Biology and seasonal incidence of the jack shoot and fruit borer, Diaphania caesalis (Walker) (Lepidoptera: Crambidae)

Abstract

The biology and seasonal incidence of the shoot and fruit borer of jackfruit tree, Diaphania caesalis (Walker) (Lepidoptera: Crambidae) has been studied. The male and female moths completed their life cycle in 30.4 ± 2.3 and 31.8 ± 2.3 days respectively with five larval instars. The mean incubation period of the egg, developmental duration of larva, prepupa and pupa were 4.9 ± 0.6, 17 ± 0.6, 3.6 ± 0.4, 8 ± 0.4 days respectively. The first and last instar larva measured 2.6 ± 0.3 and 22.4 ± 0.4 mm in length respectively. Unfed moths lived significantly shorter duration (6–9 days) than those with access to water (9–12 days), honey (12–14 days), and honey with vitamin supplement (14–17 days). The incidence of D. caesalis was recorded throughout the year during 2013–2016 indicated an overlapping of generations. However, two distinct peaks in the population level were recorded during June–July and October–November. Subsequently, the pest population declined at the beginning of the winter and was at a very low level in summer. Further, analysis of the data with population density and weather parameters revealed that relative humidity, minimum temperature and rainfall were positively correlated, whereas evaporation was negatively correlated with the incidence of D. caesalis.