The Reproductive Potential and Fate of Chlorfluazuron and Leufenuron Against Cotton Leafworm Spodoptera littoralis (Boisd.)

摘要

The Egyptian cotton leafworm is one of the most destructive insect pests which attacks many field crops. So the the present work aims to investigate the potential and fate of two new acylurea compounds, chlorfluazuron and leufenuron to reduce the reproductive capability of the Spodoptera /littoralis.The results indicated that all treatments succeeded to decrease the percent pupation, pupal weight and adult emergence. A significant reduction in longevity and mating frequency was found. All reciprocalcrosses of chlorfluazuron and leufenuron treatments resuted in a very low percentage of fecundity which ranged between (33.3 to 53.9 %). Egg hatchability was also significantily reduce, it ranged between (44.5 to 61.7%) for chlorfluazuron and (59.7 to 73.2%) for leufenuron compared to (94.7% )for the control. In conparison with fertility of control chlorfluazuron caused (62.2 to 80.4 %) sterility whereas leufenuron caused (52.1 to 74.9 %). So treatments with chlorfluazuron appeared to be more efficientthan leufenuron. In order to elucidate the observed differences between the activities of chlorfluazuron and leufenuron, the amount of residues as parent compound existed in differential developmental stages of 5. littoralis were determined. The resultsindicated that after 3 days of treatment 58.9 % chlorfluazuron and 36% leufenuron were recovered. Analysis of extract of emerged moths and eggs showed that sufficient quantities of the tested compounds were retairned by treated insects to cause the previously profound reduction in fecundity and egg hatchability. The results also indicated that leufenuron was eliminated two times faster than chlorfluazuron.