Egg Parasitoids Attacking <I>Cactoblastis cactorum</I> (Lepidoptera: Pyralidae) in North Florida

Abstract

Interest in the natural enemies of Cactoblastis cactorum (Berg) has increased since the moth was found in Florida in 1989. Previous surveys for natural enemies in Argentina identified egg parasitoids in the family Trichogrammatidae as potentially important control agents of C. cactorum. A study was conducted in north Florida to identify and to assess occurrence of egg parasitoids attacking this invasive moth in its new homeland. Surveys undertaken at 6 locations in north Florida from Jul 2008 to Dec 2009 revealed that eggsticks of C. cactorum were attacked by egg parasitoids from the Trichogramma genus: T. pretiosum Riley, T. fuentesi Torre, and an additional unidentified Trichogramma species belonging to the T. pretiosum group. In order to assess the importance of these egg parasitoids, the fate of individual C. cactorum eggsticks was determined during weekly visits to each site. This assessment showed that the combined level of parasitism of C. cactorum eggsticks was very low with less than 0.2% of host eggs attacked at any one of the 6 sites. While parasitoids attacked smaller eggsticks, there was no correlation between the numbers of eggs in an eggstick attacked with increasing number of eggs/eggstick. Comparing the mean number of eggs/eggstick, there was no difference between the 3 flight periods of C. cactorum, but there was a difference between the 6 sites. Based on these results, the use of Trichogramma wasps as an inundative biological control agent, complementary to the Sterile Insect Technique application, is discussed.

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