Heat sensitivity of eggs attributes to the reduction in Agasicles hygrophila population

AbstractAgasicles hygrophila has been introduced worldwide as a control agent for the invasive weedAlternanthera philoxeroides. However, global warming has potential impact on its controlling efficacy. The aim of this research was to explore the primary factors responsible for the greatly reducedA. hygrophila population in hot summers. To imitate the temperature conditions in summers, different developmental stages ofA. hygrophila were treated with high temperatures from 32.5  °C to 45 °C for 1–5 h. Based on the survival rate, the heat tolerance of each developmental stage was ranked from lowest to highest as follows: egg, 1st, 2nd, 3rd instar larva, adult and pupa. Eggs showed the lowest heat tolerance with 37.5 °C as the critical temperature affecting larval h atching. Heat treatment of theA. hygrophila eggs at 37.5  °C for 1 h decreased the hatch rate to 24%. Our results indicated that when compared with the control at 25 °C, 1 h treatment at 37.5 °C prolonged the duration of the egg stage, shortened the duration of oviposition and total longevity, and changed the reproductive pattern ofA. hygrophila. The net reproductive rate, intrinsic rate and finite rate were all significantly reduced. The results suggest that low heat tolerance of the eggs was the major factor responsible for the reduction ofA. hygrophila populations, and the key temperature was 37.5  °C. Therefore, appropriate measures should be taken to protect eggs in order to maintain the effica...

Source: Insect Science - August 9, 2018 Category: Biology Authors: Dong Jia, Xiao ‐Fang Yuan, Yan‐Hong Liu, Chao‐Qian Xu, Yuan‐Xin Wang, Ling‐Ling Gao, Rui‐Yan Ma Tags: ORIGINAL ARTICLE Source Type: research