Effects of leaf surfaces on first‐instar Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae) behaviour

Helicoverpa armigera is a common pest insect on several economically important crops. While the feeding behaviour of later instars of this and other herbivorous larvae has been studied extensively, less has been done on the behaviour of newly hatched larvae. The behaviour of neonate H. armigera larvae on leaves from a variety of food plants and on two artificial diets was detailed. Recordings of the individual neonate larva's behaviour were taken for 3 h following the initiation of feeding. Analysis of the data suggested that larvae behaved differently in response to plant surfaces. Larvae took more bouts when feeding on the significantly thicker leaves of canola, with longer first meals on waxy canola than on a wax‐less variety. Analysis of feeding holes using a scanning electron microscope suggested that the longer feeding bouts were due to the pre‐processing time required to remove the wax from the leaf surface. Larvae feeding on trichome‐rich plants like tobacco and tomato also had to remove these obstacles before feeding. Increased time spent feeding or moving on the leaf surface could lead to increased exposure to predation, indicating that larval food choice or host choice by the ovipositing adult moth may have important implications in larval survival.