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

• 来源期刊: 中国昆虫科学（英文版）
• 关键词: age-stage two-sex life table alligator weed flea beetle heat tolerance population dynamics
• 年，卷（期）: 2020,（1）
• 页码范围: 159-169
• 页数: 11页
• 语种: 英文
• DOI: 10.1111/1744-7917.12611

摘要

Agasicles hygrophila has been introduced worldwide as a control agent for the invasive weed Alternanthera 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 reduced A.hygrophila population in hot summers.To imitate the temperature conditions in summers,different developmental stages of A.hygrophila were treated with high temperatures from 32.5 ℃ to 45 ℃ 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 ℃ as the critical temperature affecting larval hatching.Heat treatment of the A.hygrophila eggs at 37.5 ℃ for 1 h decreased the hatch rate to 24％.Our results indicated that when compared with the control at 25 ℃,1 h treatment at 37.5 ℃ prolonged the duration of the egg stage,shortened the duration ofoviposition 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 of A.hygrophila populations,and the key temperature was 37.5 ℃.Therefore,appropriate measures should be taken to protect eggs in order to maintain the efficacy ofA.hygrophila in the biological control of A.philoxeroides in hot summers.