Zur Kenntnis der Obstbaumminiermotte Lyonetia clerkella L. unter besonderer Berücksichtigung des Massenwechsels während der Jahre 1951 bis 1953

Abstract

1 L. clerkella L. is widespread in Europe, including Great Britain and Scandinavia. Its occurrence in Japan has not been definitely proved. 2 Outbreaks of this species have been known for centuries. 3 The moth, egg, the three larval instars and the pupa are described. The adult varies greatly in colour which could be connected with temperature. The 1st. and 2nd. instar larvae which are fully described for the first time are legless and thus very different from the 3rd. instar. In last stage larvae and pupae, the well marked testes are the only character differentiating the sexes. 4 The biology of all stages is explained. At 20° C., development from egg to adult takes about 30 days. 3–4 generations per annum are normal. In summer, the adults, which do not feed, live only a few days. The larvae of the last generation hibernate. The number of eggs per female can be approximated at 50. The eggs are laid singly on the underside of the leaves. 5 Host plants are Pomoid and Prunoid spp., also the genus Betula. The main hosts are sweet and sour cherry, apple, ornamentals of the genus Malus, medlar and quince. The larvae die on peach and other Prunus spp. During the vegetative period, a transfer takes place from apple to cherry. 6 The damage caused by mines and other effects on attacked plants are described. In the area studied, no damage of economic importance was found. 7 The outbreaks up to the present are summarized. The course of a gradation (1947–1950) and its associated collapse are described, together with the climatic and biological factors influencing them. Various Ichneumons are parasites, 11 species being found in large numbers. The most striking limiting factor is a mortality of young larvae, the cause of which is not clear. The effect of unfavorable weather on the hibernating moths appears to be more important. 8 „Nikopren”, „E 605 forte” and „Aralo” (Parathion) + lead arsenate are suitable for the control of eggs and young larvae. The time for control is: the appearance of young mines. 9 Judging by the morphological, biological and nutrition physiological differences, the Lyonetia species occurring in Japan is not the same as the European L. clerkella.