Continuous measuring of leaf area for analyzing feeding behavior of Spodoptera litura (Lepidoptera: Noctuidae) larva

Abstract Leaf area and removed area with as results of herbivory was automatically measured at every one minute interval. Feeding behavior of Spodoptera litura larva was clearly divided into feeding phase and non-feeding phase within a stadium. When feeding phase was initiated, larvae immediately ate a leaf after ecydsis. The meal was sustained as a bout during 10–20 min and repeatedly represented 20–30 times during feeding phase. Averaged interval between meals was about 1 h. Non-feeding phase was from last meal to next ecydsis. These patterns repeated over the whole stadium, and feeding time and frequency did not differ among stadia. Only feeding amount increased exponentially according to instar. We further obtained the precise developmental period of each instar by estimating time from first meal after ecydsis to next ecdysis. Averaged developmental periods of 2nd, 3rd, 4th and 5th instar were 2314, 2752, 2363 and 2737 min, respectively. This proposed protocol of continuous and automatic measuring of leaf area could be helpful to analyze of feeding behavior of lepidopteran larvae.