Effects of temperature on the reproductive life history of the black vine weevil,Otiorhynchus sulcatus

Abstract

AbstractOtiorhynchus sulcatus(F.) (Coleoptera: Curculionidae) is one of the most serious pests of horticultural crops but despite this, the effects of temperature on its reproduction are not fully understood. This study investigates the effects of temperature on the full set of reproductive traits ofO. sulcatusat nine temperatures between 11 and 36 °C and develops descriptive models for each trait. Cohorts of newly eclosed adults were subjected to these temperatures and fed onRhododendronspec. leaves. Adults oviposited at temperatures from 11 to 27 °C. Significant differences among treatments were found in the preoviposition period, oviposition period, longevity, per capita egg production, and egg viability. The preoviposition period was the shortest at 24 °C and the longest at 11 °C. With a non‐linear model fitted to the data across the full range of experimental temperatures, the lower and upper threshold temperatures and optimum temperature for reproductive maturation were estimated to be 6.8, 30.0, and 22.7 °C, respectively. The developmental threshold and calculated thermal constant were estimated to be 6.7 °C and 505.0 degree‐days, respectively, using a linear model at temperatures between 11 and 21 °C. Maximum per capita egg production (1094.1 eggs) and highest egg viability (90.1%) were both observed at 21 °C. The median longevity ofO. sulcatusadults in the 18–36 °C range decreased linearly as temperatures increased. At 27 °C or above, the reproductive success ofO. sulcatuswas substantially impaired, and the optimum temperature range was 21–22 °C. Production of viable eggs in relation to temperature and weevil age was simulated by incorporating four models of life history traits, including egg production, egg viability, cumulative pattern of egg production, and adult survival. Overall, the present study demonstrates that temperature is a key factor in determining the reproductive success ofO. sulcatusadults. We hypothesize that temperature may influence the phenology and geographic distribution ofO. sulcatuspopulations.