Adequabilidade ambiental de Anastrepha grandis e efeito das mudanças climáticas no número de gerações no Brasil

Abstract

Anastrepha grandis (Macquart, 1846) is known as the South American cucurbit’s fly and it is characterized by attacking native or introduced species of cucurbitaceae. Although the insect causes damage due to its infestation in the fruits, its main problem refers to the exportation embargoes. This work aims to know the environmental suitability for the occurrence of A. grandis of a few Brazilian regions taking into account the temperature predicted by the Intergovernmental Panel on Climate Change (IPCC) and how it affects the increment of the generation’s quantity that A. grandis. Glass desiccators with air relative humidity ranges of 20-39, 40-59, 60-79 and 80-100% were used to determine the water requirements. These moisture ranges were obtained by using sulfuric acid (H2SO4). The periods of pre-oviposition and oviposition, fecundity, fertility and longevity were analyzed. Based on the ideal relative humidity and temperature ranges, thermohygrograms were elaborated using historical data of these variables for the selected cities. The climatic variations were analyzed in the reference scenarios related to the climatological norm obtained from 1961-1990 and climate change scenarios A2 and B1 of the IPCC, focusing on a less pessimistic scenario (B1), and on a more pessimistic scenario (A2) for the next decades, thus establishing a zoning limitation based on the definition of ecologically favorable and/or unfavorable environments. It was determined that the relative air humidity optimum range for the development of A. grandis adults is between 60 and 79% and the areas of cucurbit production located in the Southeast, Midwest and Northeast regions have a greater environmental suitability for A. grandis in relation to those in the South region of Brazil. Regarding the future projections for the number of generations of A. grandis, taking into account the reference period, it was possible to observe that in the colder seasons (autumn and winter), the South and Southeast regions were less suitable for the development of A. grandis, presenting at most one generation, whereas in the hotter seasons (spring and summer) the insect can have two generations, unlike the other regions of the Country, where temperatures are highest throughout the year, which means that the number of generations does not vary from one station to another. For scenario A2, it was possible to observe a variation in the number of generation if it takes into account the three future climate cenarios, 2011-2040, 2041-2070 and 2071-2100, doubling the number of generations of A. grandis, whatever which season is, mainly due to the global temperature increase. For scenario B1, a smaller variation was observed in the number of generations of A. grandis, mainly in the South region of the Country, whereas in the Southeast region, this variation is more accentuated, due to the increase of the temperature, being able to double the number of even in the coldest seasons of the year.