Effects of Extreme Low Winter Temperatures on the Overwintering Survival of the Introduced Larval Parasitoids Spathius galinae and Tetrastichus planipennisi: Implications for Biological Control of Emerald Ash Borer in North America

Abstract

Climate change has been linked to shifts in the distribution and phenology of species although little is known about the potential effects that extreme low winter temperatures may have on insect host–parasitoid interactions. In late January 2019, northern regions of the United States experienced a severe cold wave caused by a weakened jet stream, destabilizing the Arctic polar vortex. Approximately 3 mo later at six study sites in southern Michigan and three in southern Connecticut, we sampled the overwintering larvae of the emerald ash borer, Agrilus planipennis Fairmaire (Coleoptera: Buprestidae), and two larval parasitoids, Spathius galinae (Hymenoptera: Braconidae) and Tetrastichus planipennisi (Hymenoptera: Eulophidae), that are being introduced as emerald ash borer biocontrol agents in North America. At these nine study sites, emerald ash borer-infested ash trees and/or saplings were debarked and each overwintering emerald ash borer and parasitoid larva was then examined for cold-induced mortality, as indicated by a brown coloration, flaccid, and watery consistency. In early spring in Michigan, we found 4.5–26% of emerald ash borer larvae, 18–50% of S. galinae larvae, and 8–35% of T. planipennisi larvae were killed by cold. In Connecticut where temperatures were more moderate than in Michigan during the 2019 cold wave, <2% of the larval hosts and parasitoids died from cold injury. Our findings revealed that cold-induced mortality of overwintering larvae of emerald ash borer and its larval parasitoids varied by location and species, with higher mortality of parasitoid larvae in most Michigan sites compared to host larvae. The potential impacts of our findings on the management of emerald ash borer using biocontrol are discussed.

Fruit Fly in a Challenging Environment: Impact of Short-Term Temperature Stress on the Survival, Development, Reproduction, and Trehalose Metabolism of Bactrocera dorsalis (Diptera: Tephritidae)

“…Several studies have been conducted over the last few decades focusing on the survival and adaptation strategies of ectotherm animals under temperature stress [ 9 ]. Although many insects have evolved mechanisms that enable them to respond effectively to normal temperature changes, they continue to be affected by abnormal climate change in nature, which sometimes exceeds their physiological limit and results in the death [ 10 , 11 ]. For instance, a high temperature of 45 °C and a low temperature of −10 °C significantly affected the development and feathering rhythm of Sarcophaga crassipalpis [ 12 ].…”

Gradually Increasing the Temperature Reduces the Diapause Termination Time of Trichogramma dendrolimi While Increasing Parasitoid Performance

“…However, some of the measured parameters were not affected by fluctuating temperatures, possibly because of the fluctuating temperature regimes used in this study (20:15 °C for 16:8 h per day, the average temperature was 18.3 °C; 25:20 °C for 16:8 h per day, the average temperature was 23.3 °C) did not provide average temperature levels exceeding threshold temperature for population development and parasitism activity [ 46 ]. Exposure to prolonged constant low temperatures has been studied in many other insects and shows a detrimental effect on the survival of parasitic wasps [ 47 , 48 , 49 , 50 ]. Low temperatures can induce lesions, and several types of metabolic waste products such as lactic acid and nitrogenous substances can accumulate to toxic concentrations [ 51 ].…”

Five Visual and Olfactory Target Genes for RNAi in Agrilus Planipennis

“…Since most of its life cycle is hidden under the bark of host and only appears outside the bark about 1 month during the adult stage, it is difficult to be controlled (Wang et al, 2010). Currently, physical (Crook et al, 2009;Poland and Mccullough, 2014;Ryall et al, 2015), chemical (Nicole et al, 2010;Mccullough et al, 2016;Poland et al, 2016) and biological (Duan et al, 2020) methods are mainly used to control A. planipennis. All these methods are useful, but there are still some shortcomings.…”