Predators can limit prey abundance and/or levels of activity. The magnitudes of these effects are contingent on predator and prey traits that may change with environmental conditions. Aberrant thermal regimes could disrupt pest suppression through asymmetric effects, e.g. heat-sensitive predator vs. heat-tolerant prey. To explore potential effects of warming on suppressing pests and controlling herbivory in a vegetable crop, we performed laboratory experiments exposing an important pest species to two spider predator species at different temperatures. Heat tolerance was characterised by the critical thermal maxima parameter (CTM50) of the cucumber beetle (Diabrotica undecimpunctata), wolf spider (Tigrosa helluo), and nursery web spider (Pisaurina mira). Cucumber beetles and wolf spiders were equally heat tolerant (CTM50 > 40 °C), but nursery web spiders had limited heat tolerance (CTM50 = 34 °C). Inside mesocosms, beetle feeding increased with temperature, wolf spiders were always effective predators, nursery web spiders were less lethal at high temperature (38 °C). Neither spider species reduced herbivory at ambient temperature (22 °C), however, at warm temperature both species reduced herbivory with evidence of a dominant non-consumptive effect. Our experiments highlight the contingent nature of predator-prey interactions and suggest that non-consumptive effects should not be ignored when assessing the impact of temperature change.
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This research was supported by a grant from the Kentucky Department of Agriculture and conducted with the assistance of Andre Lage Perez, Andrew Dale, Micheal Sitvarin and Neil Wilson, and other members of the staff at the University of Kentucky Horticulture Research Farm. O. Beleznai and F. Samu were funded during data analysis by NKFIH research grant No. K116062. During the data analysis, Z. Tóth was supported by the ‘Lendület’ programme of the Hungarian Academy of Sciences No. LP2012-24/2012 and the NKFIH grant No. PD108938.
Supplementary information accompanies this paper at doi:10.1038/s41598-017-07509-w
Beleznai, Orsolya; Dreyer, Jamin; Tóth, Zoltán; and Samu, Ferenc, "Natural Enemies Partially Compensate for Warming Induced Excess Herbivory in an Organic Growth System" (2017). Entomology Faculty Publications. 124.