Melittobia acasta (Hymenoptera: Eulophidae) female longevity and life stage-dependent parasitism using commercially managed Megachile rotundata (Hymenoptera: Megachilidae) as hosts.

Melittobia acasta Walker is one among other hymenopterous parasitoids of Megachile rotundata F. Commercial M. rotundata populations are employed to pollinate North American alfalfa for seed production. This wasp can be prolific when using M. rotundata as a host and can reduce or destroy bee stocks. Hundreds of M. acasta female offspring can develop in a single M. rotundata cell and disperse to infest other cells, producing thousands of more parasitoids. In this study, we determined (i) upon what bee life stages M. acasta females choose to lay eggs and if those eggs ultimately become adults and (ii) M. acasta female longevity when exposed to various resources within M. rotundata cells. We found that M. acasta females lay eggs on M. rotundata prepupae and pupae and that those eggs can hatch and survive to adulthood. Eggs are not laid on early instar bee larvae; eggs laid on adults do not survive. Average female life span is 5 days without feeding, 8-9 days if a pollen-nectar provision is available while the bee develops through larval stages, and 34 days if the wasp can feed on prepupal hemolymph. Wasp females can emerge from bee cells several days after trays of cells are taken to fields. Therefore, adult females could survive long enough for new bee offspring to become prepupae. Our findings support a better understanding of host life stage preference and the longevity of M. acasta females that can inform the timing of the implementation of possible control measures.

Venom is beneficial but not essential for development and survival of Nasonia.

Parasitoid wasps sting and inject venom in arthropod hosts, which alters host metabolism and development while keeping the host alive for several days, presumably to induce benefits for the parasitoid young.Here we investigate the consequences of host envenomation on development and fitness of wasp larvae in the ectoparasitoid Nasonia vitripennis, by comparing wasps reared on live unstung, previously stung, and cold-killed hosts. Developmental arrest and suppression of host response to larvae are major venom effects that occur in both stung and cold-killed hosts, but not unstung hosts; while cold-killed hosts lack venom effects that require a living host. Thus, cold-killed hosts mimic some of the effects of venom, but not others.Eggs placed on live unstung hosts have significantly higher mortality during development, however successfully developing wasps from these hosts have similar lifetime fecundity to wasps from cold-killed or stung hosts. Therefore, although venom is beneficial, it is not required for wasp survival.While wasps developing on cold-killed versus stung hosts have similar fitness, multiple generations of rearing on cold-killed hosts results in significant fitness reductions of wasps.We conclude that the largest benefits of venom are induction of host developmental arrest and suppression of host response to larva (e.g. immune responses), although more subtle benefits may accrue across generations, or under stressful conditions.

Behavioral Modification of Leucauge mariana Induced by an Ichneumonid Spider-Parasitoid, Hymenoepimecis castilloi, in the Colombian Andes.

Hymenoepimecis is a genus of Darwin wasps in the Polysphincta group of genera (Hymenoptera: Ichneumonidae: Pimplinae) known as ectoparasitoids of a broad spectrum of spiders. The parasitoid induces production of a web known as cocoon web, which provides shelter and support for the wasp pupa. In this study, we describe for the first time the interaction between Hymenoepimecis castilloi Pádua & Sääksjärvi (Hymenoptera: Ichneumonidae) and its host spider Leucauge mariana (Taczanowski) (Araneae: Tetragnathidae) in the Colombian Andes, provide new records of wasp genus distribution, and described the behavioral modifications induced in the spider. Web modifications occurred in the webs of both solitary and aggregated individuals. Adhesive spirals were lacking, and webs were connected to vegetation by multiple threads in all cocoon webs, which was not seen attached to webs of non-parasitized spiders. All parasitoid cocoons were observed hanging on a vertical line in the hub of the cocoon web. As previously described for other species, we believe that this modified web design results in increased web strength and favors parasitoid development during the pupal stage.

A New Darwin Wasp (Hymenoptera: Ichneumonidae) and New Records of Behavioral Manipulation of the Host Spider Leucauge volupis (Araneae: Tetragnathidae).

Some ichneumonid wasps of the Polysphincta group of genera (Hymenoptera: Ichneumonidae: Pimplinae) induce behavioral modifications in their host spiders during a specific moment of their development, resulting in the construction of webs that differ in several aspects from those constructed by unparasitized individuals. In this study, we describe the parasitoid wasp Hymenoepimecis pinheirensis sp. n. (Ichneumonidae: Pimplinae) and present information on behavioral modifications in the orb-web structure of its host, the spider Leucauge volupis (Keyserling 1893). Previously, reported observation on this host/parasitoid interaction was restricted to one locality, and the wasp species was misidentified as Hymenoepimecis jordanensis Loffredo and Penteado-Dias 2009. Modified webs built by parasitized spiders lack adhesive spirals and have several radii that converge to the web hub. The cocoon built by the wasp larvae is attached to the web hub, suspended by horizontal radial lines, and surrounded by a tridimensional tangle positioned below the hub. This modified web structure is similar to the most frequent architecture of webs constructed by individuals of Leucauge mariana (Taczanowski 1881) parasitized by Hymenoepimecis tedfordi Gauld 1991. However, cocoon webs built by L. volupis parasitized by H. pinheirensis sp. n. differ from the cocoon webs described for the other Leucauge species parasitized by Hymenoepimecis wasps. This evidence suggests that the modified web pattern in Leucauge species is determined by specific responses of each spider species to the behavioral manipulation mechanism displayed by the wasps.

Limited gains in native parasitoid performance on an invasive host beyond three generations of selection.

Co-evolved natural enemies provide sustainable and long-term control of numerous invasive insect pests, but the introduction of such enemies has declined sharply due to increasing regulations. In the absence of co-evolved natural enemies, native species may attack exotic invasive pests; however, they usually lack adaptations to control novel hosts effectively. We investigated the potential of two native pupal parasitoids, Pachycrepoideus vindemmiae and Trichopria drosophilae, to increase their developmental success on the invasive Drosophila suzukii. Replicated populations of the two parasitoids were subjected to 10 generations of laboratory selection on D. suzukii with Drosophila melanogaster serving as the co-evolved host. We assessed developmental success of selected and control lines in generations 0, 3, and 10. Changes in host preference, sex ratio, development time, and body size were measured to evaluate correlated responses with adaptation. Both parasitoid species responded rapidly to selection by significantly increasing their developmental success on the novel host within three generations, which remained constant for seven additional generations without further improvement. The generalist parasitoid species P. vindemmiae was able to reach similar developmental success as the control populations, while the performance of the more specialized parasitoid T. drosophilae remained lower on the novel than on the co-evolved host. There was no increase in preference towards the novel host over 10 generations of selection nor were there changes in development time or body size associated with adaptation in either parasitoid species. The sex ratio became less female-biased for both parasitoids after three generations of selection but rebounded in P. vindemmiae by generation 10. These results suggest that a few generations of selection may be sufficient to improve the performance of native parasitoids on invasive hosts, but with limits to the degree of improvement for managing invasive pests when exotic co-evolved natural enemies are not available.

Host Deprivation Effects on the Functional Response and Parasitism Rate of Habrobracon hebetor (Hymenoptera: Braconidae) on Ephestia elutella (Lepidoptera: Pyralidae) in the Laboratory.

Habrobracon hebetor (Say) is an important biological control agent for lepidopteran pests of stored products. In this study, the age-specific functional response, paralysis rate, and parasitism rate of H. hebetor under different host deprivation treatments (PC: without host deprivation, used as the control, P1d: host deprivation, but the host was removed after 1 d contact, and PW: host deprivation from beginning) were evaluated at different larval densities (5, 10, 20, 40, and 80) of the Ephestia elutella (Hübner) at 28 ± 1°C, 75 ± 5% RH and 16:8 h L:D. Ages of parasitoid females used were 2, 5, 10, and 20 d old. The logistic regression results indicated that the functional response of H. hebetor females under different host deprivation treatments was type II. The longest handling time was observed in 20-d old females, while the shortest handling time and highest maximum attack rate (T/Th) were estimated at the age of 2 d in all treatments. The paralysis and parasitism rates of H. hebetor were the highest at 2, 5, and 10-d old in all treatments. The results of this study suggest that H. hebetor females up to 10-d old can be used as an efficient biological control agent against E. elutella. The data of this study can also be used to predict the efficacy of different aged H. hebetor females in controlling E. elutella populations.

Temperature-Dependent Biological Control Effectiveness of Tamarixia radiata (Hymenoptera: Eulophidea) Under Laboratory Conditions.

The parasitism rate and host-feeding rate of Tamarixia radiata (Hymenoptera: Eulophidae), an ectoparasitoid of Diaphorina citri (Hemiptera: Liviidae), were evaluated at 20, 27.5, 30, and 35°C, at 70 ± 5% RH, and 14 h of photoperiod. The biological control efficacy of T. radiata was evaluated by linking the age-stage predation rate with the two-sex life table. The net host-feeding rate (C0) by T. radiata was 32.05, 54.40, 17.25, and 1.92 nymphs per female parasitoid at 20, 27.5, 30, and 35°C, respectively. The total net nymphs killing rate (Z0) was 103.02, 223.82, 72.95, and 6.60 nymphs per female parasitoid at 20, 27.5, 30, and 35°C, respectively. Noneffective parasitism rate was observed at 35°C because of high mortality at this temperature. Our results indicated that temperature had meaningful effects on parasitism and host-feeding rate parameters in the laboratory, and may affect biological control efficiency of the parasitoid in the field. The highest host-feeding rate and total biological control efficiency of T. radiata were recorded at 27.5°C. Most importantly, we found that host-feeding activity of the parasitoid is temperature-dependent, and changed across temperature regimes: the host-feeding rate increased as the temperature increased up to 30°C, started to decrease after this temperature and declined to its minimum level at 35°C. This information is valuable for developing biological control and integrated pest management techniques for Asian citrus psyllid management.

A review of the spider-attacking Polysphinctadizardi species-group (Hymenoptera, Ichneumonidae, Pimplinae), with descriptions of seven new species from South America.

The Neotropical Polysphinctadizardi species-group is revised. We describe seven new species from South America: P.bonita sp. nov., P.cosnipata sp. nov., P.inca sp. nov., P.macroepomia sp. nov., P.organensis sp. nov., P.pichincha sp. nov., and P.teresa sp. nov. In addition, we provide a diagnosis and an identification key to all species of the group.

First description of the male of Solenura ania (Walker) (Hymenoptera: Pteromalidae), a giant pteromalid parasitoid of Trichoferus campestris (Faldermann), with special reference to its sexual dimorphism.

BACKGROUND: The giant pteromalid wasp Solenura ania (Walker) has a distinct sexual dimorphism. The metallic blue female is about 28 mm long and the metallic green male is only about 6 mm in length. This species is an ectoparasitoid of some woodborers, such as Trichoferus campestris (Faldermann), a pest of many live trees and wood furniture and a quarantine pest in many countries. However, the male of this pteromalid was not described prior to this study. NEW INFORMATION: The male of the species is first described, based on newly-collected material. Photographs of habitus, head, mesosoma, metasoma and other structures of both sexes are provided to facilitate recognition of this giant pteromalid. Sexual dimorphism is also compared in the present study.

Optimizing Parasitoid and Host Densities for Efficient Rearing of Ontsira mellipes (Hymenoptera: Braconidae) on Asian Longhorned Beetle (Coleoptera: Cerambycidae).

Ontsira mellipes Ashmead is a gregarious larval ectoparasitoid of woodboring cerambycids. It is native to North America but can readily attack the exotic Asian longhorned beetle, Anoplophora glabripennis (Motschulsky). This study aimed to develop an efficient rearing system for this parasitoid, as a potential novel association biocontrol agent for the beetle, by investigating the effects of different densities of host (two, three, or four larvae) and parasitoid (one, two, three, four, five, six, seven, and eight female wasps) on Ontsira's parasitization efficiency and reproductive outcomes. Results showed that overall parasitism and total numbers of parasitized hosts or progeny produced increased with host and/or parasitoid densities, but the number of parasitized hosts or progeny produced per female parasitoid decreased with parasitoid density at each given host density. Nonlinear regression indicated a consistent pattern of mutual interference as parasitoid density increased. Additional experiments showed that superparasitism (indirect interference) did not occur probably because the parasitoid detects hosts through vibration cues from host feeding and attacked (thus paralyzed) hosts are no longer detectable. Thus, the interference probably results from direct or exploitative competition. Interestingly, female parasitoids responded to increased parasitoid density with a significant increase in clutch size. Overall, per capita parasitization efficiency or reproductive outcomes were optimized at a low parasitoid-host ratio but with large group size of hosts and parasitoids. Therefore, an optimal combination of exposing three or four parasitoids to four hosts is proposed for efficient mass-rearing of this parasitoid.

A new genus and species of Neotropical gregarious braconine parasitoid (Hymenoptera: Braconidae) of a caterpillar (Lepidoptera: Hesperiidae).

A new genus of braconine parasitoid wasp, Acgorium Sharkey Quicke gen. nov., based on a new species from Costa Rica, Acgorium felipechavarriai Sharkey sp. nov., is described and illustrated, based on specimens reared from wild-caught hesperiid caterpillars of Dyscophellus phraxanor (Hewitson). Acgorium felipechavarriai is the first known braconine gregarious ectoparasitoid of a butterfly caterpillar.

Koinobint life style of the spider wasp Minagenia (Hymenoptera, Pompilidae) and its consequences for host selection and sex allocation.

Spider wasps of the genus Minagenia have evolved koinobiontism as a relatively rare life strategy within the widely diversified hymenopteran family Pompilidae. In this study, we evaluated several aspects of the parasitic strategy of the wasp Minagenia sp. (hereafter, Minagenia) - namely host specificity, ontogeny, and sex determination as a function of host size. We found that Minagenia is highly host specific, being associated only with the genus Lycosa from the family Lycosidae, namely Lycosa u-album (Mello-Leitão, 1938), Lycosa erythrognatha (Lucas, 1836) and Lycosa poliostoma (Koch, 1847) with a parasitism incidence of 18.9%, 15.8% and 12.5%, respectively. Both ecological and taxonomical host traits determine the host selection and sex allocation of Minagenia female wasps. Charnov's host-size model explains Minagenia's host-size-dependent sex ratio in combination with the effect of host development stage, host species, and host foraging strategy. We also found that the final instar larva of Minagenia induces behavioural changes in spider hosts. The manipulated spider builds a protective silk chamber as a shelter for parasitoid pupation. Our results suggest that host manipulation seems to be narrowly connected with koinobiont life style throughout Hymenoptera. This study provides new information about the host-parasitoid koinobiont life strategy among spider wasps, which probably arose convergently in distant taxonomical groups within Pompilidae.

The Venom of the Ectoparasitoid Wasp Pachycrepoideus vindemiae (Hymenoptera: Pteromalidae) Induces Apoptosis of Drosophila melanogaster Hemocytes.

The pupal ectoparasitoid Pachycrepoideus vindemiae injects venom into its fly hosts prior to oviposition. We have shown that this venom causes immune suppression in Drosophila melanogaster pupa but the mechanism involved remained unclear. Here, we show using transgenic D. melanogaster with fluorescent hemocytes that the in vivo number of plasmatocytes and lamellocytes decreases after envenomation while it has a limited effect on crystal cells. After in vitro incubation with venom, the cytoskeleton of plasmatocytes underwent rearrangement with actin aggregation around the internal vacuoles, which increased with incubation time and venom concentration. The venom also decreased the lamellocytes adhesion capacity and induced nucleus fragmentation. Electron microscopy observation revealed that the shape of the nucleus and mitochondria became irregular after in vivo incubation with venom and confirmed the increased vacuolization with the formation of autophagosomes-like structures. Almost all venom-treated hemocytes became positive for TUNEL assays, indicating massive induced apoptosis. In support, the caspase inhibitor Z-VAD-FMK attenuated the venom-induced morphological changes suggesting an involvement of caspases. Our data indicate that P. vindemiae venom inhibits D. melanogaster host immunity by inducing strong apoptosis in hemocytes. These assays will help identify the individual venom component(s) responsible and the precise mechanism(s)/pathway(s) involved.

A new species of Acrotaphus Townes (Hymenoptera: Ichneumonidae: Pimplinae) from the Brazilian Amazon, with notes on its host spider behavioral modification.

Some Ichneumonidae wasps, including the genus Acrotaphus Townes, 1960 (Ephialtini: Pimplinae), induce behavioral modification in their spider hosts. Acrotaphus is a New World parasitoid wasp genus with 26 described species. This genus belongs to the Polysphincta genus group, which are ectoparasitoids of spiders of the Araneidae. In this study, we describe a new species (Acrotaphus wagnerianae sp. n.) found in the Brazilian Amazon. In addition, we discuss for the first time the behavioral modification of spiders of the Wagneriana genus (Araneidae) by wasps of the Polysphincta genus group.

Two new species of Zatypota (Hymenoptera: Ichneumonidae, Pimplinae) sharing the same host spider in Northeast Brazil.

 Some polysphinctine wasps of the genus Zatypota complete their life cycles upon theridiid host spiders. The host range of these wasps is usually species-specific, although in some less common associations more than one wasp species interacts with the same host spider. Here we describe and illustrate the polysphinctine wasps Zatypota baezae sp. n. and Zatypota mulunguensis sp. n. (Hymenoptera: Ichneumonidae), both koinobiont ectoparasitoids of the spider Anelosimus baeza (Theridiidae). The two parasitoid wasps show the same development time (12 days) which was longer when compared with other parasitoid wasps Z. anomala Holmgren and Z. riverai Gauld (nine days). As described for other species of Zatypota and Hymenoepimecis, the second larval instar remains attached to the spider by the remains of the chorion and also by a rigid brownish-semitransparent membrane called a saddle.

The Pupal Ectoparasitoid Pachycrepoideus vindemmiae Regulates Cellular and Humoral Immunity of Host Drosophila melanogaster.

The immunological interaction between Drosophila melanogaster and its larval parasitoids has been thoroughly investigated, however, little is known about the interaction between the host and its pupal parasitoids. Pachycrepoideus vindemmiae, a pupal ectoparasitoid of D. melanogaster, injects venom into its host while laying eggs on the puparium, which regulates host immunity and interrupts host development. To resist the invasion of parasitic wasps, various immune defense strategies have been developed in their hosts as a consequence of co-evolution. In this study, we mainly focused on the host immunomodulation by P. vindemmiae and thoroughly investigated cellular and humoral immune response, including cell adherence, cell viability, hemolymph melanization and the Toll, Imd, and JAK/STAT immune pathways. Our results indicated that venom had a significant inhibitory effect on lamellocyte adherence and induced plasmatocyte cell death. Venom injection and in vitro incubation strongly inhibited hemolymph melanization. More in-depth investigation revealed that the Toll and Imd immune pathways were immediately activated upon parasitization, followed by the JAK/STAT pathway, which was activated within the first 24 h post-parasitism. These regulatory effects were further validated by qPCR. Our present study manifested that P. vindemmiae regulated the cellular and humoral immune system of host D. melanogaster in many aspects. These findings lay the groundwork for studying the immunological interaction between D. melanogaster and its pupal parasitoid.

Natural Parasitism of Diaphorina citri (Hemiptera: Psyllidae) Collected From Two Host Plants in the Apatzingán Valley, Mexico, by Tamarixia radiata (Hymenoptera: Eulophidae).

Tamarixia radiata (Waterson) (Hymenoptera: Eulophidae) is an idiobiont ectoparasitoid of the Asian citrus psyllid, Diaphorina citri Kuwayama (Hemiptera: Psyllidae). This study evaluated natural parasitism of the different nymphal instars of D. citri by T. radiata on three different dates in 2015 at four sites with Mexican lemon (Citrus aurantifolia Swingle) groves and at one site with orange jasmine (Murraya paniculata [L.] Jacq.) plants in the Apatzingán Valley, Michoacán state. Different patterns of parasitism by T. radiata were observed among the different nymphal instars of D. citri, sites, and collection dates. No parasitism of first and second instars was observed, and it only reached up to 5.0% in third instars. In fourth and fifth instars, parasitism was highly variable (2-69 and 1-38%, respectively). In terms of the accumulated parasitism across host instars, the highest percentages were observed in the collections conducted in May in Crucero de Parácuaro (86%) and Antúnez (91%), and they were approximately 45% in the collections conducted on 23 March in Antúnez and on 10 April in Nueva Italia-2. In the remaining collections, parasitism was between 2 and 15%. Our results suggest that T. radiata is an important mortality factor for populations of D. citri; this could have potentially important implications for the biological control of D. citri and for the management of huanglongbing, a disease transmitted by D. citri, in citrus groves.

A new species of Pnigalio (Hymenoptera, Eulophidae) parasitizing Eriocrania semipurpurella alpina (Lepidoptera, Eriocraniidae) in China, with its biology and a key to Chinese known species.

A new species of Eulophinae, Pnigalio eriocraniae Li & Yang, sp. n., is described and illustrated. This new species is a larval ectoparasitoid of Eriocrania semipurpurella alpina Xu (Lepidoptera, Eriocraniidae), a leaf miner in birch trees, Betula spp. (Betulaceae), in Qinghai Province, northwest China. The biology of the new species and a key to the known species from China are provided.

An enigmatic new genus of Hormiinae (Hymenoptera: Braconidae) from South India.

A new Hormiinae genus Indohormius gen. nov. with type species I. keralensis sp. nov. is described and illustrated. Comparison of this genus with some Hormiinae and Rhyssalinae genera are provided. The composition of the subfamily Hormiinae and the position of the new genus on a molecular phylogenetic tree are discussed.

Parasitism of Hymenoepimecis manauara Pádua & Oliveira (Hymenoptera: Ichneumonidae: Pimplinae) on Leucauge henryi Mello-Leitão (Araneae: Tetragnathidae) in Brazilian Amazonian.

BACKGROUND: A parasitoid wasp Hymenoepimecis manauara Pádua & Oliveira, 2015 was recorded parasitizing, for the first time, a female spider of Leucauge henryi Mello-Leitão, 1940 in the Amazon rainforest, Brazil. Images, description of the cocoon and comments about this interaction were added. NEW INFORMATION: First record of Hymenoepimecis manauara parasitizing Leucauge henryi with description of cocoon and comments about this interaction.