Takashi Wada

Starvation tolerance of macropter brown planthopper, Nilaparvata lugens, from temperate, subtropical, and tropical populations in East and South‐East Asia

We compared the starvation tolerance of macropter brown planthopper, Nilaparvata lugens Stål (Homoptera: Delphacidae), a characteristic favoring long‐distance migration, among populations collected from subtropical and temperate East Asia, tropical Indochina, and the Malay Peninsula. Starvation tolerance of planthoppers was significantly affected by climatic zone in which the planthoppers had been collected and by feeding duration after adult eclosion. After 24 h feeding on rice, newly emerged macropters originating from East Asia lived longer without feeding (starvation tolerance) than macropters from the tropical populations. The difference in longevity between the two groups of populations became more conspicuous when macropters fed on rice for 48 or 72 h, indicating that post‐eclosion feeding markedly increased starvation tolerance in East Asian populations relative to the tropical populations. These facts provide evidence that N. lugens populations that are adapted for long‐distance migration are distributed in subtropical and temperate East Asia. From the data on post‐eclosion feeding together with starvation tolerance, we discuss the timing of planthopper takeoff from paddies and the difference in resource allocation (vitellogenesis or stored resources) between East Asian and tropical populations.

Detection of symbionts and virus in the whitefly Bemisia tabaci (Hemiptera: Aleyrodidae), vector of the Mungbean yellow mosaic India virus in Central India

Legume crops in Central India, the main soybean production area of the country, may suffer from yellow mosaic disease caused by the Mungbean yellow mosaic India virus (MYMIV). MYMIV is transmitted by the sweet potato whitefly, Bemisia tabaci (Gennadius), which is a species complex composed of various genetic groups. This vector species harbors different endosymbionts among regional strains and among individuals. To elucidate fundamental aspects of this virus vector in the state of Madhya Pradesh, the infection status of the symbionts and the virus in whiteflies was studied. A polymerase chain reaction (PCR) survey of the whiteflies collected in Madhya Pradesh found four secondary endosymbionts, Arsenophonus, Hemipteriphilus, Wolbachia, and Cardinium, in addition to the primary endosymbiont Portiera. Arsenophonus and Hemipteriphilus were highly infected but the infection rates of Wolbachia and Cardinium were low. MYMIV was detected in whitefly populations collected from various host plants in Madhya Pradesh. The whitefly populations belonged to the Asia I and II genetic groups; several different Asia II populations were also distributed. Specific relations were not observed among symbiont infection status, virus infection, and the whitefly genetic groups in the populations of Madhya Pradesh, though Cardinium was highly detected in the Asia II-1 group. New primers, which can be used for PCR template validation and for discriminating two phylogenetically close endosymbionts, were designed.