|SHARMA, EEVA - Fresno State University|
|BUSHOVEN, JOHN - Fresno State University|
Submitted to: International Congress of Entomology
Publication Type: Abstract Only
Publication Acceptance Date: 6/17/2016
Publication Date: 6/17/2016
Citation: Sharma, E., Cervantes, F.A., Backus, E.A., Bushoven, J. 2016. Anatomical damage in cotton squares by nymphal Lygus lineolaris in relation to EPG-recorded feeding behavior. International Congress of Entomology. Available: https://esa.confex.com/esa/ice2016/meetingapp.cgi/Paper/112172.
Technical Abstract: Lygus lineolaris is a key pest affecting cotton, Gossypium spp. The pest is widely distributed in the U.S., especially in eastern and mid-southern states. Nearly 53% of U.S. cotton acreage was infested by Lygus spp. in 2002. An individual lygus bug is capable of destroying up to 23,400 cotton squares per hectare. Fifth instar nymphs are the most aggressive feeders, hence, cause more economic loss. Nonetheless, little is known about how lygus feeding causes square damage. The objective of this research was to better understand damage to cotton squares from fifth instar nymphs, by performing a time course study of internal anatomical changes to squares after a standardized amount of feeding. Four hours of nymphal probing was applied via electropenetrography (EPG) to one cotton square on each of 32 plants. Each plant was held for either 0, 4, 12, or 24 hours (8 plants per treatment). Squares were then excised and prepared for light microscopy. Compared with healthy, undamaged control squares, L. lineolaris nymphal feeding caused grossly enlarged empty spaces, varying amounts of cellular degradation, and discoloration of tissues. Also, fifth instar nymphal feeding induced histological signs of tannin accumulation as a defensive response, at all time periods. Cellular degradation and tannin accumulation increased over the first 12 hours, whereas empty spaces in tissues were larger at 24 hours, suggesting a progression of damage symptoms. This study will be helpful in studying the role of tannins in cotton-lygus interactions, and in eventual development of new, resistant cotton varieties.