STUDIES ON CERTAIN FACTORS AFFECTING THE BIOLOGICAL CONTROL OF INSECT PESTS

Abstract

The predators group in cotton and other crops play an important role in the natural control of insect pests. Since predators derive most or all of their nourishment from prey, which occur on a particular crop, their abundance would seem to relate to the abundance of the prey. So some basic information on the population densities of predators in cotton fields and the hampering effects of pesticides on their abundance have to be known to help on the integration of possible methods in an attempt to lead to an equilibrium of pest populations below the economic injury levels. Therefor, the present studies deal with the abundance and seasonal fluctuations of the prevailing predators in untreated cotton fields and their relationship with some sucking insects and the mainly weather factors, also deal with the non-target effect of eertain biocides and insecticides on the predators group during two successive cotton seasons of 1997 and 1998 at Shebin El-kom region, Minufiya Governorate.

The results obtained signify the following points:

4.1. Seasonal fluctuations of certain predators in cotton field

4.1.1. Paederus allierii

Results showed three peaks of abundance in the two successive seasons, the first occurred during the 2nd week of June and followed by the second one during the 2nd week of July, while the third peak or the highest population appeared during the last week or the 3rd week of August, for the 1997 and 1998 cotton • seasons, respectively.