Invasive Species Compendium

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Abstract

Parasites of the males of the California scale Diaspidiotus perniciosus Comst. (Homoptera, Coccoidea).

Abstract

Observations over many years in orchards on the Black Sea coast of the Krasnodar region in the USSR indicated that natural enemies were not of outstanding importance in the control of Quadraspidiotus perniciosus (Comst.) (Diaspidiotus perniciosus.). The most effective in 1947 was the parasite Prospaltella perniciosi Tower, which parasitised females only. In 1951, this parasite was found in some places other than the coastal areas, and it was still more widespread in 1952-53, when parasitism reached 60-90% in some places. Its distribution extended to the Kabardino-Balkarskaya Republic and Georgia. Other parasites (Aphytis proclia (Wlk.), A. mytilaspidis (LeB.), Aspidiotiphagus citrinus (Craw) and Thysanus ater Wlk.) occurred in the high mountain region, and also a species at first thought to be Pteroptrix chinensis (How.) (Casea chinensis) but since identified as Archenomus maritimus (Nikol'skaya). All these likewise parasitised only females or future females. In the early 1960s, some change in the behaviour of some of them and a fresh species parasitising the males were noted. The fresh parasite was a species of Aphytis close to A. proclia, and the true A. proclia was found parasitising males in an orchard in which females were scarce. The fresh species parasitised male prepupae and occasionally nymphs and pupae. It overwintered as eggs in nymphs and developed very slowly, all immature stages being present in early July and adults by the end of the month. Development became more rapid with the onset of summer heat, so that there were 2-3 generations a year, 3 being common on the coast. Aspidiotiphagus citrinus was also found parasitising males, though it was commoner on females. Prepupae of the males were the preferred stage. Details of the development of both these are given. Parasitism of males became important in 1970 and later, and in the spring of 1972 up to 36.1% of the females were found not to have been fertilised. Similar lack of males occurred in 1973 and 1974 in coastal regions. This is an important development in the parasitism of Q. perniciosus.