INNATE DIFFERENCES IN CONSUMPTION AND UTILIZATION OF FOOD BY THE FAST-GROWING AND SLOW-GROWING LARVAE OF CABBAGE-LOOPER, TRICHOPLUSIA-NI (HUBNER) (LEP, NOCTUIDAE)

Consumption and utilization of soybean leaves by the fast versus slow- growing larvae of the cabbage looper, Trichoplusia ni were studied und er laboratory conditions. Fast-growing larvae consumed more food/unit of body mass, and gained weight 10 times faster than the slow-growing larvae. Slow-growing larvae were less efficient in consumption and uti lization of food, and the differences in indices of food utilization w ere greater between the fast- and slow-growing larvae on the relativel y resistant soybean cultivar, ''PI 227687'' than on the susceptible cu ltivar, ''Davis''. Implications of differences in growth rates and foo d utilization by the fast- and slow-growing larvae on resistant and su sceptible cultivars are discussed in relation to evolution of new biot ypes and host-plant resistance.