Adult behaviour and oviposition of five noctuid and tortricid moth pests and their control in glasshouses

Abstract

Adult behaviour and oviposition patterns of Cacoecimorpha pronubana (Hb.), Phlogophora meticulosa (L.), Autographa gamma (L.), Mamestra brassicae (L.) and Lacanobia oleracea (L.) were studied by introducing laboratory reared pupae into glasshouses. Adults emerging from these pupae were located by direct visual searching of chrysanthemum plants and of the greenhouse structures for up to three weeks after emergence.

In small houses (2·9×3·3×2·5 m), 49 adults of C. pronubana emerged. At least 15 stayed inside the house and laid 1 750 eggs. With P. meticulosa, A. gamma and L. oleracea, 262 adults emerged and escaped from the houses without laying eggs inside.

In a large glasshouse (9·8×13·1×5·1 m) with automatic ventilators, 840 adults of P. meticulosa, A. gamma and M. brassicae emerged and many were prevented from escaping when the ventilators were closed during the moths' flight period. Moths were inactive in daytime and most were found on the highest parts of the aluminium framework, mainly on the sides which received most external light overnight. None were found on the glass. Only 27·3% of the P. meticulosa were found on the plants. Moth distributions probably result from moths flying until they reach a barrier, which they then tend to follow, with directional responses to gravity, light, settling site, food plant and oviposition site superimposed in varying degrees on this basic pattern. About 30 470 eggs were laid, more in outer than in inner beds and more in the outer than in the inner rows of a bed. P. meticulosa and A. gamma laid eggs only on plants. M. brassicae laid about 1 854 eggs on the undersides of leaves and 2 972 on glass and framework, mainly in the direction of external light.

All five species can cause serious damage to crops. Initial infestations can be controlled by sprays of chemical insecticides or Bacillus thurin-giensis. Usually a few larvae survive a single spray and, in the absence of further control measures, they may produce a troublesome second generation, although in certain circumstances further control measures may not be required. If biological control of other tomato pests becomes widespread, steps should be taken to prevent L. oleracea again becoming an important pest.