The parasitoid Aphidius colemani Viereck, 1912 presents higher mortality at constant temperatures above 25°C, and probably it is the cause of the failure on the biological control of Aphis gossypii Glover, 1877 when this parasitoid is used at higher temperatures in greenhouses. The aim of this work was to evaluate the influence of different temperatures on individuals of A. colemani from different climatic regions of Minas Gerais state, Brazil. Individuals of A. colemani were collected in the localities of Juramento, Lavras and São Gotardo, and reared in laboratory (22±2°C, 70±10% RH and 12h photophase) for three generations in the host A. gossypii, on cucumber plants. One mated female of A. colemani, 24-48 h old, was released for one hour, in a Petri dish (15cm) with 20 nymphs of 2nd instar of A. gossypii on a leaf disk of cucumber (4 cm of diameter) laid on a layer of agar-water (1%). The parasitized aphids were kept at 16, 19, 22, 25 and 28±1°C, 70±10% RH and 12h photophase. The emergence rates of individuals from Juramento (65.9 and 35.4%) and São Gotardo (71.4 and 47.6%) were lower compared to those from Lavras (87.1 and 80.9%) at 16 and 28°C. The more suitable temperature for the development of A. colemani from Lavras was higher than those for individuals from Juramento and São Gotardo. The individuals from Lavras showed highest emergence at 28°C, and this demonstrated the existence of individuals of A. colemani with tolerance to higher temperatures. These results open news perspectives on the use of different strains of A. colemani on biological control of A. gossypii in protected cultivation.
Aphis gossypii; biological control; biology; parasitoids; strains
