• Korean journal of applied entomology
• /
• v.30 no.3
• /
• pp.212-218
• /
• 1991

Pathogenicity of Spodoptera exigua nuclear polyhedrosis virus (SeMNPV) against the host insect and 8 species of lepidopterous insects and cross infection of baculoviruses to third instar of S. exigua larvae were studied to determine as a biocontrol agent for S. exigua. The median lethal concentrations($LC_{50}$)of the SeMNPV to egg mass was $2.855\times10^5$ PIBs/ml and higher than that to the larvae of S. exigua. Mortality of the SeMNPV in third ins tar larvae was more increased than that in first and fifth instar of S. exigua larvae by 1.16 and 4.11 times, respectively. The median lethal times($LT_{50}$) to $1.56\times10^6$ PIBs/ml was in the range of 4.25 to 5.04 days. Infectivity of the SeMNPV against eight species of lepidopterous insects was showed only in the host insect, S. exigua. Autographa cali/ornica MNPV, Mamestra barassicae MNPV, and Trichoplusia ni MNPV were cross-infected to third instar of S. exigua larvae among ten of baculoviruses tested.

• Korean journal of applied entomology
• /
• v.30 no.2
• /
• pp.111-116
• /
• 1991

Larvae of beet armyworm. Spodoptera exigua are extremely polyphagous. A total of 42 host p plants were identified in the field observations. Among them, vegetables were 13 species. upland crops 12 species, flowers species, and others including weeds 11 species. The damage by b beet armyworm was severe on Allium fistulosum in southern Chonnam. The percentage of hills d damaged was 86% in Jindo, Chonnam and 1.92% in Sesan. Chungnam. Nomuraea rileyi and nuclear polyhedrosis virus were identified on the larvae of Spodoptera exigua in Allium fistulosum fields and the percentage of parasitization was 4.3-9.7% and 3.2%, respectively. M Mortality of Spodoptera exigua larvae by Nomuraea rileyi in perilla was 13.4% in July 5, 28.9% in Aug. 7, and 18.5% in Sept. 10.

• Korean journal of applied entomology
• /
• v.46 no.1 s.145
• /
• pp.27-35
• /
• 2007

Seasonal occurrences of tobacco cutworm, Spodoptera litura and beet armyworm, Spodoptera exigua were observed using sex pheromone traps at different locations and climatic regions in Yeongnam district. In Gyeongnam province, S. litura male adults kept occur from mid or late March to mid or late November Whereas in Gyeongbuk province, S. litura occurred from mid or late April to early or mid November with exception at Uljin where it was late May to late October. According to the climatic regions, the peak occurrence of S. litura was middle September at the southern coast region, late August at the inland and the basin region, middle August at the inland mountainous region, and early September at the eastern middle coast region. The occurrence rate of S. litura was the highest at Jinju with 20.0% and the lowest at Changyeong with 8.6% in Cyeongnam province, while it was the highest at Sungju with 3.3% and the lowest at Uljin with 0.8% in Gyeongbuk province. In accordance with the climatic regions, the occurrence rate of S. litura was the highest at the inland region with 43.7%, and followed by the southern coast region (36.3%), the basin region (8.4%) and the inland mountainous region (7.0%), and was the lowest at the eastern middle coast legion with 4.6%. On the other hand, S. exigua occurred from early March to middle November with the exception of the eastern middle coast region including Pohang, Yeongdeog and U]ien in Cyeongbuk province where it occurred from mfd April to middle November. The peak occurrence of s. exigua was early August at the inland region, the basin region and the inland mountainous region, and was late of August at the southern coast region and the eastern middle coast region. The occurrence of S. exigua was the highest at Changyeong with 1.6% and the lowest at Busan with 0.4% in Gyeongnam province, while it was the highest at Sungju with 37.2% and the lowest at Uljin with 2.7% in Gyeongbuk province. The climatic regional occurrence rate of S. exigua was the highest at the basin region with 54.3%, and followed by the inland mountainous region (29.9%), the eastern middle coast region (9.3%) and the inland (3.9%), and was the lowest at the southern coast region with 2.6%. As a whole, S. litura occurred more in Gyeongnam province than Cyeongbuk province, while S. exigua occurred more in Gyeongbuk province than Gyeongnam province. According to the regions grouped by climatic differences, the occurrence of S. litura and S. exigua was the highest at the inland region in Gyeongnam province and at the basin region in Gyeongbuk province. The total number of S. litura captured by sex pheromone trap was 2.4 times higher than that of S. exigua. However, the first occurring time and the peak occurrence of S. exigua were slightly earlier than those of S. litura.

• Korean journal of applied entomology
• /
• v.35 no.3
• /
• pp.228-231
• /
• 1996

To produce Spodoptera exigua nuclear polyhedrosis virus (SeNPV) using S. exigua larvae, the efficiency of the in vivo production was analysed by larval instar, inoculum and mortality. The results revealed that the mortality of 4th instar larvae inoculated with 1.OX 10' EIBs per ml was 86.7% and the yields of SeNPV was maximal, demonstrating that 4th instar larvae inoculated with 1 . 0l~o6 PIBs per ml were effective to mass production of SeNPV.

• Korean journal of applied entomology
• /
• v.32 no.2
• /
• pp.225-235
• /
• 1993

This study was carried out to investigate effects of diazinon, an organophosphate, and nicotine, a plant~originated toxic chemical, on larval mortality and activity of cytochrome P-45D monooxygenases, a major detoxifwation enzyme system, in Helicoverpa assulta and Spodoptera exigua. Diazinon treatment gave a higher mortaliLy to H. assulta larvae than S. exigua larvae. In contrast to the case of diazinon, nicotine caused a higher mortahty to S. exigua than to H. assulla larvae. It was partly due to the fact that nicotine induced the actiVIty of midgut cytochrome P-450 monooxygenases (MFO) more than diazinon did in If assulta larvae. When If. aSSlllta larvae were reared on their host p\am. NicotwlIa tuoocum leaves, other componentS were mostly metabolized with the exception of dietary nicotine.

• The Korean Journal of Pesticide Science
• /
• v.4 no.1
• /
• pp.44-50
• /
• 2000

Tolerance mechanism to flupyrazofos was examined with Plutella xylostella (L.) and Spodoptera exigua by investigating the penetration rate of flupyrazofos into larvae body. On determining effective washing of $^{14}C$-flupyrazofos, the washing volume to recover over 98% of $^{14}C$-flupyrazofos was observed at three times (each time: 1 mL). To select a suitable solvent, the recovery rates of each solvent in 3rd instar larvae of DBM were above 98%, but the washing rates of acetone, hexane and ethyl-acetate were 85.1%, 67.2% and 68.4%, respectively. In the BAW larvae, although the recovery rates of each solvent were above 99%, the washing rates of acetone, hexane and ethyl-acetate were 83.5%, 65.9% and 71.7%, respectively. The $PT_{50}$ values of $^{14}C$-flupyrazofos were 0.731 h (44 min) in the DBM larva and 0.504 h (30 min) in the BAW larva. Radiocarbon in acetone washing (external fraction) decreased more quickly in the BAW larva than in the DBM larva, and amount of radiocarbon in larvae body increased more quickly with time in the DBM larva than in the BAW larva. In contrast, amount of radiocarbon in excreta increased more rapidly with time in the BAW larva than in the DBM larva.

• The Korean Journal of Pesticide Science
• /
• v.13 no.3
• /
• pp.197-202
• /
• 2009

Based on the insecticidal efficacy by insecticide treatment methods, neurophysiological responses were compared with the larvae of diamondback moth (DBM) and beet armyworm (BAW) using pyrethroids working on nervous system. By body spray method, all pyrethroids were showed lower insecticidal activity below 50% on the larvae of DBM and BAW. By leaf dipping method, DBM larvae were showed the insecticidal activity as 100% at 50 ppm deltamethrin, 80.0% at fenvalervate and 63.3% at permethrin. However, BAW larvae were showed lower insecticidal activity as similar as control in all concentration. In order to examine electrophysiological response on nervous system on DBM and BAW larvae when treated three insecticides, we investigated the voltage and reaction degree. The voltage of DBM were responded as high as $10^{-7}M$ in deltamethrin, $10^{-5}M$ in fenvalerate and $10^{-3}M$ in permethrin. However, those of BAW were showed dull responses with small variation of voltage to all three insecticides.

• The Korean Journal of Pesticide Science
• /
• v.18 no.4
• /
• pp.417-421
• /
• 2014

The beet armyworm, Spodoptera exigua is pest which is difficult to control. For eco-friendly beet armyworm managements, we isolated entomopathogenic fungi from soil samples by insect-bait method using Tenebrio molitor and conducted bioassay to larvae of beet armyworm. The result of bioassay, a selected strain Metarhizium anisopliae FT83 caused 100% mortality against first ~ third instar larva of S. exigua at $1{\times}10^8conidia/ml$ and medial lethal time ($LT_{50}$) were 0.5 days, 2.6 days and 2.5 days respectively. Mortality against fourth and fifth larvae were $83.3{\pm}6.2%$ and $86.0{\pm}5.7%$ and medial lethal time ($LT_{50}$) were 4.2 days and 3.6 days respectively. Mortality against pupae and eggs of S. exigua were 100%. M. anisopliae FT83 showed high virulence at all developmental stages of S. exigua.

• The Korean Journal of Pesticide Science
• /
• v.19 no.2
• /
• pp.125-133
• /
• 2015

Entomopathogenic fungi have been studied to develop for biological control agents as an alternative to chemical control agents in insect pest management. Two Lepidopteran insects, Spodoptera exigua and Plutella xylostella, are serious insect pests infested various crops, but not effectively controlled by commercial chemical pesticides due to its high insecticide resistance. A fungal isolate was isolated from S. exigua larvae collected from green onion field in Andong, Korea. To identify the fungal isolate, 18srRNA sequence for internal transcribed spacer (ITS) and ${\beta}$-tubulin regions were sequenced. The ITS and ${\beta}$-tubulin sequence were highly matched to Beauveria bassiana and morphological characteristics also was fit to known B. bassiana. Finally, isolated fungus has identified as B. bassiana and named B. bassiana ANU1. The result of bioassay, median lethal concentrations were $2.7{\times}10^3$ and $0.9{\times}10^3conidia/ml$ and medial lethal times were 65.6 and 60.8 h to S. exigua and P. xylostella, respectively. B. bassiana ANU1 showed high pathogenicity to two insect pests from $20^{\circ}C$ to $30^{\circ}C$ at 50% relative humidity (RH) and more than 40% RH at $25^{\circ}C$ with $10^7conidia/ml$ of concentration.

• The Korean Journal of Pesticide Science
• /
• v.6 no.3
• /
• pp.224-229
• /
• 2002

In vivo metabolism study was carried out to find out the biochemical or metabolic tolerance mechanism between Diamond backmoth (DBM), Plutella xylostella and Beet armywarm (BAW), Spodoptera exigua to flupyrazofos. They showed some differences between the DBM and BAW. About 20% of flupyrazofos applied to the 3rd instar larvae of DBM was metabolized within 1 h and about 50% of that was metabolized within 4 h. The metabolites of flupyrazofos-oxon in 3rd instar larvae of DBM were increased 10 times more at 4 h than 1 h after application. The amounts of flupyrazol were nearly same between at 1 h and 4 h. The amount of unknown and origin increased 2 and 3 times more at 1 h than 4 h after application, respectively. In the 4th instar BAW larva, about 50% of flupyrazofos was metabolized within 1 h and about 70% of that was metabolized within 4 h. As metabolites, the amounts of flupyrazofos-oxon increased 2 times more at 4 h than 1 h after application. The amounts of flupyrazol increased 4 times more at 4 h than 1 h after application. The amount of unknown and origin increased 2.5 and 2 times more at 4 h than 1 h after application, respectively. From the study, it is supposed that hydrolytic enzyme, esterase, cleave the alkyl bond of flupyrazofos and conjugates with flupyrazofos. This seems to be the main tolerance mechanism of BAW to flupyrazofos.