Collaria scenica (STAL, 1859) (HEMIPTERA: MIRIDAE) EM POACEAS HIBERNAIS NA REGIÃO CENTRO SUL DO PARANÁ: BIOLOGIA E DANOS

Abstract

Collaria scenica (Hemiptera: Miridae) population has increased in Guarapuava region, Southern Parana, feeding on pasture and cereal crops. Experiments were conducted at the Laboratory of Entomology and at the Experimental Field in UNICENTRO - CEDETEG Campus in 2007 to 2008 on C. scenica biology, host plants, feeding and oviposition preference on Poaceae, percentage of damage in wheat (Triticum aestivum) and lopsided oat (Avena strigosa), and biological control with the entomopathogenic fungus Beauveria bassiana. In laboratory, nymphal developmental time (total and each instar) was similar for nymphs reared on lopsided oat and ryegrass (Lolium multiflorum), but mortality nymph was higher on ryegrass. Nymphs showed five instars on both plant hosts. The total number of eggs laid female varied from 32 to 178, and from 45 to 245 eggs on ryegrass and on lopsided oat, respectively. Egg masses were laid inside the leaf sheaths. Pre-oviposition period of C. scenica females was longer on ryegrass (4.8 days) than on lopsided oat (2.8 days). No statistical difference on longevity of adults reared on both host plants was observed. The feeding preference among Poacea hosts follow at the decreasing order: lopsided oat, wheat, oat (Avena sativa), barley (Hordeum vulgare) and ryegrass. There was no difference in oviposition preference (number of eggs/host) among species of Poacea, despite the numbers of eggs following the same pattern of feeding preference. In laboratory and field assays, a positive correlation of to insect increased population and damage percentage in leaves was observed both crops tested lopsided oat and wheat; statistical difference in dry wealth of leaves in different population infestation was observed. The entomopathogenic fungus Beauveria bassiana - isolate CG460 colonized C. scenica, mortality was above 80% and the median lethal time (LT50) was 4.3 days at 109 conidia.mL-1 concentration.