• Korean journal of applied entomology
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• v.61 no.4
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• pp.529-537
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• 2022

The susceptibilities of five insecticides to the larvae of Spoladea recurvalis, a major pest of spinach, were evaluated. Lufenuron EC, chromafenozide EC, chlorantraniliprole WP, tebufenozide WP, and pyridalyl EW showed 90% or more insecticidal activity at dilution concentrations of 2 (12.5 ppm), 4 (12.5 ppm), 8 (2.5 ppm), 4 (20.0 ppm), and 8 (12.5 ppm), respectively. At their recommended concentrations, Chromafenozide EC, chlorantraniliprole WP, tebufenozide WP, and pyridalyl EW showed very high insecticidal activity of 98.3%, 100%, 95.0%, and 100%, respectively, after 72 h on S. recurvalis larvae exposed after 7 days of treatment. Field tests at two spinach greenhouses in Hwaseong and Yeoncheon showed a high control effect of over 90% after 7 days of treatment in both areas. In addition, the insecticides can be used as exclusive agents for S. recurvalis that occurs in spinach, as there is no phytotoxicity even at double doses.

• The Korean Journal of Pesticide Science
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• v.18 no.3
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• pp.175-180
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• 2014

This study was carried out to determine the economic injury level and economic threshold level on beet (Beta vulgaris L.) infested with Spoladea recurvalis in the plastic greenhouse condition in 2010. The second instar larvae of S. recurvalis were inoculated with 7 different density levels on the each 10 beet plants as a replication. Injury levels of beet leaves and density of S. recurvalis were increased with the inoculation density of S. recurvalis. However, yield and marketable commodity of beet were decreased. Linear relationship between the percent yield reduction (Y) of beet leaves and different infestation densities of S. recurvalis (X) was estimated by the following equation Y = 1.226x + 3.36. Based on the relationships between the densities of S. recurvalis larvae and yield index of beet leaves, the number of second instar larvae which caused 5% loss of yield, economic threshold level was estimated as 1.1 larvae/10 plants for the planting 10 days. The percent yield reduction (Y) of beet roots infested with different densities of S. recurvalis (X) estimated by the following equation Y = 1.537x + 1.4634 after inoculation for 10 days at 3rd harvesting of leaves. Based on the relationships between the densities of S. recurvalis larvae and yield index of beet roots, the number of second instar larvae which caused 5% loss of yield, economic threshold level was estimated as 6.4 larvae/10 plants for the planting 10 days.

• Korean journal of applied entomology
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• v.52 no.1
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• pp.5-12
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• 2013

The Hawaiian beet webworm (Spoladea recurvalis) is one of the serious insect pests found on red beet (Beta vulgaris var. conditiva) in Korea. The study was conducted to investigate the development period of S. recurvalis at various constant temperatures, 15.0, 17.5, 20.0, 22.5, 25.0, 27.5, 30.0, 32.5 and $35.0^{\circ}C$, with $65{\pm}5%$ RH and a photoperiod of 16L:8D. The developmental period from egg to pre-adult was 51.0 days at $17.5^{\circ}C$ and 14.6 days at $35.0^{\circ}C$. The developmental period of S. recurvalis was decreased with increasing temperature. The relationship between the developmental rate and temperature was fitted well by linear regression analysis ($R^2{\geq}0.87$). The lower developmental threshold and effective accumulative temperature of the total immature stage were $10.4^{\circ}C$ and 384.7 degree days, respectively. The nonlinear relationship between the temperature and developmental rate was well described by the Lactin model. The relationship between the cumulative frequency and normalized distributions of the developmental period for each life stage were fitted to the Weibull function with $R^2=0.63{\sim}0.87$.

• Korean journal of applied entomology
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• v.60 no.3
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• pp.305-312
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• 2021

This study was carried out to investigate insect pests and their damage caused to commercial amaranth in Gangneung, Gangwon-do, Korea, during 2019-2020. A total of seven families and 18 species were identified including three species of aphids, twelve species of stink bugs, and four species of moths. Among them, five species caused significant economic damage due to a large number of occurrences; Aphis fabae, Nysius plebejus, Polymerus cognatus, Spoladea recurvalis and Spodoptera exigua. Aphids started to occur from the end of April, and showed the greatest incidence in early June. Three Nysius species occurred from mid-May and showed the maximum density in late August, and then its population decreased from the beginning of September. Two species of moth caterpillars began to occur from mid-August and damaged amaranth until mid-October. Comparing the yields between amaranth plants with and without a spray of pesticides for each pest, the yield loss of seed by aphids and stink bugs were 51.9% and 69.8%, respectively. Also, the reduction rates of leaf biomass by S. recurvalis and S. exigua were 72.5% and 36.5%, respectively.