Lethal effects of heat stress on Bradysia difformis and Bradysia odoriphaga and its subsequent effects on development and fecundity
Author of the article:LUO Yin** ZHU Guo-Dong SUN Xia WANG Xin-Hui XUE Ming***
Author's Workplace：College of Plant Protection, Shandong Agricultural University, Key Laboratory of Biology of Vegetable Pests and Diseases, Tai`an 271018, China
Key Words：Bradysia difformis Fey, Bradysia odoriphaga Yang et Zhang, heat stress, lethal effect, development, fecundity
Abstract：
Bradysia difformis Fey and Bradysia odoriphaga Yang et Zhang are important pests of edible mushrooms that cause significant economic losses to mushroom growers. Heat treatment is a common measure to prevent crop damage caused by these pests and other pathogens during the production of edible fungi. However, it remains unclear whether heat treatment is effective in controlling B. difformis and B. odoriphaga in mushroom houses. [Objectives] To determine the effects of high temperature on the survival and fecundity of B. difformis and B. odoriphaga, and determine the practicality of using heat treatment to control these pests. [Methods] We tested the effects of long- and short-term heat stress on the survival of B. difformis and B. odoriphaga, and on the development, longevity and fecundity of larvae and adults of both species. [Results] Temperatures above 36℃ had rapid lethal effects on the survival of both B. difformis and B. odoriphaga. Of the four life-stages examined, pupae were the most tolerant to heat stress and adults were the most sensitive. At 38℃, the LT50 (the median lethal time) of B. difformis and B. odoriphaga adults were 0.493-0.553 h and 1.335-1.431 h respectively, while the corresponding values for pupae were 1.402 h and 2.356 h, respectively. Short-term heat shock adversely affected the development and fecundity of surviving larvae. Exposure to 38℃ for 2 h delayed the development of surviving B. difformis and B. odoriphaga larvae by 1.93 d and 3.09 d, respectively, and reduced fecundity by 74% and 60%, respectively compared to the respective 25℃ control groups. Exposure to 38℃ for 1 h reduced the longevity of surviving B. difformis and B. odoriphaga adults by 1.60 d and 1.57 d, respectively, and fecundity by 59% and 40%, respectively compared to the respective 25℃ control groups. [Conclusion] Short-term heat shock (≥ 36℃) had lethal effects on B. difformis and B. odoriphaga and also significantly inhibited the development and fecundity of surviving larva and adults. These results indicate that heat treatment can be used to control B. difformis and B. odoriphaga in mushroom houses.