Effects of Purpureocillium lilacinum (Hypocreales: Ophiocordycipitaceae) on food consumption and sexual behavior of Anastrepha ludens (Diptera: Tephritidae) fruit flies

Abstract

Purpureocillium lilacinum is an entomopathogenic fungus. An experiment was conducted to see the sublethal effects of P. lilacinum on Anastrepha ludens adults. The infection of P. lilacinum reduced daily food consumption per fly ranging from 4.25 ± 0.28 to 6.44 ± 0.27 µl for infected flies, and from 6.30 ± 0.28 to 7.81 ± 0.22 µl for non-infected control flies. The age of treatment in males showed a significant effect on their ability to mate (χ² = 5.32, P < 0.02). Early stage infection (4 days-old), reduced the male mating propensity significantly (10 ± 0.46 treated to 15.4 ± 0.26 untreated, F _{8, 5.94} = 5.592, P < 0.01), compared to later stage (8 days-old) insignificant effect. No effect of fungal infection on an ability of male to inseminate the females was noticed, as fertility of the females mated with infected males was not declined. An inoculated single female (mixture of talc and P. lilacinum) was able to transmit conidia to four groups of 10 males within four days. Males exposed to females on the first day acquired in average 1.7 ⋅ 10⁶, on the second day 1.7 ⋅ 10⁵, on the third day 7.3 × 10⁴ and the fourth day 3.5 ⋅ 10⁴ conidia/ male; which resulted 67.5, 55.0, 20.0, and 7.5 % male mortality, respectively. Our study demonstrated that horizontal transmission through copulation could be used to suppress A. ludens populations.