Effect of temperature, population density, and sex on feeding damage caused by adult pea leaf weevil (Coleoptera: Curculionidae)

Abstract

Sitona lineatus (Linnaeus) (Coleoptera: Curculionidae) is an important pest of Pisum sativum Linnaeus (Fabaceae) and Vicia faba Linnaeus (Fabaceae). Managing S. lineatus is difficult. There is currently no forecast that can be used to predict S. lineatus population densities between growing seasons (when management decisions are made). Sitona lineatus populations are monitored in spring by assessing adult-induced feeding damage. We assume the quantity of feeding damage is indicative of population density. However, the effects of abiotic factors, including temperature, on feeding rate are not known. We assessed the effects of temperature, population density, and sex on S. lineatus feeding rate by counting feeding notches on host plants exposed to adult weevils for 24 hours at four densities and under five temperature regimes. Individual females consumed more than male weevils. As expected, feeding damage increased with weevil density. The influence of temperature increased as weevil densities increased. Feeding rate did not differ between constant and fluctuating temperature regimes of equal mean daily temperature. Thus, a model based on mean daily temperature may predict weevil density if temperature and damage levels are known. Historical survey data for S. lineatus could be used to develop and validate new models.

Pea leaf weevil, Sitona lineatus (L.) (Coleoptera: Curculionidae), adult feeding preference and larval development on pulse crop varieties in Montana

“…This dryland production site supported these high larval populations despite the low average rainfall in the 2020 growing season, half that of the long‐term average. Dry seasons compared to wet growing seasons are not believed to favor PLW populations 6,47 . During the following 2021 season PLW populations were noticeably lower, adult feeding on pea foliage was approximately 23–30% less and approximately 60% fewer larvae were collected.…”

“…61 Ambient temperature may influence the severity of PLW. 47,48 During both years adult pheromone trap catches were highest during the first 2 weeks of June. Breeding programs that produce crop varieties able to resist pest damage through non-preference or negative effects on insect development have been one cornerstone of IPM programs.…”

“…Dry seasons compared to wet growing seasons are not believed to favor PLW populations. 6,47 During the following 2021 season PLW populations were noticeably lower, adult feeding on pea foliage was approximately 23-30% less and approximately 60% fewer larvae were collected. While the 2021 growing season received more precipitation compared to 2020, June 2021 received less than a quarter of the June 2020 rainfall; adequate soil moisture during late May to early July may be an important factor for larval development and survival.…”

“…In addition, lower temperatures during May 2021 (last frost was 6 June) compared to May 2020, followed by higher average daily temperatures during June and July 2021, may have reduced the duration of adult activity and pest pressure compared to 2020 61 . Ambient temperature may influence the severity of PLW 47,48 . During both years adult pheromone trap catches were highest during the first 2 weeks of June 2 …”