Biology and morphometry of Megaselia halterata, an important insect pest of mushrooms

This paper aims to provide insights into knowledge on morphology, biology and development of Megaselia halterata (Wood), one of the most common insect pests of mushroom houses. We focus on such traits as body length and weight and width of pseudocephalon, and show how these traits differ in subsequent development stages as well as across time. The development time of a generation, from egg to adult, lasted 16-19 days at 24 °C; for larval stage this time lasted 12-14 days. Mean weight of particular stages ranged from 0.003 mg for eggs up to 0.492 mg for pupae, while mean length from 0.35 mm for eggs to 2.73 mm for 3 rd instar larvae. During larval development, mean body weight increased about 48 times and mean body length three times. Measurements of pseudocephalon of larvae showed that between the successive instars it increased approximately 1.4 times. Using the statistical technique inverse prediction, we develop formulae for estimation of larvae development time based on mean body weight and length of larvae found in a sample taken from a mushroom house, on which basis one can decide whether the infection occurred in the mushroom house or during compost production.