Details

Autor(en) / Beteiligte

• Mullins, Maria
• Den Uyl, James
• Cruz, Emily
• Trail, Samantha
• Davidson, Benjamin
• Campbell, Diane
• Mooney, Emily

Titel

Advanced phenology of intraguild predators shifts herbivore host plant preference and performance

Ist Teil von

• Ecological entomology, 2020-10, Vol.45 (5), p.1004-1014

Ort / Verlag

Oxford, UK: Blackwell Publishing Ltd

Erscheinungsjahr

2020

Quelle

Wiley Online Library All Journals

Beschreibungen/Notizen

• 1. The abundance of insect herbivores is mediated by interactions with higher and lower trophic levels. This research asks (i) how phenological change across trophic levels affects host plant quality and selection for aphids, and (ii) what higher trophic level mechanisms drive aphid abundance. 2. Ligusticum porteri is a perennial host for the sap‐feeding aphid Aphis asclepiadis and intraguild mirid predators (chiefly Lygus hesperus) in Colorado. We used long‐term observational data to discover that aphids and mirids respond differently to phenological cues. These unique responses can impact aphid abundance through changes to host plant selection and quality. 3. We used behavioural choice assays to assess how advanced mirid phenology influences aphid host plant selection. More alates landed and reproduced on mirid‐free control plants relative to host plants with prior mirid feeding. However, this preference did not correlate with aphid performance when we compared aphid relative growth rates between treatments. This suggests that advanced mirid phenology would impact aphid populations more through host plant choice, rather than reductions in host quality. The addition of mirids to experimental aphid colonies also demonstrated reduced aphid colony growth via predation. 4. We measured plant cues involved in host selection and found differences in volatile composition between plants with prior mirid feeding compared to control plants, providing the potential for aphids to detect enemy‐free space using volatile cues. Early snowmelt is associated with low aphid abundance and high early‐ season mirid abundance on host plants. Higher mirid abundance reduces the likelihood of aphid colonisation. Experimental aphid colony growth rate was not affected by prior mirid feeding on host plants, while the addition of mirids to aphid colonies resulted in reduced aphid colony growth. Our results suggest that on early snowmelt years, mirids impact aphid abundance through their role as predators, rather than through effects on plant quality.