LEVELS OF RESISTANCE TO PAINTED SPROUT, ZABROTES SUBFASCIATUS (BOHEMAN) IN CULTIVATED AND WILD BEANS

Abstract

Low levels of resistance were detected among more than 5661 accessions of cultivated dry beans (Phaseolus vulga­ris L.) exposed to Zabrotes subfasciatus (Boheman). Although significant differences were found among the accessions for all of the parameters of resistance measured, the most consistent separation among accession was obtained by using deve­lopmental time and weight of adult progeny. Expression of resistance was maintained when the number of bean seeds per adult. was varied; however, the stan­dard method used (7 pairs of adults infesting 50 seeds) was the best infestation level to detect differences in resist stance. Successive rearing for five generations on resistant or susceptible classified entries did not change expression or reduce the reproduction of Z. subfasciatus on resistant fines. Resistance levels were too low to be of economic value. Ins­tead, excellent sources of resistance were found among wild P. vulgaris accessions. Resistant wild accessions had a signi­ficant effect on the biology of the insect; thus, the progeny was significantly reduced and the developmental time was prolonged.