S.M. AHMED, M.K. EL-KHISHIN. S.H. TAHER*, AND S.M. NAGUB*
Plant Protection Dept., Fac. Agric., Zagazig Univ.
* Plant Protection Research Institute, Dokki, Cairo , Egypt .

ABSTRACT

Newly hatched larvae of Pecrinophora gossypiella (S.) were reared on artificial diet contained gossypol and coumarin at different concentrations and at constant temperature of 27 ± I °C. and 80 ± 5 R.H. Treated larvae suffered mortality throughout the larval stage. Mortalities were concentration dependent. Coumarin was about 4.56 times more toxic than gossypol at LC 50 level. The two compounds decreased the rate of larval development. The two compounds caused reduction in larval and pupal weight and percentage of pupation. The reduction was proportional to concentration. Coumarin caused more malformation and elongation of pupal stage than gossypol. The two compounds reduced the percentage of emergency. Adults emerged from larvae reared on the diet containing the two compounds laid less number of eggs than control, and the frequency of mating was reduced. The tested compounds did not prove to be diapause inducers.

Key Words: Allelochemics , Gossypol , Coumarin , Biological aspects, Pectinophora gossypiella.