Attack and aggregation of a major squash pest: Parsing the role of plant chemistry and beetle pheromones across spatial scales

Successful management of insect crop pests requires an understanding of the cues and spatial scales at which they function to affect rates of attack of preferred and non‐preferred host plants. A long‐standing conceptual framework in insect–plant ecology posits that there is hierarchical structure sp...

Full description

Saved in:
Bibliographic Details
Published in:The Journal of applied ecology 2020-08, Vol.57 (8), p.1442-1451
Main Authors: Brzozowski, Lauren J., Gardner, Jeffrey, Hoffmann, Michael P., Kessler, André, Agrawal, Anurag A., Mazourek, Michael, Kaplan, Ian
Format: Article
Language:English
Subjects:
Acalymma vittatum
Aggregation pheromone
Agricultural practices
Allelochemicals
Beetles
Chemical stimuli
Coleoptera
Cucurbita pepo
Cultivars
Emigration
Farm management
Farms
Herbivores
Herbivory
host acceptance
Host location
Host plants
Insect ecology
Insects
Integrated pest management
Pest control
Pests
Pheromone emission
Pheromones
Plant breeding
plant volatiles
plant–herbivore interactions
squash
Volatile compounds
Volatiles
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:Successful management of insect crop pests requires an understanding of the cues and spatial scales at which they function to affect rates of attack of preferred and non‐preferred host plants. A long‐standing conceptual framework in insect–plant ecology posits that there is hierarchical structure spanning host location, acceptance and attack that could be exploited for integrated pest management. We investigated how plant‐ and insect‐derived chemical cues affect successive decisions of host choice in aggregating insects, and tested predictions in the Cucurbita pepo–Acalymma vittatum system. Acalymma vittatum is an aggregating specialist beetle pest that strongly prefers zucchini (C. p. pepo) to summer squash (C. p. ovifera), two independent domesticates of C. pepo. We hypothesized that subspecies‐specific plant traits, especially volatile cues, interact with the male‐produced aggregation pheromone to amplify beetle preference for C. p. pepo. Differential beetle attack of C. pepo subspecies in the field is not determined by plant traits that affect host finding or differential aggregation due to pheromones: across two years, beetles had strong density‐dependent attraction to both subspecies when male beetles were feeding, and no interactions between plant volatiles and the male‐produced pheromone were detected. In the absence of male pheromone emission, beetles were equally unattracted to plants with or without beetle feeding. In contrast, plant traits that mediate insect acceptance appear to underlie differences in preference. At a local scale, beetles did not accept and emigrated from C. p. ovifera compared to C. p. pepo. Distinct volatile emissions were observed between subspecies, but further work is needed to identify if these volatiles promote emigration. Synthesis and applications. By dissecting pest preference during successive host choice decisions, we isolated a trait with implications for pest management. Beetles on cucurbits can be managed by employing cultivars with differential susceptibility (e.g. trap cropping), and the mechanistic knowledge presented here informs best practices and limitations for on‐farm applications. More broadly, pest management in diversified cropping systems can be enhanced through understanding how plant preference gradients affect herbivore movement and behaviour, and plant breeders can target traits to reduce herbivory in such systems. By dissecting pest preference during successive host choice decisions, we isolate
ISSN:0021-8901
1365-2664
DOI:10.1111/1365-2664.13689