Submitted to: Southwestern Entomologist
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/1/2013
Publication Date: 9/1/2013
Citation: Snodgrass, G.L., Jackson, R.E., Perera, O.P., Allen, K.C., Portilla, M. 2013. A comparison of diapause termination in tarnished plant bugs (Hemiptera: Miridae) from the Mississippi Delta and Springfield, Illinois. Southwestern Entomologist. 38(3):385-392.
Interpretive Summary: Wild hosts are available as food for diapausing tarnished plant bugs in the mid-South during the winter. The diapausing population overwintering on these hosts break diapause (become reproductive) during December despite the short diapause-maintaining day length found in December. This occurs as a response to good food (winter hosts) and the warm temperatures that allow the hosts to grow. Diapausing adults from Springfield, Illinois (where winter hosts do not occur) were also found to be able to break diapause under a diapause-maintaining day length in response to food and temperature stimuli. However, their emergence was slower and at a significantly lower rate than those from the mid-South. This showed that plant bugs in the mid-South are being selected for more rapid emergence from diapause. The significance of earlier emergence from diapause is discussed.
Technical Abstract: In a laboratory test, we compared diapausing adult tarnished plant bugs, Lygus lineolaris (Palisot de Beauvois), from Stoneville, MS and Springfield, IL for their ability to break diapause when held at 25°C on a good food source (broccoli, Brassica oleracea variety botrytis L.) under a diapause-maintaining photoperiod of 10:14 (L:D) h. The temperature, photoperiod, and food simulated environmental conditions found in the mid-South region during December when overwintering tarnished plant bugs on blooming winter hosts break diapause. It was unknown if plant bugs from areas such as Springfield (upper mid-west) in which the winters are too cold for winter hosts to be available also had the ability to break diapause under a diapause-maintaining day-length. One-day-old diapausing adults from Stoneville and Springfield were placed in environmental cabinets under the above environmental conditions and held for five weeks. Males and females from both locations were dissected at weekly intervals to determine their reproductive status. Diapausing adults from both colonies and both sexes were able to terminate diapause. Higher percentages of males and females from Stoneville terminated diapause each week compared to those from Springfield, and the differences were significant in four of the five weeks for males and three of the five weeks for females. These results showed that the presence of winter hosts in the mid-South has probably selected tarnished plant bugs for more rapid emergence from diapause. The importance of this more rapid emergence from diapause to plant bug populations in the mid-South is discussed.