ASSESSMENT TOXICITY OF RECOGNIZED INSECTICIDES AGAINST Pectinophora gossypiella (SAUNDERS) AND THEIR IMPACT ADVERSE ON DEVELOPMENT AND REPRODUCTIVE PERFORMANCE OF Bracon brevicornis (WESMAEL) (HYMENOPTERA: BRACONIDAE)

In the current work, the toxicity of three compounds(belong to three different insecticidal groups); Flufenoxuron, Spinetoram, and Lambda-cyhalothrin were evaluated against the newly hatched larvae of Pectinophora gossypiella to estimate the LC50 values, in addition to study the adverse effects on some biological parameters of the insect and its larval parasitoid Bracon brevicornis. According to LC50 values, Lambda-cyhalothrin was the highest potency and the most toxic (0.358) followed by spinetoram (2.62) and Flufenoxuron (4.312). Moreover, all tested compounds significantly increased P. gossypiella larval duration to 23.5, 19.0, and 21.4 days/larvae for Lambda-cyhalothrin, Spinetoram, and Flufenoxuron, respectively, compared to 15.3 days for control. In addition, the highest percentage of total larval mortality was recorded (71%) for Flufenoxuron followed by (67%) for Lambda-cyhalothrin then (57%) for Spinetoram, compared to (4%) for untreated. Besides, percent of (5, 10, and 8 %) of pupal mortality were recorded for previously mentioned three tested compounds, respectively. Furthermore, rearing B. brevicornis on the full-grown host of P. gossypiella resulted from Flufenoxuron, Spinetoram, and Lambda-cyhalothrin treatments cussed significant elongations of both larval and cocoon durations recorded 10.9, 9.8, and 11.9 days/ larvae, and 8.3, 7.6, and 6.6 days/ cocoon, respectively, compared with 7.3 days/ larva and 5.6days/ cocoon in control. Therefore, the total immature period of the parasitoid B. brevicornis was observed to increase as a result of treatments. Besides, some biological parameters of B. brevicornis adults were also affected whereas, the oviposition periods were reduced to 9.6, 8.3, and days in rearing parasitoid females on Flufenoxuron, Spinetoram, and Lambda-cyhalothrin treated larvae, respectively, compared to 12.3 days for control, at the same time, the total number of deposited eggs by parasitoid females were reduced to 132.0, 109, and 74.3 eggs/ female, for Flufenoxuron, Spinetoram, and Lambda-cyhalothrin treatments, respectively, compared to 197.0 eggs/ untreated females.