Spurgeon Dale W, Brent Colin S
Pest Management and Biocontrol Research Unit, USDA, ARS, ALARC, Maricopa, AZ.
J Insect Sci. 2019 Jan 1;19(1):20. doi: 10.1093/jisesa/iez003.
Thermal environments of the arid western United States are often harsh compared with the ranges of temperatures favorable for development and survival of crop insect pests. In cotton [Gossypium spp. (Malvales: Malvaceae)], new irrigation practices such as deficit irrigation may impact populations of pest and beneficial arthropods by temporarily altering temperature profiles within the plant canopy. Most information regarding the temperature-dependent development and survival of an important cotton pest, the western tarnished plant bug (Lygus hesperus Knight), is derived from constant temperature studies. We examined the development and survival of L. hesperus nymphs under constant (±0.2°C) and variable (±8°C) temperature regimes at daily mean temperatures of 15, 22, and 29°C. Under the low temperature (15°C), stadium lengths and duration of the nymphal stage were shorter when temperatures were variable compared with a constant temperature. No differences in development times were observed between regimes at the medium temperature (22°C). Except for the first stadium, development times under the high variable temperature regime were longer compared with the high constant regime (29°C). Nymph survival was unaffected by temperature regime except at the lowest temperature, where daily thermal fluctuations substantially improved survival compared with the constant conditions. These results suggest that temporarily increased crop canopy temperatures caused by altered irrigation schemes are unlikely to substantially reduce the growth of L. hesperus populations. However, enhanced nymphal development and survival under low variable temperatures likely contribute to the survival of overwintering L. hesperus in the absence of acute, low-temperature mortality.
与有利于农作物害虫生长和存活的温度范围相比，美国西部干旱地区的热环境往往很恶劣。在棉花[棉属（锦葵目：锦葵科）]中，诸如亏缺灌溉等新的灌溉方式可能会通过暂时改变植物冠层内的温度分布来影响害虫和有益节肢动物的种群数量。关于一种重要的棉花害虫——西部牧草盲蝽（Lygus hesperus Knight）的温度依赖性发育和存活的大多数信息都来自恒温研究。我们在日平均温度为15℃、22℃和29℃的恒温（±0.2℃）和变温（±8℃）条件下，研究了西部牧草盲蝽若虫的发育和存活情况。在低温（15℃）条件下，与恒温相比，变温时若虫的龄期长度和若虫期持续时间更短。在中等温度（22℃）条件下，两种温度模式下的发育时间没有差异。除了第一龄期外，高温变温模式下的发育时间比高温恒温模式（29℃）更长。若虫的存活不受温度模式的影响，除非在最低温度下，与恒温条件相比，每日的热波动显著提高了存活率。这些结果表明，灌溉方案改变导致的作物冠层温度暂时升高不太可能大幅减少西部牧草盲蝽种群的增长。然而，在低温变温条件下若虫发育和存活的增强可能有助于西部牧草盲蝽在没有急性低温死亡的情况下越冬存活。
