A study was carried out to develop a diet for mass rearing of the pink bollworm Pectinophora gossypiella (Saund.) and optimize bioassays for testing the bollworm's sensitivity to two insecticidal proteins from Bacillus thuringiensis (Bt). A P. gossypiella colony was established in the laboratory from field collections and its developmental biology was compared on various test diets. Larvae reared on a diet of cottonseed and chickpea flours for the first 10 days and subsequently on pieces of okra attained rapid growth and development. This two-phase diet has been used for successful laboratory rearing of 51 generations of the bollworm. Neonates were found to be sensitive to both the Bt proteins Cry1Ac and Cry2Ab2, which are produced by the transgenic Bt cotton products Bollgard™ and Bollgard II™.

The most important cotton pests in Egypt are the Egyptian cotton leafworm, Spodoptera littoralis, and the pink bollworm, Pectinophora gossypiella, together with localized infestations of spiny bollworm, Earias insulana.

Control of S. littoralis is achieved by the hand collection of egg-masses every 3 days during the early part of the cotton season by teams of children. Alternative control techniques currently being investigated include the use of microbial pesticides and insect growth regulators.

Large scale commercial applications of slow-release pheromone formulations are used to control P. gossypiella by the mating disruption technique as an alternative to four or five sprays of conventional pesticides. Similar pheromone formulations are being developed for control of E. insulana, which occurs towards the end of the cotton season.

As a result of using such a combination of selective control methods, beneficial insect populations have remained at high levels throughout the season and acceptable levels of infestation have been achieved associated with relatively few applications of conventional pesticides.

Pheromones have been successfully used on a large scale for control of pink bollworm, Pectinophora gossypiella, by mating disruption in Egypt and Pakistan using various slow release formulations. Similar formulations are being developed for control of other cotton bollworms, Earias insulana and E. vittella. Small-scale trials are in progress to evaluate pheromone formulations for control of sugar-cane borers, Chilo sacchariphagus and C. auricilius in Mauritius and India, and the tropical warehouse moth, Ephestia camelia, as a pest of stored cocoa in Brazil. Traps baited with the pheromone of the African armyworm, Spodoptera exempta, have been extensively used in Eastern and Southern Africa as the basis of a forecasting system of pest incidence.

Traps baited with the synthetic aggregation pheromone of the larger grain borer, Prostephanus truncatus, have been developed and are in use in E and W Africa for detection and monitoring of this pest of stored grain.

Diapause in the pink bollworm, Pectinophora gossypiella, is a quantitative genetic character that is in turn regulated by external environmental factors. A naturally occurring non-diapause strain of the insect from south India and two diapause strains from Arizona (U.S.A.) were used in crosses to study the inheritance of diapause. The F progeny expressed a diapause response intermediate between the two parents and no clear dominance was evident for the non-diapause character. It was not possible to classify the phenotypes of backcross and F2 progeny in accordance with simple Mendelian ratios. Comparisons of reciprocal crosses indicated that the progeny from male parents of the Indian strain usually had a lesser incidence of diapause. Such sex related differences were more evident in F2 progeny and backcrosses. It is therefore concluded that diapause in the pink bollworm is inherited in a complex way and that non-diapause is not completely dominant over the diapause trait. The study also indicated that incomplete dominance for non-diapause involves a sex-linked gene.