• The Korean Journal of Pesticide Science
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• v.17 no.4
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• pp.454-459
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• 2013

Beet armyworm, Spodoptera exigua is difficult to control using chemical insecticides because of the fast development of insecticide resistance. For eco-friendly beet armyworm managements, various control agents are required. Entomopathogenic fungus is one of the promise control agents as an alternative to chemical control agent. We isolated entomopathogenic fungi from soil samples of Yangpyeong, Gyeonggi-do by insect-bait method using Tenebio molitor and conducted bioassay to larva of beet armyworm. The result of bioassay, a selected strain FT83 showed 100% mortality against third instar larva of S. exigua. On the basis of morphological characteristics and analysis of 18srRNA sequence for ITS, the strain FT83 was identified as a Metarhizium anisopliae. The mortality of beet armyworm showed $81.6{\pm}9.3%$ at $1{\times}10^6$ conidia/ml, 100% at $1{\times}10^7$ conidia/ml and 100% at $1{\times}10^8$ conidia/ml respectively. Therefore, we recommend to proper control efficacy against S. exigua in which more than $1{\times}10^7$ conidia/ml suspension of M. anisopliae FT83.

• Korean journal of applied entomology
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• v.50 no.1
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• pp.39-46
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• 2011

This study analyzed effects of different sound treatments in frequencies and intensities on digestion and immune physiological processes of the beet armyworm, Spodoptera exigua larvae. Without effect on egg hatch, sound treatments with 100-5,000 Hz at 95 dB suppressed feeding behavior and inhibited a digestive enzyme activity. In addition, two dimensional electrophoresis of midgut luminal proteins indicated a marked difference of the sound-treated larvae. In response to 5,000 Hz at 95 dB, larvae showed a significant decrease in hemocyte nodule formation against fungal challenge along with significant suppression in phospholipase $A_2$ activity in hemocyte and plasma. With increase of sound frequencies, the treated larvae showed an enhanced susceptibility to insecticides. Such sound frequency effect was significantly modulated with different sound intensities. These results suggest that sound treatment may give adverse stress to physiological processes of S. exigua larvae and may be applied to a nonchemical insect pest control.

• The Korean Journal of Pesticide Science
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• v.19 no.4
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• pp.411-417
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• 2015

This study is conduced to investigate control efficacy of mixture of plant extracts which has been reported to control pest and Bacillus thuringiensis or alone. Control efficacy of 0.025% matrine or mixture of 0.016% matrine and BT ($5{\times}10^4cfu$) against $3^{rd}$ instar larvae of beet armyworm were best as 98.7% and 93.3%. Treatment of mixture of 0.01% matrine and BT ($5{\times}10^4cfu$) showed the mortality of 69.3%. In the case of neem, when the mixture of 0.1% neem and BT was applied to larvae of S. exigua, their mortality was 50.0% and weight of larvae were significantly different compare with control and only neem treatment. Therefore For effective control reducing population of beet armyworm and possibility to develop resistance against BT and eco-friendly agents, mixture of 0.016% Matrine and BT ($5{\times}10^4cfu$) could be used.

• Korean journal of applied entomology
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• v.38 no.1
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• pp.53-57
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• 1999

Simple diagnostic kits for monitoring insecticide susceptibility of beet armyworm, Spodoptera exigua (Hiibner) were developed and applied to the field populations. The operation of the kits was based on the correlations between enzyme activities of esterase (EST) and acetylcholinesterase (AChE) and the insecticide susceptibilities. Four different kinds of diagnostic kits (ED, EM, AD, and AM) were designed and classified by diagnostic enzymes (E for esterases and A for acetylcholinesterase) and inhibitors (D for dichlorvos and M for monocrotophos). Diagnostic inhibitor concentrations were 1 mM for ED, 10 mM for EM, 100 mM for AD, and 100 mM for AM. Resistant larvae which were not inhibited by the diagnostic amounts of insecticides developed positive staining (red color), but susceptible~ s howed negative (no color). An insect was used for both EST and AChE diagnostic kits, but different in their samples: hemolymph for EST and the head for AChE. These four diagnostic kits were applied to 1 1 different populations which showed variations of insecticide susceptibilities. Four kits were different in the capability discriminating the insecticide susceptibilites according to insecticides: ED to bifenthrin, AD to methomyl, and ED and AM to chlorpyrifos-methyl. These diagnostic devices can be used for insecticide-resistance management program for this insect pest. It also provide a technical guide to insect pest management for farmers, directors, and researchers.

• Korean journal of applied entomology
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• v.51 no.3
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• pp.223-230
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• 2012

Some high frequency sounds alter physiological processes of the beet armyworm, Spodoptera exigua. This study investigated the effect of ultrasound (${\geq}$ 20 kHz) on larval feeding, pupal development, and adult mating behavior of S. exigua. Ultrasound suppressed feeding behavior of fifth instar larvae, and 30 or 45 kHz treatment inhibited more than 50% of feeding activity. Larvae treated with ultrasound exhibited alterations in major nutrient compositions in the hemolymph plasma. Plasma protein levels decreased with an increase in ultrasound frequency. In contrast, sugar levels increased with an increase in ultrasound frequency. Lipid levels increased with an increase in ultrasound frequency up to 30 kHz and then decreased at treatments > 30 kHz. Hemocytes, the fat body, and epidermis expressed three heat shock proteins and apolipophorin III. Ultrasound treatment markedly inhibited expression of some stress-related genes. Ultrasound treatment also inhibited S. exigua pupal development by extending the pupal developmental period and preventing adult emergence. Last, ultrasound treatment significantly inhibited adult mating behavior, which resulted in a significant decrease in female fecundity. These results show that ultrasound is a physiological stress to S. exigua.

• Korean journal of applied entomology
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• v.54 no.4
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• pp.359-367
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• 2015

Physiological plasticity of insects can be closely related with their epigenetic change. This hypothesis was tested using a polyphagous lepidopteran insect, Spodoptera exigua, by assessing the effects of different diets on development and DNA methylation. Three different diets (Welsh onion (WO), Chinese cabbage (CC), artificial diet (AD)) were assessed by feeding a cohort of larvae from neonate to last instar. There were significant differences in larval developmental rate, pupal weight and adult emergence according to diet treatments. AD-fed larvae exhibited the fastest developmental rate along with the highest pupal weight and adult emergence. Among natural hosts, WO was more favorable for development of S. exigua than CC. Total hemolymph proteins and sugars in the last instar larvae were varied among different diets. Gene expression of an insulin-like peptide (SeILP1) presumably associated with development was also varied among diets. Cytosine methylation of genomic DNA was assessed using a monoclonal antibody. Genomic DNA of S. exigua larvae was methylated. DNA methylation was apparently varied among different diet-fed larvae. The facts that a cohort of S. exigua was differentiated in developmental rate and cytosine methylation by different diets suggest that epigenetic factor(s) may play a crucial role in the physiological plasticity.

• 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.

• Proceedings of the Korean Society of Applied Entomolohy Conference
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• 2002.11a
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• pp.169-169
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• 2002

• Journal of Bio-Environment Control
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• v.31 no.1
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• pp.22-27
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• 2022

The attraction effects of light emitting diode (LED) trap to Spodoptera exigua and Spodoptera litura adults were evaluated in greenhouse and compared with those of no light trap, which is typical used in commercial trap. At this time, in order to attract these two species of moths, sex pheromone traps were installed at the top side according to the degree of tomato growth inside the tomato cultivation greenhouse around the LED trap. In addition, two types of light-emitting traps (420 nm, 470 nm) were installed in the greenhouse at 1/40 m², respectively. Also two sex pheromone were installed inside of the greenhouse according to the height of the tomato plants. 10 days later, Blue-light trap(BLB, 470 nm wavelength) was 3.1-3.5 times more attractive than Violet-light trap(VLB, 420 nm wavelength) in S. exigua (105.6 ± 7.3) and S. litura (42.0 ± 3.1) respectively, whereas the no-light trap was little attractive to S. exigua (33.7 ± 2.8) and S. litura (12.0 ± 1.5). On the other hand, after the installation of the sex pheromone trap and the LED trap, there was no damage to S. litura (Fabricius) and S. exigua in the pesticide-free area, indicating a high possibility of control. At this time, the operating cost of the two types of LED traps was 80 won/m² per unit area, and it was confirmed that both types of moths could be controlled. In addition, as a result of confirming the number of two types of moths caught in the sexual pheromone trap and two types of LED traps after 4 months, it was judged that eco-friendly control was possible as more than 373 moths/trap were attracted to the two types of moths.

• Korean journal of applied entomology
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• v.43 no.3 s.136
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• pp.217-223
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• 2004

Polydnavirus is a symbiotic virus of some endoparasitic wasps and plays crucial roles in inhibiting immune responses and retarding development of the parasitized hosts. Cotesia plutellae bracovirus (CpBV) is a polydnavirus suggesting a major causative to change developmental physiology of the parasitized host. Here, we investigated whether CpBV can interrupt development of non-natural host. Beet armyworm, Spodoptera exigua, is used as a non-permissible host for parasitization of C. plutellae. Extract from the calyx region of C. plutellae contained CpBV, which was confirmed by immunoblotting with a polyclonal antibody raised against CpBV. One female equivalent of CpBV extract was injected into hemocoel of late 4th instar larvae of S. exigua. The injected larvae showed delayed larval period, decrease of body weight gain, and inability of pupal metamorphosis. These inhibitory effect of the CpBV extract was rescued by injection along with CpBV antibody, though the antibody itself did not give any effect on development of the larvae. This result clearly shows that CpBV can interrupt developmental physiology of a non-natural host for its symbiotic wasp.