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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.

Forty wheat leaf rust (Puccinia triticina) pathotypes were collected from eleven Egyptian governorates during the two growing seasons 2016/2017 and 2017/2018 were analyzed based on both virulence and molecular marker analysis. Virulence analysis was carried out on the basis of infection type of the tested pathotypes on 20 differential monogenic lines, each carrying single leaf rust resistance genes (Lr). Six simple sequence repeats (SSR) markers were used for molecular characterization of P. triticina to detect the genotypic variation among pathotypes. Almost all of the tested pathotypes were phenotypically and genetically varied that confirms a high diversity within Egyptian leaf rust populations. Cluster analysis based on both virulence analysis and molecular patterns classified the tested pathotypes to three main groups. A relatively weak correlation was found between virulence and molecular analysis (r = 0.03). High similarity was found between leaf rust populations in the three governorates; Sohag, Bani Sweif and Fayoum. Also, high similarity was found between leaf rust populations in the five; Egyptian governorates; Minufiya, Kafr-Elsheikh, Gharbiya, Alexandria and Qalyubia, while, wide variation was found between leaf rust populations of the three governorates; Beheira, Sharqiya and Dakahlia. The results of this study support using molecular markers analysis to estimate genetic diversity between P. triticina pathotypes.

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