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This study examined the fumigant efficacy of seven essential oils from rosemary, caraway, coriander, thyme, dill, camphor and basil against the adult of Sitophilus oryzae (L.), Tribolium confusum (J. du Val) and Callosobruchus maculates (Fabr.). The rosemary and caraway oil showed the highest fumigant efficacy against the rice weevil at a concentration of LC 50 (26 µl/l air) and (38 µl/l air), respectively. Rosemary (19 µl/l air) and coriander (23 µl/l air), had potent fumigant activities against the T. confusum. The caraway and rosemary were the most effective against C. maculates at LC 50 (19 µl/l air) and LC 50 (25 µl/l air) respectively. In conclusion rosemary and caraway showed strong fumigant toxicity to the S. oryzae, T. confusum and C. maculates. However, thyme and coriander had a lower fumigant activity than rosemary to insects. On the other hand, camphor, dill and basil also showed promising fumigant toxicities on the insects. The toxicity of the essential oils in combination (21 combinations) was investigated. The results obtained indicate that the mixture (caraway + coriander) was the most toxic to the S. oryzae and T. confusum with synergic category 86 and 71.6, respectively. Whereas the mixture (caraway + camphor) was the most toxic to the C. maculates with synergic category 71.2. Therefore, rosemary and other natural volatiles could be safe fumigants to control stored-grain insect pests, and can be used in the IPM programmes.

The red alga Laurencia obtusa (Huds), has long been known as a reliable source of secondary metabolites. The toxicity of dichloromethane extract and its fractions against Tetranychus urticae (Koch) and Panonychus ulmi (Koch) spider mites was assessed. Bioassay efficacy guided to isolate two halogenated terpene and one nonterpenoid compounds. The latent effects of three compounds were also investigated. The results showed that the crude extract and its three fractions were active against both mites. It was found that T. urticae was more sensitive than P. ulmi to the isolated fractions of L. obtusa and to the reference acaricide dicofol. The number of progeny and the longevity of the exposed adults of both mites were used as criteria for the deleterious effects of the fractions .It was observed that the three fractions showed highly effect on the hatchability of eggs. Significant variations were recorded on the reduction in total numbers of eggs/female against the two mites.

The cowpea aphid, Aphis craccivora management relies mainly on chemical control. As a result extensive and repeated treatment of insecticides has led to the development of aphid resistance to commonly used insecticides. To investigate chlorpyrifos-methyl resistance in A. craccivora, a field strain was selected for 24-generations to achieve a resistance factor of 82.3 fold compared with a susceptible strain. In the resistant strain, malathion and lambda-cyhalothrin exhibited obvious cross-resistance; while fenvalerate and dinotefuran showed moderate cross-resistance. In contrast, slight or no cross-resistance was obtained with the other tested insecticides. To investigate metabolic resistance mechanisms, integration of biochemical and synergism assays was conducted. Results showed the key role of esterase (EST) and mixed function oxidases (MFO); however, glutathione-s-transferase (GST) contributed less to resistance. Cross-resistance studies showed the need for rotation with non-cross resistant insecticides as a resistance management tactic.