Wildflower plantings have mixed effects on insect herbivores and their natural enemies

Abstract

Flower strips are advocated as a strategy to promote beneficial insects as well as the services they deliver to adjacent crops. Flower strips have, however, often been developed separately for pollinators and natural enemies and, additionally, little consideration has been given to effects on insect herbivores. We sampled insect herbi-vores, their natural enemies and parasitism of pest eggs using vacuum sampling, sticky cards and egg cards in nine pairs of bee-attractive wildflower plantings and control field borders, as well as in adjacent tomato and watermelon crop fields in Yolo County, California 2015-2016. Control field borders had a higher total number of herbivores on sticky traps than did wildflower plantings, a pattern that was driven by more aphids, hoppers, psyllids and whiteflies, whereas wildflower plantings had more lace bugs and Lygus bugs. The total number of herbivores in the adjacent crop fields did not differ between treatments, but there were more leaf beetles near (at 10 m but not 50 m from) wildflower plantings. Control field borders had a higher total number of predators, driven by more big-eyed bugs, lady beetles and minute pirate bugs, whereas spiders were more common in wildflower plantings. The total number of predators in adjacent crop fields was, however, higher in those next to wildflower plantings, which was driven by more minute pirate bugs. Parasitoid wasps were more common in wildflower plantings and at 10 m but not 50 m into adjacent crop fields. Stink bug egg parasitism rate did not differ between treatments, either in the borders or in the crop fields. In conclusion, wildflower plantings clearly affect the insect herbivore and natural enemy community, but do so in a highly taxon-specific manner, which can lead to both positive and negative outcomes for pest control as a result.

Keywords

Arthropod; Field border; Grindelia; Herbivore; Natural enemy; Parasitic wasp; Stink bug; Wildflower

Published in

Agriculture, Ecosystems and Environment
2023, volume: 355, article number: 108587
Publisher: ELSEVIER

SLU Authors

• Lundin, Ola

  • Department of Ecology, Swedish University of Agricultural Sciences
    
  • University of California Davis (UC Davis)

• Bötzl, Fabian

  • Department of Ecology, Swedish University of Agricultural Sciences
    

Associated SLU-program

SLU Plant Protection Network

UKÄ Subject classification

Agricultural Science
Ecology

Publication identifier

• DOI: https://doi.org/10.1016/j.agee.2023.108587

Permanent link to this page (URI)

https://res.slu.se/id/publ/122893