First record of the invasive woodwasp,Urocerus albicornis (Hymenoptera: Siricidae), from a local forest in Japan

The woodwasp Urocerus albicornis (Fabricius, 1781) (Hymenoptera: Siricidae) is a forest pest native to North America and occasionally introduced into European countries. One of these invasive woodwasps was collected in a local forest in Nagano Prefecture, Central Japan. The collected individual was an adult female ovipositing on a log from a Japanese larch (Larix kaempferi (Lamb.) Carrière). Although several of these woodwasps have been found on imported logs in Japan, this is the first record of the alien woodwasp in a local forest within Japan and Asia. This finding indicates that a population of this invasive woodwasp may be established in Japanese forests.     

Parasitism of three attelabid weevils by Bracon (Uncobracon) apoderi Watanabe (Hymenoptera: Braconidae) in Kyushu,Japan

The larval parasitoid Bracon (Uncobracon) apoderi Watanabe (Hymenoptera: Braconidae) is reported from Kyushu for the first time. Two host weevils, Phymatapoderus latipennis and Paroplapoderus pardalis (Coleoptera: Attelabidae), are newly recorded. Bracon apoderi parasitized three attelabid species, including Apoderus balteatus, but did not parasitize Cycnotrachelus roelofsi even though it is a dominant attelabid species in the study site. In addition, B. apoderi mainly parasitized suspended cradles rather than cut‐off cradles.     

Host plants of the herbivorous insect Mythimna separata (Lepidoptera: Noctuidae) affect its susceptibility to parasitism by the larval parasitoid Cotesia kariyai (Hymenoptera: Braconidae)

Previous studies have shown that the food plant species consumed by herbivorous insects affect their parasitism by parasitoid wasps or flies, but this phenomenon has only been observed in a limited number of systems. Here, we investigate how feeding on different plant species affects the survival of the rice armyworm Mythimna separata (Walker) (Lepidoptera: Noctuidae) and its successful parasitism by the larval endoparasitoid Cotesia kariyai (Watanabe) (Hymenoptera: Braconidae). Survival rate and pupal weight of unparasitised M. separata fed with daikon Raphanus sativus L. var. longipinnatus was lower than with maize Zea mays L. In addition, caterpillars fed with daikon were less susceptible to parasitism by C. kariyai than those fed with maize, and parasitised M. separata larvae fed with daikon had higher survival rates than those fed with maize. These results indicate that while daikon is not an optimal food for unparasitised caterpillars, it may protect the larvae from death by C. kariyai parasitism.     

Cytotoxic effects of β‐asarone on Sf9 insect cells

β‐Asarone is the predominant component of the essential oil of rhizomes of Acorus calamus Linn ( Sweet flag). Although rhizome extracts from this plant have long been used for insect pest control, their cytotoxic effects on insect cells are not well understood. In this study, we evaluated the potency of β‐asarone as a natural insecticide by using a Spodoptera frugiperda cell line (Sf9). To assess the cytotoxic effects of β‐asarone on Sf9 cells, we observed morphologic changes in treated cells and performed a cell proliferation assay and a DNA fragmentation assay. After 24 and 48 h of treatment with β‐asarone, the proliferation of the Sf9 cells was inhibited in a dose‐dependent manner, with IC₅₀ values of 0.558 mg/ml at 24 h and 0.253 mg/ml at 48 h. Morphologic changes in β‐asarone‐treated cells were typical of apoptosis and included loss of adhesion, cell shrinkage, and small apoptotic bodies. The DNA laddering present in β‐asarone‐treated SF9 cells and annexin V assay confirmed that this compound can induce apoptosis in insect cells. Together, these findings suggest that apoptosis induction may be one mechanism through which β‐asarone inhibits the proliferation of insect cells and thus exerts insecticidal effects.     

Delayed Response after Learning Associated with Oviposition Experience in the Larval Parasitoid,Cotesia kariyai (Hymenoptera: Braconidae)

Journal of Insect Behavior - The ability of female parasitoid wasps, Cotesia kariyai (Hymenoptera: Braconidae), to learn to recognize plant volatiles associated with an oviposition experience was...     

Deterrent effects of intact plants on host-searching behavior of parasitoid wasps

Female parasitoids distinguish between host-infested and intact plants using chemical cues; however, the contribution of intact plants to host searching of parasitoids has not been investigated so far. Here, we tested how host-searching behavior of the parasitoid wasp, Cotesia kariyai (Watanabe) (Hymenoptera: Braconidae), was affected by intact maize plants in a wind tunnel. To determine the best color for material to create a plant model, we observed flight responses of female wasps to paper plant models of four different colors. Wasps tended to land more frequently on green models than other models. Therefore, a green paper model was used for subsequent experiments. In a no-choice test, female wasps showed higher landing rates on a paper plant model treated with herbivore-induced plant volatiles (HIPVs) than on an intact plant. Moreover, in two-choice tests, wasps preferred the plant model with HIPVs over an intact plant with HIPVs. Intact plants seem to deter C. kariyai females. Our findings suggest that information from intact plants also contributes to the host-searching behavior of females in the natural environment.