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The evolutionary processes that shape host‐parasitoid coexistence in a changing environment are poorly understood. We examined the large‐scale distribution of highly specialised polysphinctine Darwin wasps associated with spiders along an elevational gradient and tested the hypothesis that distribution and parasitism rates depend on elevation, habitat type and the species and age composition of the host community. Further, on the basis of a large‐scale dataset, we examined the hypothesis that three‐dimensional webs in spiders may be an evolutionary adaptation against polysphinctine parasitoids. We found significant variation in parasitoid distribution and parasitism rates along a 1500 m elevational gradient in central Europe. The optimal model showed a humped shape for the parasitism rate on an elevational gradient. Overall, we found relatively low parasitism rates (4%) on spiders, with the highest parasitism rates in non‐forested riparian vegetation and the lowest in agroecosystems. Rates of parasitism varied significantly among spiders forming different types of webs (foraging guilds). Spiders spinning 3D webs were dominant in the spider community, but parasitism on them was lower compared to spiders spinning 2D webs, probably because of the defensive function of the 3D web architecture. The bottom‐up approach, in which the entire spider host community is analysed for parasitism rate, supports the hypothesis that 3D webs are evolutionarily novel and could have arisen as a result of the need for defence against enemies such as parasitoids. We examined the large‐scale distribution of highly specialised parasitoids associated with spiders along an elevational gradient and tested the hypothesis that distribution and parasitism rates depend on elevation, habitat type and the species and age composition of the host community. Further, on the basis of a large‐scale dataset, we examined the hypothesis that three‐dimensional webs in spiders may be an evolutionary adaptation against polysphinctine parasitoids.

Anastrepha fraterculus (Wiedemann) (Diptera: Tephritidae) is a significant fruit pest of economic and quarantine importance in South America. Biological control using augmentative releases of parasitoids or conservation strategies for these natural enemies are handy tools in integrated fruit fly management programs. The functional response describes the natural enemy consumption rate with increasing resource density. Such information may be relevant for selecting the parasitoid species that is potentially most suitable to serve as a biocontrol agent of A. fraterculus. Furthermore, the number of discarded hosts determined from functional response analysis might be used to estimate suitable host densities, avoiding wastage of larvae/puparia associated with host overproduction. Therefore, the current study aimed to evaluate the functional response of four Neotropical-native parasitoid species commonly associated with species of the Anastrepha genus in the Americas, such as the pupal parasitoid Coptera haywardi (Ogloblin) (Hymenoptera: Diapriidae) and the larval parasitoids Ganaspis pelleranoi (Brèthes) (Hymenoptera: Figitidae), Doryctobracon crawfordi (Viereck), and Opius bellus Gahan (Hymenoptera: Braconidae). The package “frair” from R software was used to determine the functional response type and parameter estimation, enabling selection, fitting, and comparison among standard functional response models and integral parameters. Four relevant conclusions can be highlighted: (a) G. pelleranoi showed a flexible functional response, with a statistically significant deviation to a Type III rather than a Type II response found among the three other parasitoid species; (b) G. pelleranoi had a handling time significantly lower than the other tested parasitoid species; (c) the number of attacked hosts varied among all four parasitoid species, with C. haywardi and G. pelleranoi exhibiting the highest proportion of attacks at low and high host densities, respectively; and (d) the percentage of discarded hosts was significantly low at 1–5 and 1–20 hosts per parasitoid in C. haywardi and G. pelleranoi, respectively, whereas in both D. crawfordi and O. bellus, it was high at any offered host density. Results provide helpful comparative information about the possible performance of these species as biocontrol agents against A. fraterculus populations within augmentative and/or conservative biological control programs.

Dryinidae are a diverse family of parasitoids, and they are important natural enemies of Auchenorrhyncha (Hemiptera) pests. A comprehensive understanding of the diversity and host interaction networks of these parasitoids is critical to their application in biological control programs and their conservation. However, traditional methods such as morphological identification and rearing are insufficient to understand the diversity and host associations of dryinids. In this paper, we assessed the effectiveness of DNA barcode techniques for surveying dryinid diversity and their host associations on the Xisha Islands. Based on the analyses of the mitochondrial cytochrome c oxidase subunit I (COI) sequences of adults and larvae, we recognized 11 dryinid species, including an undescribed species and one re-instated species, on the Xisha Islands. We also confirmed the host associations of each dryinid species and constructed a dryinid–hopper interaction network which suggests that the population sizes of some dryinid species are extremely small and further conservation assessments of dryinids for the Xisha Islands are needed. Our study demonstrates that DNA barcoding methods are potent for assessing parasitoid diversity and their host associations.

Ecologists have long tried, with little success, to develop ecological theory for biological control. Biological control illustrates how science often follows, rather than precedes, technological advances. A scientific theory of biological control remains a worthy and achievable goal. We need to (1) combine deductions from mathematical models with rigorous empiricism measuring and modeling the effects of abiotic and biotic environmental drivers on demography and population dynamics of real biological control systems in the field, (2) use a wider range of model systems to explore how population structure, movement, spatial heterogeneity, and external environmental conditions influence population and community dynamics, and (3) combine deductive and inductive approaches to address the day-to-day concerns of biocontrol scientists including how to rear and release a control organism, suppress the target organism, and minimize harm to non-target organisms. Further progress will require more fundamental research in population and community ecology directly relevant to biological control.

Habrobracon hebetor is a globally acknowledged larval ectoparasitoid that is widely used to control lepidopteran pests. Wolbachia is a natural endosymbiont that regulates various aspects of the insect host biology. The ability of H. hebetor to paralyze and develop on lepidopteran larvae from five families was tested under laboratory conditions. Two lines of the wasp were used, “W+” containing a naturally occurring Wolbachia from the supergroup B, and “W−”, with the endosymbiont eradicated by antibiotic treatment, followed by propagation of 20 subsequent generations. The proportions of larvae in which host paralysis, as well as parasitoid oviposition, larval, pupal, and adult development were observed, were usually higher in W+ compared to W−. In Loxostege sticticalis, differences in these indices were not statistically significant. In Galleria mellonella, Mamestra brassicae, and Ostrinia nubilalis, some of the parasitism indices were significantly higher in W+ than in W−. In Bombyx mori and Plutella xylostella, H. hebetor could not complete its life cycle, but parasitism levels at the initial steps (from paralysis symptoms to the presence of larvae/pupae of the parasitoid) were 2–5 times lower in W− compared to W+ (p < 0.01). It can be suggested that the presence of Wolbachia is advantageous for H. hebetor, as it increases the success of parasitism in a broad range of lepidopteran hosts.

(1) Torymus sinensis, the biocontrol agent of the Asian chestnut gall wasp Dryocosmus kuriphilus, is univoltine, but in NW Italy a small percentage of individuals exhibits a prolonged diapause, mainly as late instar larva. (2) In 2020, the diapause was investigated to evaluate its trend over the years. Due to the low survival rate of diapausing T. sinensis adults, the seasonal variation in the galls’ toughness was evaluated, thus assuming that dry galls over time can negatively affect emergence. The window of vulnerability of the gall wasp galls was also evaluated in controlled conditions. (3) The results showed that the average number of second year T. sinensis emerging per 100 cells was 0.41 ± 0.05, and dead adults accounted for 4.1 ± 0.23 per 100 cells. Gall toughness resulted in lower values for galls collected in May and June, and then gradually increased over time. In general, no difference was detected in the wall toughness of galls formed during the previous year when compared to current-year dry galls. Oviposition was recorded on all the tested galls collected in May and June, and no difference in the number of oviposition events was detected. Conversely, no oviposition was observed in July. Comparing the number of oviposition events by T. sinensis and the gall toughness, a negative correlation was found (R2 = −0.99). (4) The present findings contribute descriptive information on this gall’s structural traits, and the influence on gall wasp management is also discussed.

The first case of parasitoidism of a Myrmicinae ant by a sarcophagid fly has been observed in the Brazilian Cerrado. The larva of a Helicobia Coquillet (Sarcophagidae) specimen fed on head tissues of an Atta laevigata Smith, 1858 soldier and an adult male fly emerged from a puparium formed outside the host. Resumo: O registro do parasitoidismo de uma formiga Myrmecinae por uma mosca Sarcophaginae foi relatado no Cerrado brasileiro. A larva de um exemplar de Helicobia Coquillet (Sarcophagidae) se alimentou dos tecidos da cabeça de um soldado de Atta laevigata Smith, 1858 e um adulto macho emergiu de um pupário que se formou fora do hospedeiro.

The parasitic wasp Anaphes flavipes (Förster, 1841) (Hymenoptera: Mymaridae) is an important egg parasitoid of cereal leaf beetles. Some species of cereal leaf beetle co-occur in the same localities, but the host specificity of the wasp to these crop pests has not yet been examined in detail. A lack of knowledge of host specificity can have a negative effect on the use of this wasps in biological control programs addressed to specific pest species or genus. In this study, laboratory experiments were conducted to assess the host specificity of A. flavipes for three species of cereal leaf beetles (Oulema duftschmidi Redtenbacher, 1874, Oulema gallaeciana Heyden, 1879 and Oulema melanopus Linnaeus, 1758) in central Europe. For the first time, a new host defence against egg parasitoids occurring in O. gallaeciana from localities in the Czech Republic, a strong dark sticky layer on the egg surface, was found and described. The host specificity of A. flavipes was studied in the locality with the presence of this defence on O. gallaeciana eggs (the dark sticky layer) (Czech Republic) and in a control locality (Germany), where no such host defence was observed. Contrary to the idea that a host defence mechanism can change the host specificity of parasitoids, the wasps from these two localities did not display any differences in that. Respectively, even though it has been observed that eggs with sticky dark layer can prevent parasitization, the overall rate of parasitization of the three species of cereal beetles has not been affected. However, in our view, new host defence can influence the effects of biological control, as eggs of all Oulema spp. in the locality are protected against parasitization from the wasps stuck on the sticky layer of the host eggs of O. gallaeciana.

Fil: Salvo, Silvia Adriana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto Multidisciplinario de Biología Vegetal. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto Multidisciplinario de Biología Vegetal; Argentina

Recent studies of parasitoid-host interactions have demonstrated that parasitoids and their hosts are geographically structured for traits such as virulence and encapsulation defenses, but no studies have yet compared the geographic structure of parasitoids and hosts using neutral genetic markers. Such studies of geographic structure are needed to evaluate the underlying geographic scale at which these interactions evolve and allow assessment of the relative effects of selection and gene flow on the geographic structure observed in traits under selection. We used sequence data from the mitochondrial DNA cytochrome oxidase I and II subunits to document and compare the geographic structures of the parasitoid Agathis thompsoni and its moth host Greya subalba. We also documented the geographic structure of G. enchrysa and compared it to the geographic structure of its parasitoid Agathis n. sp. The results demonstrated that parasitoids and their hosts may have incongruent patterns of geographic structure as assessed by molecular markers. As a consequence, the geographic scale at which the interaction evolves may be different for each species involved in the interaction. Depending on the interplay of selection and gene flow, there may not be a one-to-one correspondence of traits important in the interaction between parasitoids and their hosts at the level of local populations. The geographic structures of A. thompsoni and G. subalba and Agathis n. sp. and G. enchrysa provide further evidence of the potential importance of the formation of geographic mosaics in coevolving parasitoid-host interactions and evolving interactions in general.