Effects of abiotic conditions on interactions among three predators of Tetranychus urticae (Acarina: Tetranychidae)

Abstract: Tetranychus urticae (Koch) is a key pest of citrus in Spain and elsewhere, especially in clementine mandarins. In the Spanish citrus orchards, Euseius stipulatus (Athias-Henriot), Neoseiulus californicus (McGregor) and Phytoseiulus persimilis (Athias-Henriot) are its main natural enemies. Climate change, especially rising temperatures, may alter the food web configuration of arthropod communities through its effects on species interactions. In agricultural communities, such effects could have important implications for the success of biological pest control. In this work we evaluated in the laboratory how abiotic conditions affect the performance of the three species of phytoseiid mites, both while interacting with each other and in the presence or absence of either pollen or T. urticae eggs. Our results show that abiotic conditions significantly affected different biological parameters of the three predatory mite species. N. californicus was more tolerant to high temperatures and low humidity than the other two species. Intraguild (IG) interactions between predatory mite species were also affected by abiotic conditions. The implications of our results for conservation biological control using these species of predatory mites in a scenario of climate change are discussed.