Egg production and longevity of Lygus hesperus (Hemiptera: miridae) adult females under constant and variable temperatures

Authors: Brent, Colin; Spurgeon, Dale

Submitted to: Journal of Entomological Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/31/2018
Publication Date: 4/23/2019
Citation: Brent, C.S., Spurgeon, D.W. 2019. Egg production and longevity of Lygus hesperus (Hemiptera: miridae) adult females under constant and variable temperatures. Journal of Entomological Science. 54(2):69-80. https://doi.org/10.18474/JES18-102.
DOI: https://doi.org/10.18474/JES18-102

Interpretive Summary: Changing irrigation practices and rising global temperatures will impact pest insect populations, but limited knowledge of the thermal ecology of individual species prevents accurate modeling of their likely responses. Most studies focusing on temperature responses of the western tarnished plant bug, a major pest of cotton, have been limited to constant conditions, whose relevance to the variable temperatures of field environments is unknown. To address this, newly emerged adults were reared under environmentally relevant low (mean = 15°C), medium (mean = 22°C), or high (mean = 29°C) temperatures that were either constant or fluctuated on a daily cycle by ± 8°C. Females raised under the warmest conditions produced eggs sooner and at a faster rate than those reared under the coolest conditions, but also had reduced lifespans. Variable temperatures shorten the pre-oviposition period under cool conditions and lengthened the duration under high heat. Lifetime egg production was unaffected by temperature regime. The adaptive responses of adult plant bugs to environmental temperature indicate that implementing a control strategy that uses the heat stress created by reduced irrigation practices may be difficult, although other developmental stages of this pest may be more susceptible.

Technical Abstract: Changing irrigation practices and rising global temperatures will impact pest insect populations, but limited knowledge of the thermal ecology of individual species prevents accurate modeling of their likely responses. Most studies focusing on temperature responses of the western tarnished plant bug (Lygus hesperus Knight) (Hemiptera: Miridae), a major pest of cotton (Gossypium spp.), have been limited to constant conditions, whose relevance to the variable temperatures of field environments is unknown. To address this, newly emerged adults of L. hesperus were reared under environmentally relevant low (mean = 15°C), medium (mean = 22°C), or high (mean = 29°C) constant (± <0.5°C) or diurnally fluctuating (± 8°C) temperatures. Females under the warmest conditions produced eggs sooner and at a faster rate than those reared under the coolest conditions, but also had reduced lifespans. Variable temperatures shorten the pre-oviposition period under cool conditions and lengthened the duration under high heat. Lifetime egg production was unaffected by temperature regime. The adaptive responses of adult L. hesperus to environmental temperature indicate that implementing a control strategy that utilizes the thermal stress created by deficit irrigation may be difficult, although other developmental stages of this pest may be more susceptible.