ANTIBIOSIS MECHANISM OF RESISTANCE TO THE LEGUME POD BORER, MARUCA-TESTULALIS GEYER (LEPIDOPTERA, PYRALIDAE) IN COWPEA

The biology of Maruca testulalis Geyer was studied on different parts of 18 cowpea cultivars to determine the role of antibiosis in their le vels of resistance. M. testulalis larvae were successfully reared from first instar to adult stage on floral buds, flowers and sliced pods, but not on stems, terminal shoots and intact (unsliced) pods, where th ere was complete larval mortality. The mean pupal weight ranged from 4 3.5-54.5 mg on floral buds, 38.5-58.6 mg on flowers and 42.7-58.6 mg o n sliced pods, with highly significant differences between (P < 0.01) resistant and susceptible cultivars on each part. Growth indices showe d that sliced pods were the most suitable for larval growth and develo pment, followed by flowers and floral buds. The levels of resistance r ound were inadequate for solving the M. testulalis problem in cowpea. Selection and breeding for cowpea ideotypes (architypes), to combine s uch resistance with morphological, biochemical and biophysical traits, could enhance the low levels of resistance in the cowpea crop and ult imately lead to the effective management of this pest. The correlation s between growth and development parameters showed that larval period had the most influence on M. testulalis survival and population build- up in the succeeding generations.