Submitted to: National Cotton Council Beltwide Cotton Conference
Publication Type: Proceedings
Publication Acceptance Date: December 4, 2002
Publication Date: N/A
Interpretive Summary: Despite its ability to cause significant damage to the cotton crop, little research has been done on environmental factors that prompt tarnished plant bugs (TPB)to abandon their reproductive mode and fatten up for winter survival. Greater knowledge of TPB overwintering biology may allow us to attack this link in its life cycle to suppress this pest before it enters cotton fields. No studies of TPB overwintering have been done in environmental cabinets programmed to simulate the increasing/decreasing day lengths occurring in nature. Our system demonstrated that we could use it to produce levels of overwintering in TPB that approximate those of natural conditions. Percentages of overwintering TPB in our cabinets increased from 15 to 60 to 89% at day lengths programmed to mimic Stoneville, MS day lengths starting on August 7, August 22, and September 6, respectively. Similar numbers of males and females developed overwintering characteristics. We determined that an overdeveloped fat body coupled with underdeveloped accessory glands (structures involved in sperm transfer to females) were the best criteria for classifying overwintering in TPB males and confirmed that overdeveloped fat body coupled with no egg production were the best criteria for classifying females. Almost no overwintering females had mated and almost all reproductive females had mated. Almost all males, whether overwintering or reproductive, had well-developed reproductive organs as demonstrated by significant sperm accumulation.
Technical Abstract: Percentages of diapause in tarnished plant bugs, Lygus lineolaris (Palisot de Beauvois) varied with photoperiods dynamically controlled in temperature cabinets. Photoperiods beginning on Julian Date 220, 235, and 250 resulted in 15, 60, and 89% diapause, respectively. Males and females exhibited similar percentages of diapause. Hypertrophied fat body combined with undeveloped accessory glands and supported by testis condition were criteria used for classifying male diapause, and hypertrophied fat body and lack of eggs at time of dissection were used to classify female diapause. Almost all males had developed testes and large quantities of sperm in their seminal vesicles at the time of dissection, but diapausing females did not exhibit ovarian development. Hypertrophied fat body in males was strongly associated with undeveloped accessory glands. A decline in number of eggs per egg-harboring female appeared to be related to photoperiod.