Influence of temperature on the occurrence of Myzus persicae (Sulzer) (Hemiptera: Aphididae) parasitoids in tobacco crops in Rio Grande do Sul, Brazil

The aphid Myzus persicae (Sulzer) (Hemiptera: Aphididae) is considered one of the main pests in tobacco crops. By knowing their natural enemies, such as parasitoid wasp, is the first step to develop management strategies for the biological control of the aphids using local agents. For the success of using this tool, it must be considered some environmental factors like thermal tolerance. Therefore, the objective of this work was to survey the occurrence of the parasitoids of M. persicae associated with tobacco crops in the state of Rio Grande do Sul, Brazil, as well as to evaluate the influence of temperature on the occurrence of these parasitoid species. During four crop seasons, tobacco leaves infested with aphids were collected in 42 cities of Rio Grande do Sul. The leaves with aphids were conditioned in plastic containers for ten days for later screening and verification of parasitoids’ emergence. In total, 2963 individuals of two emerging species were sampled: 78% were Aphidius colemani Viereck (Hymenoptera: Braconidae), and 22% were Praon volucre (Haliday) (Hymenoptera: Braconidae). Among the 42 cities sampled, the occurrence of parasitoids was detected in 25 of them. Under the conditions of this study, it was confirmed the influence of the temperature on the populations of the parasitoids of M. persicae. Individuals of P. volucre occurred preferably in temperatures below 22 °C, unlike to A. colemani, which preferred higher temperatures, above 22 °C, showing a different thermal tolerance between both species.