Investigations on Natural Enemies, Some Biological Characteristics and Population Fluctuations of Lepidosaphes Ulmi (L.) (Homoptera, Diaspididae) and Palaeolecaniutn Bituberculatum (Targ. and Tozz.) (Homoptera, Coccidae) Harmful To Apple Trees in Van Province

Abstract

This study was carried out from 1991 to 1993, in Van province (Erciş, Edremit, Gevaş), which aimed to find out the population fluctations, some biological characteristics and natural enemies of L. ulmi and P. bituberculatum harmful to apple trees. Samples were collected periodically every 15 day from 7 trees (Starting variety) in every orchard determined in Gevaş, Edremit and Erciş. All the biological stages, either alive or death, of pests, parasitized individuals and natural enemies were counted on the branches or leaves infested. According to the results obtained, it was determined that L. ulmi and P. bituberculatum overwintered as egg stage on apple trees in Van province. They reproduced sexually and have one generation a year. The average number of eggs laid per female for L. ulmi and P. bituberculatum were determined as 50(9-90) eggs and 259(14-646) eggs, respectively. The mobile nymphes of two species, which were the most susceptible stage to insecticide, were found in orchards in May. Aphytis mytilaspidis (Le Baron) and Hemisarcoptes malus (Shimer) were found to be the most effective natural enemies of L. ulmi. A parasitoid, Coccophagus palaeolecanii Jasn, was obtained from P. bituberculatum, but it was observed that its population was very low.