关键词: 甜菜夜蛾, 寄主植物, 产卵选择, 取食选择, 植物挥发物抽提物, 行为反应

Abstract: To explore the adult oviposition and larval feeding preferences of Spodoptera exigua (Hübner) to different host plants and their relationship, adult oviposition and larval feeding preferences of the moth on seven host plants, i.e., maize Zea mays L., cowpea Vigna unguiculata (L.) Walp., cabbage Brassica oleracea L. var. capitata L., cucumber Cucumis sativus L., cotton Gossypium hirsutum L., pepper Capsicum frutescens L. and tomato Lycopersicon esculentum Miller, were assessed by selection and non-selection tests. Behavior response of S. exigua females to three plants (maize, cabbage and cucumber) and their volatile extracts were also tested by Y-type olfactometer. The results of the field non-selection oviposition preference test indicated that the amount of S. exigua eggs on different plants ranked as maize > pepper > cotton > cucumber, cowpea, and tomato > cabbage. In the Y-type olfactometer tests, females showed the strongest behavioural response to maize and its volatile extract, less response to cucumber, and the weakest response to cabbage. The results of behavioural response tests were in accordance with the results of the oviposition preference tests. Host plant feeding preference of S. exigua larvae at different instars differed to some extent with the prolonged observation period. Young larvae of the 1st and 2nd instars preferred to feed on cowpea, maize and cucumber, but not on cabbage, tomato, pepper and cotton. Larvae of the 4th and 5th instars also showed feeding preference to pepper. Feeding preference of the 5th instar larvae was not as obvious as the earlier larvae. These results suggest that the oviposition preference of S. exigua to different host plants differs significantly, the plant volatiles play important roles in its oviposition host selection, and adult oviposition and larval feeding preferences of S. exigua are not consistent.

Key words: Spodoptera exigua, host plant, oviposition preference, feeding preference, plant volatile extract, behavioural response