Nutrition of the Pale Western Cutworm, Agrotis Orthogonia Morr. (Lepidoptera: Noctuidae): Ii. Dry Matter and Nitrogen Economy of Larvae Fed on Sprouts of a Hard Red Spring and a Durum Wheat

Abstract

Dry matter and nitrogen balances, determined for individual instars of the pale western cutworm fed ad libitum on wheat sprouts, showed that reliable data were obtained for only the fourth, fifth, and sixth instars. During the larval period a single cutworm consumed about 10 g of fresh wheat sprouts containing about 25 mg of nitrogen. Of the consumed food, 40–50% of the dry matter and 60–70% of the nitrogen were excreted. Five days after the fifth molt the fresh weights of larvae fed on sprouts of durum wheat were significantly less than those fed on sprouts of the hard red spring wheat, but the dry weights were the same. The quantities of nitrogen found in excreta and body tissue approximated that consumed by the larvae. In contrast, however, much of the consumed dry matter (14–33%) could not be accounted for; recovery varied with variety. The percentage of the dry matter utilized, about 50%, remained constant during the last three instars. Nitrogen utilization by fourth-, fifth-, and sixth-instar larvae ranged between 25 and 45%. However, a consistently lower percentage of the nitrogen was utilized from Thatcher than from Golden Ball sprouts. On both varieties the lowest values were obtained in the sixth instar. In the excreta the percentages of insoluble dry matter, insoluble nitrogen, and volatile bases showed no consistent change during the last four instars. Seventy to eighty per cent of the excreted nitrogen was soluble in 80% ethanol, and about one-fifth of this was in the form of volatile bases. The variety of wheat sprouts fed had little, if any, effect on the composition of the excreta.

Difference in Weight Gain During Final Stadium of Pale Western and Army Cutworms Related to Life History and Crop Damage

“…Between 37% and 40% of the final larval live weight was gained during the ultimate stadium and about the same amount was gained during the penultimate stadium. Similar results were reported for pale western cutworm larvae fed on wheat sprouts (McGinnis and Kasting and McGinnis 1959). The few larvae with seven instars usually had only a 1.5-fold increase during the ultimate stadium.…”

Stabilization of the Rate of Nitrogen Accumulation by Larvae of the Cabbage Butterfly on Wild and Cultivated Food Plants

“…The effects on such efficiencies of variation in nitrogen content of food are poorly known, but the few results available are all consistent with our findings for P. rapae. Agrotis orthogonia (Kasting and McGinnis 1959) and Melanoplus bivittatus (Mc-Ginnis and Kasting 1966) exhibit relationships between feeding efficiencies and food nitrogen content which are similar to those exhibited by P. rapae. Larvae of P. maculipennis consume more food and exhibit a reduced dry matter assimilation efficiency as the protein content of the food plant declines with age, but the nitrogen utilization efficiency cannot be calculated because the nitrogen content of the larvae was not measured (Taylor and Bardner 1968).…”

“…Alteration of the rate of food consumption by animals in response to variation in the levels of nutrients is a well-established phenomenon. Larvae of the large white butterfly Pieris brassicae (Evans 1938), the fruit fly Drosophila melanogaster (Sang 1956), the pale western cutworm Agrotis orthogonia (Kasting and McGinnis 1959), the cabbage armyworm Mamestra brassicae (Hirano and Noguchi 1963), the sphinx moth Celerio euphorbia (House 1965), the diamond-back moth Plutella maculipennis and mustard beetle Phaedon cochleariae (Taylor and Bardner 1968), and the black carpet beetle Attagenus megatoma (Baker 1975) all tend to consume more food when feeding on nutritionally-poor plants or diets, especially those low in nitrogen, than when feeding on nutritionally-good food sources, especially those high in nitrogen. The aphid Tuberolachnus salignus produces more honeydew when feeding on mature stems of willow (low in nitrogen) than on the actively growing stems which are high in nitrogen (Mittler 1958), and this response is apparently due to the phagostimulatory effect of certain amino acids (Mittler 1967, Harrewijn and Noordink 1971.…”

“…Efficiencies of nitrogen utilization have been reported for several insects and others can be calculated from the published data (McCay 1938, Evans 1939a, I939b, Sharada and Bhat 1957, Kasting and McGinnis 1959, Hirano and Ishii 1962, Hirano and Noguchi 1963, McGinnis and Kasting 1966, Waldbauer 1968). The effects on such efficiencies of variation in nitrogen content of food are poorly known, but the few results available are all consistent with our findings for P. rapae.…”

NUTRITION OF THE PALE WESTERN CUTWORM, AGROTIS ORTHOGONIA MORR. (LEPIDOPTERA:NOCTUIDAE): III. LYOPHILIZED SPROUTS AND LEAVES OF WHEAT AS A BASAL DIET FOR LARVAE, AND EFFECTS OF SUPPLEMENTATION WITH L-LEUCINE

“…Fresh wheat sprouts have been used for nutritional studies on the pale western cutworm (16,18) but are not suitable for supplementation studies. Thus a suitable basal medium had to be obtained before it was possible t o test the effects on cutworm development of supplementing the diet with a n amino acid.…”