Discovery of a Paedogenetic Gall Midge (Diptera: Cecidomyiidae) in Japan and Notes on Its Reproduction in vitro and Infestation in a Cultivating Factory of the Oyster Mushroom

Abstract

A gall midge which attacks the mycelium of “Hiratake, ” the oyster mushroom, Pleurotus ostreatus, was recently found in Miyazaki Prefecture, and was identified as a paedogenetic species of the genus Mycophila, which is new to Japan. Although this species is quite small in size (wing length about 0. 9 mm), the ovarian eggs are relatively large (major axis 0. 25 mm) and few (4–6) in number. Larvae exhibited variations in body length and colour, and in the presence or absence of the sternal spatula. The time required to complete one paedogenetic cycle was 4—5 days at 25°C. The number of young larvae produced by a mother larva varied from 2 to 33, depending on the different breeding conditions. The reproduction rate of larval paedogenesis was highest at 27°C, followed by 22°C and 17°C, and very low at 12°C. The larvae also reproduced well by feeding on mycelia of other fungus species than P. ostreatus, such as “Kikurage,” Auricularia auriculajudae, “Nameko,” Pholiota nameko, and mushroom, Agaricus bisporus. This indicates that the gall midge has a potentiality to become a pest of various edible fungi in Japan. The midge population which was first found in Miyazaki Prefecture has been completely eradicated from the factory by spraying an insecticide. © 1986, JAPANESE SOCIETY OF APPLIED ENTOMOLOGY AND ZOOLOGY. All rights reserved.