In our work we study the toxic effects of the prepared pyridine and pyradazine derivatives. Five compounds have been synthesized in pure state as reported procedures, and their toxicity as potential insecticidal agents against adult and nymphs of Aphis nerii were screened. The toxicity data in adults, exhibited that compound 6a is more toxic than other synthesized compounds, which LC50 was1.04 ppm while, in nymph compound 4a is more toxic than other synthesized compounds, which LC50 was 0.02 ppm. The other screened compounds showed weak to strong toxicological activity. The structure-activity relationships (SAR) for these compounds were also discussed.

In this study, seven cyano-benzylidene and bisbenzylidene derivatives were designed and synthesized. All synthesized compounds were evaluated to determine their insecticidal activities as potential insecticides against nymphs and adults of Aphis nerii. These efforts led to the discovery of compounds 3a-d, 5, 7 and 10 with potent insecticidal activity (LC50 range from 0.0141 to 3.4351ppm). Compound 5 exhibited the highest insecticidal potency with 0.0141ppm. In addition, it indicated that compound 3b is less toxic than benzylidene and other precursors. Therefore, our results suggest that compound 5 has strong potential as a candidate component for developing a novel eco-friendly insecticide for control Aphids.