Monday, December 10, 2007 - 9:29 AM

Billbug seasonal phenology, bermudagrass and zoysiagrass damage potential in Florida

Ta-i Huang, and Eileen Amber Buss, University of Florida, Entomology and Nematology, 970 Natural Area Drive, Gainesville, FL

Billbugs (Sphenophorus spp.) cause damage that is often underrecognized or misdiagnosed of golf courses and lawns. Thus, we sought to identify the billbug species complex on two golf courses in southern and two in northcentral Florida, and determine hunting billbug development time on four bermudagrass cultivars and damage potential on 17 zoysiagrass cultivars. Adult billbug populations were monitored weekly from January 2006 to July 2007 with four linear pitfall traps on each golf course. Hunting (S. venatus vestitus, Chittenden) and uneven (S. inaequalis, Say) billbugs constituted 82.7% and 16% of the total 16,030 billbugs collected, and the remainder consisted of seven other Sphenophorus spp. Adult S. vestitus vestitus were collected in every weekly sample, which indicates the presence of overlapping generations, but were most abundant from April to May. Both S. vestitus vestitus and S. inaequalis females also produced mature eggs every month. From greenhouse rearing studies, S. vestitus vestitus develops from egg to adult within 9 weeks and thus may have about four generation per year in Florida. In greenhouse cultivar tests, adult female S. vestitus vestitus caused more damage to bermudagrass plants than males. Adult survival and amount of damage were lowest in ‘Celebration’, intermediate in ‘Tifway’ and ‘Tifeagle’, and highest in ‘Tifdwarf’. In a zoysiagrass resistance test, more S. vestitus vestitus eggs were laid on ‘Crowne’, ‘Jamur’, and ‘El Toro’ compared to 14 other zoysiagrass cultivars. Adults caused more damage in the cultivars ‘Crowne’, ‘Cashmere’, and ‘Empire’.

Species 1: Coleoptera Curculionidae Sphenophorus venatus vestitus (hunting billbug)
Species 2: Coleoptera Curculionidae Sphenophorus inaequalis (uneven billbug)