[Effects of azadirachtin on rice plant volatiles induced by Nilaparvata lugens].

With the method of solid phase microextraction (SPME), a total of twenty-five volatiles were collected from rice plants induced by Nilaparvata lugens, and after applying azadirachtin fourteen of them were qualitatively identified by gas chromatography coupled by mass spectrometry (GC-MS), mainly of nine kinds of sesquiterpenes. Comparing with healthy rice plants, the plants attacked by N. lugens had more kinds of volatiles, including limonene, linalool, methyl salicylate, unknown 6, unknown 7, zingiberene, nerolidol, and hexadecane. Applying azadirachtin did not result in the production of new kind volatiles, but affected the relative concentrations of the volatiles induced by N. lugens. The proportions of limonene, linalool, methyl salicylate, unknown 6, zingiberene, and hexadecane changed obviously with the concentration of applied azadirachtin, while those of methyl salicylate, unknown 6, unknown 7, zingiberene, and nerolidol changed significantly with the days after azadirachtin application. Azadirachtin concentration, rice variety, and N. lugens density had significant interactions on the relative concentrations of all test N. lugens-induced volatiles.

[Flight behaviors of Bemisia tabaci and corresponding IPM strategies].

Bemisia tabaci, a pest insect with stronger capabilities of flying and host plant-exploitation, is capable of flying 150 m high and over a distance as far as 7 km, but hardly flies higher than 0. 5 m and long distance in food-abundant areas. B. tabaci has the characteristics of both searching-and migrating flying, which enable it to exploit and locate on suitable hosts. Up to now, no oogenesis-flight syndrome of B. tabaci has been detected. Visual spectrum, air temperature and relative humidity, host quality, and wind speed are the main factors affecting the flight behavior of B. tabaci. In this paper, the flying capability of B. tabaci and the factors affecting its flight behavior were summarized, and the corresponding IPM strategies in the areas where B. tabaci could not overwintering in open field were discussed.