Midgut transcriptome assessment of the cockroach-hunting wasp Ampulex compressa (Apoidea: Ampulicidae)

The emerald jewel wasp Ampulex compressa (Hymenoptera: Ampulicidae) is a solitary wasp that is widely known for its specialized hunting of cockroaches as larvae provision. Adult wasps mainly feed on pollen and nectar, while their larvae feed on the cockroachs’ body, first as ecto- and later as endoparsitoids. Little is known about the expression of digestive, detoxification and stress-response-related genes in the midgut of A. compressa, or about its transcriptional versatility between life stages. To identify gut-biased genes related to digestion, detoxification, and stress response, we explored the midgut transcriptome of lab-reared A. compressa, for both adults and larvae, by focusing on the top 100 significantly up- and down-regulated genes. From the top 100 significantly differentially expressed genes (DEGs), we identified 39 and 36 DEGs putatively related to digestion and detoxification in the adult wasps and larvae, respectively. The two carbohydrases alpha-glucosidase (containing an alpha-amylase domain) and glycosyl hydrolase family 31, as well as the two proteinases chymotrypsin and trypsin, revealed the highest gene diversity. We identified six significant DEGs related to detoxification, which comprise glutathione S-transferase, cytochrome P450s and UDP-glucuronosyltransferase. The gene expression levels that were significantly expressed in both life stages vary strongly between life stages, as found in genes encoding for chymotrypsin and trypsin or glycosyl hydrolases family 31. The number of genes related to alpha-glucosidase, glycosyl hydrolase family 31, and cytochrome P450s was found to be similar across nine reference hymenopteran species, except for the identified glycosyl hydrolase family 31 gene, which was absent in all reference bee species. Phylogenetic analyses of the latter candidate genes revealed that they cluster together with their homologous genes found in the reference hymenopteran species. These identified candidate genes provide a basis for future comparative genomic and proteomic studies on (ontogenetic) dietary transitions in Hymenoptera.

Chemoreceptor diversity in apoid wasps and its reduction during the evolution of the pollen-collecting lifestyle of bees (Hymenoptera: Apoidea)

Chemoreceptors help insects to interact with their environment, to detect and assess food sources and oviposition sites, and to aid in intra- and inter-specific communication. In Hymenoptera, species of eusocial lineages possess large chemoreceptor gene repertoires compared to solitary species, possibly because of their additional need to recognize nest-mates and caste. However, a critical piece of information missing so far has been the size of chemoreceptor gene repertoires of solitary apoid wasps. Apoid wasps are a paraphyletic group of almost exclusively solitary Hymenoptera phylogenetically positioned between ant and bee, both of which include eusocial species. We report the chemosensory-related gene (CRG) repertoire sizes of three apoid wasps: Ampulex compressa, Cerceris arenaria, and Psenulus fuscipennis. We annotated genes encoding odorant (ORs), gustatory (GRs), and ionotropic (IRs) receptors and chemosensory soluble proteins (CSPs) and odorant-binding proteins (OBPs) in transcriptomes of chemosensory tissues of the above three species and in early draft genomes of two species, A. compressa and C. arenaria. Our analyses revealed that apoid wasps possess larger OR repertoires than any bee lineage, that the last common ancestor of Apoidea possessed a considerably larger OR repertoire (ca. 160) than previously estimated (73), and that the expansion of OR genes in eusocial bees was less extensive than previously assumed. Intriguingly, the evolution of pollen-collecting behavior in the stem lineage of bees was associated with a notable loss of OR gene diversity. Thus, our results support the view that herbivorous Hymenoptera tend to possess smaller OR repertoires than carnivorous, parasitoid, or kleptoparasitic species.

Comparative morphology of the musculature of the sting apparatus in Ampulex compressa (Hymenoptera, Ampulicidae) and Sceliphron destillatorium (Hymenoptera, Sphecidae)

The sting apparatus of aculeate Hymenoptera is derived from the ovipositor and is their most prominent apomorphy. In contrast to the frequently analysed sclerites of the sting apparatus, the associated musculature has largely been neglected. In this study, we use micro-computed tomography to present a detailed description of the musculature of the sting apparatus of Ampulex compressa (Ampulicidae) and Sceliphron destillatorium (Sphecidae). We found that 12 of 15 muscles corresponding to the sting apparatus are homologous between both species examined and 13 muscles in comparison with Hymenoptera described in the literature. All muscles identified as critical for the act of stinging were found in both species. Moreover, we found the ventral tergum 8-tergum 9 muscle and the tergum 8-tergum 8 muscles in A. compressa and the second valvifer-second valvifer muscle in S. destillatorium. For the first time, we describe the ventral tergum 8-tergum 9 muscle and the second valvifer-second valvifer muscle that interconnects both body sides, in Hymenoptera.

Stinging apparatus of apoid wasps and bees as never seen before

The stinging apparatus is expected to vary depending on the type of prey taken and the way it is carried in apoid wasps and the purpose of defense it serves in bees. To understand the differences in sting morphology, members of two apoid wasp families (Ampulicidae and Crabronidae) and a bee family (Halictidae) were studied. Scanning Electron Microscope images of lancets revealed tooth like projections on dorso-lateral aspect in Ampulex compressa (Fabricius, 1781) and blunt barbs on the lancets of Liris aurulentus (Fabricius, 1787) and Tachysphex bengalensis Cameron, 1889 whereas, in Halictus fimbriatellus Vachal, 1894 barbs are arranged in two rows on lancet, which includes four barbs on one side and three barbs on the other side of lancet which are not acutely pointed. The SEM images also indicated the presence of campaniform sensilla on the lancets of compressa. These findings help us to know the possible relationships of hunting behavior and modification of the sting in accordance.

Identification and ecology of wasps (apocrita: hymenoptera) of Dhaka city

During the study period a total 351 wasp was collected from three different areas of Dhaka city viz Curzon Hall, Ramna Park and Sher-e-Bangla Agricultural University from October 2017 to May 2019. Among them 14 species belonging to four families- Ampulicidae, Sphecidae, Vespidae and Scoliidae were identified. The species were Ampulex compressa, Chalybion bengalense, Scolia sp., Laeviscolia frontalis, Delta esuriens, Rhynchium quinquecintum, Antodynerus flavescens, Parapolybiavaria sp., Ropalidia marginata, Polistes olivaceus, Polistes watti, Polistes stigma, Vespa tropica, and Vespa affinis. Standard taxonomic keys and sharp perception of outside morphology like head, wing venation, antennal sort, physical coloration etc. of the wasps were examined to identify them. Maximum of the distinguished species were beneath the family vespidae (72%). In the present study, it was observed that the maximum number of wasps were collected in May (29.63%). The richness of wasp species was more plenteousin Curzon Hall area (47.58%) than the Sher-e-Bangla Agricultural University area (40.17%) and was less abundant in Ramna park (12.25%). The main reason for finding more richness of wasp species in Curzon Hall area was the presence of various types of hedging plants than other two areas as the wasps were found to prefer hedging plants for foraging. It was also observed that Polistes olivaceus (21.93%) was the most abundant and Chalybion bengalense was (0.85%) the least abundant species in the study areas. Bangladesh J. Zool. 48(1): 37-44, 2020

A comparative description of the mesosomal musculature in Sphecidae and Ampulicidae (Hymenoptera, Apoidea) using 3D techniques

Conflicting hypotheses about the relationships among the major lineages of aculeate Hymenoptera clearly show the necessity of detailed comparative morphological studies. Using micro-computed tomography and 3D reconstructions, the skeletal musculature of the meso- and metathorax and the first and second abdominal segment in Apoidea are described. Females of Sceliphron destillatorium, Sphex (Fernaldina) lucae (both Sphecidae), and Ampulex compressa (Ampulicidae) were examined. The morphological terminology provided by the Hymenoptera Anatomy Ontology is used. Up to 42 muscles were found. The three species differ in certain numerical and structural aspects. Ampulicidae differs significantly from Sphecidae in the metathorax and the anterior abdomen. The metapleural apodeme and paracoxal ridge are weakly developed in Ampulicidae, which affect some muscular structures. Furthermore, the muscles that insert on the coxae and trochanters are broader and longer in Ampulicidae. A conspicuous characteristic of Sphecidae is the absence of the metaphragma. Overall, we identified four hitherto unrecognized muscles. Our work suggests additional investigations on structures discussed in this paper.

Getting the Most Out of Your Zombie: Abdominal Sensors and Neural Manipulations Help Jewel Wasps Find the Roach’s Weak Spot

The parasitoid emerald jewel wasp (<i>Ampulex compressa</i>) subdues the American cockroach (<i>Periplaneta americana</i>) with a sting to the 1st thoracic ganglion, followed by a sting to the roach’s brain, causing long-term pacification. The wasp then leads the cockroach to a hole where it lays an egg on the roach middle leg before barricading the entrance and departing. Although many aspects of the wasp’s initial attack have been investigated, few studies have detailed the egg-laying process and the subsequent fate of the larvae. Here I show that larval survival depends on precise egg positioning on the cockroach by the female wasp. Ablation of sensory hairs on the wasp’s abdomen resulted in mislaid eggs, which seldom survived. In addition, the cockroach femur may block the oviposition site. The wasp contended with this challenge with a newly discovered suite of stings, 3 directed into the 2nd thoracic ganglion which resulted in extension of the femur, thus exposing the oviposition site and removing a potential barrier to the wasp’s successful reproduction. When the femur was glued in place, the wasp stung the cockroach over 100 times, in an apparent fixed action pattern triggered by the obscured oviposition target. These findings highlight the importance of proper egg placement by the wasp, and reveal sensors and new neural manipulations that facilitate the process.

How Not to Be Turned into a Zombie

The emerald jewel wasp (Ampulex compressa) is renowned for its ability to zombify the American cockroach (Periplaneta americana) with a sting to the brain. When the venom takes effect, the cockroach becomes passive and can be led by its antenna into a hole, where the wasp deposits an egg and then seals the exit with debris. The cockroach has the ability to walk, run, or fly if properly stimulated, but it does not try to escape as it is slowly eaten alive by the developing wasp larva. Although the composition and effects of the wasp’s venom have been investigated, no studies have detailed how cockroaches might prevent this grim fate. Here it is shown that many cockroaches deter wasps with a vigorous defense. Successful cockroaches elevated their bodies, bringing their neck out of reach, and kicked at the wasp with their spiny hind legs, often striking the wasp’s head multiple times. Failing this, the elevated, “on-guard” position allowed cockroaches to detect and evade the wasp’s lunging attack. If grasped, the cockroaches parried the stinger with their legs, used a “stiff-arm” defense to hold back the stinger, and could stab at, and dislodge, the wasp with tibial spines. Lastly, cockroaches bit at the abdomen of wasps delivering the brain sting. An aggressive defense from the outset was most successful. Thus, for a cockroach not to become a zombie, the best strategy is: be vigilant, protect your throat, and strike repeatedly at the head of the attacker.