Resistance of squash genotypes to Bemisia tabaci (Germ.) biotype B (Hemiptera: Aleyrodidae)

Whitefly control using resistant cultivars can be considered the ideal option in integrated pest management programs. Squash cultivars and lines with different genealogies have been developed and released by private and public research institutions. However, little information is available about the resistance or susceptibility of those genotypes to insects. The main squash (Cucurbita spp.) cultivars available in the Brazilian market were evaluated as to Bemisia tabaci biotype B resistance, under greenhouse conditions. The cultivar 'Golden Delight' was the most attractive to adults, while 'Menina Brasileira', 'Barbara' and 'Atlas' presented the lowest numbers of adults on the abaxial leaf surfaces. Oviposition was evaluated in free-choice and no-choice tests. 'Novita', 'Exposicao' and 'Caserta' behaved as resistant and showed oviposition nonpreference as the resistance mechanism. The cycle from egg to adult emergence was determined in six genotypes. In 'Golden Delight', the duration of this cycle was the shortest one (24.9 days), and the percentage of adult emergence, the highest one (93.8%), thus indicating that this cultivar is suitable to the insect. On the other hand, 'Exposigao' and 'Menina Brasileira' prolonged this cycle (35.8 and 33.5 days, respectively) and reduced the adult emergence (46.3 and 58.1%), showing to be resistant.