Field and laboratory experiments on the site of oviposition by the potato mothPhthorimaea operculella(Zell.) (Lepidoptera, Gelechiidae)

Abstract

AbstractCounts of first-instar larvae showed that in a potato plot near Canberra, A.C.T., eggs ofPhthorimaea operculella(Zell.) were more prevalent around the bases of plants than between the rows or 2 m outside the plot; the few eggs on the plants were on dead leaves. In small plots each of different plant species, with due allowance for predation, many eggs were laid around tobacco and potato, and few or none near tomato, maize, lettuce or pea. Older larvae were most numerous on tobacco plants, while adults were most numerous on potato plants. A series of laboratory experiments using different oviposition substrates showed that the factors favouring oviposition could be ranked, in descending order: coarse substrate, shade, and treatment of the substrate with juices of potato tubers or foliage; foliage of potato or tobacco was not preferred.