EFFECT OF GAMMA IRRADIATION COMBINED WITH B.T.BIOCIDE TREATMENTS ON SOME INSECT PESTS IN LABORATORY

Abstract

The study was done in the laboratories of Bollworms, Leafworm and piercing & sucking Research Departments of Plant Protection Research Institute during 2010. The tested pests and the biocide, Protecto were exposed to gamma irradiation doses at National Center for Radiation Research and Technology, Egypt. Three tested insects were tested includes: pink bollworm, Pectinophora gossypiella (Saund.) newly hatched and fourth instar larvae, cotton leafworm, Spodoptera littoralis (Boisd.) 4th instar larvae and the nymph & adult of cowpea aphid, Aphis craccivora (Koch). Insects were exposed to three doses of gamma irradiation, 150, 250 & 350 Gy. Also, the biocide compound, Protecto (Bacillus thuringiensis, Kurs.) was applied on the same pests to assess the insecticidal activity of Protecto in three combinations (Protecto +150 Gy, Protecto +250 Gy and Protecto +350 Gy). Data showed that the tested γ- irradiation doses of 150, 250 and 350 Gy increased the newly hatched larval mortality of P. gossypiella to 52, 65 and 85% at zero day, respectively. While, it was reached to 100% kill at third day for 350 Gy and fifth day for 150 and 250 Gy. Larval mortality of P. gossypiella fourth instar was reached to 100% at eight and tenth days after radiation. Also, the larval mortality of S. littoralis fourth instar larvae was reached to 100% at tenth and twelfth days after treatment, respectively. While, A. craccivora adults and nymphs mortality was reached to 100% at zero day just after treatment. Generally, LC50 ,s on subjected insects treated with Protecto and exposed to gamma doses were lower than untreated Protecto. The aim of present work was to evaluate the insecticidal activity of the biocide Protecto in combination with γ-irradiation exposure against three key insect pests in laboratory.