Sublethal abamectin exposure alters intraguild predation and population structure of predatory mites

Chemical contaminants can disrupt predator-prey dynamics in agroecosystems, particularly through intraguild predation (IGP), a key interaction influencing population structure and dynamics. The objective of this study was to investigate intraguild predation between Amblyseius largoensis (Muma) and Euseius alatus DeLeon (Mesostigmata: Phytoseiidae), with particular emphasis on how an extraguild food resource (pollen), sublethal exposure to the acaricide abamectin, and their combined effects influence predator feeding behavior, oviposition, and population dynamics. Adult females of both predators were exposed to intraguild prey (eggs and larvae) in the presence or absence of extraguild food (pollen) and abamectin residues. In addition, population-level experiments were conducted to evaluate long-term interaction outcomes. Experimental results revealed that both feeding activity and oviposition of the two predator species were significantly affected by the presence of pesticide residues and the availability of pollen as an extraguild food source. Population dynamics assays indicated that A. largoensis was the dominant species; however, exposure to pesticide residues reduced the longevity of both predator populations.