Use of Osmia cornifrons for Pollination of Apples in Aomori Prefecture, Japan
A mite, Chaetodactylus nipponicus, invades nests of Osmia cornifrons to feed on pollen which has been stored by the bees in the nests for their offspring. The mite also adversely affects the flight of the bees by clinging to their bodies. Two methods of control of the mite were developed. In the first one a selective insecticide was used. Egg mortality from the mite decreased markedly by supplying the bees with nest sources treated with 60 ppm endosulfan. Furthermore, by spraying the nest entrance two to three times every second or third day during the flying period, the mite could be controlled without any lethal effect on the bees. In the second method, differential mortality from high temperatures was used, as pre-pupae of O. cornifrons are resistant to high temperatures due to the diapause while during this period, the mites are still reproducing and are sensitive to high temperatures. Most orchards require the application of insecticides in late April. To avoid the exposure of the bees to insecticide sprays, emergence from nests is delayed by storing the nests at 0-5℃ from early to late April. Even though the period of storage exceeds 20 days, the activity of the bees is normal.
|作成者||Norio SEKITA Masateru YAMADA|