Rearing impacts on dispersal and biocontrol performance: A case study on Phytoseiulus persimilis

Authors: WILLDEN, SAMANTHA - Cornell University; NYROP, JAN - Cornell University; SANDERSON, JOHN - Cornell University; WENTWORTH, KAREN - Cornell University; Stockton, Dara; LOEB, GREGORY - Cornell University

Submitted to: Journal of Applied Ecology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/8/2024
Publication Date: 10/10/2024
Citation: Willden, S.A., Nyrop, J., Sanderson, J., Wentworth, K., Stockton, D.G., Loeb, G.M. 2024. Rearing impacts on dispersal and biocontrol performance: A case study on Phytoseiulus persimilis. Journal of Applied Ecology. https://doi.org/10.1111/1365-2664.14798.
DOI: https://doi.org/10.1111/1365-2664.14798

Interpretive Summary: Predatory mites are often used at biocontrol in protected culture, including greenhouse, high and low tunnel environments. However, predator retention is an ongoing challenge to implementation as dispersal following release is quite high. This study assessed whether rearing host type affected the dispersal behavior of Phytoseiulus persimilis, a generalist predator often used for spider mite management. Using a combination of lab and greenhouse trials, we compared P. persimulus movement and predation efficacy when reared and released on either strawberry or bean plants. This study showed that these factors were important in determining predator dispersal habits. Predators released on strawberry in particular were more dispersive, however the also showed increased predation behavior and were better at locating and consuming spider mite eggs. This suggests that it is likely possible to improve biocontrol efficacy by manipulating the rearing host relative to the release crop.

Technical Abstract: Phytoseiulus persimilis (Phytoseiidae) is an important predator to the augmentative biocontrol industry for management of the twospotted spider mite. However, efficacy of this species can be variable. We hypothesized that the simplified rearing conditions present in commercial insectaries may produce predators less adept to navigate complex and challenging crop systems leading to variable biocontrol success. To test this hypothesis, we established colonies of P. persimilis reared on bean (commercial rearing host plant) and strawberry (target crop plant) for over generations and compared patterns of ambulatory dispersal of these colonies when released on bean or strawberry. We also compared feeding efficacy of these colonies against spider mite infested strawberry plants in the greenhouse. Our results indicate that dispersal of P. persimilis was largely predicted by the presence of prey followed by the host on which predators were released. Predator movement was significantly lower when prey was present and was especially low when released onto strawberry, regardless of rearing host. We consistently found a higher dispersal tendency for individuals reared on strawberry compared to bean, but this colony effect was not supported statically for most experiments. We also found little evidence of an interaction between these main effects, rather we found that the effects of released host plant and rearing colony are likely independent and additive. Spider mite egg consumption by P. persimilis on strawberry was higher for P. persimilis reared on strawberry compared to bean, but this did not translate into higher rates of oviposition. Overall, this study provides insight into possible sources of variation in dispersal behavior of P. persimilis that may help to explain cases of low biocontrol success.