THE POTENTIAL FOR USING ENTOMOPATHOGENIC NEMATODES TO CONTROL DARKWINGED FUNGUS GNATS BRADYSIA COPROPHILA (LINTNER) ON SUCCULENTS IN GLASS HOUSES.

Abstract

Darkwinged fungus gnat Bradysia coprophila Lintner (Diptera: Sciaridae) is known as a pest of ornamental plants in commercial green and glass houses in nurseries worldwide. There have been reports about significant Bradysia coprophila damage of succulent plants in five Botanical gardens in Ukraine, including Academician Fomin's Botanical garden (Kiev) for the last three years. In pot experiments the commercial strain of S.feltiae to control B. coprophila was tested on Mammilaria, Opuntia, Echinocerus plants grown individually in plastic pots at rate 500,000 IJs/m². Efficacy of EPN was evaluated based on the percentage of fly emergence from compost and captured in yellow sticky traps in treated and untreated benches with pots. It was shown that Steinernema feltiae application causes significant reduction (90%) of flies captured in yellow traps in comparison with the control. To evaluate virulence of EPNs to B. coprophila in laboratory bioassays, fourth instar larvae were exposed to 20, 50, 75, 100 IJs. B. coprophila was susceptible to all commercial and wild isolates of Steinernema and Heterorhabditis spp. Percentage mortality of B. coprophila larva ranged between 49 and 95%. Wild and commercial isolates of S. feltiae were highly virulent to the pest. The highest mortality--95% was obtained by using a wild strain of S. feltice. The nematode concentration tills to 50 IJ and all nematode species significantly affected the mortality rate of B. coprophila. Increasing the dosage of Steinernema spp. from 75 to 100 IJs did not affect significantly the mortality rate of the insect.