Effective Predator Research Articles

The Predatory Mites (Phytoseiidae, Parasitiformes) in the Fauna of Ukraine: of the Genera Paragigagnatus, Carinoseius, Kampimodromus, Eharius, Typhlodromips, and Euseius

Phytoseiid mites (Phytoseiidae, Parasitiformes) are well known as effective predators that are successfully used for biological control of plant pests. Despite significant progress in finding and using effective species of these mites in the practice of plant protection, in general, the amount of knowledge about this important group of small arthropods remains insufficient. This article continues previous publications about research results, some of which were published earlier (Kolodochka, 2022; 2023). The article summarises the results of the study of the species composition of phytoseiid mites of six genera conducted in Ukraine over the past decades, namely, Paragigagnatus Amitai & Grinberg, Carinoseius Wainstein, Kampimodromus Nesbitt, Eharius Tuttle & Muma, Typhlodromips De Leon, Euseius Wainstein. It provides the main elements of the characteristics of these taxa: detailed species redescriptions are accompanied by species identifiers, drawings, morphological data and measurements, diagnoses, places of storage of types, data on the distribution of species in the world and Ukraine, places of residence, estimation of abundance etc.

Still a good dog! Long-term use and effectiveness of livestock guardian dogs to protect livestock from predators in Australia’s extensive grazing systems

Context Livestock predation is a significant problem for livestock producers all over the world. Livestock guardian dogs (LGDs) can protect livestock from predators, but little is known about the factors that affect their use over long periods of time. Aims Our aims were to investigate the long-term use of LGDs in Australia and determine whether their effectiveness remained high over time, and to establish the reasons for discontinued use. We also wanted to collect data on the fate of LGDs, and how using LGDs affected the use of other methods for predation control. Last, we wanted to estimate the rate at which the use of LGDs is spreading through word-of-mouth. Methods We re-contacted participants from a previous survey of LGD users in Australia and interviewed them about their long-term experience. We were able to include 82% (112) of the original participants, a mean of 8.9 (±0.08) years after the first survey. Key results Half of all original participants were still using LGDs, and in most cases the effectiveness of LGDs had not changed since the first survey. The main reason for ceasing use of LGDs was a change in business that made the dogs unnecessary, followed by unwanted behaviour of dogs, and problems with neighbours. Most LGDs that died prior to old age were euthanised, fell victim to lethal predator control, or were killed by wildlife. Farmers with LGDs reduced other forms of predation control. Informal information transfer among farmers is leading to a net increase in the use of LGDs in Australia. Conclusions LGDs can remain an effective predator control method in Australia with long-term use, and their use is spreading. However, a substantial number of livestock producers experience difficulties in properly training and managing LGDs, leading to failure of the method in some cases and presumably limiting uptake. Implications Given the effectiveness of LGDs for predation management and the many advantages gained by their use, Australia could greatly benefit from programs by government or management agencies both to promote uptake of LGDs and to reduce the incidence of problems by providing farmers with advice and information on best-practice management.

Predatorska stenica Nesidiocoris tenuis (Heteroptera: Miridae), prirodni neprijatelj štetnih insekta u plasteničkoj proizvodnji paradajza

Species of zoophytophagous genus Dicyphina, plant bugs (Hemiptera: Miridae: Bryocorinae) are among the most abundant and effective predators of tomato pests. Nesidiocoris tenuis Reuter, 1895 (Hemiptera: Miridae) is the predominant species of Dicyphina sp. and it is considered to be a major natural enemy of insect pests in tomato crops in the Mediterranean region. This predatory bug is proved to be particularly successful in suppressing Tuta absoluta Meadow, 1917 (Lepidoptera: Gelechiidae), a major pest of tomato in greenhouse production. Aims of the study were to 1) investigate the efficiency of the mirid predatory bug N. tenuis in greenhouse tomato production and 2) to estimate the possibilities of its application in commercial vegetable production in Western Balkan countries of Europe. The significance of the study results relies on the possibility of commercialisation and general promotion of biological agent N. tenuis in tomato production in South East part of Europe, where the usage of pesticides still dominates the field of plant protection, both in vegetables and other agricultural sectors. According to the obtained results, the biological agent N. tenuis represents a reliable tool for controlling the level of the tomato leaf miner population by keeping the pest below its economic and intervention threshold.

Outer Membrane Porin F in E. coli Is Critical for Effective Predation by Bdellovibrio.

Bdellovibrio and like organisms (BALOs) are a unique bacterial group that live by predating on other bacteria, consuming them from within to grow and replicate before the progeny come out to complete the life cycle. The mechanisms by which these predators recognize their prey and differentiate them from nonprey bacteria, however, are still not clear. Through genetic knockout and complementation studies in different Escherichia coli strains, we found that Bdellovibrio bacteriovorus strain 109J recognizes outer membrane porin F (OmpF) on the E. coli surface and that the activity of the E. coli EnvZ-OmpR regulatory system significantly impacts predation kinetics. OmpF is not the only signal by which BALOs recognize their prey, however, as B. bacteriovorus could eventually predate on the E. coli ΔompF mutant after prolonged incubation. Furthermore, recognizing OmpF as a prey surface structure was dependent on the prey strain, as knocking out OmpF protein homologues in other prey species, including Escherichia fergusonii, Klebsiella pneumoniae, and Salmonella enterica, did not always reduce the predation rate. Consequently, although OmpF was found to be an important surface component used by Bdellovibrio to efficiently recognize and attack E. coli, future work is needed to determine what other prey surface structures are recognized by these predators. IMPORTANCE Bdellovibrio bacteriovorus and like organisms (BALOs) are Gram-negative predatory bacteria that attack other Gram-negative bacteria by penetrating their periplasm and consuming them from within to obtain the nutrients necessary for the predator's growth and replication. How these predators recognize their prey, however, has remained a mystery. Here, we show that the outer membrane porin F (OmpF) in E. coli is recognized by B. bacteriovorus strain 109J and that the loss of this protein leads to severely delayed predation. However, predation of several other prey species was not dependent on the recognition of this protein or its homologues, indicating that there are other structures recognized by the predators on the prey surface that are yet to be discovered.

Far from home: Bat activity and diversity in row crop agriculture decreases with distance to potential roost habitat

As demand for food increases, agricultural production is poised to increase dramatically. Pesticides are commonly used to maintain high crop yield, though they have several drawbacks, including reduced efficacy over time and harmful effects to human and ecosystem health. Bats are highly effective predators of crop pests and have great potential to reduce crop damage resulting from insects. However, few studies have investigated how pest control by bats might change over large expanses of continuous row crop agriculture, which is common in the midwestern USA. Agricultural landscapes offer few roosting opportunities and could be difficult for bats to traverse, which might affect the degree of ecosystem services provided by bats. We hypothesized that with increasing distance into uninterrupted row crop agriculture 1) bat activity would decrease and 2) bat species richness would decrease, but that these effects would be buffered when insect pest abundance is high. We deployed 50 acoustic bat detectors over 10 transects in east-central Illinois from July to September 2021. In each transect, we placed detectors on crop field edges at increasing distance from a large riparian corridor assumed to be frequented by bats. Bat activity was high across the landscape but declined by 56% from the forest edge to 4000 m into row crop agriculture, while bat diversity decreased by 34%. Pest abundance seemed to decrease overall bat activity but had no effect on bat diversity. These results indicate that bats, although able to have a large effect on crop pest reduction, might not be as efficient in suppressing crop pests in vast uninterrupted agricultural landscapes which offer scant roost availability. Our work will inform recommendations to landowners and private lands managers on ways to increase bat access to roosts and forest cover near agricultural areas, thereby enhancing the potential for bats to provide pest control services.

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.

Efficacy of native cyclopoid copepods in biological vector control with regard to their predatory behavior against the Asian tiger mosquito, Aedes albopictus

BackgroundThe control of the Asian tiger mosquito Aedes albopictus (Diptera: Culicidae) is crucial owing to its high vector competence for more than 20 arboviruses—the most important being dengue, chikungunya and Zika virus. Aedes albopictus has an enormous adaptive potential, and its invasive spreading across urban and suburban environments poses challenges for its control. Therefore, all suitable, cost-effective and eco-friendly control tools should be put into practice. In this context, cyclopoid copepods are already known as effective predators of mosquito larvae. This study reports an essential preliminary step towards the integration of copepods into the vector control strategy in Germany, in order to provide a sustainable tool in an integrated control strategy based on the elimination or sanitation of breeding sites, the use of formulations based on Bacillus thuringiensis israelensis (Bti.) and the sterile insect technique (SIT).MethodsThe predatory potential of native cyclopoid copepods, namely the field-derived species Megacyclops viridis (Crustacea: Cyclopidae), was examined against the larvae of Ae. albopictus, and for comparison, against the larvae of the common house mosquito, Culex pipiens sensu lato (Diptera: Culicidae). The use of different larval instars as prey, and various predator-to-prey ratios, were examined under laboratory and semi-field conditions. The compatibility of Bti. applications along with the use of copepods was assessed in the laboratory.ResultsHigh predation efficiency of M. viridis upon first-instar larvae of Ae. albopictus was observed under laboratory (up to 96%) and semi-field conditions (65.7%). The copepods did not prey upon stages further developed than the first instars, and in comparison with Ae. albopictus, the predation rates on the larvae of Cx. pipiens s.l. were significantly lower.ConclusionsThe results indicate a high predation potential of M. viridis against Ae. albopictus larvae, even though strong larval stage and mosquito species preferences were implicated. The integration of copepods as a promising biocontrol agent to the vector control strategy in Germany is therefore highly recommended, especially because of the excellent compatibility of copepods with the use of Bti. However, further research is required, concerning all the probable parameters that may impact the copepod performance under natural conditions.Graphical

Impact of constant temperatures on population characteristics of Amblyseuis swirskii (Acari: Phytoseiidae)

Temperature can influence the developmental rate and reproductive potential of herbivorous insects and mites. Amblyseius swirskii Athias-Henriot is an effective phytoseiid predator with a significant ability to repress pest populations. To better understand the effect of temperature on the performance of A. swirskii, we studied temperature-dependent population growth and reproductive potential of the predatory mite under six constant temperatures (20, 22, 25, 27, 30, and 32°C), providing 75 ± 5% RH and a photoperiod of 16 L: 8 D h. The average fecundity was 12.85, 18.24, 22.2, 27.24, 28.6, and 52.57 eggs/female at 20–32°C, respectively. The highest gross reproductive rate (GRR= 26.08 eggs/individual), net reproductive rate (R0= 22.51 eggs/individual), and intrinsic rate of increase (r= 0.174 day−1) were recorded at 27°C. The finite rate of increase (λ) and mean generation time (T) of A. swirskii were profoundly affected by temperature and varied from 1.101 to 1.190 day−1 and 10.85 to 19.09 days, respectively. Data obtained during this study indicated that 27°C is the best temperature for rearing this predatory mite. This study improves our findings of the temperature range to optimize the mass rearing of A. swirskii as an effective predatory mite.

The Control of the Desert Locusts (Schistocerca Gregaria) in Somalia During the Upsurge Between 2019 and 2021

The desert "empty quarter" area of Saudi Arabia, together with Oman and, Yemen, was hit by a cyclone in May 2018, that resulted in vegetation flourishing and enabled the locust population present to increase 400-fold over the following six months. Following a second cyclone in October 2018, the population continued to increase an estimated 8000-fold. Swarms of these locusts in March 2019 flew east into southern Iran and thence to India and Pakistan. A change in wind direction enabled others to fly south into Yemen, where a civil war hindered any control operations. From Yemen, swarms moved to Ethiopia and Somalia in October 2019 and later into Kenya. In contrast to most countries, nomadic pastoralists in Somalia are nearly two-thirds of the population and occupy about two-thirds of the country. The ecology of nomadic pastoralism is an adaptation to an environment in which the availability of water and grass are critical factors. The life of pastoralists differs significantly from sedentary agriculturalists and is based on natural resource management that respects the limitations imposed on their environment, the necessity for mobility. To protect the pastoral system, the Government was concerned about the applying insecticides over vast areas due to the adverse impact on bees in the environment and on livestock that grazed on the pastures. Assisted by FAO, it was decided that locusts had to be controlled by the biopesticide, based on the fungus Metarhizium acridum, which produces a toxin that kills only locusts and related grasshoppers. The biopesticide, originally called "Green Muscle" was developed in the LUBILOSA Project organised with international funding and managed by CABI (Prior et al. 1992; Lomer et al. 2001). Developments in the production of the biopesticide had reduced costs and it is more effective to apply, although it takes longer to kill locusts, it can spread through a population and be particularly effective against the hopper bands of young locusts before they fly. Since 2004, the use of Metarhizium acridum had increased in China from only 5% to over 30% as over 100,000 hectares were treated. An advantage of the biopesticide is that birds are not killed and remain effective predators of the locusts. The programme confirmed the importance of using the biopesticide to protect the environment from the use of hazardous chemical insecticides. It also indicated that there were a number of Key challenges that had to be faced, namely: Difficulty in carry out field evaluations during intensive control operations; Remoteness of control areas where caged experiments could not be conducted; Limited number of government officers capable of carrying out field / laboratory assessments; Lack of suitable laboratory facilities to carry out subsequent observations on field collected samples; Narrow daily window for control operations with Metarhizium acridum operations are required as the air temperature quickly rises beyond 30°C as early as 11.00am; Sparse vegetation cover in semiarid areas affecting barrier treatment approach using aircraft.

Ovipositional response of Antilochus coquebertii and Dysdercus koenigii in different media under controled conditions

Cotton stainer, red cotton bug (Dysdercusspp., Heteroptera: Pyrrhocoridae) is one of the economical pest of cotton crop. Pyrrhocorid bugs have multiple hosts and are highly mobile, rendering their insecticidal control less effective. Among pyrrhocorid bugs, Antilochus coquebertii (Heteroptera: Pyrrhocoridae) is considered highly effective predator of cotton stainers. However, predator and prey proportion and their ecological behavior are very important and there is no previous study regarding oviposition behaviour both of predator and prey. In this study, effects of different media on the fecundity both of predator (A. coquebertii) and prey (D. koenigii) were explored for the first time under controlled conditions. Eight different media consisted of Dry Soil + Dry Leaves (DSDL), Dry Soil + Wet Leaves (DSWL), Wet Soil + Dry Leaves (WSDL), Wet Soil + Wet Leaves (WSWL), Dry Soil (DS), Wet Soil (WS), Dry Soil + Cylindrical Perforated Plastic Bottle (DS-CPPB), and Wet Soil + Cylindrical Perforated Plastic Bottle (WS-CPPB). The results revealed significantly higher number of egg batches both of predator and prey on WSWL followed by WSDL. It is, therefore concluded that both the predator and prey preferred WSWL and WSDL media for egg deposition.

Natural enemies of Pentalonia nigronervosa Coquerel, a vector of bunchy top of banana and biology of its most effective predator Scymnus nubilus Mulsant

Natural enemies of Pentalonia nigronervosa Coquerel (Hemiptera: Aphididae), a vector of bunchy top of banana, are reported from Tamil Nadu, South India. Totally four predators including three coccinellids (Pseudaspidimerus trinotatus (Thunberg), Scymnus (Scymnus) nubilus Mulsant, Cheilomenes sexmaculata (F.)) and one hemerobiid (Micromus timidus Hagen) were recorded. Only one parasitoid, Aphelinus sp. nr. gossypii Timberlake (Hymenoptera: Aphelinidae) was recorded. Biology of S. nubilus, the most effective predator of P. nigronervosa, was also studied in the laboratory and the results are presented.

Effect of Abiotic Climatic Factors on the Gonadal Maturation of the Biocontrol Agent Sphaerophoria rueppellii (Wiedemann, 1830) (Diptera: Syrphidae).

Simple SummaryKnowledge about the morphology and functioning of the male and female reproductive system in insects is key to understanding their reproductive biology, and to assessing the effects that environmental factors, such as temperature or photoperiod, can have on oviposition, fecundity, and lifespan. This knowledge is particularly interesting in those species that are mass-reared, as in the case of the predatory syrphid Sphaerophoria rueppellii. Given the lack of published information regarding sexual maturation in syrphids, this type of study, applied to beneficial insects used as biological control agents, offers, firstly, the chance to improve their mass breeding under controlled conditions and, secondly, to know their capability for pest control response under field conditions. Our results show that photoperiod and temperature affect development and gonad maturation in S. rueppellii males and females.The hoverfly Sphaerophoria rueppellii is currently one of the most effective predators commercially available for aphid pest control. However, knowledge of the reproductive system of males and females of this syrphid is limited. The present article aims to report how changes in the temperature and photoperiod may affect development of the gonads (ovaries and testes), oviposition, and fecundity during the lifespan of S. rueppellii. Four environmental conditions (14L:10D, T: 20 ± 1 °C; 12L:12D, T: 20 ± 1 °C; 14L:10D, T: 25 ± 1 °C; and 12L:12D, T: 25 ± 1 °C) were used to determine oviposition, hatching percentage, and lifespan during a period of 30 days after the adult emergence. The maturation of the ovaries was done under three treatments (barley leaves with aphids always available; barley leaves two days per week with aphids available; no barley leaves available), and in the same environmental conditions noted above. Males at 14L:10D, 20 ± 1 °C; and 14L:10D, 25 ± 1 °C; were used to analyze and study the maturation of the testes. Females at 14L:10D; T: 25 ± 1 °C showed a significant difference in oviposition, percentage of hatching, and rate of eggs. A detailed description of the male and female gonads was undertaken, and it was determined that the conditions in which males sexually mature early are at 14L:10D, 25 ± 1 °C. These results will improve the application of S. rueppellii in crops, for the control of aphid pests.

Ants (Hymenoptera: Formicidae) increase predation of Belenois solilucis (Lepidoptera: Pieridae) eggs in organic agriculture production systems: a multiple-site field study at Rashad, Sudan

Organic farming is becoming more popular as there is a greater demand for pesticide-free food. Pest control in organic agricultural production requires a set of skills, including the identification of effective predators and land-use practices. Predation by selected Coleopteran, Dipteran, and Hemipteran insects and Araneae is well established, whereas the predatory role of ants (Hymenoptera: Formicidae) has received little attention in the Rashad district, Sudan. This study was carried out to assess the predation rates of Belenois solilucis eggs and the impact of the land use type around the properties on these rates. An experimente involving predation tests on Belenois solilucis eggs and fauna sampling were conducted in 18 areas of organic agriculture in the Rashad district. The study showed that ants can reduce the eggs population by 26.8% per day. At the same time, other predator taxa, primarily Coleoptera, from Coccinellidae and Staphylinidae families, removed only 13% of the eggs. Ant species with the most significant recruiting power were Axinidris acholli, Tapinoma carininotum, and Technomyrmex moerens. Ant genera such as Linepithema, Dorymyrmex, and Camponotus ants were also frequently observed. The proportion of the planted area within a 500-meter radius, in addition to the interaction of other landscape categories, had a minor influence on predation, but only when the predators were not ants. The landscape does not affect predation by predators in general, including ants, or on ant predation in particular.

Contrasting patterns from two invasion fronts suggest a niche shift of an invasive predator of native bees.

BackgroundThe accuracy of predictions of invasive species ranges is dependent on niche similarity between invasive and native populations and on our ability to identify the niche characteristics. With this work we aimed to compare the niche dynamics of two genetically related invasive populations of Vespa velutina (an effective predator of honeybees and wild pollinators), in two distinct climatic regions, one in central Europe and another one in the north-western Iberian Peninsula, and hence to identify uninvaded regions susceptible to invasion.MethodsNiche dynamics and shifts of V. velutina were assessed by comparing the environmental niches of the native and of the two invasive populations, using climatic, topographic and land use variables. We also ran reciprocal distribution models using different algorithms and records from both native and invasive ranges to compare model predictions and estimate which regions are at a greater risk of being invaded.ResultsAn apparent niche shift was detected in the population of the NW of Iberian Peninsula, where the species is living under environmental conditions different from the native niche. In central Europe, large suitable areas remain unoccupied. The fact that both invasive populations are well established, despite occupying environmentally distinct regions indicates that V. velutina has a high ability to successfully invade different environmental envelopes from those existing in its native range. For example, in north-western Iberian Peninsula the species is now thriving out of its native niche limits. Moreover, the large extent of still unoccupied environmental space with similar conditions to those used by the species in its native range suggests that there is still a large area of central and eastern Europe that can be potentially invaded by the species.

Use of UV-LED light to enhance establishment of Nesidiocoris tenuis for control of Bemisia tabaci infesting greenhouse tomato

Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae) is a major pest of greenhouse tomato and Nesidiocoris tenuis (Reuter) (Hemiptera: Miridae) is an effective predator of this whitefly. Previously, we found that 385 nm LED lighting improved the predatory performance of N. tenuis on B. tabaci under laboratory conditions, ostensibly via mutual attraction of bugs and whiteflies to this wavelength, and improved aggregation of both insects around the light sources. Here we verified that LED lighting at 385 nm enhances the establishment of N. tenuis releases on tomato plants infested with B. tabaci under greenhouse conditions. In the first trial, conducted May-July, both whiteflies and predators were released three times; whitefly densities were not affected by LED lighting when predators were absent, but ended the experiment at lower densities when N. tenuis releases were combined with LED lighting than when they were not. In a second trial, conducted September-November under cooler conditions, a single whitefly release established an infestation and was followed by a single release of N. tenuis in two treatments, with and without LED. The LED lighting treatment maintained lower whitefly densities over a two month period in the crop, and higher densities of predators, than the predators-only treatment. Therefore, possible applications of short wavelength LED lighting to enhance N. tenuis augmentation programs in greenhouse settings appear worthy of further evaluation.

Analysis of mammal mesopredator scat samples indicates significant predation on the endangered Hungarian meadow viper (Vipera ursinii rakosiensis)

Animal populations are regulated by multiple factors, e.g. resource availability, diseases and predators. However, these factors can be significantly influenced by anthropogenic effects (e.g. biological invasions, mesopredator release) and either subserve populations or push them towards local extinction. The Hungarian meadow viper Vipera ursinii rakosiensis is an endangered reptile, with only a few surviving populations following recent alterations and fragmentation of their habitats. In Hungary, all documented populations are located within nature conservation areas. Significant practical conservation efforts have been made, including habitat reconstruction and development, as well as ex situ breeding and reintroductions. Nevertheless, the estimated overall population size of Hungarian meadow viper remains very low, and the impact of conservation interventions is practically immeasurable according to low densities. It is hypothesized that predation is the main factor interfering with conservation efforts of the vipers. Here, we analysed the diet of two mammalian predators (European badger and red fox) in a Hungarian meadow viper habitat. We found a high prevalence of viper remains in the processed faecal samples, indicating that a high number of individuals vipers are subject to predation even within a short period of time. We conclude that effective predator control might be necessary to increase the impact of standard conservation measures (e.g. habitat development, ex situ breeding and reintroduction) that target the restoration of Hungarian meadow viper populations.

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.

Lakshmi Nayak: striving to contain the brain's deadliest killers

High-grade gliomas and CNS lymphoma are some of the most effective predators this world has seen. Aggressive, elusive, and seemingly able to resurrect like a supernatural being, they are also the domain of Lakshmi Nayak, a neuro-oncologist serving as director of the Center for CNS Lymphoma within the Center for Neuro-Oncology at Dana-Farber Cancer Institute in Boston, MA, USA. Nayak, who was born in the coastal Indian state of Goa and grew up in Mumbai, had always aspired to be a scientist, and at an early age was “fascinated by the functioning of the brain and the nervous system”.

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.

Social predation by ants as a mortality source for an arboreal gregarious forest pest

Biocontrol of caterpillars by ants is highly variable, and we investigate how the strength of the trophic relationship between ants and an important outbreaking forest pest depends on phenological synchrony and on social foraging. We test the hypothesis that early spring foraging by ants, coupled with eusocial recruitment behavior, could undermine the caterpillar's strategies to achieve either enemy-free space or predator satiation.We use a series of field surveys and experiments in trembling aspen stands (Populus tremuloides) in the boreal forest of eastern Canada to assess the role of ants in early-instar mortality of the outbreaking, gregarious forest tent caterpillar (Malacosoma disstria). We also investigate individual-level mechanisms related to phenology and social behavior that underlie the effectiveness of ants as biocontrol on caterpillars. Our results show that ants climb trees early in the spring and harvest young forest tent caterpillars, suggesting that early phenology does not provide an entirely enemy-free space for caterpillars. Our findings further show that recruitment-based social foraging enables ants to deplete groups of gregarious prey, suggesting that these eusocial insects are particularly effective at generating predation pressure on gregarious herbivores since they do not satiate easily. Finally, a manipulative predator exclusion experiment confirms that ant predation is a significant mortality source for early-instar forest tent caterpillars. Taken together, these results suggest that phenology and sociality could modulate the role of ants as effective caterpillar predators and thus showcase the importance of considering natural history and behavioral traits when studying trophic interactions and their role in population dynamics.