Behavioral aspects of Helicoverpa armigera in the cotton vegetative phase1

ABSTRACT Helicoverpa armigera (Hübner) is part of an important complex of insects-pests that attack the cotton crop. This study aimed to identify the preferential plant parts for the oviposition of moths, as well as the movement and feeding behavior of caterpillars, in the vegetative phase of the cotton cultivar BRS 369 RF. Plants emitting floral buds were used to study the oviposition behavior of moths. For this, a completely randomized design, with three treatments (adaxial and abaxial sides of the leaf and floral buds) and twenty replications (plants in pots), was used. In order to evaluate the behavior of the caterpillars in the cotton vegetative phase, another 3 × 5 factorial design, with nine replications, was used. The treatments were three ages (first, second and third instars) combined with five behaviors (walking, resting, waving, eating and drop-off). In this trial, the period of the day when caterpillars are more active was also evaluated. It was observed that H. armigera moths prefer to lay their eggs on the adaxial leaf side and on the last two nodes of the plant, in a descending direction. The adaxial leaf side is also the part of the plant preferred by caterpillars for walking, eating and resting, being this last behavior the most frequent in all instars. In general, the caterpillars walk more in the morning.

摘要：棉铃虫（Helicoverpa armigera (Hübner)）是为害棉花的重要害虫复合种群之一。本研究以棉花品种BRS 369 RF的营养生长期植株为对象，旨在明确棉铃虫成虫的产卵偏好部位，以及幼虫的移动与取食行为。针对成虫产卵行为的探究，采用处于现蕾期的棉花植株，试验采用完全随机设计，设置3个处理组（叶片正面、叶片背面与花蕾），并设置20次重复（盆栽植株）。为评估棉花营养生长期的幼虫行为，本研究采用另一套3×5因子设计，共设置9次重复；处理组为3个幼虫龄期（1龄、2龄、3龄）与5种行为模式（行走、静息、摆体、取食及坠地）的组合。本试验同时评估了幼虫每日活跃度最高的时段。试验结果显示，棉铃虫成虫偏好于在叶片正面以及植株沿向下方向的最后两个节位产卵。叶片正面同样是幼虫进行行走、取食与静息行为的偏好部位，其中静息行为在所有龄期中均为最频繁的行为类型。总体而言，幼虫的行走行为在晨间最为活跃。