The comparative resistance of some recent releases of cotton cultivars against the sucking insect pests [whiteflies; jassids, thrips and aphids]

The main aim of the present investigations was to find out the comparative resistance of some recent introductions of cotton to the sucking insect-pest-complex as well as to see how it compares with that of the individual pest. To proceed with, therefore, the materials employed were comprised of a field grown crop of 5 cotton cultivars, viz., FH634, FI1-910, F14-919, CIM-473 and MNI1-552, as well as, field available lot of 4 sucking insect-pests, viz., cotton whiteflies, cotton Jassids, cotton thrips and cotton aphids. The trials were, however laid out at the Ayub Agricultural Research Institute, Risalewala, Faisalabad, in a Randomized Complete Block Design, and there were, in all, 5 treatments of 3 repeats, each. The estimates on the overall pest population and its varietal and weekly distribution were finally presented in the form mean values. The pest-resistance in plants was, however considered to be an indirect reflection of the population counts of the insect-pests taken per leaf. On the basis of a thorough discussion of the data collected, it was concluded that: The comparative resistance the cotton cultivars tested varied not only with reference to the sucking insect-pest-- complex, but also with its components. CIM-473 was found to be the most resistant to the sucking pest complex as well as to the whiteflies. The changes in the overall resistance of the test cultivars against the sucking insect-pests were significant. In reducing the in-built resistance of cultivars, whiteflies contributed outstandingly major part sucking insect- pests. Based on these conclusions, it would be suggested, for practical purposes, that the cultivation of CIM-473, cotton variety which is the most resistant against the sucking insect-pests should be encouraged and/or the cultivation of FH-634, cotton variety which is highly susceptible to the sucking pests complex should be discouraged. On the fundamental side, however there is need for some studies regarding physicomorphic factors responsible for the resistance of certain varieties against the sucking pest- complex, which may be considered in future.