The Selection and Rearing of Leaf-eating Insects for Use as Test Subjects in the Study of Insecticides

Abstract

A number of leaf-eating insects have been studied with the object of selecting species suitable for rearing in the laboratory.Four species have proved satisfactory for large-scale rearing throughout the year. These arePlutella maculipennis, Plusia gamma, Diataraxia oleraceaandPhaedon cochleariae. A number of species possess certain disadvantages : (1) apparently obligate diapause (Mamestra brassicae, Sphinx ligustri). (2) The same as (1) with the additional disadvantage of lack of food-plant in winter (Lymantria dispar). (3) Uncertain copulation and oviposition (Pieris brassicae). When available, these species may be reared satisfactorily in large numbers.Mesographe forficalis, Xanthorhoë fluctuata, Lema melanopaandCrioceris asparagihave been reared in relatively small numbers. They possess certain disadvantages but should be satisfactory for large scale rearing at any rate during some part of the year.At present laboratory rearing ofPhlogophora meticulosa, Agrotis segetum, Triphaena pronuba, Aclypea opacaandAthalia colibriis considered impracticable. A number of leaf-eating species, particularly Hymenoptera, which appear to possess suitable qualities for laboratory rearing, have not yet been obtained and studied in the laboratory.Particular attention has been paid to factors influencing development of leaffeeding insects with the object of determining the conditions under which healthy stocks of uniform resistance can be maintained. The results of experiments on the effect of food-plant, temperature, humidity and illumination are described. Studies on the factors influencing diapause in the various species are mentioned. Descriptions, are given of the rearing techniques that have been developed.