Schädlichkeit der Linsenblütengallmücke Contarinia lentis Aczél (Diptera, Cecidomyiidae) und ihre Verbreitung in der ČSSR

There has been an outbreak of lentil gall midge C. lentis on lentil in Czechoslovakia since 1984. Its extent and cause are given below. Infestation symptom-the gall-is described. The level of damage is defined as percent rate of the amount of galls and flower buds containing eggs of C. lentis from the amount of pods, flowers, galls, flower buds containing eggs and flower buds not containing eggs. As estimation is taken mostly at the end of lentil vegetation the level of damage is simplified to percent rate of the amount of galls from the amount of galls and pods. The level of damage of small parts of lentil stands can achieve 80%. Single plants with 95% level of damage were found. Proportional dependence of thousand-kernel weight on the level of damage was found out. Two functions of dependence of yield on the level of damage were compared: a simple linear one and a quadratic one which included the dependence of thousand-kernel weight on the level of damage. The generally valid linear function of dependence of yield y on the level of damage x is recommended: y=0.01 e (100-x) where e means yield at 0% damage level. Recent distribution area of this species in Czechoslovakia is given. In 1985-1988 the average level of damage of lentil stands from outbreak centre ranged from 3.08 to 52.05%. The average yield losses in Czechoslovakia were 5.49% in 1985, 4.98% in 1986, 2.87% in 1987 and 3.97% in 1988. Concentration of lentil fields in a small area was recognized as the main cause of the outbreak of C. lentis in Czechoslovakia.