Seasonal Abundance of Various Hymenopteran Parasitoids of Leafminers in Beans and Comparative Abundance in Bean, Tomato, and Squash

Simple Summary Vegetable leafminer, Liriomyza trifolii (Burgess) is a common pest of almost all vegetable crops grown in Florida, USA. Leafminer infestation begins as soon as vegetable seedlings are above the ground. Growers start using insecticides of various chemical classes to control leafminer. They continue insecticide sprays until 2-3 weeks before harvesting crops. This practice of using insecticides deleteriously affects our biotic and abiotic environments. In our four-years research study, we recorded thirteen species of hymenopteran parasitoids of L. trifolii belonging to three families: Braconidae, Eulophidae, and Pteromalidae. Among all parasitoids, Opius, Euopius, Diglyphus, and Diaulinopsis were the predominant ones on beans and other vegetables. Their peak abundance occurred in November-January while most vegetable crops are in their peak growing stage. This study also investigated the preference of parasitoids for the three major vegetable crops: bean, squash, and tomato planted in randomized complete block design in field plots. This information could be of great benefit in developing an IPM of vegetable leafminers balancing biocontrol agents and insecticide application. The composition and seasonal abundance of hymenopteran parasitoids of Liriomyza trifolii (Burgess) was investigated on snap bean (Phaseolus vulgaris L.), tomato (Solanum lycopersicum L.), and squash (Cucurbita pepo L. 'Enterprise') from 2010 to 2016 in South Florida in two studies. In the first study (2010-2016), 13 species of parasitoids were collected from the snap bean crop. Opius dissitus Muesebeck (Braconidae) was the most abundant parasitoid throughout the study period from September 2010 to February 2016. Diaulinopsis callichroma Crawford (Eulophidae) was the second most abundant parasitoid on bean in 2010, 2012, 2014, and 2016. Other parasitoids included Euopius sp. (Braconidae)., Diglyphus begini (Ashmead), D. intermedius (Girault), D. isaea (Walker), Neochrysocharis sp., Closterocerus sp., Chrysocharis sp., Zagrammosoma lineaticeps (Girault), Z. muitilineatum (Ashmead), Pnigalio sp. (all Eulophidae), and Halticoptera sp. (Pteromalidae). In the second study on the comparative abundance of parasitoids in three crops conducted in 2014 and 2016 using bean (Phaseolus vulgaris L., tomato (Solanum lycopersicum L.) and squash (Cucurbita pepo L.) arranged in a randomized complete block design, bean attracted more parasitoids than tomato and squash irrespective of parasitoid species and years. This information will help in devising a biocontrol-based integrated program for managing leafminers in beans and other vegetable crops.