| Abstrakt: |
Simple Summary: Differences in plant quality can alter patterns of ecological interactions, changing complex relationships among organisms within ecological communities. Hidden (asymptomatic) plant disease might have a previously little considered influence on insect ecology. This study investigated how a hidden fungal pathogen affects plants and their associated insects, using two varieties of lettuce as a model system. The presence of hidden disease changed plant quality, affecting insect populations differently depending on the lettuce variety. While the diversity and abundance of aphids remained unaffected in one variety, infection changed aphid assemblages in another. At the same time, aphids on infected lettuce varieties were less attractive to natural enemies, and so this reduced the benefits to aphids of colonising uninfected plants. Understanding the consequences of hidden pathogen infections for plant–insect interactions is important for pest management, biological control and broader ecological science, offering insights into both insect community ecology and sustainable agriculture. Few studies have considered whether hidden (asymptomatic) plant pathogen infection alters ecological interactions at the higher trophic levels, even though such infection still affects plant physiology. We explored this question in two field experiments, where two varieties of lettuce (Little Gem, Tom Thumb) infected with Botrytis cinerea were either (1) naturally colonised by aphids or (2) placed in the field with an established aphid colony. We then recorded plant traits and the numbers and species of aphids, their predators, parasitoids and hyperparasitoids. Infection significantly affected plant quality. In the first experiment, symptomatically infected plants had the fewest aphids and natural enemies of aphids. The diversity and abundance of aphids did not differ between asymptomatically infected and uninfected Little Gem plants, but infection affected the aphid assemblage for Tom Thumb plants. Aphids on asymptomatically infected plants were less attractive to predators and parasitoids than those on uninfected plants, while hyperparasitoids were not affected. In the second experiment, when we excluded natural enemies, aphid numbers were lower on asymptomatically and symptomatically infected plants, but when aphid natural enemies were present, this difference was removed, most likely because aphids on uninfected plants attracted more insect natural enemies. This suggests that hidden pathogen infection may have important consequences for multitrophic interactions. [ABSTRACT FROM AUTHOR] |
