&lt;p&gt;The studies were undertaken to study genetic improvement in Trichogramma spp. for resistance to pesticides. In this study, susceptability of four species of Trichogramma viz., T. bactrae, T. chilonis, T. japonicum and T. pretiosum was tested against four insecticides viz,. carbaryl, deltamethrin, endosulfan and malathion. Selection of Trichogramma chilonis for endosulfan tolerance and study on mode of inheritance of endosulfan tolerance was carried out in the laboratory.&lt;br /&gt;
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Results of susceptibility tests indicated that T. bactrae was comparatively more susceptible to deltamethrin (LC50 0.0324 %) followed by malathion (LC50 0.0334 %), carbaryl (LC50 0.0336 %) and endosulfan (LC50 0.038 %). The susceptibility of T. chilonis in descending order was carbaryl (LC50 0.03633 %) &amp;gt; deltamethrin (LC50 0.0391 %), malathion (LC50 0.0399 %) &amp;gt; endosulfan (LC50 0.0437 %).&lt;br /&gt;
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Among the four insecticides tested T. japonicum was comparatively most susceptible to deltamethrin (LC50 0.033 %) followed by malathion (LC50 0.0345 %) and endosulfan (LC50 0.0362 %). The descending order of susceptibility of T. pretiosum to insecticides was carbaryl (LC50 0.033 %) &amp;gt; deltamethrin (LC50 0.0371 %) and endosulfan (LC50 0.0371 %) &amp;gt; malathion (LC50 0.0382 %).&lt;br /&gt;
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The selection for T. chilonis for endosulfan tolerance in laboratory for 15 consecutive generations indicated that the LC50 value of endosulfan is increased by 13.27% from 0.0432 % of base colony (S) to 0.0495% of selected F15 colony (R).&lt;br /&gt;
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In the study of mode of inheritance of endosulfan tolerance in T. chilonis, LC50 value of backcross progency obtained wa 0.0476 % which was intermediate between parents i.e. base colony (S) (LC50 0.0437 %) and F15 colony (R) (LC50 0.0495 %). This clearly indicated that the gene for endosulfan tolerance is completely dominant.&lt;br /&gt;
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Present findings indicated that Trichogramma chilonis may be genetically manipulated for endosulfan tolerance which may serve as key aspect for integration of chemical and biological control.&lt;/p&gt;
