Antennal courtship and functional morphology of tyloids in the parasitoid wasp Syrphoctonus tarsatorius (Hymenoptera: Ichneumonidae: Diplazontinae)

Courtship behaviour and associated morphological characters are believed to evolve under diversifying sexual selection. In Hymenoptera, sexually dimorphic antennal structures, the 'tyloids', show a large variability. Although crucial for functional interpretation, the link between tyloid morphology and courtship behaviour has gained only limited attention. Here, we investigate antennal morphology and antennal courtship in the parasitoid wasp Syrphoctonus tarsatorius (Hymenoptera: Ichneumonidae: Diplazontinae). We confirm the glandular nature of the tyloids by light and scanning electron microscopy. Moreover, we report a new form of antennation during courtship, antennal double-coiling, which links morphology and behaviour by bringing the tyloids in direct contact with the antennae of the female, thus probably facilitating the transfer of a contact pheromone. We show that a change in haemolymph pressure is the activator of the antennal movement and that it can be reproduced in the laboratory using amputated antennae. Investigations of antennal structure and movement in three additional hymenopteran species suggest that the number and location of tyloids coincide with the modality of antennal coiling. Our method for simulating antennal movement will enable retrieving information about courtship behaviour from museum specimens, thus leading to a better understanding of the evolution of courtship behaviour in Hymenoptera.

Honey Bee Apis mellifera Parasites in the Absence of Nosema ceranae Fungi and Varroa destructor Mites

Few areas of the world have western honey bee (Apis mellifera) colonies that are free of invasive parasites Nosema ceranae (fungi) and Varroa destructor (mites). Particularly detrimental is V. destructor; in addition to feeding on host haemolymph, these mites are important vectors of several viruses that are further implicated as contributors to honey bee mortality around the world. Thus, the biogeography and attendant consequences of viral communities in the absence of V. destructor are of significant interest. The island of Newfoundland, Province of Newfoundland and Labrador, Canada, is free of V. destructor; the absence of N. ceranae has not been confirmed. Of 55 Newfoundland colonies inspected visually for their strength and six signs of disease, only K-wing had prevalence above 5% (40/55 colonies = 72.7%). Similar to an earlier study, screenings again confirmed the absence of V. destructor, small hive beetles Aethina tumida (Murray), tracheal mites Acarapis woodi (Rennie), and Tropilaelaps spp. ectoparasitic mites. Of a subset of 23 colonies screened molecularly for viruses, none had Israeli acute paralysis virus, Kashmir bee virus, or sacbrood virus. Sixteen of 23 colonies (70.0%) were positive for black queen cell virus, and 21 (91.3%) had some evidence for deformed wing virus. No N. ceranae was detected in molecular screens of 55 colonies, although it is possible extremely low intensity infections exist; the more familiar N. apis was found in 53 colonies (96.4%). Under these conditions, K-wing was associated (positively) with colony strength; however, viruses and N. apis were not. Furthermore, black queen cell virus was positively and negatively associated with K-wing and deformed wing virus, respectively. Newfoundland honey bee colonies are thus free of several invasive parasites that plague operations in other parts of the world, and they provide a unique research arena to study independent pathology of the parasites that are present.