Voltinism of Diabrotica speciosa (Coleoptera: Chrysomelidae) in Argentina: latitudinal clines and implications for damage anticipation
Correspondence to: Guillermo Cabrera Walsh, FUEDEI, Bolívar 1559, B1686EFA Hurlingham, Buenos Aires, Argentina. E-mail: email@example.com
Diabrotica speciosa (Germar) is an important pest in South America. Both the adults and the larvae are polyphagous, and its most susceptible host is maize. Factors behind the appearance of adults in the field and geographical variations in voltinism are unknown. This hinders the chances of implementing rational control strategies.
This study compiles field collection data from four agricultural regions of Argentina to examine the number of generations and phenology of D. speciosa in the field. These data are correlated with climatic data in order to provide evidence of regional variations and probable environmental causes for the appearance of adult generations in the field. Results indicate that temperature has an important role in the appearance of new generations in the temperate distribution areas of D. speciosa, but not within its subtropical range, where teneral adults appeared all year round.
Results suggest that the emergence of adults may be elicited by weekly average temperatures above 13 °C. In the temperate distribution areas of D. speciosa there could be at least three generations a year, and in the subtropical region at least five. No obvious or discrete voltinism pattern could be observed for D. speciosa in southern South America. © 2013 Society of Chemical Industry