iobc

This study was carried out to investigate persistency of four insecticides (thiodicarb, indoxacarb, proclaim fit and lufenuron) on cotton plants and their toxicity against Trichogramma brassicae .Cotton seeds were sown under greenhouse condition and cotton plants were sprayed with insecticides . Cotton leaves were removed at one-day intervals and were kept in a rearing container with female parasitoids and host eggs. Mortality and sublethal effects of insecticides were recorded every day and their toxicity and persistency were categorized according to the International Organization of Biological Control standard. Results showed that toxicity (with up to 100% mortality) and persistency (>17 days) of thiodicarb was higher than other insecticides and was categorized as a “harmful” and at least a “moderately persistent insecticide. Indoxacarb with up to 52.8% mortality, 62.8% reduction in parasitism and 7 days persistency, was classified as a ”harmful” and “slightly persistent” insecticide. Proclaim fit with up to 37.3% mortality, 47.4% reduction in parasitism and 6 days persistency, was classified as a “moderately harmful” (Group 3) and slightly persistent insecticide. Lufenuron with up to 2.68% mortality, 60.69% reduction in parasitism and 3 days persisitency, was classified as a “slightly harmful” (Group 2) to ”moderately harmful” and short-lived (group 1) insecticide. In conclusion, because of high toxicity and long-term persistency, thiodicarb is not recommended to use in cotton field against cotton bollworm, and a 7, 6 and 3 days “waiting period” was required, respectively between spraying with indoxacarb, proclaim Fit and lufenuron and mass releasing of T. brassicae in cotton fields.

Lysiphlebus fabarum Marshall,an endoparasitoid of the black bean aphid, Aphis fabae Scopoli is an important component of integrated pest management of this pest and it is necessary to study its interaction with insecticides used against this pest. In this study, the lethal effects of recommended concentrations of three insecticides, thiacloprid痩浪枭蚸, pirimicarb and pymetrozine were investigated on pupal and adult stages of the parasitoidunder laboratory conditions. The pupae and the adults were exposed to insecticides with mummy dipping and dry residues of insecticides on glass plates methods, respectively. Thiacloprid痩浪枭蚸 and pirimicarb significantly caused mortality rates in pupal and the adult stages, while pymetrozine had no significant effect. According to International organization for biological control (IOBC)(toxicity of insecticides), thiacloprid痩浪枭蚸 at the pupal and the adult stages were classified as moderately harmful (class 3) and harmful (class 4), respectively. Pirimicarb was also classified as slightly harmful (class 2) and harmless (class 1), respectively. Pymetrozine in the two tested stages were classified as harmless (class 1). In this study, the persistent toxicity of insecticides against the adult wasps was also investigated under semifield conditions. According to the IOBC (persistence) classification, thiacloprid痩浪枭蚸, pirimicarb and pymetrozine were classified as moderately persistent (class C), slightly persistent (class B) and short lived (class A), respectively. According to the present study, pymetrozine and pirimicarb had low side effects on L. fabarum at the pupal and adult stages, but thiacloprid痩浪枭蚸 caused deleterious effects on this parasitoid at two stages tested.