A temperature-dependent phenology model for Plutella xylostella

The diamondback moth, Plutella xylostella (L.) (Lepidoptera: Plutellidae), is an important pest of crucifers distributed along different climatic regions of the world. Experiments were carried out at different temperature regimes, viz., 31, 32, 33, 34, 35 and 36˚C, in Open-Top Chambers. Observations made on the life cycle parameters of P. xylostella at different temperatures were used for developing forecasting models. The prediction models developed using Insect Life Cycle Modeling (ILCYM) showed that the developmental rate and developmental duration of different life stages of P. xylostella decreased when there was an increase in temperature, whereas the mortality, senescence and fecundity of P. xylostella increased with elevated temperatures. We also observed the non-viability of P. xylostella eggs when the temperature reached 36˚C. The prediction models showed that the upper threshold temperature for the complete development of P. xylostella larvae into adults was between 34 and 35˚C. The lifetime fecundity and cumulative oviposition rate were also temperature-dependent. The phenology models predicted 32˚C as the most favourable temperature for the survival of eggs, larvae and pupae. Geospatial modeling of P. xylostella risk, based on the outputs of a temperature-driven phenology model linked to GIS, will allow for a detailed analysis of the impact of climate change on the future invasiveness and spread of this pest in various parts in the context of global climate change.