الفهرس 
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Abstract
SUMMARY
Cabbage plants were sprayed with each of three
organophosphorus insecticides; malathion, pirimiphos-methyl and
prothiofos at recommended dose. All the insecticides used were in
commercial emulsifiable concentrate formulations.
I - Residues of certain organophosphorus insecticides in and
on cabbage leaves:
Cabbage plants were sprayed with each of the studied
insecticides at recommended dose after formation of plant heads.
Outer and inner leaves were sampled and analysed for residues of
insecticides. Results indica ted the following:
1 - The largest initial deposit was that of malathion followed by
.,
pirimiphos-methyl and prothiofos.
2 - Residues of pirimiphos-methyl were the least persistent of
the three studied insecticides, followed by malathion, while
prothiofos was more persistent.
3 - Detectable residues of the tested insecticides could be
estimated in the inner leaves of cabbbage after I, 144 and
216 hrs. of spraying with malathion, pirimiphos-methyl
and prothiofos, respectively indicating the lowest ability for
penetration into the leaves in case of malathion.
4 - Residual analysis of insecticides in cabbage leaves showed
that malathion and pirimiphos-methyl remained on the
outer leaves in a rate of unpermitted limits for a period of
288 hrs. after which both insecticides surpassed the
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tolerance limit (3 and 1 ppm for malathion and
pirimiphos-methyl, respectively). In case of prothiofos
treatment, the insecticide become undetectable after 15 days
of spraying.
5 - A ccording to the former result, it was recommended to use
the crop commercially after 12 days of spraying in cases of
malathion and pirimiphos-methyl and after 360 hrs. (15
days) in case of prothiofos.
11- Side effect of certain organophosphorus insecticides on
some biochemical aspects of cabbage plants:
Plants were sprayed three times with each of insecticide to
study the impact of insecticidal treatments on and in cabbage
plants. Effect of the investigated insecticides can be summarized as
follows:
1-On chlorophyll content:
The effect depended mainly on the spraying frequency. While
no significant effect could be observed after the first pesticides
application. A gradual and continuous decline was observed after
the second and third spray.
2 - On carbohydrates metabolism :
A. Soluble, insoluble and total carbohydrates :
Generally, soluble carbohydrates content were reduced as a
results of pesticide applications. The magnitude of trod decline was
greatly dependant on the individual organophosphorus insecticides
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and frequency of applications. Malathion was more effective than
prothiofos or pirimiphos-methyl.
Similar effect was observed with concern to the insoluble
carbohydrate content as affected by the tested pesticides. All
insecticides under investigation induced deplation of insoluble
carbohydrate content in treated plants.
Data of total carbohydrate content showed more or less similar
trends as those noticed for the soluble and insoluble carbohydrates.
Malathion was the most effective pesticide in reduction of total
carbohydrates content followed by prothiofos and
pirimiphos-methyl.
It could be also observed that the carbohydrate metabolism as a
result of treating cabbage plants with the applied insecticides might
be attributed to its inhibition effect on the enzymatic reactions
involved in the biosynthesis of the carbohydrates.
B. Reducing and non.;.reducing sugars content:
1 - Reducing sugars were delated in cabbage plant leaves due
to insecticidal treatment. Reduction was dependent on
individual pesticide and the sampling date under the
different frequencies of application malathion was the
lowest effective pesticide, followed by pirimifos-methyl and
prothiofos after the first and second sprays. While, after the
third application, prothiofos was the lowest effective
pesticide followed by malathion and pirimiphos-methyl.
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2 - Non-reducing sugars content, significant reduction was
observed in cabbage leaves after the first spray with all of
the studied pesticides, but no pronounced differences could
be observed between the values of the treated plants.
Malathion was the most effective insecticide to reduce
decline in the non-reducing sugars content after the second
and the third spray as compared with either
pirimiphos-methyl or prothiofos.
III - Absorption and Translocation of C14-malathion in
laboratory :
Results indicated that the C14-malathion was hardly
translocated inside tissues of cabbage leaves. It is well know that
malathion is classified under the quasi-systemic compounds
(Hassal, 1981). This group is characterized to have low solubility in
water and accordingly hardly to penetrate into leaves.