친환경재배 감귤원에서 썩덩나무노린재의 가해습성 및 관리전략

Abstract

The brown marmorated stink bug, Halyomorpha halys (St?l) (Hemiptera: Pentatomidae) is polyphagous pest insect, originated in East Asia including Korea, China, Japan and Taiwan, injuring leguminous and fruit plants and many ornamental trees. H. halys was introduced into the U.S. and the Europe in 1996 and 2006, respectively. In Jeju island, Korea, H. halys is considered as the most significant stink bug pest of citrus. H. halys sucks up fruits and leaves of citrus, and finally causes severe fruit-fall damage in the growth season. It can controlled by application of practical insecticides such as organo phosphorous, pyrethroids and neo-nicotinoids, but there is lack of environmentally-friendly management strategy. In this study, 20 of H. halys adults were originally collected in 2009, in a citrus orchard in Jeju, and successfully established its laboratory colony by feeding fresh peanut and fleshy potted-plants (Peperomia spp.) for water source and oviposition substrate. The laboratory colony was maintained in acrylic cage (110 x 70 x 55cm) with 24 ± 1℃, RH40-70% and 16L:8D. This method seems to need less effort to keep H. halys population than previous rearing methods. The body sizes between laboratory and wild colony were not different in male and female adults, while tibia of hind-leg was significantly longer than in laboratory males than that of wild males. The feeding of H. halys was regarded as causing factor of fruit drops and resultant decay of the citrus fruits. So, we examined the feeding effect of H. halys on fruit drop before harvest and decay rate during cold storag (4℃) according to different feeding times: pre-coloring, coloring and harvesting season of citrus. In this study, a branch with 9-12 fruits were embraced with a mesh-net bag, then 0 to 1.0 H. halys adults per fruit were introduced in. In pre-coloring stage of citrus (16, September), the feeding by 1.0 and 0.2 H. halys per fruit induced 70% and 20% fruit drop, respectively, in 2010. In fruit coloring stage (6, October), however, 0.5 H. halys adults per fruit caused 8% fruit drop in 2011. When the fruits that were not dropped by H. halys feeding were held in cold storage, the fruits decay rate were 2-10%, and there was no significant different between feeding treatment and non-treated control. In environmentally-friendly managed Shiranui greenhouse, seasonal fluctuation of each developmental stages of H. halys and its preferring host sites were investigated by visual counting method. The adult population peaks (summer generation) occurred in mid-July for 1st generation and late-October for 2nd generation. Most H. halys was found on young leaves of shoots before fruit coloring (September) with few-individuals were observed on fruits, while thereafter 4-5th nymphs of H. halys moved to citrus fruits for feeding resulting in the fruit drop. The insecticidal effects of eco-friendly materials such as pyrethrin(extract of Dalmatian chrysanthemum) and commercial products of rotenone, azadirachtin and machine oil were evaluated by spray method. Mortality of H. halys adults were highest in pyrethrin treatment (50%) and its effectiveness was same as synthetic insecticide, dinotefuran. Nymphs (3-4th instar) were hardly killed by all chemicals tested, and machine oil 100x showed only 20% mortality against 1st nymphs, indicating a control program of H. halys with a stage-specific spraying. The mortality effect of rotenone were much higher in infection treatment than in spray treatment; increasing to a 80%. This result indicates that researches for transporting target chemicals into insect body by increasing penetration ability or through feeding bait is required in the future. Integrating results obtained in this study, the management strategy of H. halys in greenhouse environment can be summarized: timing spray of machine oil against young nymphs in early June and August, and pyrethrin sprays against adult populations during overwintering, 1st and 2nd generation period. In open citrus orchards, however, further studies are required to control immigrating population form outside habitats.