The Response of Larvae of the Large White Butterfly (Pieris brassicae (L.)) to Diets of Mineral-deficient Leaves

Abstract

The direct approach to the study of the food requirements of insects is to rear them on artificial diets. This has, however, proved difficult in the case of those normally feeding on living plants, although larvae of the European Corn Borer (Pyrausta nubilalis (Hb.)) have been raised successfully in this way (Bottger, 1942;Beck & Lilly, 1949). Changes in the food value of leaves may, nevertheless, be readily induced under controlled conditions by growing plants in sand or water culture. Studies on insect growth and egg-laying rates on plant food raised in this way have been reported by Smith & Northcott (1951) (Melanoplus mexicanus mexicanus (Sauss.) on wheat), Dahms (1947) (Blissus leucopterus (Say) on sorghum); Wittwer & Haseman (1945) (Heliothrips haemorrhoidalis (Bch.) on New Zealand spinach); Haseman (1946) (greenhouse whitefly (Trialeurodes vaporariorum (Westw.)) on petunia and tomato; Toxoptera on wheat); Creighton (1938) (Alabama on cotton); Barker & Tauber (1951) (Myzus persicae (Sulz.) on Tropaeolum); Allen & Selman (1955) (Phaedon cochleariae (F.) on watercress). Similar work has also been carried out with a mite (Tetranychus) by Garman & Kennedy (1949) and by Eodriguez (1952). There are also numerous relevant field observations of uncertain value (reviewed by Allen, 1954).Little is known concerning the response of leaf-eating caterpillars to the mineral nutrition of the food-plant, although Evans (1938) obtained indications that the carbohydrate and nitrogen content of the plant affected the rate of growth of Pieris brassicae (L.). He found that larvae fed on plants grown in the shade increased in weight more slowly and pupated later than those fed on plants grown in normal light. This slower rate of growth was probably related to the lower carbohydrate and nitrogen content of the plants grown in the shade.In the present work it was found that larvae of P. brassicae were well suited to the study of the effect on insect development of mineral deficiencies in plants, since they are not limited to one species of food-plant, and are easily reared and handled. Technique.In the first experiment, larvae of P. brassicae were fed on leaves of cauliflower grown in sand culture at two levels of nitrogen; in the second experiment the diets consisted of leaves of turnip grown in sand culture with complete nutrients and with deficiency of nitrogen, phosphorus or potassium, respectively; in the remainder of the experiments leaves of watercress grown in complete nutrient or in iron-deficient water culture solutions were used. Apart from the differences between culture solutions (described below) the mineral-deficient and normal plants were grown under similar conditions and, in any one experiment, the different groups of plants were of similar ages. Before being supplied as food,

Effects of Changing the Phosphorus Content of the Food Plant on the Migratory Grasshopper, Melanoplus bilituratus (Walker) (Orthoptera: Acrididae)

“…There was no indication whether phosphorus or some other substance whose abundance was correlated with that of phosphorus was the effective factor, but there were no marked differences between the two treatments in the amounts of any of the other elements shown in Table 11. Allen and Selman (1957) have reported that Pieris brassicae (L.) has a small larval weight and a long development period when reared on turnip leaves grown in a phosphorus-deficient medium whereas Dahms (1947) has reported that Blissus leucopterus (Say) laid more eggs when reared on seedling sorghum grown in a phosphorus-deficient medium. It may be that these two investigations were conducted on ranges of phosphorus content that were on opposite sides of an optimum.…”