Effects of spinosad and emamectin benzoate on the blood picture and DNA structure of the cotton leaf worm spodoptera littoralis [boisd]

ABSTRACT

The physiological and genetical effects of spinosad and emamectin benzoate were studied on the cotton leaf worm Spodoptera littoralis [Boisduval] [Lepidoptera Noctuidae]. The effect of these two insecticides, on the total and different haemocytes count of the 5[th] instar larvae of S. littoralis [Lepidoptera Noctuidae] were evaluated. Results revealed that emamectin benzoate at LC[25] and LC[50] values decreased the total haemocytes counts [THCs] to 55.8% and 52%, respectively. In this respect, spinosad decreased the THCs to about 22.4% and 24.4%, respectively. The six haemocyte types identified as prohaemocytes [pr], granulocytes [gr], non-granulocytes [n-gr], plasmatocytes [pl], oenocytes [oe] and spherule [sph] cells were monitored. Generally, all the tested concentrations of emamectin benzoate decreased the counts of all the haemocyte types. However, the application of spinosad increased the pr, pl, oe and sph. While it dercreased both n-gr and gr. Spinosad and emamectin benzoate have had an effect on the larval DNA. Presence and absence of several bands were observed, as well as differences in the band intensity among the treatments. The toxicological profile of the tested pesticides described herein characterizes their effects on S. littoralis larval DNA. Results clearly proved that pesticides treatments induce DNA strand fragmentations at different sites when compared with the untreated check. In addition, the fluctuations occurred in THCs and translation systems represented in DNA were ongoing on the same direction. These results have drawn a new proposed mode of action to those friendly environmental promising compounds