Submitted to: Journal of Agricultural and Urban Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/8/2004
Publication Date: 1/1/2005
Citation: Villavaso, E.J., Snodgrass, G.L. 2005. Diapause in tarnished plant bug, lygus lineolaris (heteroptera: miridae): seasonal occurrence in a mississippi population. Journal of Agricultural and Urban Entomology. Interpretive Summary: Tarnished plant bugs can cause significant damage to cotton in the midsouth and other areas. Nonetheless, not much research has been done on the environmental factors that cause these insects to delay reproductive activity and prepare for winter survival or bypass overwintering status to become reproductive. Greater knowledge of this insect's overwintering biology may allow us to suppress this pest during its preparation for winter or between overwintering and the time it enters cotton fields the following spring. Some tarnished plant bugs are able to continue reproduction and others can revert from their overwintering status to reproductive status during mild winters that do not kill their host plants. The purpose of our study was to determine the percentages of tarnished plant bugs developing into overwintering or reproductive adults year-round. We determined that most eggs hatching between September and February, about half of eggs hatching between March and August, and few eggs hatching between April and July developed into winter-status adults. Thus, March and August were transitional months during which the population is reverting to reproductive and overwintering status, respectively. Between those months, almost all bugs were reproductive, and outside of them, almost all were in overwintering status.
Technical Abstract: The incidence of diapause was determined in adult tarnished plant bugs, Lygus lineolaris (Palisot de Beauvois), reared in environmental cabinets that simulated field photoperiods for every month of the year occurring at Stoneville, MS. Temperature was held constant at 26.7oC. Photoperiod played a major role in diapause development. Most eggs (86.0 to 96.8%) that hatched between 7 September and 4 February, about half of eggs that hatched in early March (44.3%) and mid August (57.0%), and few eggs that hatched between 5 April and 4 July (1.5 to 3.9%) developed into diapausing adults. Thus, early March and late August are transitional periods during which about half of the nymphs developed into diapausing adults. Between those periods, almost all bugs were reproductive, and outside of them, almost all were in diapause. Hypertrophied fat body coupled with underdeveloped accessory glands were used to classify male diapause, and hypertrophied fat body coupled with lack of mature eggs were used to classify female diapause. A simple SAS program was used to categorize the condition of adults using these criteria.