylogenetic analysis including CYP sequences from Drosophila and Tribolium. Further, differential expressions of CYP genes have been validated using qRT-PCR. We found nine CYP genes to be downregulated and one to be upregulated after imidacloprid treatment. The information from current study can be exploited for the effective implementation of IPM as it aims at sustainable and eco-friendly crop yield improvement.The aphid lion, Chrysoperla zastrowi sillemi (Neuroptera: Chrysopidae) is a highly effective beneficial predator of many agricultural pests and has developed resistance to several insecticides. Understanding the molecular mechanism of insecticide resistance in the predators is crucial for its effective application in IPM programs. Therefore, transcriptomes of imidacloprid-resistant and susceptible strains have been assessed using RNA-seq. Cytochrome P450 is one of the important gene families involved in xenobiotic metabolism. Hence, our study focused on the CYP gene family where mining, nomenclature, and phylogenetic analysis revealed a total of 95 unique CYP genes with considerable expansion in CYP3 and CYP4 clans. Further, differential gene expression (DGE) analysis revealed ten CYP genes from CYP3 and CYP4 clans to be differentially expressed, out of which nine genes (CYP4419A1, CYP4XK1, CYP4416A10, CYP4416A-fragment8, CYP6YL1, CYP6YH6, CYP9GK-fragment16, CYP9GN2, CYP9GK6) were downregulated and one (CYP9GK3) was upregulated in the resistant strain as compared to the susceptible strain. Expression validation by quantitative real-time PCR (qRT-PCR) is consistent with the DGE results. The expansion and differential expression of CYP genes may be an indicator of the capacity of the predator to detoxify a particular group of insecticides.

Flavonoid-producing tomato plants have a direct negative effect on the zoophytophagous biological control agent Orius sauteri.

Orius sauteri (Poppius) (Hemiptera: Anthocoridae) is often used for biological control of small arthropod pests in greenhouse vegetable production systems in Asia. In addition to feeding on arthropod prey, O. sauteri consumes small quantities of plant material. Previous studies demonstrated that tomato plant chemistry confers antixenosis resistance to phloem-feeding whiteflies, but the potential nontarget effects of phytochemicals on the beneficial predator O. sauteri are unknown. Comparison of O. sauteri confined to near-isogenic lines (NILs) of tomatoes producing high levels of flavonoids (NIL-purple hypocotyl; resistant to whiteflies) and low levels of flavonoids (NIL-green hypocotyl; susceptible to whiteflies) revealed that O. sauteri had reduced oviposition, nymphal survival, and development on resistant plants, even if they were also provided with prey that did not feed on the host plant. Moreover, O. sauteri showed a significant ovipositional preference in choice assays, laying significantly more eggs on susceptible than on resistant plants. Molecular gut content analysis using the specific chloroplast trnL gene from tomato confirmed that adult and immature O. sauteri feed on both resistant and susceptible genotypes, and feeding behavior assays revealed that resistance did not affect plant feeding or prey acceptance by O. sauteri adults. These results demonstrate a direct negative effect of phytochemicals on a nontarget beneficial species and indicate that resistance mediated by phytochemicals can affect organisms that do not solely feed on phloem sap. The results also indicate that the mode of action and the potential ecological effects of phytochemical-mediated resistance are broader than previously recognized.

A near-chromosome level genome assembly of the European hoverfly, Sphaerophoria rueppellii (Diptera: Syrphidae), provides comparative insights into insecticide resistance-related gene family evolution

BackgroundSphaerophoria rueppellii, a European species of hoverfly, is a highly effective beneficial predator of hemipteran crop pests including aphids, thrips and coleopteran/lepidopteran larvae in integrated pest management (IPM) programmes. It is also a key pollinator of a wide variety of important agricultural crops. No genomic information is currently available for S. rueppellii. Without genomic information for such beneficial predator species, we are unable to perform comparative analyses of insecticide target-sites and genes encoding metabolic enzymes potentially responsible for insecticide resistance, between crop pests and their predators. These metabolic mechanisms include several gene families - cytochrome P450 monooxygenases (P450s), ATP binding cassette transporters (ABCs), glutathione-S-transferases (GSTs), UDP-glycosyltransferases (UGTs) and carboxyl/choline esterases (CCEs).Methods and findingsIn this study, a high-quality near-chromosome level de novo genome assembly (as well as a mitochondrial genome assembly) for S. rueppellii has been generated using a hybrid approach with PacBio long-read and Illumina short-read data, followed by super scaffolding using Hi-C data. The final assembly achieved a scaffold N50 of 87Mb, a total genome size of 537.6Mb and a level of completeness of 96% using a set of 1,658 core insect genes present as full-length genes. The assembly was annotated with 14,249 protein-coding genes. Comparative analysis revealed gene expansions of CYP6Zx P450s, epsilon-class GSTs, dietary CCEs and multiple UGT families (UGT37/302/308/430/431). Conversely, ABCs, delta-class GSTs and non-CYP6Zx P450s showed limited expansion. Differences were seen in the distributions of resistance-associated gene families across subfamilies between S. rueppellii and some hemipteran crop pests. Additionally, S. rueppellii had larger numbers of detoxification genes than other pollinator species.Conclusion and significanceThis assembly is the first published genome for a predatory member of the Syrphidae family and will serve as a useful resource for further research into selectivity and potential tolerance of insecticides by beneficial predators. Furthermore, the expansion of some gene families often linked to insecticide resistance and selectivity may be an indicator of the capacity of this predator to detoxify IPM selective insecticides. These findings could be exploited by targeted insecticide screens and functional studies to increase effectiveness of IPM strategies, which aim to increase crop yields by sustainably and effectively controlling pests without impacting beneficial predator populations.

Management of Date Palm Pests: Lack of Commercial Input

According to Statista, the global date market was valued at about $13.4 billion in 2019 and is forecast to reach $16.25 billion by 2025. However, this valuable crop is threatened by numerous pests. In fact, the date palm is associated with 132 species of insect and mite pests, which feed on the leaves, roots, trunk, and fruits on the palm, as well as stored dates. The most economically important pests include the red palm weevil, (Rhynchophorus ferrugineus), old world date mite (Oligonychus afrasiaticus), lesser date moth (Batrachedra amydraula), Dubas date bug (Ommatissus lybicus), green pit scale (Palmaspis phoenicis), carob moth (Ectomyelois ceratoniae), date palm longhorn beetle (Jebusaea hammerschmidti) and almond moth (Cadra castellan). It has been estimated that effective curative approaches for red palm weevil infestations alone could result in savings as high as $104 million. Several research groups are working to find effective solutions to control these pests, but as yet no commercial biocontrol products are registered or available for curative control of the palm beetle and larvae. Therefore, a more robust Integrated Pest Management(IPM) system is needed to reduce the pest damage. Commercial formulations include root treatments, insecticide-based capsules that are injected into the trunk, or foliage/fruit sprays. However, chemical insecticides should not be the only solution to the management of date palm pests, especially those concealed inside the trunk or beneath palm tissues, making them difficult to target. This is primarily because chemical insecticides frequently just kill the target pest's natural enemies, while the pests themselves remain protected within the date palm. Several approaches are used but it has also been shown that resistance against a range of commonly used chemical insecticides (profenophos, imidacloprid, chlorpyrifos, cypermethrin, deltamethrin, spinosad, lambda-cyhalothrin, phosphine) develops after extensive use. Resistance ratios as high as 79-fold have been reported, compared with susceptible control pests. Researchers have reported significantly improved populations of natural enemies of target pests in date palm plantations when chemical insecticide use is reduced. Around 90 species of beneficial predators and parasitoids have so far been reported, suggesting that biological control with microbials could be incorporated into a synchronised IPM programme.

Benefits of Cover Cropping Systems in Walnut Orchards as Sustainable Agricultural Practice

In recent years walnut orchards implemented cover crops in between rows to improve soil’s quality, lessen soil’s erosion, increase organic matter, manage nutrient movement and availability, enhance water retention, and expand microbe, insect, and flora diversity. Commonly selected cover crops in California are from families Poaceae, Brassicaceae, and Fabaceae. Considerations should be made when choosing a particular cover crop mixture to enhance multiple benefits and improve sustainable practices in orchard settings. An experiment was conducted in a walnut orchard to compare functionality and benefits of three systems multi-crop, monocrop, and no vegetation cover crop system. The following components were evaluated: cover crop and weed biomass, cover crop species field distribution, and ability to provide better coverage and weed suppression properties. Brassica mixture, clover and grasses showed highest presence in field conditions and excellent weed competition attributes, while peas and faba beans had low presence and did not compete well growing in a mixture with other cover crops. Multi-crop treatment demonstrated the highest dry and wet biomass as well as the greatest weed suppression. Recommendations are to carefully consider current practices in walnut orchards, to seasonally include vegetation cover rather than bare soil, and to choose multi-crop cover rather than monocrop. Implementation of multi-crop species as a sustainable practice would increase soil’s quality, improve biological management through rise of natural beneficial predators and enhance integrated pest management methods.

A scaffold-level genome assembly of a minute pirate bug, Orius laevigatus (Hemiptera: Anthocoridae), and a comparative analysis of insecticide resistance-related gene families with hemipteran crop pests

BackgroundOrius laevigatus, a minute pirate bug, is a highly effective beneficial predator of crop pests including aphids, spider mites and thrips in integrated pest management (IPM) programmes. No genomic information is currently available for O. laevigatus, as is the case for the majority of beneficial predators which feed on crop pests. In contrast, genomic information for crop pests is far more readily available. The lack of publicly available genomes for beneficial predators to date has limited our ability to perform comparative analyses of genes encoding potential insecticide resistance mechanisms between crop pests and their predators. These mechanisms include several gene/protein families including cytochrome P450s (P450s), ATP binding cassette transporters (ABCs), glutathione S-transferases (GSTs), UDP-glucosyltransferases (UGTs) and carboxyl/cholinesterases (CCEs).Methods and findingsIn this study, a high-quality scaffold level de novo genome assembly for O. laevigatus has been generated using a hybrid approach with PacBio long-read and Illumina short-read data. The final assembly achieved a scaffold N50 of 125,649 bp and a total genome size of 150.98 Mb. The genome assembly achieved a level of completeness of 93.6% using a set of 1658 core insect genes present as full-length genes. Genome annotation identified 15,102 protein-coding genes - 87% of which were assigned a putative function.Comparative analyses revealed gene expansions of sigma class GSTs and CYP3 P450s. Conversely the UGT gene family showed limited expansion. Differences were seen in the distributions of resistance-associated gene families at the subfamily level between O. laevigatus and some of its targeted crop pests. A target site mutation in ryanodine receptors (I4790M, PxRyR) which has strong links to diamide resistance in crop pests and had previously only been identified in lepidopteran species was found to also be present in hemipteran species, including O. laevigatus.Conclusion and significanceThis assembly is the first published genome for the Anthocoridae family and will serve as a useful resource for further research into target-site selectivity issues and potential resistance mechanisms in beneficial predators. Furthermore, the expansion of gene families often linked to insecticide resistance may be an indicator of the capacity of this predator to detoxify selective insecticides. These findings could be exploited by targeted pesticide screens and functional studies to increase effectiveness of IPM strategies, which aim to increase crop yields by sustainably, environmentally-friendly and effectively control pests without impacting beneficial predator populations.

The effect of plastic low tunnels on natural enemies and pollinators in New York strawberry

Although growing strawberries under low tunnels is increasing in popularity across the northeastern United States, little is known of how they impact the presence of natural enemies and pollinators that provide key ecosystem services on strawberry. We employed passive (fruit collections, sticky cards and pitfall traps) and direct (direct observations, leaf brushing and fruit bagging) monitoring over 2–3 growing seasons to compare the abundance and impact of beneficial insects and mites on strawberry grown under low tunnels versus the open field. Three different low tunnel plastics ranging in UV-selectivity were included to determine any effect of UV exclusion on natural enemy and pollinator presence. Plant yield and fruit marketability was higher under low tunnels compared to the open field for two of three years observed. The abundance of predators, and to a lesser extent parasitoids, was similar or higher under low tunnels compared to the open field. However, catch on sticky cards revealed lower densities of parasitoids under tunnels. There was some evidence that UV-selecting plastics resulted in poorly pollinated fruit compared to UV-transmitting and open-field treatments. However, there was no difference in pollinator presence among treatments, so the mechanisms causing the plastic effect are unclear. Overall, we conclude that growing strawberries under low tunnels, regardless of UV selectively, can support higher and more marketable yield in some years while likely having neutral to positive impacts on beneficial predators, parasitoids and pollinators.

Evaluation of Sequences of Certain Insecticide Groups and Biocide Application on Cotton Bollworms, Associated Predators and Cotton Yield in Cotton Fields Egypt

Field experiments were conducted during 2019 and 2020 seasons in Sakh Agricultural Station Farm, Kafr El-Sheikh Governorate, to evaluate the sequences of certain insecticide six groups and biocide on cotton bollworms, associated predators in cotton fields and cotton yield. Sequence of Ictafos (chlorpyrifos) of organic phosphorus – Topron (chlorofluoezuron) of insect growth inhibitor – Cyperco (cypermethrin) of pyrethroids resulted in the greatest means of reduction (51.07, 71.57 and 83.58%) in number of cotton pink bollworm, pectinophora gossypiella (Saund.), Spiny bollworm, Earias insulana (Boisd.) and American bollworm, Helicoverpa armigera Hubner larvae, respectively. The least means of reduction (25.87, 30.28 and 37.78%) of number of pink, spiny and American bollworms larvae with sequence of biocide, (Agrein) only, respectively. All treatments of insecticides were associated with the greatest reduction by range of (65.60 – 69.90%) and (70.34 – 76.14%) on the populations of the six insect predators by the application of sequences of insecticides and each insecticide alone, respectively. Contrast, sequence of biocide Agrein had the minimum side effect on beneficial predators with mean of reduction (29.05%). The highly effective insecticidal sequence against cotton bollworms had the highly increase in cotton yield production.

Field Borders Provide Winter Refuge for Beneficial Predators and Parasitoids: A Case Study on Organic Farms.

Semi-natural field borders are frequently used in midwestern U.S. sustainable agriculture. These habitats are meant to help diversify otherwise monocultural landscapes and provision them with ecosystem services, including biological control. Predatory and parasitic arthropods (i.e., potential natural enemies) often flourish in these habitats and may move into crops to help control pests. However, detailed information on the capacity of semi-natural field borders for providing overwintering refuge for these arthropods is poorly understood. In this study, we used soil emergence tents to characterize potential natural enemy communities (i.e., predacious beetles, wasps, spiders, and other arthropods) overwintering in cultivated organic crop fields and adjacent field borders. We found a greater abundance, species richness, and unique community composition of predatory and parasitic arthropods in field borders compared to arable crop fields, which were generally poorly suited as overwintering habitat. Furthermore, potential natural enemies tended to be positively associated with forb cover and negatively associated with grass cover, suggesting that grassy field borders with less forb cover are less well-suited as winter refugia. These results demonstrate that semi-natural habitats like field borders may act as a source for many natural enemies on a year-to-year basis and are important for conserving arthropod diversity in agricultural landscapes.

Modelling the trophic roles of the demersal Chondrichthyes in the Northern Ionian Sea (Central Mediterranean Sea)

The maintenance of natural capital and the stability of regulation services of marine ecosystems has proved to be linked to the conservation of key species supporting the ecosystems function. Chondrichthyes are key top-predators and their removal from marine ecosystems due to fishing exploitation could lead to changes in species interactions and biomass that can negatively influence the provision of ecosystems services. The ecological role of the demersal Chondrichthyes living in the marine food web of the Calabrian area in the Northern Ionian Sea (Central Mediterranean Sea) was analysed by means of ecological indicators derived from Ecopath mass-balance food web models estimated in their stationary states during the periods 1995–1997, 2003–2005 and 2013–2015. The trophic web model was described by 57 functional groups (7 of which representing the demersal Chondrichthyes), which were described by their Biomass (t/km2), Production and Consumption rate, Diet, Landings (t/km2) e Discards (t/km2). Remarkable changes in biomass were recorded for shark and rays, as a consequence of changes in fishing patterns and oceanographic regime shift named Bimodal Oscillating Systems (BiOS).Demersal Chondrichthyes occupy high trophic positions in the Calabria food web showing trophic levels higher than 4.1, with the D. licha identified as the main apex predators, while E. spinax and G. melastomus as meso‑predators. The pattern of the consumption flows highlighted a potential sensitivity of E. spinax and G. melastomus to the changes in deep waters circulation caused by the BiOS acting on the entire ecosystem of the Ionian Sea. D. licha was identified as the main keystone predators in all the investigated periods. The analysis of the trophic indirect and direct impacts shows the role of the demersal Chondrichthyes as beneficial predators, with positive effects on several preys. Results also showed that G. melastomus and the Shelf Elasmobranchs group (e.g. Raja asterias, Mustelus mustelus, etc.…) were overexploited in 1995 and that all groups of sharks and rays underwent to a decrease of exploitation rate over time. Chondrichthyes showed medium-low values of overlap with the fishing gears (<0.50), with the more relevant values estimated between the shelf elasmobranch group and passive nets and other gears. According to the findings of this work, the protection of Chondrichthyes could combine biodiversity conservation and fisheries management objectives. Therefore it is envisaged the implementation of appropriate spatial planning and conservation measures for these top-predators to guarantee valuable and sustainable flows of ecosystem goods and services.

Cohort Development and Population Growth of &amp;lt;i&amp;gt;Amblydromalus hum&amp;lt;/i&amp;gt; (Acari: Phytoseiidae) on Citrus Red Mite in Comparison to Maize Pollen

Phytoseiidae mites suppress pest mites and small arthropods below injury levels. A study on cohort life stage of <i>Amblydromalus hum</i> Pritchard & Baker was carried out to determine development and growth of the Phytosiidae mite. General observation showed a lower turnover of the larval stage to the Protonymph stage from the 12^th day onward, probably this could be attributed to some cannibalism taking place where adults could prey on the larvae and the nymphal stages. Significantly, the larvae were most abundant within 21 days when <i>A. hum</i> was fed <i>E. africanus</i> showing a cohort life stage composition of 39% overall population among other motile life stages. Similarly, same larvae appeared significantly most abundant when feed on maize pollen at 61% over other cohort life stage within a period of 4 days. Female adults starved death by 3^rd day and were found not to lay eggs within the period. It was observed that female adult <i>A. hum</i> did not live beyond the 3^rd day when 100% mortalities occurred where maize. The study results showed that <i>A. hum</i> preference for <i>E, africanus</i> prey over maize pollen limited the predator’s survival in the absence of the preferred diet and hence need to explore alternative substrates in citrus orchards to boost information on how to conserve the beneficial predator in citrus production.

Efficacy and Residual Effect of Abamectin and Chlorpyrifos-Methyl against the Second Larval Instar of the Cotton Leafworm, Spodoptera littoralis (BOISD.) Under Field and Semi-Field Condition

The initial mortality and residual effect of abamectin and chlorpyrifos-methyl against the second instar larvae of the leafworm, Spodoptera littoralis (Boisduval) and beneficial arthropods were evaluated on tomato crop during 2019 and 2020 growing seasons under field and semi field conditions.The obtained data were revealed that Chlorpyrifos-methyl gave 100% initial mortality one to five days in 2019 and one to three days in 2020 growing season after application when the recommended rate was used in both seasons.Also, abamectin expressed 100 and 96% initial mortality during the first 24 hr after application in 2019 and 2020 growing seasons, respectively.When the recommended rate was applied,abamectin and chlorpyrifos-methylwere completely lost their toxic residues after 7.55 and 18.39 in 2019 and7.64 and 16.77 days during 2020 growing season of field application, respectively.On the other hand, abamectin had negatively effection on the population of predators at the first day after application then the population was turned back to its normal abundance after 48hr, particularly with half of the recommended rate as well as the field rate of application in both seasons. However, chlorpyrifos-methyl was showed negative impact on the predators, which resulted 100% reduction of predators' population within 96 hr post application, and then the percentage reduction continuously increased till day 13 then it decreased starting from day 14.Therefore, it could be recommended that using abamectin for controling Lepidopterous pests on vegetables to minimize the pre-harvest interval, which makes these crops edible for human use shortly after treatment and also to preserve beneficial predators.