Screening of Predatory Natural Enemies of Lygus pratensis in Cotton Fields and Evaluation of Their Predatory Effects

<i>Lygus pratensis</i> is a major pest of cotton, causing serious damage to cotton production. This study designed species-specific PCR detection primers for <i>L. pratensis</i>, established a detection system to identify <i>L. pratensis</i> DNA in the intestinal contents of predatory natural enemies, and investigated the control potential of four species' predatory natural enemies against <i>L. pratensis</i>. The results indicated that 826 predatory natural enemies were collected from cotton fields belonging to two classes, five orders, and twelve families. Among these, 9 species of insecta natural enemies accounted for 54.12% of the total number of predatory natural enemies collected, while 14 species of arachnida predatory natural enemies comprised 45.88%. Of the 806 natural enemies tested, 5.58% were found to be positive for <i>L. pratensis</i>, all of which were arachnid predators, specifically <i>Ebrechtella tricuspidata</i>, <i>Xysticus ephippiatus</i>, <i>Hylyphantes graminicola</i>, and <i>Oxyopes sertatus</i>. The predation response of these four spider species to the fourth to fifth instar nymphs and adults of <i>L. pratensis</i> adhered to the Holling II model. The theoretical predation (<i>a'</i>/<i>Th</i>), daily maximum predation rate (<i>T</i>/<i>Th</i>), and searching effect for the fourth to fifth instar nymphs and adults of <i>L. pratensis</i> of the four spider species were assessed. According to the results, the species can be ranked in terms of their predatory and searching efficiency as follows: <i>O. sertatus</i> > <i>E. tricuspidata</i> > <i>X. ephippiatus</i> > <i>H. graminicola</i>. Four species of spiders had the highest theoretical predation against <i>L. pratensis</i> nymphs, ranging from 23.71 to 60.86, and adults, ranging from 22.14 to 50.25. Therefore, these four spider species could be utilized for <i>L. pratensis</i> management. This study identified the main predatory natural enemies of <i>L. pratensis</i> and their pest control capabilities, providing a scientific basis for selecting and utilizing natural enemies in integrated pest management (IPM) strategies. This will help promote ecological and green pest control of <i>L. pratensis</i> in cotton-growing areas.