الفهرس 
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Abstract
The widespread and intensive use of insecticides in agriculture
caused several problems. The most serious problems were the
development of resistance in insects and the environmental pollution.
During the past decades, many insect species have acquired resistance to
insecticides. Insecticides resistance has become a major obstacle to
successful chemical control. The occurrence of insect resistance to an
insecticide is mainly clue to the action of enzymes, which are either
insensitive to the insecticide or able to degrade it to non-toxic metabolites
, so it is convenient to study the enzymes that playa role in change of
response to some compounds on the cotton leafworm, Spodoptera
littoralis (Boisd.), which has its importance as one of the most
destructive phytophagous lepidopterous pests in Egypt for it causes
various ravages not only for cotton plants, but also other field crops an
vegetables such as leguminous crops (AI-Elmi, 1994 and Hanafy, 1999).
Cowpea, Vigna ungu;culata (L.) is one or the most important
leguminous crops. It can be considered as one of the major crops for the
majority of the Egyptian people and their domestic animals. Moreover, it
is very promising as it provides the soil with nitrogen (Soliman, 1994).
Therefore, it is essential to ensure that cowpea crops are free from
i nseclicides residues, ill other words, the insecticides residues nrc below
the maximum residues limits (MRL’s) and the edible parts become safe
for human consumption as recommended by FAO/WHO meeting 1988,
1990, 1992 and 1994.