Impacto do clima futuro na fenologia da cultura do milho (Zea mays L.), e no ciclo de vida da lagarta-do-cartucho (Spodoptera frugiperda) em Moçambique

Abstract

In Mozambique, maize is a crop of great importance, occupying about 1/3 of the total cultivated area and with highest production concentrated in the central and northern regions of the country. It is known that, the development of maize plants and survival of ectothermal insects are dependent on the climate. However, the country is cyclically affected by extreme weather events, and the advent of climate change can exacerbate these impacts. Therefore, as a consequence of climate change, agricultural activity in the country may be compromised, both by the change in the regional climate pattern as well as in the agroecological environment. On the other hand, in 2017 the presence of an important agricultural pest, the fall armyworm (Spodoptera frugiperda) (Lepidoptera: Noctuidae), was identified in Mozambique. This insect, with high capacity to attack several agricultural crops, but with preference for maize, has now become one of the main obastacles to increasing agricultural productivity causing huge economic losses in the country. Thus, considering that maize and fall armywarm has its phenology conditioned mainly by air temperature, the goal of this research was to determine the impact of the future climate on maize crop phenology and the life cycle of fall armywarm in Mozambique. For this purpose, the regional model RegCM4 driving by global model HadGEM2-ES to simulate the present (1970-2000) and future (2070-2099) climate of Mozambique, was used. In the simulation of the future climate, two representative climate scenarios of the IPCC-AR5 were considered, namely RCP4.5 and RCP8.5. The daily mean air temperature data resulting from the model runs, complemented by cardinal temperatures, were used for the calculation the total thermal units through the Growing Degrees-Day by the bilinear method. The results indicate a spatio-temporal change in the climate pattern (air temperature) under both climate scenarios, relative to present climate in Mozambique. Predominantly, these changes lead to a significant reduction in the thermal needs available for the development of maize crop in the study domain. On the other hand, it is estimated the increase in the number of fall armyworm generations as a consequence of the reduction of the length of their life cycle in most of the country.