Abstract
Extreme heat in summer is frequent in parts of China, and this likely affects the fitness of the beetle Ophraella communa, a biological control agent of invasive common ragweed. Here, we assessed the life history parameters of O. communa when its different developmental stages were exposed to high temperatures (40, 42 and 44 °C, with 28 °C as a control) for 3 h each day for 3, 5, 5, and 5 days, respectively (by stage). The larval stage was the most sensitive stage, with the lowest survival rate under heat stress. Egg and pupal survival significantly decreased only at 44 °C, and these two stages showed relative heat tolerance, while the adult stage was the most tolerant stage, with the highest survival rates. High temperatures showed positive effects on the female proportion, but there was no stage-specific response. Treated adults showed the highest fecundity under heat stress and a similar adult lifespan to that in the control. High temperatures decreased the F1 egg hatching rate, but the differences among stages were not significant. Negative carry-over effects of heat stress on subsequent stages and progenies’ survival were also observed. Overall, heat effects depend on the temperature and life stage, and the adult stage was the most tolerant stage. Ophraella communa possesses a degree of heat tolerance that allows it to survive on hot days in summer.
Highlights
Common ragweed, Ambrosia artemisiifolia, an invasive weed, is a nationwide problem with ecological and health costs in China[1]
Our previous study showed that the pre-adult development and survival, adult survival, longevity and fecundity of O. communa were all adversely affected after 2 h of heat stress at ≥35 °C in the laboratory and that populations of the beetle may be significantly affected in summer days in southern China[3]
The developmental stage exposed, and their interaction all had a significant influence on the survival of O. communa (P < 0.05; Table 1)
Summary
Ambrosia artemisiifolia, an invasive weed, is a nationwide problem with ecological and health costs in China[1]. Broad dispersal, high productivity, high feeding amount[8], and rapid evolution of O. communa[9], the beetle has provided complete defoliation and prevented flowering and seed set in ragweed plants in Europe[10] In recent years, this natural enemy has been reported in eastern[11], central[12], and southern parts of China[13], and it has been shown to provide effective control of A. artemisiifolia in the field in China at some sites[1]. Based on the extreme summer temperatures in central and southern China, the objective of the present study was to investigate the effects of short-term high-temperature exposure on the life history parameters (survival, female proportion [F/(F + M)], adult longevity, and F1 egg hatching rate [that of the subsequent generation]) of O. communa to provide valuable information for forecasting the population dynamics of this biocontrol agent in areas with periods of extreme heat
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