The efficiency of some pesticides (malathion, pirirniphos methyl. hlorpyrifos
methyl, carbosulfan and methomyi ) were lested against melon aphid adults Aphis
gossypii (Glover) and the fourth ins tar larvae of cotton leatworm Spodoptera /Ittoralls
(Bo\sd.) For melon aphid adults. carbosulfan pesticide was the mo t effective
compound against Aphis gossyp < /em>ii rollowed bv chlorpyrifos-methyl, pirimlp os-rnethyl
and methomyl pestiCide. LCso values of previous insecticides were: 0.49 • 0.75.3.31
and 5.46 ppm. respectively. Malathion showed the lowest toxicity with the Cso value
of 34.89 ppm. While. chlorpyrifos-methyl was the most effective pestlclde towards
Spodoptera litloralis larvae rollowed by methomyl and malathion. The obtained LCso
values were 10.29,47.84 and 270.22 ppm, respectively). However, pirimip os·methyl
and carbosullan exhibited lowest toxicity agair.lst S. littoralis larvae wit the LCse
values of 1079.00 and 3245.06 ppm, respectively.
Residues of the tested pesticides were determined in watermelon peel. pulp
and seeds after zero time, one, three and five days from treatments. The initial
concentrations or different pesticides tested were detected after one hour of
treatments wilh different variations in samples and tested pesticides by using GLC
and colorimetric methods . These residues were changed In examined samples at
intervals with limes to reach at the end of experiments (5 days): For Malat ion (0.083,
0.052 and 0.026 ppm in watermelon peel, pulp and seeds, respec ively.) For
pirimiphos methyl (0.0232, 0.0274 and 0.0083 ppm in watermelon). For chlorpyrifos
methyl (0.975, 7.54 and 9.892 ppm) in watermelon peel, pulp and seeds, repectively.
For methomyl Ihe residues were Increased in watermelon peel and pUlp recording
1.377 ppm and 0.764 ppm, respectively while the residue was descended to 0.452
ppm in watermelon seeds.