Submitted to: Entomologia Experimentalis et Applicata
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/26/2013
Publication Date: 7/19/2013
Citation: Brent, C.S., Klok, C.J., Naranjo, S.E. 2013. Effect of diapause status and gender on activity, metabolism and starvation resistance in the plant bug Lygus hesperus Knight. Entomologia Experimentalis et Applicata. 148(2):152-160.
Interpretive Summary: The western tarnished plant bug is a key pest of crops in the western United States. This insect survives winter as an adult in a state of diapause, which is a period of relative dormancy characterized by a lack of reproduction. The diapause period may represent a time when plant bug populations are vulnerable to management tactics that would not be effective during the cropping season. However, current knowledge of the mechanisms controlling diapause and their ecological implications is not sufficient to foster development of improved management strategies. Studies of laboratory-reared plant bugs showed that, when denied food and water, diapausing bugs lived longer than bugs that were not in diapause. This difference in survival is probably explained by the higher fat stores and lower overall levels of activity of the diapausing insects. When food was available, the diapausing bugs also fed less than those that were not in diapause. In many insects diapause is accompanied by a lower rate of metabolism that maximizes the benefit of stored fat and nutrients. In the plant bug diapause did not influence metabolic rate, but males exhibited higher rates of metabolism than females regardless of diapause status. In contrast, non-diapausing females spent more time flying than non-diapausing males or diapausing bugs of either gender. Collectively, the results suggest diapause in the western tarnished plant bug is accompanied by increased amounts and conservation of metabolic resources, which enhances resistance to starvation or dehydration during the non-cropping season.
Technical Abstract: Lygus hesperus Knight, a key pest species distributed throughout the western United States, survives winter in a state of diapause. A laboratory population was examined to elucidate the changes in behavior and physiology linked to this period of relative dormancy and to determine how these changes are affected by gender. It was found that under starvation conditions, diapausers lived significantly longer compared to non-diapausers in both genders. This may be attributable to the greater lipid reserves that diapausers have compared to non-diapausers. Diapausers also spent more time at rest and less time feeding than non-diapausers. Gender did not impact these behaviors. There was no difference in resting metabolic rate or flight activity between diapausers and non-diapausers, however, there were significant gender differences when the data was pooled. Males had higher resting metabolisms than females, while females spent more time flying. Collectively, these results point towards a greater degree of resource conservation in diapausers, enhancing their resistance to starvation and dehydration conditions that they are likely to encounter while overwintering.