Climate change impact on Spodoptera frugiperda (Lepidoptera: Noctuidae) life cycle in Mozambique

Abstract

Although different seasonal cues are important for fall armyworm (FAW, Spodoptera frugiperda J.E. Smith) survival, it is known that the life cycle of this insect is strongly dependent on air temperature, means that its development rate proceeds faster when the weather is warm. To develops the insect needs to accumulate an amount of thermal units, as known as Growing Degree-Days (GDD). However, with the climate change driven by global warming, the GDD pattern must be changed and therefore, the life cycle of this new bug in Mozambique may be different from that observed in its native region. In the present study it is estimated the possible changes of FAW life cycle by applying the GDD method over Mozambique, under two representative scenarios of climate changes, RCP4.5 and RCP8.5 for 2070–2099 relative to present climate (1971–2000). For this purpose, dynamical downscaling process through the regional model RegCM4, nested to global model HadGEM2 were used. The outputs of air temperature dataset from the simulations were used to compute the accumulated GDD and hence the FAW number of generations (NG) during the summer-season over the study domain. The findings indicate that there is a bipolar pattern of GDD accumulation, being negative over most of central and restricted areas in southern region, and positive in northern region, altitude-modified climate areas over central region, and over southernmost areas for both representative climate scenarios, relative to present climate. Meanwhile, there is an increase (decrease) in NG in the areas of higher (lower) increase in air temperature for both future scenarios relative to present climate.