Diapause termination and post-diapause in lygus hesperus (heteroptera: miridae)

Authors: Brent, Colin

Submitted to: Journal of Insect Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/25/2020
Publication Date: 1/5/2021
Citation: Brent, C.S. 2021. Diapause termination and post-diapause in lygus hesperus (heteroptera: miridae). Journal of Insect Science. 21(1). Article 4. https://doi.org/10.1093/jisesa/ieaa142.
DOI: https://doi.org/10.1093/jisesa/ieaa142

Interpretive Summary: The western tarnished plant bug survives inhospitabe winter conditions by entering a state of dipasue, in which metabolism is slowed and internal resources are stored as fat rather than used in reproduction. Short day lenghts induce this state, but once environmental conditions are again favorable, the bugs begin to produce offspring. To determine whether different developmental trajectories has any effect on the bugs, diapausing and non-diapausing females were reared from the same egg batches. Body mass, ovary maturation, egg laying and lifespan were monitored starting either at the time of release from diapause-inducing conditions or when the matured into adults for diapausers and non-diapausers, respectively. Females that had gone through two weeks of diapause were larger and able to mobilize the resources necessary for ovarian activity faster than non-diapausers, producing and laying eggs sooner and at a faster initial rate. However, lifetime egg production and average daily rates were similar for both groups. Post-diapausers lived longer than non-diapausers by an average of 19 days, which is five more than the two-week period when they were reproductively inactive while in diapause. Overall, the results indicate that short-term diapause does not have a negative impact on these bugs. Further, the extra resources stored as fat during diapause may be able to enhance the speed with which the bugs can take advantage of improved environmental conditions and may extend their lives by shielding them against environmental stressors such as temperature extremes and food shortages.

Technical Abstract: The western tarnished plant bug, Lygus hesperus Knight (Heteroptera: Miridae), overwinters as a diapausing adult in response to short day lengths. Once environmental conditions are favorable, the bugs revert to an active reproductive state. To determine the impact on life history traits of diverting resources towards diapause rather than oogenesis during early adulthood, diapausing and non-diapausing L. hesperus females were reared from the same cohorts. Body mass, ovarian maturation, ovipositional activity and survivorship were monitored starting either at the time of release from diapause-inducing conditions or at adult eclosion for diapausers and non-diapausers, respectively. Females that had gone through two weeks of diapause were larger and able to mobilize the resources necessary for oogenesis faster than non-diapausers, initiating oogenesis and ovipositing sooner and at a faster initial rate. However, lifetime egg production and average daily rates were similar for both groups. Post-diapausers lived longer than non-diapausers by an average of 19 days, which is five more than the two-week period when they were reproductively senescent. Overall, the results indicate that short-term diapause does not have a negative impact life history. Further, the extra endogenous resources stored during diapause may be able to enhance the alacrity with which the female can take advantage of improved environmental conditions and may prolong life by shielding the females against environmental stressors such as temperature extremes, oxidative agents or food deficits.