Black fungus gnats Lycoriella ingenua (Dufor, 1989) and Bradysia impatiens (Johannsen, 1912) (Diptera: Sciaridae) in Pinus montezumae Lamb.

Abstract

The black fungus gnats Lycoriella ingenua and Bradysia impatiens are insects that affect meaningfully the seedling production of Pinus montezumae in some forest nurseries and greenhouses located at Central Mexico. During the months from springtime to autumn, the environmental conditions of high moisture and temperature are right for a fast growth of the population and it becomes abundant in a few weeks. To offer an alternative to control these insects, in a forest nursery located in Temamatla, Mexico, five chemical insecticides were tested: oxamil, spirotetramat, imidacloprid, carbofuran, chlorpyrifos and the biopesticide Bacillus thuringiensis var. israelensis (BTI). These products were applied in three doses for a four month period. The efficiency of the treatments was evaluated on the percentage of unharmed plants. Of the treatments, the imidaclopridin a high and medium doses generated a protection of 100 %. Then, the spirotetramat and oxamil protected 96.17 % and 95.75 % of the treated plant respectively; the medium dose of chlorpyrifosprotected 95.74 %, and the low dose of imidacloprid 95.29 %. Eight treatments protected from 91.5 % to 79.43 %. Four were no different to control. The results suggest that not all the evaluated products, in different doses, are effective to control the black fungus gnats. Nevertheless, some doses and products can be effective to control the pest in P. montezumae seedlings.