ABSTRACT
The leafroller Argyrotaenia sphaleropa (Meyrick) is an important pest of temperate fruits. Its biology and population dynamics are strongly influenced by temperature. In this context, this study aims to select a mathematical model that accurately describes the temperature-dependent development rate of A. sphaleropa and applies this model to predict the impact of climate change on the number of annual generations (voltinism) of the pest in southern Brazil. Nine mathematical models were employed to fit the species' developmental rate at different constant temperatures. Voltinism was projected using climate data from the current period (1994-2013) and projections for 2050 and 2070. The Brière-1 model (D(T) = aT(T-TL)(TH-T)1/2) provided the best fit for the temperature-dependent developmental rate of A. sphaleropa. According to this model, the regions with the highest voltinism under current climatic conditions are the northern and central areas of Paraná, the western and northeastern regions of Santa Catarina, and northwestern Rio Grande do Sul. The model also predicts a rise in A. sphaleropa voltinism as a consequence of climate change, especially in the mountainous regions of Santa Catarina and Rio Grande do Sul, with projected increases of up to 25.1%. These regions encompass most areas where temperate fruits used as hosts by the leafroller are cultivated. This study represents a significant advancement in understanding the implications of global warming on A. sphaleropa voltinism and suggests that forthcoming climatic conditions will likely favor the species across much of southern Brazil.
Subject(s)
Climate Change , Fruit , Brazil , Animals , Models, Theoretical , Hemiptera , Temperature , Population DynamicsABSTRACT
BACKGROUND: The southern armyworm, Spodoptera eridania, is a polyphagous species native to the American tropics that recently invaded Africa. Knowledge of the impact of temperature on its development and survival is important to understand the risks of this species spreading to other regions and to develop phenological models for pest management. This study evaluated the effects of temperature on the development and survival of S. eridania and selected mathematical models to simulate its development. RESULTS: The southern armyworm completed its development between 15 and 32 °C, but eggs did not hatch at 34 °C. Lower survival and higher rates of deformities in adults were recorded at 15 and 32 °C. Among the ten mathematical models evaluated, Briere-2, Lactin-2 and Shi were considered suitable for describing the temperature-dependent development rate of S. eridania. The lower thermal threshold estimated by these models for the egg to adult life cycle ranged from 10.8 to 12.1 °C, whereas the upper threshold ranged between 33.9 and 35.0 °C. CONCLUSIONS: The southern armyworm can develop within a wide range of temperatures, which partially explains its wide distribution in regions with different climatic conditions, and demonstrates its potential to occur in regions outside its native range. Our findings can be employed in the development of management strategies using the selected models to predict the occurrence of S. eridania in the field and determine the most effective times to implement control measures.