The possibility of trophic transfer of neonicotinoid insecticides from crop plants to Pterostichus melanarius (coleoptera: Carabidae) via prey

Open Access
Author:
Zhao, Sherry
Area of Honors:
Biology
Degree:
Bachelor of Science
Document Type:
Thesis
Thesis Supervisors:
  • Michael Craig Saunders, Honors Advisor
  • John Frazier Tooker, Thesis Supervisor
Keywords:
  • neonicotinoids natural enemies P. melanarius
Abstract:
1. Neonicotinoids are the newest class of insecticides and there is ongoing research about their effects on beneficial species, including natural enemies. Because of their prevalence and variety of application methods, there are many different potential routes of exposure to non-target insects. Ground beetle Pterostichus melanarius L. is an important polyphagous predator of agricultural ecosystems and previous research has shown that this and other species of ground beetles are susceptible to neonicotinoids. 2. I conducted a simple experiment to test if toxicity from thiamethoxam, one of the principal neonicotinoids, can be transferred from black cutworms (Agrotis ipsilon), a target pest, to P. melanarius, a non-target predator, through predation. Black cutworms suffered high mortality rates after ingesting thiamethoxam-treated corn seedlings, but no significant mortality differences were seen between experimental groups of P. melanarius that had fed on dead toxified cutworms and the control groups. However, some indications of sub-lethal effects were seen in P. melanarius that had fed on toxic prey, from which the beetles recovered after several hours. 3. I argue that, given the limitations of this experiment, these sub-lethal effects are relatively mild, and that neonicotinoid exposure through such indirect methods can be more detrimental, especially in field situations where there might be increased risk of predation. I also review literature about existing research on neonicotinoids and ground beetles, as well as literature on neonicotinoids’ effect on other beneficial natural enemies, and further research needs in this area.