Toxicological and biochemical parameters of microbial preparations on the cotton leafworm Spodopter alittoralis (Lepidoptera : Noctuidae)‎

Abstract EN

Laboratory experiments were conducted to evaluate the efficacy by sequential treatments of the two entomopathoginc nematode isolates, Heterorhabditis bacteriophora and Steinernema carpocapsae and the entomopathoginc fungus, Beauveria bassiana (Biopower1.4%WP) as well as the combined effect of them against the 3rd instar larvae of the cotton leaf worm, Spodoptera littoralis (Boisduval) (Lepidoptera: Noctuidae).

Data revealed that the nematode, H.

bacteriophora was more potent than S.

carpocapsae where their Lc50 values after 72h of treatment recorded 53.3 and 81.41 Jv/ml, respectively.

On the other hand, the LC50 value of the entomopathoginc fungi, B.

bassiana scored 20.08 gm/l.

The combination between the three tested bio-agents using sequential method (B.

bassiana+ H.

bacteriophora) and (B.

bassiana + S.

carpocapsae) against S.

littoralis 3rd instar larvae indicated a potantiation effect .The highest larval mortality percentage (93.75%) was recorded by treatment with the combination of the two bioagents.

The effect of these pathogens on certain biochemical and physiological aspects of the treated larvae showed that the total protein content and the activity of transaminases were decreased post-infection with each tested bio-agent individually and this reduction was higher when they were used in combination.

In contrast, there were an increase in the activity of acid and alkaline phosphatases.

The increased activities were higher in treatment with the combined bio-agents than in treatment with each bio-agent only.