Temperature-dependent development and life tables of Palpita unionalis (Lepidoptera: Pyralidae)

Abstract

Abstract Palpita unionalis Hubner (Lepidoptera: Pyralidae) is one of the primary pests in olive orchards, damaging buds and fruits of the olive tree. The present study investigated the biology of P. unionalis across a temperature gradient and elaborated on the corresponding life tables for a better understanding of its population dynamics in the environment. The biology of the pest was studied at six temperatures (17, 20, 22, 25, 27, and 30 °C). The duration and survival of immature stages, sex ratio, and survival of emerged adults were evaluated. The female fecundity and longevity (pre-oviposition, oviposition, and post-oviposition periods) were calculated. The life tables were elaborated from these parameters. The life cycle of P. unionalis was significantly longer at 17 °C and shorter at 30 °C. Larval survival was significantly reduced at 30 °C, however, adult survival was at a maximum, yet their sex ratio was not affected by temperature. The lower temperature, 20 °C, was optimal for fecundity (586.3 eggs), which was reflected in the highest net reproductive rate (105.7 offspring per individual). The thermal constant (K) and the lower thermal threshold (t 0) for egg to adult period were 582.9° days and 7.1 °C, respectively. Based on the current study, it is concluded from the parameters of biology and life tables that temperature has a significant role in the population growth of P. unionalis. This should be considered throughout the monitoring and management of P. unionalis at different agro-ecologies in the context of global warming.