ABSTRACT
The toxicity and the physiological effects of insecticides, chlorozan, marshal and deltamethrine and the alternative pesticides spinosad and proclaim on the desert locust Schistocerca gregaria were tested. The toxicity index, LC50 values after 24 hrs were 171.16, 44.29 and 410.05 ppm. for chlorozan, marshal and deltamethrine, respectively. Also the
values of LC50 after 48 hrs were 425.58 and 101.58 ppm. for spinosad and proclaim, respectively. The effect of all tested insecticides, on the total and different haemocytes count of the 4th instar nymphs of Schistocerca gregaria were evaluated. The obtained results
revealed that the total haemocyte counts were clearly affected by insecticides tested at LC50
values. Chlorozan and proclaim decreased the total haemocytes count (THCs ) 50 %
compared to control. Also marshal and deltamethrine decreased the total haemocyte count
by 35 and 18.3%, respectively. While spinosad showed a slight decreasing in the total haemocyte by 8.9% compared to control. Six different haemocyte types were identified as prohaemocytes (pr), granulocytes (gr), non-granulocytes (n-gr), plasmatocytes (pl),
oenocytes (oe) and spherulocytes (sph) cells were monitored. In general, all the tested insecticides decreased the counts of all the haemocyte types. The application of spinosad increased the pr, pl, oe and sph. While it dercreased both n-gr. and gr. The toxicological
profile of the tested pesticides described herein characterizes their effects on S. gregaria haemocyte types and the total haemocytes count (THCs) when compared with control. These results could be indicate a new proposed mode of action to those friendly environmental promising compounds.
Key words: Schistocerca gregaria, insecticides, haemocyte, total haemocytes count (THCs). |
