Researchers may be able to protect cultivated fungi from fungal mosquitoes through development of light traps

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As with all cultivated crops, there are significant pest assemblages in mushroom cultivation that, in the absence of proper control, can cause enormous damage. Fungal mosquitoes belonging to the order of dicotyledons are considered to be the most dangerous pests in mushroom cultivation. The staff of the ELKH Centre for Ecological Research (ÖK), the ELKH Centre for Agricultural Research (ATK) and the Hungarian University of Agricultural and Life Sciences have studied the effect of light of different wavelengths on the organization and behavior of fungal mosquitoes. The aim of the study is to develop effective light trapping methods for the protection of cultivated fungal cultures. A study summarizing the results has been published in the prestigious journal Scientific Reports.

In nature, fungal mosquitoes are primarily degrading organisms. The larvae most often develop in the soil, where they feed on various microfungi or the hairy roots of plants, but they can also be present in manure heaps, leaf litter, under the bark of dead trees, in mammal nests or cavities or in bird nests.

In agriculture, fungal mosquitoes are generally only marginal pests. The damage they cause only becomes significant if they multiply in very large numbers. However, these tiny, black, fragile flying insects can cause extremely significant damage to mushroom cultivation. Because the most important environmental condition for the development of fungal mosquitoes is a moist, damp habitat, mushroom growing provides these pests with an ideal habitat for them all year round. In large numbers, fungal mosquitoes can even destroy complete waves of cultivation, causing signficant losses for growers. Adult insects carry pathogens of various fungal and bacterial diseases within the greenhouse, while larvae damage the fruiting bodies of cultivated fungi.

For this reason, there is a struggle to combat mushroom mosquitoes not only in Hungary, but all over the world. "As a result of the unilateral use of pesticides, resistant and tolerant populations have long appeared abroad.This means that chemicals no longer always provide adequate protection against pests," says Sándor Kecskeméti, research assistant at ATK. In Hungary, conventional chemical preparations are no longer allowed in the various cultivated cultures, neither can we count on the appearance of a new product.

The rapid development of cultivated fungi is difficult to reconcile with the food health waiting period for pesticides. Which is why nematodes – as organic preparations – are used in cultivation in Hungary against fungal mosquitoes. However, these preparations do not provide complete protection either. Growers are therefore trying to reduce pests with agro-technical solutions: they place yellow sticks or adhesive strips at the appropriate points in the greenhouse, and also place ultraviolet light traps in the corridors and cultivation blocks.

The European Union wants to reduce the quantity of pesticides used by 50 percent by 2030. In order to achieve this goal, it is necessary to encourage the development of alternative, chemical-free control methods in agriculture. Although growers use ultraviolet light traps, it had not been previously investigated whether the radiation emitted by the traps is actually effective or whether there is another spectral range that attracts fungal mosquitoes more effectively.

Researchers have now studied the spectral sensitivity and wavelength dependence in light of one of the most common fungal mosquitoes (Lycoriella ingenua) in electroretinographic and various behavioral experiments. “We carefully examined how the attraction of a fungal mosquito to light depends on the wavelength and intensity of the light. We then came to the interesting conclusion that the wavelength dependence of attraction is intensity dependent: at very low light intensities, the green spectral range proved to be the most attractive, while at higher light intensities ultraviolet was the most attractive,” explains Ádám Egri, an ÖK researcher.

Based on the test results reported in the study just published, it would therefore be a good idea to use light traps in greenhouses that emit in the green range in addition to the ultraviolet spectral range. The researchers now want to help mushroom growers control fungal mosquitoes by developing a more effective light trap than previously.

Publication:

Kecskeméti, S., Geösel, A., Fail, J., Egri, Á. (2021) In search of the spectral composition of an effective light trap for the mushroom pest Lycoriella ingenua (Diptera: Sciaridae). Scientific Reports 11, 12770.