Reduction of population numbers of Melolontha spp. adults – a review of methods

The article provides information about control of Melolontha spp. adults, the methods used in the past, chemical pest control as well as treatments applied today. In old times, cockchafer populations were reduced mechanically, by manual collection during the swarming period or by covering soil surfaces to prevent egg lying by females. Chemical pest control methods were introduced in the fifties of the 1900s, and in subsequent 50 years, they were improved to be less and less environmentally threatening. In many countries, including Poland, there have recently been introduced progressive restrictions on the use of insecticides in forestry. Banning chemical treatments against cockchafers resulted in going back to traditional methods and seeking alternate solutions, e.g. biological control agents. In the 1990s, polyethylene nets were used to prevent egg laying in the soil by cockchafer females. At the same time, there was tested possible usefulness of a botanical insecticide derived from neem (Azadirachta indica) to combat cockchafer adults. The net, which needs to be spread flat on the ground, can be effective in orchards, however, in forested areas, the success of this method was limited due to the specific structure of forest land. In general, both methods stimulated no interest on the part of forestry on account of technical obstacles and too high cost of the botanical insecticide. Neglecting treatments toward reduction of cockchafer excessive numbers during their ongoing outbreak can bring about adverse changes in the forest structure.