New predatory midge with potential to control mites

Although the crops where these mites cause problems are completely different, they all have in common that the mites are very difficult to control due to their extremely small dimensions. Predatory mites are, in principle, effective predators, but they cannot get to the places where these small mites are hiding.

Entomologists from Wageningen University & Research have investigated new natural enemies for the control of small mites in a top sector project. During this research, the tiny gall midge Trisopsis tyroglyphi was discovered, whose larvae proved to be good predators of both eriophyid and tarsonemid mites. The species was for the first time found in the Netherlands. The larvae can develop very well on the storage mite Tyrophagous putrescentiae. It was striking that juvenile development was particularly slow at 15 degrees (>80 days). At 25 degrees, the life cycle is relatively short, on average 23 days. The midge adults are very fragile and live only 4 days.

The application of these predatory midges as biological control agents is very crop-dependent. In amaryllis they were found deep in the bulb where they preyed on bulb scale mites, but in practice they failed to establish. In bromeliads, under humid and warm conditions, the predatory midge was found to settle surprisingly well in flowers. However, the contribution to the control of the pineapple tarsonemid mite or has not yet been demonstrated. A trial with gerbera showed that the predatory midges can contribute to the control of the broad mite, but complete control was not achieved.

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Photo Courtesy of Wageningen University & Research

Source: Wageningen University & Research