ISHS Acta Horticulturae 777: IX International Rubus and Ribes Symposium
BIOLOGY AND CONTROL OF ROOT WEEVILS ON BERRY AND NURSERY CROPS IN OREGON |
| Authors: | J.R. Fisher, D.J. Bruck |
| Keywords: | Otiorhynchus sulcatus, host plants, reproduction, bifenthrin, entomopathogenic fungi |
| Abstract:
The root weevils, Otiorhynchus sulcatus and Otiorhynchus ovatus, the black vine and strawberry root weevil, respectively, are perennial, ubiquitous pests of berry and nursery crops throughout the world. Recently, we developed a mass rearing system for these pests and now are able to conduct controlled experiments to study their biology and to develop chemical and biological management systems. Here we highlight our findings from these studies. We tested the hypothesis that feeding on multiple hosts may promote reproductive success. We used three hosts: strawberry, rhododendron and birds nest spruce (Picea abies ‘Nidiformis’) in a permutated array where adults were placed on a host for 15, 30, 45 or 60 days and then moved to another host for the remainder of their lives, or up to 300 days. Strawberry was the best sole host. Birds nest spruce alone, and in combination with other hosts, adversely affected reproductive processes. Some combinations of strawberry and rhododendron appeared to have a ‘synergistic’ effect when considering egg production. We devised a soil bioassay for screening pesticides or biological agents. In our first studies with the system we tested two formulations of bifenthrin. Granular bifenthrin prevented only the establishment of larvae, whereas the liquid formulation was efficacious on later instars. We have also performed field studies to compare the efficacy of bifenthrin and the entomopathogenic fungus Metarhizium anisopliae in which we observed no significant difference between chemical and fungal treatments. Laboratory bioassays were also performed to access the virulence of M. anisopliae against field collected O. ovatus. The fungus was highly virulent even at the low dose of 1 × 104 spores per g dry soil. | |
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