Inducing a summer brood break increases the efficacy of oxalic acid vaporization for Varroa destructor (Mesostigmata: Varroidae) control in Apis mellifera (Hymenoptera: Apidae) colonies.

The ectoparasitic mite, Varroa destructor (Anderson and Trueman), is the leading cause of western honey bee colony, Apis mellifera (L.), mortality in the United States. Due to mounting evidence of resistance to certain approved miticides, beekeepers are struggling to keep their colonies alive. To date, there are varied but limited approved options for V. destructor control. Vaporized oxalic acid (OA) has proven to be an effective treatment against the dispersal phase of V. destructor but has its limitations since the vapor cannot penetrate the protective wax cap of honey bee pupal cells where V. destructor reproduces. In the Southeastern United States, honey bee colonies often maintain brood throughout the year, limiting the usefulness of OA. Prior studies have shown that even repeated applications of OA while brood is present are ineffective at decreasing mite populations. In the summer of 2021, we studied whether incorporating a forced brood break while vaporizing with OA would be an effective treatment against V. destructor. Ninety experimental colonies were divided into 2 blocks, one with a brood break and the other with no brood break. Within the blocks, each colony was randomly assigned 1 of 3 treatments: no OA, 2 g OA, or 3 g OA. The combination of vaporizing with OA and a forced brood break increased mite mortality by 5× and reduced mite populations significantly. These results give beekeepers in mild climates an additional integrated pest management method for controlling V. destructor during the summer season.

Impact of a nonnative parasitoid species on intraspecific interference and offspring sex ratio.

In an assemblage of multiple predators sharing a single prey species, the combined effects of the component species may scale unpredictably because of emergent interspecific interactions. Prior studies suggest that chaotic but persistent community dynamics are induced by intra-/interspecific interactions between native and nonnative parasitoids competing over a shared host. Here, we test the impact of the nonnative parasitoid Heterospilus prosopidis (Hymenoptera: Braconidae) on the intraspecific interference and offspring sex ratio of the native parasitoid Anisopteromalus calandrae (Hymenoptera: Pteromalidae). We found that the nonnative parasitoid reduced intraspecific interference among native parasitoids and decreased the proportion of female offspring produced by the native parasitoid (predicted under conditions of reduced host availability). At higher host densities, the nonnative parasitoid contributed less to the total proportion of hosts parasitized, as its innate saturating Type II response changed to a dome-shaped Type IV response with increasing density of the native parasitoid, while the native parasitoid retained its increasing Type I response. This inverse host-density-dependent response between the two parasitoids and associated competitive superiority can explain the observed changes in parasitism; at high host densities, the searching efficiency of the native parasitoid increases via host feeding while the nonnative parasitoid experiences egg limitation. These results highlight the importance of the complementary top-down effects of multiple consumers on a single resource.

Identification of pathogens in the invasive hornet Vespa velutina and in native Hymenoptera (Apidae, Vespidae) from SW-Europe.

Invasive species contribute to deteriorate the health of ecosystems due to their direct effects on native fauna and the local parasite-host dynamics. We studied the potential impact of the invasive hornet Vespa velutina on the European parasite-host system by comparing the patterns of diversity and abundance of pathogens (i.e. Microsporidia: Nosematidae; Euglenozoa: Trypanosomatidae and Apicomplexa: Lipotrophidae) in European V. velutina specimens with those in the native European hornet Vespa crabro, as well as other common Hymenoptera (genera Vespula, Polistes and Bombus). We show that (i) V. velutina harbours most common hymenopteran enteropathogens as well as several new parasitic taxa. (ii) Parasite diversity in V. velutina is most similar to that of V. crabro. (iii) No unambiguous evidence of pathogen release by V. velutina was detected. This evidence together with the extraordinary population densities that V. velutina reaches in Europe (around of 100,000 individuals per km2 per year), mean that this invasive species could severely alter the native pathogen-host dynamics either by actively contributing to the dispersal of the parasites and/or by directly interacting with them, which could have unexpected long-term harmful consequences on the native entomofauna.

Impact of Environmental Variables on Parasitism and Emergence of Trichogramma pretiosum, Telenomus remus and Telenomus podisi.

Environmental variables may markedly influence egg parasitoid performance and must be considered when choosing the best release strategy. Thus, this study aimed to investigate the effects of light, temperature, soil moisture, and precipitation on the emergence and parasitism of parasitoid releases of unprotected and encapsulated pupae. The presence of light favored the parasitism of Trichogramma pretiosum Riley, 1879, and Telenomus remus (Nixon, 1937) but did not impact the parasitism of Telenomus podisi (Ashmead, 1893). The release strategy adopted (release of encapsulated or unprotected pupae) also impacted the results. On one hand, card capsules gave protection against rainfall, limited to 10 mm regarding Tr. pretiosum, while on the other hand, card capsules led to a reduction in the number of captured adults for Te. podisi at 25°C and 30°C. Therefore, Tr. pretiosum, Te. remus, and Te. podisi can be released using both encapsulated and unprotected pupae, with advantages and disadvantages for each strategy, depending on each studied environmental variable. In addition, parasitoid pupae should be released so that the majority emerge during daylight, especially for Te. remus and Tr. pretiosum, since parasitism was greatly reduced in dark environments. Telenomus podisi is not affected by this variable as it demonstrated similar parasitism in light and dark environments.

Effect of Leaf Maturity on Host Habitat Location by the Egg-Larval Parasitoid Ascogaster reticulata.

Adoxophyes honmai, a serious pest of tea plants, prefers to lay eggs on mature tea leaves rather than young leaves. Here, we examined a hypothesis that Ascogaster reticulata, an egg-larval parasitoid of A. honmai, increases the likelihood of encountering host egg masses by searching mature tea leaves when host-derived cues are not available. In a dual-choice bioassay using a four-arm olfactometer, A. reticulata preferred odor from intact, mature leaves versus young leaves. Based on volatile analysis with gas chromatography-mass spectrometry (GC-MS), we identified 5 and 10 compounds from mature and young leaf volatiles, respectively. The 5 components in the extract from intact mature leaves included (Z)-3-hexenyl acetate, (E)-ß-ocimene, linalool, (E)-4,8-dimethyl-1,3,7-nonatriene (DMNT), and methyl salicylate. When each individual compound, or quaternary and quintenary blends of them, ratios of which were adjusted to match those of mature leaf volatiles, were provided, parasitoids preferred the full mixture and the quaternary blend devoid of DMNT to the solvent control. Methyl salicylate, one of the components of preferred blends, was not detected among young leaf volatiles. We concluded that the volatile composition of tea leaves changes, depending on their maturity, and that this composition affects foraging behavior of the parasitoid, which is closely related to the host herbivore's oviposition preference.

Molecular identification of Stylops advarians (Strepsiptera: Stylopidae) in western Canada.

Strepsiptera are an enigmatic order of insects with extreme sexual dimorphism which makes it difficult to "match-up" free-living adult males with parasitic conspecific females of the Stylopidia, and free-living females of the Mengenillidae using morphological characters. Species identification is further complicated for the Stylopidia because adult females are endoparasitic and neotenic. Therefore, we used DNA sequencing of the mitochondrial cytochrome c oxidase subunit 1 gene (cox1) to confirm the species identity of adult strepsipterans that were morphologically identified as Stylops advarians. These specimens, collected from Saskatoon (Saskatchewan, Canada), included one adult male, and eight females, the latter of which had been collected from solitary bees (Andrena milwaukeensis). Also included in the analyses were three pools of first-instar larvae that had emerged from three of the females. The results of the molecular analyses revealed that all specimens had an identical cox1 sequence, and belonged to a clade, with total statistical support (bootstrap value of 100%), that contained specimens of S. advarians from New York and Maine (USA). Hence, the results were consistent with the morphological identification of S. advarians. This study demonstrates the usefulness of a molecular approach for the identification of endoparasitic adult female and larval strepsipterans, life cycle stages that lack significant morphological characters for species identification.

Multivariate ratio analysis and DNA markers reveal a new Australian species and three synonymies in eucalypt-gall-associated Megastigmus (Hymenoptera: Megastigmidae).

The genus Megastigmus Dalman, 1820 (Hymenoptera: Megastigmidae) contains potential biocontrol agents of the invasive eucalypt galling chalcid Leptocybe spp. (Hymenoptera: Eulophidae), with several species reported in various parts of the world. Species discrimination is challenging due to intraspecific morphological variation, difficulty in measuring sizes of body parts, and the lack of information regarding the global distribution of parasitic Megastigmus. We used two species commonly associated with Leptocybe in its native range to review taxonomic methods and determine the most reliable morphological characters in species delimitation. We examined size variation of body characters, and conducted species discrimination using multivariate ratio analysis, mitochondrial Cytochrome c oxidase subunit 1 (COI) and nuclear 28S rDNA (28S) sequences. Morphological traits were effective in species delimitation yet revealed high variation in several characters employed in current keys. Knowledge generated on morphology and DNA justified the description of a new species, M. manonae, sp. n., the first record of M. pretorianensis in Australia, and revised diagnostic characters for M. zvimendeli. Based on these diagnostic characters and molecular data, we synonymize three species (M. judikingae, syn. n., from Australia, M. sichuanensis, syn. n., from China and M. icipeensis, syn. n., from Kenya) with M. zvimendeli. Our findings highlight the importance of molecular markers in assisting taxonomic decision-making and the need for coordinated work in identifying Megastigmus associated with Leptocybe spp.

Phylogeny and biogeography of the cleptoparasitic bee genus Epeolus (Hymenoptera: Apidae) and cophylogenetic analysis with its host bee genus Colletes (Hymenoptera: Colletidae).

The bee genus Epeolus Latreille (Hymenoptera: Apidae) consists of 109 species, which are known to be exclusively cleptoparasites of polyester (or cellophane) bees of the genus Colletes Latreille (Hymenoptera: Colletidae). Both genera have a nearly cosmopolitan distribution and are represented on all continents except Antarctica and Australia. We present the most comprehensive phylogeny for Epeolus to date, based on combined molecular and morphological data. In total, 59 ingroup taxa (species of Epeolus) and 7 outgroup taxa (other Epeolini) were scored for 99 morphological characters, and sequence data were obtained for seven genes (one mitochondrial and six nuclear, 5399 bp in total). Epeolus was found to be monophyletic, with a crown age estimated to be 25.0-13.4 Ma (95% HPD) and its origins traced to the Nearctic region. Epeolus was found to contain six major clades, five of which were well supported. The evolutionary history of Epeolus is explored in the context of earth history events and the evolutionary history of its host genus Colletes, for which a molecular phylogeny was constructed based on the same seven genes. A comparison of Epeolus and Colletes phylogenies limited to taxa for which there is evidence of an association suggests there was some cospeciation. However, more cladogenetic events in Epeolus were linked to instances of dispersal/vicariance. It is not yet clear the extent to which allopatric speciation contributed to diversification in Colletes, but the genus' success in having colonized and diversified across much of the globe made it possible for Epeolus to do the same.

Do parasitoid density and host age affect the parasitism of Palmistichus elaeisis (Hymenoptera: Eulophidae)? / Densidade de parasitoides e idade do hospedeiro afetam o parasitismo de Palmistichus elaeisis (Hymenoptera: Eulophidae)?

The incidence of lepidopteran defoliants is one of the environmental factors that regulate the productivity of cultivated forests. The parasitoid Palmistichus elaeisis (Hymenoptera: Eulophidae) has significant importance for its efficiency in the parasitism of pupae of these Lepidoptera. The objective of this study was to evaluate the development and reproduction of P. elaeisis in different densities of pupae of Spodoptera frugiperda (Lepidoptera: Noctuidae) at different ages. Pupae of 24, 48, 72 and 96 hours were exposed at densities of 1:1, 4:1, 10:1, 19:1, 31:1 and 46:1 parasitoids/host, respectively. The parasitoids remained in contact with the pupae for 72 hours in 500 mL plastic pots, conditioned in an air-conditioned room, with temperature of 25 ± 2°C, relative humidity of 70 ± 10% and photoperiod of 12 hours. It was concluded that the density of 10:1 presented great results of parasitism, and further increase of density was not needed. Pupae of 24 and 48 hours had a higher percentage of emergence. Biological variables were affected neither by parasitoid densities nor by host age.(AU)

A incidência de lepidópteros desfolhadores é um dos fatores ambientais que regulam a produtividade das florestas plantadas. O endoparasitoide Palmistichus elaeisis (Hymenoptera: Eulophidae) destaca-se pela eficiência no parasitismo e pode ser promissor no controle de Lepidoptera pragas em diversas culturas com importância econômica. Assim, avaliaram-se o desenvolvimento e a reprodução de P. elaeisis em pupas de Spodoptera ­frugiperda (Lepidoptera: Noctuidae) com idades distintas submetidas a diferentes densidades do parasitoide. Pupas de 24, 48, 72 e 96 horas foram expostas às densidades de 1:1, 4:1, 10:1, 19:1, 31:1 e 46:1 parasitoides/hospedeiro. Os parasitoides permaneceram em contato com as pupas por 72 horas em potes plásticos de 500 mL, acondicionados em sala climatizada com temperatura 25 ± 2°C, umidade relativa de 70 ± 10°C e fotoperíodo de 12 horas. A densidade 10:1 apresentou resultados adequados de parasitismo. Pupas de 24 e 48 horas de idade apresentaram maior porcentagem de emergência. O ciclo de vida, o número de indivíduos emergidos, a razão sexual, a longevidade das fêmeas e o comprimento da cápsula cefálica e da tíbia de P. elaeisis não foram afetados pelas densidades do parasitoide nem pela idade do hospedeiro.(AU)

Within the fortress: A specialized parasite is not discriminated against in a social insect society.

Social insect colonies function cohesively due, in part, to altruistic behaviors performed towards related individuals. These colonies can be affected by parasites in two distinct ways, either at the level of the individual or the entire colony. As such, colonies of social insects can experience conflict with infected individuals reducing the cohesiveness that typifies them. Parasites of social insects therefore offer us a framework to study conflicts within social insect colonies in addition to the traditionally viewed conflicts afforded by groups of low genetic relatedness due to multiple mating for example. In our study, we use the behavior manipulating fungal pathogen, Ophiocordyceps kimflemingiae (= unilateralis) and its host, Camponotus castaneus, to ask if colony members are able to detect infected individuals. Such detection would be optimal for the colony since infected workers die near foraging trails where the fungus develops its external structures and releases spores that infect other colony members. To determine if C. castaneus workers can detect these future threats, we used continuous-time point observations coupled with longer continuous observations to discern any discrimination towards infected individuals. After observing 1,240 hours of video footage we found that infected individuals are not removed from the colony and continuously received food during the course of fungal infection. We also calculated the distances between workers and the nest entrance in a total of 35,691 data points to find infected workers spent more time near the entrance of the nest. Taken together, these results suggest healthy individuals do not detect the parasite inside their nestmates. The colony's inability to detect infected individuals allows O. kimflemingiae to develop within the colony, while receiving food and protection from natural enemies, which could damage or kill its ant host before the parasite has completed its development.

Field efficacy of Bacillus thuringiensis galleriae strain SDS-502 for the management of alfalfa weevil and its impact on Bathyplectes spp. parasitization rate.

Alfalfa weevil, Hypera postica Gyllenhal, is an important pest in forage alfalfa worldwide, and especially so on the Northern Plains of North America. Neither the weevil-specific fungus, Erynia phytonomi, nor the weevil's parasitoids are able to routinely suppress outbreaks as they do in the eastern U.S. A new Bacillus thuringiensis var. galleriae, having a Cry8Da coleopteran-active toxin, has been recently commercialized. We examined the efficacy of this B. thuringiensis product against the H. postica in replicated field trials in north central Montana. Because it has been suggested that efficiency of the parasitoids, Bathyplectes curculionis and Oomyzus incertus, was inversely proportional to host numbers (i.e., parasitoid efficiency increased when host population is low), we also sought to determine if a partial reduction of larval H. postica populations with a B. thuringiensis would yield to greater parasitoid efficiency, manifested as higher percent parasitism among the surviving larvae. The B. thuringiensis gave 27-40% reduction in weevil numbers at the low label rate, 55-59% for the high label rate. Mean parasitism at the two research locations varied from 5-26% and 17-36% respectively, but application of the B. thuringiensis had no significant effect on parasitism levels, i.e. parasitism was not greater in treated than in carrier control plots.

Selection of parasitoids of the genus Trichogramma (Hymenoptera: Trichogrammatidae) and parasitism at different eggs ages of Duponchelia fovealis (Lepidoptera: Crambidae) / Seleção de parasitoides do gênero Trichogramma (Hymenoptera: Trichogrammatidae) e parasitismo em ovos de diferentes idades de Duponchelia fovealis (Lepidoptera: Crambidae)

The European pepper moth Duponchelia fovealis (Zeller, 1847) (Lepidoptera: Crambidae), despite being among the principal pests of strawberries in Brazil. However, biological control methods are rarely documented for this pest. In the current study, the goal was to select promising Trichogramma strains to enable the control of D. fovealis and to determine the acceptance of different ages of host eggs by the parasitoid. In the first bioassay, evaluations were done on the biological parameters of five strains of Trichogramma pretiosum Riley and one of Trichogramma galloi Zucchi (Hymenoptera: Trichogrammatidae). The best performance came from the strains, Tp18 (T. pretiosum) and Tg (T. galloi), showing parasitism and viability higher than 50 and 90%, respectively. Another bioassay revealed the acceptance of both these species (Tp18 and Tg) for different ages of D. fovealis eggs. All host ages were accepted by T. pretiosum (Tp18) and T. galloi, with a preference for younger eggs (65% parasitism). Adult emergence, number of individuals per egg and sex ratio revealed no significant differences with respect to the host age. The current study provides pertinent data on the selection and performance of Trichogramma species on D. fovealis eggs of different ages.

A traça do morangueiro Duponchelia fovealis (Zeller, 1847) (Lepidoptera: Crambidae) é uma das principais pragas da cultura do morango no Brasil. Entretanto, métodos de controle biológico desta praga são raramente documentados. Este trabalho teve como objetivo selecionar linhagens de Trichogramma e avaliar o parasitismo de diferentes idades de ovos de D. fovealis. Foram avaliados os parâmetros biológicos de cinco linhagens de Trichogramma pretiosum Riley e uma de Trichogramma galloi Zucchi (Hymenoptera: Trichogrammatidae). As espécies/linhagens com melhor desempenho foram Tp18 (T. pretiosum) e Tg (T. galloi), com taxas de parasitismo e viabilidade acima de 50 e 90%, respectivamente. Em seguida, foi avaliada a suscetibilidade das duas espécies (Tp18 e Tg) em diferentes idades de ovos de D. fovealis. Todas as idades do ovo hospedeiro avaliadas foram aceitas pelos dois parasitoides e houve uma maior tendência a parasitar ovos mais jovens. Em todas as idades do hospedeiro houve emergência de parasitoides adultos, e sem diferença significativa entre idades. As variáveis número de indivíduos por ovo e razão sexual não apresentaram diferença significativa quanto à idade do hospedeiro. O atual estudo fornece informações sobre a seleção e o desempenho de espécies de Trichogramma em diferentes idades de ovos de D. fovealis.

Does the high density of trichomes influence the parasitism of Liriomyza sativae by Opius scabriventris on melon cultivars? / A alta densidade de tricomas influencia no parasitismo de Liriomyza sativae por Opius scabriventris em cultivares de meloeiro?

Opius scabriventris (Hymenoptera: Braconidae) is considered an important parasitoid of the leafminer Liriomyza sativae (Diptera: Agromyzidae) in the main melon (Cucumis melo L.) producing areas in Brazil. However, there is no information on the influence of trichomes on melon plant leaves on the parasitoids' actions. Therefore, the aim of this investigation was to relate the influence of columnar trichome density on melon cultivars in the parasitism of L. sativae larvae by O. scabriventris. The study was conducted in laboratory conditions, in which melon cultivars were infested and the leafminer larvae were subjected to the parasitism. The results demonstrated that trichome density can influence the parasitism of L. sativae larvae by O. scabriventris. Among the studied materials, Piel de Sapo cultivar showed the highest density of trichomes in the leaves (534 trichomes/cm2) and the lowest parasitism (20%).(AU)

Opius scabriventris (Hymenoptera: Braconidae) é considerado um importante parasitoide da mosca-minadora Liriomyza sativae (Diptera: Agromyzidae) nas principais áreas de produção de melão (Cucumis melo L.) do Brasil, no entanto, não há informações se a densidade de tricomas das folhas do meloeiro pode influenciar a ação desses parasitoides. Portanto, o objetivo deste trabalho foi relatar a influência da densidade de tricomas colunares de cultivares de meloeiro no parasitismo de L. sativae por O. scabriventris. O trabalho foi realizado em condições de laboratório, em que os cultivares foram infestados e as larvas da mosca-minadora submetidas ao parasitismo. Os resultados demonstraram que a densidade dos tricomas pode influenciar no parasitismo de larvas de L. sativae por O. scabriventris. Entre os materiais estudados, o cultivar pele-de-sapo apresentou a maior densidade de tricomas nas folhas (534 tricomas/cm2) e o menor parasitismo (20%).(AU)

Biological characters of Trichogramma dendrolimi (Hymenoptera: Trichogrammatidae) reared in vitro versus in vivo for thirty generations.

Trichogramma dendrolimi which is an economically important biological control agent were reared for 30 generations on a modified artificial medium and natural host. Biological characters were assessed and compared with parasitoids reared in vivo. Pupation rate and normal adults rate of in vitro-reared parasitoids were significantly higher compared with in vivo-reared parasitoids. The adult emergence rate, number of adults produced, and fecundity of T. dendrolimi reared in vitro were lower than those reared in vivo. The percentage of females and longevity did not vary between the two rearing methods. The overall fitness of the parasitoids reared artificially from the first to the 20th generation was higher than of those reared from the 21st generation onwards. No differences were observed in the fitness parameters of parasitoids reared in vivo across any of the 30 generations. The results suggest that the modified artificial medium used in this study is suitable for the continuous rearing of T. dendrolimi for at least 20 generations, and has the potential for the mass production of these parasitoids for use in biological control. Such a substrate could be examined for use in rearing other parasitoid species that are important in biological control.

Interactions Among Latitude, Nematode Parasitization, and Female Sirex nigricornis (Hymenoptera: Siricidae) Fitness.

Sirex nigricornis F. (Hymenoptera: Siricidae) is an innocuous pine-inhabiting woodwasp native to eastern North America, utilizing dead or dying pine trees as hosts. Although S. nigricornis F. does not cause economic damage, a closely related species, Sirex noctilio, was discovered in New York in 2004 and has continually spread throughout the northeastern United States and southern Canada, threatening the multi-billion-dollar pine timber industry of the southeastern United States and raising interest about potential interactions with native woodwasps and associated mortality agents. A non-sterilizing strain of the biological control agent, Deladenus siricidicola Bedding (Tylenchida: Neotylenchidae), was introduced along with S. noctilio but is not inhibiting the spread or establishment of S. noctilio A North American congener, Deladenus proximus Bedding, has been recently isolated from S. noctilio and shows promise as a biological control agent. To better understand the potential of D. proximus as a control agent for S. noctilio, we measured and dissected nearly 1,200 S. nigricornis females from Arkansas and Mississippi and evaluated differences among collection location with regard to nematode virulence, woodwasp body size, and egg load. Body size and egg load were related to collection location, and nematode infestation resulted in significantly smaller females who produced significantly fewer eggs. Female woodwasps, especially those collected in Arkansas, were often fully sterilized by nematodes, and a higher percent sterilization was inversely related to body size and fewer eggs. We propose field studies to test the nematode's ability to sterilize S. noctilio in the northeastern United States.

Tree phylogenetic diversity promotes host-parasitoid interactions.

Evidence from grassland experiments suggests that a plant community's phylogenetic diversity (PD) is a strong predictor of ecosystem processes, even stronger than species richness per se This has, however, never been extended to species-rich forests and host-parasitoid interactions. We used cavity-nesting Hymenoptera and their parasitoids collected in a subtropical forest as a model system to test whether hosts, parasitoids, and their interactions are influenced by tree PD and a comprehensive set of environmental variables, including tree species richness. Parasitism rate and parasitoid abundance were positively correlated with tree PD. All variables describing parasitoids decreased with elevation, and were, except parasitism rate, dependent on host abundance. Quantitative descriptors of host-parasitoid networks were independent of the environment. Our study indicates that host-parasitoid interactions in species-rich forests are related to the PD of the tree community, which influences parasitism rates through parasitoid abundance. We show that effects of tree community PD are much stronger than effects of tree species richness, can cascade to high trophic levels, and promote trophic interactions. As during habitat modification phylogenetic information is usually lost non-randomly, even species-rich habitats may not be able to continuously provide the ecosystem process parasitism if the evolutionarily most distinct plant lineages vanish.

Attack and Success of Native and Exotic Parasitoids on Eggs of Halyomorpha halys in Three Maryland Habitats.

Egg parasitoids of the exotic invasive brown marmorated stink bug, Halyomorpha halys (Stål), were investigated using lab-reared fresh (live) and frozen (killed) lab-reared sentinel egg masses deployed for 72h on foliage in three habitats-woods, orchard, and soybean field-in Maryland, USA, in summer 2014. Four native hymenopteran species, Telenomus podisi Ashmead (Scelionidae), Trissolcus euschisti (Ashmead) and Tr. brochymenae Ashmead (Scelionidae), and Anastatus reduvii (Howard) (Eupelmidae), developed and emerged from H. halys eggs. One exotic parasitoid, Trissolcus japonicus (Ashmead), emerged, providing the first known occurrence of this species in North America. Native parasitoids emerged from frozen eggs significantly more often than from fresh eggs (89.3% of egg masses and 98.1% of individual eggs), whereas the exotic Tr. japonicus did not show a similar difference, strongly suggesting adaptation to H. halys as a host by Tr. japonicus but not by the native species. Parasitoids were habitat-specific: all three Trissolcus species were significantly more likely to occur in the woods habitat, whereas Te. podisi was found exclusively in the soybean field. Further investigations are required to elucidate evolving host-parasitoid relationships, habitat specificity, and non-target effects of Tr. japonicus over the expanded range of H. halys in North America.

Effect of Wheat Cultivars and Blends on the Oviposition and Larval Mortality of Cephus cinctus (Hymenoptera: Cephidae) and Parasitism by Bracon cephi (Hymenoptera: Braconidae).

The wheat stem sawfly (Cephus cinctus Norton) is a major historical pest of wheat in the northern Great Plains of North America. The insect spends most of its life as a larva protected inside grass stems so that its management has relied on strategies other than insecticides. We conducted a study in southern Alberta from 2006-2009 to assess the effects of wheat species, cultivar, seeding rate, and blending a resistant and a vulnerable cultivar, on oviposition, larval infestation, and cutting damage. The mortality caused by its primary parasitoid, Bracon cephi (Gahan), was also assessed to investigate the potential benefit of cultivar blends to enhance sawfly biological control. Sawfly laid fewer eggs on plants of the durum cultivar 'AC Avonlea' and on those of the solid-stemmed cultivar 'Lillian' compared to plants of the hollow-stemmed cultivar 'CDC Go.' Larval establishments (infestation) followed a similar pattern to that of oviposition. At these locations there was low cutting damage in most years and to a large extent this was due to mortality inflicted by the parasitoid Bracon cephi (40-60%). However, the remaining mortality was attributed to other factors and host, particularly the inclusion of the solid-stemmed cultivar. Direct and indirect factors likely affected the success of the parasitoid in the crop monocultures and blends, and these mechanisms require further research.

Side effects of Bacillus thuringiensis var. kurstaki on the hymenopterous parasitic wasp Trichogramma chilonis.

Most of the detrimental effects of using conventional insecticides to control crop pests are now well identified and are nowadays major arguments for replacing such compounds by the use of biological control agents. In this respect, the bacterium Bacillus thuringiensis var. kurstaki and Trichogramma (Hymenoptera: Trichogrammatidae) parasitic wasp species are both effective against lepidopterous pests and can actually be used concomitantly. In this work, we studied the potential side effects of B. thuringiensis var. kurstaki on Trichogramma chilonis females. We first evidenced an acute toxicity of B. thuringiensis on T. chilonis. Then, after ingestion of B. thuringiensis at sublethal doses, we focused on life history traits of T. chilonis such as longevity, reproductive success and the time spent on host eggs patches. The reproductive success of T. chilonis was not modified by B. thuringiensis while a significant effect was observed on longevity and the time spent on host eggs patches. The physiological and ecological meanings of the results obtained are discussed.

Anagrus breviphragma Soyka Short Distance Search Stimuli.

Anagrus breviphragma Soyka (Hymenoptera: Mymaridae) successfully parasitises eggs of Cicadella viridis (L.) (Homoptera: Cicadellidae), embedded in vegetal tissues, suggesting the idea of possible chemical and physical cues, revealing the eggs presence. In this research, three treatments were considered in order to establish which types of cue are involved: eggs extracted from leaf, used as a control, eggs extracted from leaf and cleaned in water and ethanol, used to evaluate the presence of chemicals soluble in polar solvents, and eggs extracted from leaf and covered with Parafilm (M), used to avoid physical stimuli due to the bump on the leaf surface. The results show that eggs covered with Parafilm present a higher number of parasitised eggs and a lower probing starting time with respect to eggs washed with polar solvents or eggs extracted and untreated, both when the treatments were singly tested or when offered in sequence, independently of the treatment position. These results suggest that the exploited stimuli are not physical due to the bump but chemicals that can spread in the Parafilm, circulating the signal on the whole surface, and that the stimuli that elicit probing and oviposition are not subjected to learning.