In this paper, 2-((3-Cyano-4,6-distyrylpyridin-2-yl)thio)acetamide (2) and its cyclized form, 3-
amino-4,6-distyrylthieno[2,3-b]pyridine-2-carboxamide (3), were prepared and their structure
characterizations were performed by the means of elemental and spectroscopic analyses. Their
biological activity as insecticides against cowpea aphid Aphis craccivora Koch using
acetamiprid insecticide as a reference was studied. The bioassay results for compounds (2) and
(3) against nymphs of cowpea aphid showed that the LC50 values were 0.192 and 0.841 ppm,
respectively, after 24 h of treatment but the LC50 values were 0.041 and 0.095 ppm,
respectively, after 48 h of treatment. Furthermore, the bioassay results for compounds (2) and
(3) showed that the LC50 values were 1.233 and 2.949 ppm, respectively, after 24 h of
treatment and the LC50 values were 0.142 and 0.270 ppm, respectively, after 48 h of treatment
against adults of cowpea aphid. Given these observations, it has been found that there is a
remarkable relationship between the biological activity and the structure of the used
compounds.