The genus Rhagoletis (Diptera: Tephritidae) comprises more than 65 species distributed throughout Europe, Asia and America, including many species of high economic importance. Currently, there are three Rhagoletis species that infest fruits and nuts in Europe. The European cherry fruit fly, Rhagoletis cerasi (may have invaded Europe a long time ago from the Caucasian area of West Asia), and two invasive species (recently introduced from North America): the eastern American cherry fruit fly, R. cingulata, and the walnut husk fly, R. completa. The presence of different Rhagoletis species may enhance population dynamics and establish an unpredictable economic risk for several fruit and nut crops in Europe. Despite their excessive economic importance, little is known on population dynamics, genetics and symbiotic associations for making sound pest control decisions in terms of species-specific, environmental friendly pest control methods. To this end, the current paper (a) summarizes recently accumulated genetic and population data for the European Rhagoletis species and their association with the endosymbiont Wolbachia pipientis, and (b) explores the possibility of using the current knowledge for implementing the innovative biological control methods of sterile insect technique and incompatible insect technique.

Hypotheses about the worldwide colonization routes of the melon fly, Zeugodacus cucurbitae (Diptera: Tephritidae), are mainly based on sparse historical records. Here we aim at reconstructing the colonization history of the African continent based on an improved description of the population structure of Z. cucurbitae and approximate Bayesian analyses. Individuals of Z. cucurbitae were sampled in 17 localities from East, West and Central Africa and genotyped at 19 microsatellite markers. Bayesian analyses showed intracontinental population structuring with populations from Uganda diverging from those of Tanzania and populations from Burundi and Kenya showing traces of admixture with West African samples. Approximate Bayesian Computation provided support to the hypothesis of a single introduction Z. cucurbitae into East Africa and subsequent expansion to West Africa, each colonization event was followed by a bottleneck that promoted population divergence within Africa. Parameter estimates suggested that these events are roughly compatible with the historical records of Z. cucurbitae presence in sub-Saharan Africa (viz. 1936 in East Africa and 1999 in West Africa) and allow excluding alternative hypotheses on older or multiple introductions of Z. cucurbitae.

The eastern larch beetle (Dendroctonus simplex Le Conte) is recognized as a serious destructive forest pest in the upper part of North America. Under epidemic conditions, this beetle can attack healthy trees, causing severe damages to larch stands. Dendroctonus species are considered as holobionts, as they engage in multipartite interactions with microorganisms, such as bacteria, filamentous fungi, and yeasts, which are implicated in physiological processes of the insect, such as nutrition. They also play a key role in the beetle's attack, as they are responsible for the detoxification of the subcortical environment and weaken the tree's defense mechanisms. The eastern larch beetle is associated with bacteria and fungi, but their implication in the success of the beetle remains unknown. Here, we investigated the bacterial and fungal microbiota of this beetle pest throughout its ontogeny (pioneer adults, larvae and pupae) by high-throughput sequencing. A successional microbial assemblage was identified throughout the beetle developmental stages, reflecting the beetle's requirements. These results indicate that a symbiotic association between the eastern larch beetle and some of these microorganisms takes place and that this D. simplex symbiotic complex is helping the insect to colonize its host tree and survive the conditions encountered.

Cultivating plant mixtures is expected to provide a higher productivity and a better control of pests and diseases. The structure of the arthropod community is a major driver of the magnitude of natural pest regulations.

With the aim of optimizing pest management, a study was carried out to determine the effect of the cropping system type (tomato mono-cropping vs. mixed-cropping) on the diversity and abundance of arthropods from three trophic groups (herbivores, omnivores, predators) and the abundance of Helicoverpa armigera. Therefore, the diversity of cultivated plants and arthropod communities was assessed within tomato fields from 30 farmer's fields randomly selected in South of Benin. Results showed that the arthropod abundance was significantly higher in mixed-cropping systems compared with mono-cropping systems, although the crop type did not alter significantly the arthropod diversity, evenness, and richness. At the level of taxa, the abundances of generalist predators including ants (Pheidole spp., and Paltothyreus tarsatus) and spiders (Araneus spp. and Erigone sp.) were significantly higher in mixed fields than in mono-crop fields. Then, the abundances of omnivore-predator trophic groups have a negative significant effect on the H. armigera abundance. This study allowed better understanding of how plant diversity associated to tomato fields structures arthropod's food webs to finally enhance the ecological management of H. armigera.

Chitinase is responsible for insect chitin hydrolyzation, which is a key process in insect molting and pupation. However, little is known about the chitinase of Spodoptera exigua (SeChi). In this study, based on the SeChi gene (ADI24346) identified in our laboratory, we constructed the recombinant baculovirus P-Chi for the expression of recombinant SeChi (rSeChi) in Hi5 cells. The rSeChi was purified by chelate affinity chromatography, and the purified protein showed activity comparable with that of a commercial SgChi, suggesting that we harvested active SeChi for the first time. The purified protein was subsequently tested for enzymatic properties and revealed to exhibit its highest activity at pH 8 and 40 C. Using homology modeling and molecular docking techniques, the three-dimensional model of SeChi was constructed and screened for inhibitors. In two rounds of screening, twenty compounds were selected. With the purified rSeChi, we tested each of the twenty compounds for inhibitor activity against rSeChi, and seven compounds showed obvious activity. This study provided new information for the chitinase of beet armyworm and for chitinase inhibitor development.

The northern house mosquito (Culex pipiens pipiens L.) is a vector of several important pathogens and comprises two epidemiologically distinct ecotypes (molestus Forskål and pipiens). The delimitation of its ecotypes is a crucial, yet controversial step in vector surveillance due to varying diagnostic values of different characters. Therefore, we reviewed the success of a diagnostic assay based on the mitochondrial cytochrome c oxidase subunit I locus (COI) by analyzing previously published sequences of molestus and pipiens sampled in different geographical areas. Next, by genotyping individuals from Northern Serbia at this locus, we additionally assessed whether genetic structure of urban and rural Cx. p. pipiens ecotypes corresponded to the admixture pattern. Finally, to account for the different susceptibility of genetic markers to introgression, we also analyzed genetic structuring based on the ribosomal internal transcribed spacer 2 (ITS2). No latitude-dependent differentiation of Cx. p. pipiens ecotypes was found at a global level, with the COI assay further failing to accurately identify molestus and pipiens ecotypes. Likewise, both individual- (BAPS) and population-based (analysis of molecular variance and FST estimates) methods showed no significant urban/rural genetic differentiation in Serbia, indicating unhindered gene flow between different Cx. p. pipiens habitat types. The findings challenge the previous instances of Cx. p. pipiens ecotype identification, while also spotlighting the vectorial capacity of their hybrid offspring.

The establishment of an invasive species depends on reproductive success and dispersion capability in the new environment. One of the striking examples of invasion in urban environments is the mosquito Aedes aegypti Linnaeus, 1762 (Culicidae). The success of this species is primarily attributed to its ability to colonize urban environments, and some of the important adaptive strategies associated with this ability is the preference for humans as a blood source and intense occupation of residential (indoor) environments. This study evaluated the effects of location (indoor vs. outdoor) and water nutrient level (% organic matter) on the oviposition preference of A. aegypti in an urban environment. We used oviposition choice experiments to evaluate mosquito oviposition in containers holding 1:1 vs 1:0 ratios of water: organic matter placed indoors and outdoors. Eggs were sampled once per week for nine weeks. Our results revealed a strong oviposition preference for outdoor containers, with a significant preference for containers with higher concentrations of organic matter during the fifth to ninth weeks. However, mosquitoes occupying indoor environments did not prefer to lay eggs in containers with lower levels of organic matter. A better understanding of the preferences of A. aegypti regarding the nutrient level and location of oviposition containers can increase our understanding of the behavioral factors allowing mosquitoes to utilize anthropogenic environments.

Several elicitors, stimulating induced resistance mechanisms, have potential in preventing or mitigating pathogen infections. Some of these compounds, triggering the production of jasmonic acid (JA), a precursor of herbivore-induced plant volatiles, could also play a central role in indirect resistance to pest species, by improving beneficial arthropod performance, and necrotrophic pathogens. In the current work, Trichoderma gamsii/T. asperellum and silica gel treatments – alone and in combination – were studied to evaluate the plant defence mechanism on grapevines (Vitis vinifera L.) by laboratory and field trials. JA production level was measured before and after Plasmopara viticola infection on potted vines. JA production induced by silica gel was higher than that caused by Trichoderma before infection. In Trichoderma-treated plants, JA production increased after P. viticola inoculation. In vineyard field trials, Mymaridae (Hymenoptera: Chalcidoidea) showed higher captures in transparent sticky traps on silica gel-treated plants, in comparison with control. On the other hand, no significant attraction was detected for Ichneumonoidea and other Chalcidoidea in silica gel and T. gamsii/T. asperellum-treated plants. The potential effects of elicitors are discussed, in the frame of attract and reward strategy.

The is insufficient knowledge of arthropod communities occurring in specific microhabitats. In this study, we characterize the arthropod assemblages inhabiting burrows of the common hamster (Cricetus cricetus L.) and factors that determine their diversity and abundance. We tested the following hypotheses: (1) arthropod assemblages are associated with a particular dominant vegetation occurring in the vicinity of burrows; (2) a correlation exists between fine-scale geographic distances among burrows and assemblage dissimilarity; and (3) the type of trap influences the sampling success of captured arthropods. We found 73 morphospecies belonging to 16 families in 109 burrows, most of which were in the families Staphylinidae (Coleoptera) and Parasitidae (Arachnida: Acari: Mesostigmata). The most abundant families were Staphylinidae, Cryptophagidae (Coleoptera), Parasitidae, and Macrochelidae (Mesostigmata) (78.89%). Among the identified species, we found Aleochara irmgardis (Staphylinidae) and Poecilochirus sexclavatus (Parasitidae) which had not yet been reported in Poland, and several other rare species. Meat-baited traps captured 64.34% more individuals, which were more diverse and species-rich than the non-baited control traps, but the former was more selective for saprophages, necrophages, and coprophages. The burrows located in areas overgrown by triticale (a hybrid of wheat and rye) were inhabited by 69.86% of the identified arthropod species, and these also had the highest abundance (64.07%) in comparison with other habitats. However, differences in sample size biased our results toward and overestimate arthropods associated with this vegetation. This study underlines that the species composition detected in burrows was affected by the methods used and hamster preferences for a specific habitat rather than the geographic proximity of the burrows. More extensive sampling across multiple habitats will be necessary to confirm our findings.

When a promising natural enemy of a key pest exists locally, it is a common practice in biological control (BC) to rear and release it for supplementary control in the targeted agroecosystem even though significant knowledge gaps concerning pre/post release may still exist. Incorporating genetic information into BC research fills some of these gaps. Habrobracon hebetor, a parasitoid of many economically important moths that infest stored and field crops worldwide is commonly used, particularly against the millet head miner (MHM), a key pest of millet in Sahelian countries. To advance our knowledge on how H. hebetor that occurs naturally in open-field cropping systems and grain stores as well as being mass-produced and released for MHM control, performs in millet agroecosystems in Niger we evaluated its population genetics using two mitochondrial and 21 microsatellite markers. The field samples were genetically more diverse and displayed heterozygote excess. Very few field samples had faced significant recent demographic bottlenecks. The mating system (i.e. nonrandom mating with complementary sex determination) of this species may be the major driver of these findings rather than bottlenecks caused by the small number of individuals released and the scarcity of hosts during the longlasting dry season in Niger. H. hebetor population structure was represented by several small patches and genetically distinct individuals. Gene flow occurred at local and regional scales through human-mediated and natural short-distance dispersal. These findings highlight the importance of the mating system in the genetic diversity and structure of H. hebetor populations, and contribute to our understanding of its reported efficacy against MHM in pearl millet fields.

Tuta absoluta (Meyrick), a key pest of tomato, is quickly spreading over the world and biological control is considered as one of the control options. Worldwide more than 160 species of natural enemies are associated with this pest, and an important challenge is to quickly find an effective biocontrol agent from this pool of candidate species. Evaluation criteria for control agents are presented, with the advantages they offer for separating potentially useful natural enemies from less promising ones. Next, an aggregate parameter for ranking agents is proposed: the pest kill rate km. We explain why the predator's intrinsic rate of increase cannot be used for comparing the control potential of predators or parasitoids, while km can be used to compare both types of natural enemies. As an example, kill rates for males, females and both sexes combined of three Neotropical mirid species (Campyloneuropsis infumatus (Carvalho), Engytatus varians (Distant) and Macrolophus basicornis (Stål)) were determined, taking all life-history data (developmental times, survival rates, total nymphal and adult predation, sex ratios and adult lifespan) into account. Based on the value for the intrinsic rate of increase (rm) for T. absoluta and for the kill rate km of the predators, we predict that all three predators are potentially able to control the pest, because their km values are all higher than the rm of the pest. Using only km values, we conclude that E. varians is the best candidate for control of T. absoluta on tomato, with C. infumatus ranking second and M. basicornis last.

The major component of aphid alarm pheromone is (E)-β-farnesene (EβF), but the molecular mechanisms of EβF synthesis are poorly understood. Here we established a biological model to study the modulation of EβF synthesis in the bird cherry-oat aphid Rhopalosiphum padi by using quantitative polymerase chain reaction, gas chromatography/mass spectrometry and RNA interference. Our results showed that the rearing conditions significantly affected the weight of adult and modulated EβF synthesis in a transgenerational manner. Specifically, the quantity of EβF per milligram of aphid was significantly reduced in the individually reared adult or 1st-instar nymphs derived from 1-day-old adult reared individually, but EβF in the nymph derived from 2-day-old adult that experienced collective conditions returned to normal. Further study revealed that the production of EβF started in embryo and was extended to early nymphal stage, which was modulated by farnesyl diphosphate synthase genes (RpFPPS1 and RpFPPS2) and rearing conditions. Knockdown of RpFPPS1 and RpFPPS2 confirmed the role played by FPPS in the biosynthesis of aphid alarm pheromone. Our results suggested that the production of EβF starts at the embryo stage and is modulated by FPPS and rearing conditions in R. padi, which sheds lights on the modulatory mechanisms of EβF in the aphid.

In this study the host plant genotype effect on cabbage aphid, Brevicoryne brassicae (L.)(Hemiptera: Aphididae) preference and performance, the effect of aphid genotype on parasitoids performance, as well as the indirect effects of plant genotypes on aphid parasitoid performance, were tested using different population samples of the aphid and its primary endoparasitoid wasp, Diaeretiella rapae (M'Intosh) (Hymenoptera: Braconidae). Experiments were run as fully-factorial randomized block design in a greenhouse. Accordingly, host plant cultivar had significant effects on the total number of aphids and aphid-load whilst the fitness of the aphid genotypes were also influenced by plant cultivar. The effect of parasitism on cabbage aphids was significantly different between plant cultivars. Overall, the results revealed that cabbage aphid is under different selective pressures arising from both higher (parasitoid) and lower (host plant cultivar) trophic levels. The host plant cultivar had a significant effect on both aphid fitness and parasitism rate on particular aphid genotypes. This indicates that host-plant-adapted aphid species can create much context-dependency in the nature and strength of ‘fitness benefits parasitism’, which may in turn alter the costs and benefits of host specialization.

The aim of this study was to investigate the foraging behavior of Aphidius matricariae (Haliday) (Hymenoptera: Braconidae) as a biological control agent of Myzus persicae nicotianae Blackman (Hemiptera: Aphididae), a key and cosmopolitan pest of tobacco fields. To achieve a strategy for the control of this pest and a mass-rearing program of the parasitoid, host stage preference, switching, functional response, and mutual interference of A. matricariae were investigated at 25 ± 1°C, 70 ± 5% RH and 16:8 h L:D photoperiod. The parasitoid showed a preference for third- and fourth-instar nymphs of tobacco aphid in both choice and no-choice experiments. Using the Murdach's model, switching behavior was observed in A. matricariae between different density proportions of third- and fourth-instar nymphs. Further, the parasitoid exhibited a type II functional response when it was offered to third-instar nymphs of M. persicae nicotianae at six densities (2, 4, 8, 16, 32, and 64). Based on the linear regression analysis, there was a significance difference between the logarithm of per capita searching efficiency and the logarithm of parasitoid density. As the wasp density increased, per capita searching efficiency decreased. The result of this study revealed that A. matricariae is an effective agent in the integrated management of M. persicae nicotianae. In addition, application of these results can be important in mass-rearing program of A. matricariae.