Effect of short-term high-temperatures on the growth, development and reproduction in the fruit fly, Bactrocera tau (Diptera: Tephritidae)

Abstract

Bactrocera tau (Walker) (Diptera: Tephritidae) is an economically important invasive pest, that is capable of seriously reducing the quality and yield of vegetables and fruits, it was first recorded from Fujian province in 1849 and later introduced to Yunnan province in 1912 as a result in trade fruits and vegetables of China. In recent years, with the onset of global climate change and the accompanying increase in the greenhouse effect, elevated climatic temperatures have become one of the main environmental factors affecting growth and reproduction in insects, and the optimal developmental temperature of B. tau was found to be from 25 °C to 31 °C, the growth, development and reproduction of B. tau are normal under the optimal temperature conditions. In order to determine the repercussions that elevated temperature have on B. tau, we assessed the effects that short-term (12 h) hightemperature exposures (34 °C, 36 °C, 38 °C, 40 °C, 42 °C, 44 °C, 46 °C, and 48 °C) had on the growth, development and reproduction of B. tau at different developmental stages of the fly. The results showed that the survival rate of B. tau gradually decreased in all stages following exposure to short-term hightemperatures. The pupal stage was the least sensitive to increased temperatures. The pupae withstood the highest lethal temperature, having an LT 50 of 42.060 °C, followed by female adults (40.447 °C), male adults (40.013 °C), and larvae (36.740 °C). The egg stage, which was the most susceptible to heat increases, had the lowest LT 50 (38.310 °C). No significant effects were observed in the developmental stages of B. tau at temperatures from 24 °C to 38 °C. The development duration was significantly prolonged at 40 °C (P < 0.05) in the eggs (2.830d), larvae (7.330d), and pupae (8.170d) (P < 0.05). B. tau was unable to survive at temperatures above 42 °C. The pre-oviposition of female adults was extended, the average egg number per female showed a downward trend, the longevity of adults gradually shortened, and the ratio of female to male offspring increased as temperature increments were increased. In summary, short-term high-temperatures over 42 °C were not suitable for successful development of B. tau, while short-term high-temperatures over 40 °C were not suitable for successful reproduction in B. tau. The fruit fly Bactrocera tau (Walker) (Diptera: Tephritidae) is a major economic pest on cucurbitaceous plants, tomatoes, and other fleshy fruits 1. B. tau was first recorded from China from Fujian province in 1849 by Walker 2. The species was subsequently discovered in Yunnan, Guangdong, and Sichuan provinces from 1912 to 1913 3-5 , and has since dispersed rapidly through much of southern China. From 2000 to 2004, B. tau has been reported from much of south Asia, southeastern Asia as well as the Solomon Islands 6-9. In these countries, the B. tau has severely reduced quality and yield of vegetables and fruits. The B. tau has caused 21-34% and 21-32% yield losses of Siraitia grosvenorii and Cucurbita moschata respectively in Taiwa...

Effects of periodically repeated high‐temperature exposure on the immediate and subsequent fitness of different developmental stages ofPropylaea japonica

“…13 However, once the temperature exceeds their tolerance limits, it will lead to short (e.g., decreased survival rate or immediate death) and long-term adverse effects (i.e., potential carry-over effects on subsequent development stages and fecundity). [14][15][16][17] Most insect species suffer from temperature fluctuations in their dwelling environment throughout their ontogeny, which affects physiological processes and ecological functions. It is known that different developmental stages of insects have different thermal sensitivities, so high temperatures experienced in early ontogeny can affect biological characteristics and heat tolerance capacities in later development stages or the next generation.…”

“…29,30 To date, more and more studies have begun to pay attention to the impact of fluctuating temperature on the performance and fitness of insects, yet most studies are carried out in different constant temperatures. 8,10,15,17,19,20,[31][32][33][34][35] Although these studies have shown that high temperatures affect the performance of insects, the experiments are based on either constant high temperatures or short-time exposures to high temperatures, and thus the studies may not adequately reflect the variable temperature conditions experienced in the natural environment. In fact, some studies have shown that using constant temperature conditions to explore the performance thermal response of insects may not reflect the thermal responses of insects under real field conditions because they do not mimic the fluctuating temperature conditions that occur within the natural environment.…”

“…In general, insects possess certain physiological self‐regulation functions in order to tolerate temperature changes 13 . However, once the temperature exceeds their tolerance limits, it will lead to short (e.g., decreased survival rate or immediate death) and long‐term adverse effects (i.e., potential carry‐over effects on subsequent development stages and fecundity) 14–17 …”

“…Meanwhile, extreme heat waves often occur multiple times during the ontogeny of an organism 29,30 . To date, more and more studies have begun to pay attention to the impact of fluctuating temperature on the performance and fitness of insects, yet most studies are carried out in different constant temperatures 8,10,15,17,19,20,31–35 . Although these studies have shown that high temperatures affect the performance of insects, the experiments are based on either constant high temperatures or short‐time exposures to high temperatures, and thus the studies may not adequately reflect the variable temperature conditions experienced in the natural environment.…”

Effect of short-term exposure to high temperatures on reproductive behaviors and physiological enzyme activities in Zeugodacus tau

“…This alteration manifested mainly as a delay in the pre-oviposition and peak period of oviposition, decreased egg production and hatching rate, gradual shortening of the life span in both males and females, and an increase in the female offspring ratio (Zhou et al, 2011;Stazione et al, 2021). Huang et al (2020) reported that short-term exposure to high temperatures of over 42°C was not suitable for the successful development of Z. tau, while the short-term application of high temperatures of over 40°C was not suitable for successful reproduction in Z. tau. However, there is a lack of further observation on the reproductive behavior in Z. tau under short-term high temperature exposure.…”