살충제 저항성 목화진딧물 집단(완주, 춘천, 고성)에 대한 3종(afidopyropen, chlorfenapyr, cyantraniliprole) 약제별 감수성과 혼용에 따른 방제 효과를 평가하였다. 3개 야외집단에 대해서 3약제 모두100배 이상의 저항성비를 보였다. 혼합제의 협력작용을 평가하기 위해 반수치사농도(LC50) 을 이용한 조합지수(CI), %M(synergism), 연합독성계수(CTC), 와들리 비율(WR), 상승비율(SR)와 사충률을 이용한 아보트 비율(AR)로 비교하였 다. Afidopyropen + chlorfenapyr은 모든 야외집단에 대해서 살충활성의 증가를 보였고, chlorfenapyr + cyantraniliprole, afidopyropen + cayntraniliprole은 완주, 춘천 집단에 대해서 살충활성의 증가를 보였다. 그러나 chlorfenapyr + cyantraniliprole (CI, 1.63; %M(synergism), 30; CTC, 64.0; WR, 0.6, AR, 0.54)과 afidopyropen + cyantraniliprole (CI, 6.7; %M(synergism), 1; CTC, 19.8; WR, 0.2, AR ≤ 0.55)은 고성 집단에 서 길항작용을 나타내었다. 포장조건에서도 afidopyropen + chlorfenapyr, chlorfenapyr + cyantraniliprole, afidopyropen + cyantraniliprole 은 99% 이상의 높은 방제가를 보여 향후 살충제 저항성 목화진딧물 방제용 혼합제 개발에 유용하게 활용될 것이다.

Naturally occurring plant toxins, such as benzoates, have been shown to have insecticidal effects on some pest insects. In this study three commercially available benzoates, methyl benzoate (MB), ethyl benzoate (EB), and vinyl benzoate (VB), were assessed for their contact toxicity against Aphis gossypii Glover and its lacewing predator Chrysoperla carnea Stephens. Toxicity of 1% MB, EB, and VB showed 100%, 85% and 60% mortality of A. gossypii at 24 h. In addition, a mixture of MB and EB showed higher synergistic effect than mixtures of MB+VB or EB+VB against A. gossypii. Toxicity at 1% concentration of three benzoates against A. gossypii showed lower toxicity against the larvae of C. carnea after 72 h of exposure than A. gossypii. Our result suggest that benzoates have high potential as environmentally safe biopesticides for A. gossypii control.

Cymbidium flower is mainly grown for exportation to China and Japan, but detection of a few pests including the cotton aphid, Aphis gossypii (Hemiptera: Aphidae), necessitated post-harvest treatment for casual exportation. Thus, we irradiated electron beam to cotton aphids occurring in cymbidium to establish post-harvest method for casual exportation of the flowers. For cymbidium, six categories of product quality were examined after eight different doses were irradiated (100, 200, 300, 400, 500, 600, 800 and 1,000 Gy). One thousand Gy to cymbidium caused an extreme deterioration only in vase life in both colors compared to control (0 Gy). In the case of cotton aphids, adult longevity decreased from 11.23 (100 Gy) to 4.70 (400 Gy) when four different doses were irradiated (100, 200, 300, and 400 Gy), with control being an average of 20.89 days. The numbers of total first instar nymph produced per adult was not significantly differed among five doses (2.21 ~ 2.74 individuals), but was substantially lower compared to control (an average of 51.46; P < 0.0001). Live F1 nymphs did not develope to adults at all five doses, except for a single nymph at 100 Gy, which was dead right after emergence. The results of probit analysis indicated that majority of adults required 3.33 ~ 7.55 days for 90% mortality at 200 Gy and higher, but at 100 Gy it required 41.56 days. Therefore, higher than 100 Gy might be required for complete control of adult cotton aphids and their F1.

Biological control has emerged due to the side effects of chemical control such as residual and toxicity. One of the biological controls is entomopathogenic fungi. The entomopathogenic fungus used in this study was first detected in the insectary. The fungus was identified as Lecanicillium sp. based on the sequences of the ITS1 and 2 regions. Lecanicillium sp. infects aphids, scale insects and whiteflies, especially Myzus persicae and Aphis gossypii. In this study, we characterized the fungal phenotype, growth condition, and pathogenicity against green peach aphid. Mycelial growth of Lecanicillium sp. was 12.79±0.46 mm diameter during 7days on potato dextrose agar at 25℃. In addition, the fungus was able to annihilate 100% green peach aphids, after 8days of inoculation. Ultimately, this study would be provide new information on Lecanicillium sp. and suggest the potential utilization of this fungus as a biological control agent.

Entomopathogenic fungi have been used as important part of integrated pest management program to control aphid. In particular, Beauveria bassiana was distributed throughout the world including temperate and tropical area, various habitats from alpine soil, desert soil to running water and both insect and plant. Especially the fungus has also been isolated from the surface and the interior of plants and act as natural control agent. Viability of fungi on the plant surface may be influenced by temperature, humidity, sunlight and plant type as well as fungal isolate. Persistence of treated fungal control agent on phylloplane and control efficacy may differ from environmental conditions and isolates. In this study, we investigated the persistence of an B. bassiana which is developing as prototype wettable powder to control cotton aphid, and the residual efficacy of the prototype on cucumber under three different greenhouse conditions.

Cotton aphid, Aphis gossypii Gloever is one of the major pests on a wide range of economically important crops in the world. The sustained use of chemical insecticides to control the aphid has led to the emergence of resistant strains to numerous used insecticides. As an alternative strategy entomopathogenic fungi have been used as part of integrated pest management program to control aphid, especially insecticide-resistance population. In particular, Beauveria bassiana-based commercial bio-insecticide has been used to reduce the pest population under greenhouse conditions in various countries. In this study, we investigated the control efficacy of a prototype of commercial mycopesticide using an B. bassiana (wettable powder) against cotton aphid on potted cucumber plant in greenhouse conditions.

Glucose-regulated protein 78 (GRP78) is a member of the heat shock protein 70 (HSP70) family that is specific to endoplasmic reticulum (ER). It is known as chaperones and signaling regulators that respond to ER stresses in vertebrates. However, its function in invertebrates, including insects, is uncertain. Here we determined a full cDNA sequence and the expression patterns of grp78 of Aphis gossypii, which is a major pest of numerous crop plants worldwide. Its cDNA had highly conserved motifs of the HSP70 family and the C-terminal motif of KDEL characteristic of ER-specific HSPs. It showed 98.5% identity with the GRP78 of the pea aphid Acyrthosiphon pisum. Real-time RT-PCR analysis showed that the grp78 level was higher in the fourth instar nymph than in the younger instar and adult stages. Its level was not affected by thermal stress of 10 to 40°C for 1 h. The grp78 level was proportional to the ingestion of a sucrose solution ranging in concentration from 0% to 30% in a Parafilm feeding chamber. In addition, the grp78 level varied among aphids feeding on leaves from 14 different host plants for 24 h; it was higher with eggplant and pepper but lower with pigweed and tobacco than any other plants. Our study suggests that the grp78 level is regulated by nutritional condition of A. gossypii.

Cotton aphid infests more than 700 plants and a major pest of various horticultural crops worldwide. The glucose regulated protein 78 (GRP78) is a member of heat shock protein 70. Its expression is associated with the nutritional changes as well as environmental stresses. The full sequences of grp78 cDNA of Aphis gossypii was determined. It had conserved motifs of hsp genes and terminated in KDEL which is common to GRP78. Quantitative realtime PCR showed that its level was changed during development and also upregulated by starvation. However, its level was not much changed by heat stress. The level of grp78 can be use to understand nutritional physiology on insects.

The melon and cotton aphid Aphis gossypii Glover (Hemiptera; Aphididae) is one of the most serious pests worldwide. We surveyed insecticide susceptibility in A. gossypii field populations to 12 insecticides to examine resistance ratios. The levels of insecticide resistance were extremely high, especially to neonicotinoids. One point mutation was found in the beta1 subunit loop D region of the nicotinic acetylcholine receptor (nAChR) of the imidacloprid-resistant strain. Feeding behavior analysis using an electrical penetration graph showed that sublethal doses of imidacloprid had significant effects on the duration of phloem ingestion. In addition, higher doses of imidacloprid induced contact toxicity rather than inhibition of feeding behavior. Temperature and insecticide are two important factors that affect survival, reproduction and other physiological processes of insects. To determine interactions of temperature and insecticide treatment on susceptible and imidacloprid-resistant strains of A. gossypii, adults were exposed to three temperatures (17, 22, and 28℃) or combinations of three temperatures and imidacloprid (LC20), and the expression of several genes (heat shock protein 70, cuticle protein, cytochrome P450, and elongation factor) were analyzed. Additionally, the effect of electron beam irradiation on development, reproduction, and several gene expression of imidacloprid-resistant and -susceptible A. gossypii were compared.

The melon and cotton aphid Aphis gossypii Glover (Hemiptera; Aphididae) is one of the most serious pests worldwide. We surveyed insecticide susceptibility in A. gossypii field populations to 12 insecticides (6 neonicotinoids, 3 pyrethroids and 3 others) to examine resistance ratios. The levels of insecticide resistance were extremely high, especially to neonicotinoids, such as acetamiprid, clothianidin, thiacloprid and imidacloprid. To identify the neonicotinoid resistance mechanisms, we used an imidacloprid-resistant (IMI-R) strain as a model strain. IMI-R showed an extremely high resistance ratio and also cross-resistance to all the test neonicotinoids. However, there was little or no cross-resistance to the other insecticides, including sulfoxaflor. Synergist tests and enzyme activity assays suggested the absence of resistance mechanisms based on enhanced detoxification enzymes, such as cytochrome P450, esterase and glutathione S-transferase. One point mutation was found in the beta1 subunit loop D region of the nicotinic acetylcholine receptor (nAChR) of the IMI-R strain. This R81T point mutation was also found in field populations collected from 5 regions. Therefore, the R81T point mutation was identified as an important mechanism of imidacloprid resistance in A. gossypii.

For replacement of methyl bromide(MB) in Korea, VapormateTM, a gas formulation of ethyl formate(EF) with carbon dioxide, are firslty introduced in import bananas and VivakilTM, a gas formulation of phosphine(PH3) with carbon dioxide, are ready to commercial use in export cut flowers. Their applications are being extended for other import and export commodities. Ethyl formate have been shown to have effectiveness short exposure time(<4hr) but it has a limited application at low temperature for TSM(Two spotted spider mites) due to some phytotoxic to strawberry. Phosphine gas has demonstrated their efficacy to TSM at low temperature but only meets quarantine requirement when applying longer fumigation time(>24hr) to control CA(cotton aphids). We firstly evaluated two MB alternatives, EF and PH3, have enhansive effect within short exposure time(4hr) at low temperature(5℃) for controlling both TSM and CA without any injury to export strawberries.

In terms of aphid species identification, both host plant association and morphological characteristics are crucial factors. However, aphids in the genus Aphis Linnaeus (Hemiptera: Aphididae) often are cryptic in morphology due to their rapid radiation. Moreover, overlapping host plant species can make difficult situation worse. Three cryptic species Aphis gossypii Glover, Aphis glycines Matsumura, and Aphis rhamnicola sp. nov. occur together on the Buckthorn, Rhamnus spp. in the overwintering season in Korea. Due to lacking informative morphological characters and host plant sharing, the new species recently has been recognized as a distinct species. In this study, A. rhamnicola sp. nov. on various host plants was compared with the primary host sharing species, A. gossypii and A. glycines, based on morphological and molecular characteristics. In the results, there were significant genetic differences between three species, despite the high similarities in morphology. Our results provide strong evidence for establishing new species, which seems to be a typical heteroecious species that alternates between only primary host, Rhamnus spp., and various secondary hosts. We describe a new species, A. rhamnicola sp. nov., for apterous and alate vivipara, fundatrix, ovipara, and gynopara, including diagnostic key for host sharing species in genus Aphis.

The cotton aphid, Aphis gossypii Glover is an important sap-sucking pest of many pant, including cucumber and pepper. The objective of the present study was to determine the effects of sublethal concentrations of two insecticides (imidacloprid and flonicamid) and the action mechanisms on the feeding behavior of A. gossypii. The median lethal concentrations (LC50) of imidacloprid and flonicamid for adult A. gossypii were 2.01 and 1.92 ppm, respectively. The sublethal concentrations of imidacloprid were 0.22 ppm (LC10) and 0.82 ppm (LC30), and those of flonicamid were 0.094 ppm (LC10) and 0.56 ppm (LC30). The developmental period of A. gossypii nymphs at LC30 was 3.6 days for both insecticide which shorter than controls (4.2 days). Adult longevities at LC10 and LC30 of imidacloprid were 15.2 and 13.6 days, respectively. Adult longevity at LC10 and LC30 of flonicamid was 11.1 and 9.9 days, respectively. Control adult longevity was 15.5 days. Total fecundity was decreased at both sublethal concentration of two insecticides. Feeding behavior analysis using an electrical penetration graph showed that sublethal doses of imidacloprid and flonicamid had significant effects on the duration of phloem ingestion. However, higher doses of flonicamid induced starvation by inhibition of phloem ingestion and higher doses of imidacloprid induced contact toxicity rather than inhibition of feeding behavior.

The cotton aphid, Aphis gossypii (Glover), is one of the most serious pest in seed potato and various vegetable cultivation. The imidacloprid-resistant strain (IR) was over 300-fold more resistant to imidacloprid compared to a susceptible strain (S) as judged by LC50 values. A highly imidacloprid-resistant local field population (L) was collected from cucumber at Gangwha island in 4th August 2011. Even though neonicotinoid insecticides especially imidacloprid were sprayed six times during June and July, aphid density was too high to be counted. To identify differentially expressed genes in IR or L, comparative transcriptome analyses based on GS-FLX were conducted using total RNAs extracted from IR, L and S strains. Futhermore, to search the resistance associated proteins in IR or L, comparative proteome analyses based on 2DE were conducted using total proteins extracted from IR, L and S strains. Few common candidate genes detected among IR and L such as ABC genes. Comparison of the nucleotide sequence of six nicotinic acetylcholine receptor (nAChR) subunit (alpha 1-5, beta 1) genes from IR, L and S strain revealed a point mutation in the loop D region of the nAChR beta 1 subunit of the IR, causing an arginine to threonine substitution (R81T). These mechanisms also reported in Myzus persicae and this amino acid change confers a vertebrate-like character to the insect nAChR and results in reduced sensitivity to neonicotinoids.

Many polyphagous herbivore insects considered as a single species are indeed comprised of genetically differentiated host related races that utilize several unrelated plant families. Aphis gossypii Glover, one of the extremely polyphagous aphid species, has more than 100 host plants distributed worldwide. In Korea, it takes holocyclic life cycle, with a number of primary hosts, which is unusual for other aphid species. However, former population genetic studies on A. gossypii have dealt with the populations from only a few agricultural host plants. In this study, we hypothesized that different primary host utilization may be restricted for certain host races and this may play a key role of the genetic differentiation in this species. We collected the cotten aphid populations from 36 different host plants, 5 primary and 31 secondary hosts including various wild and non-cultivated plants. To determine population genetic structure, we analyzed genetic differentiation among those populations using 9 microsatellite loci. As results, four genetically distinct clusters were verified. Of the five primary host populations, there were significant gaps in genetic differences between Rhamnus-associated group and Hibiscus-associated group, and the other populations were affinitive with the Hibiscus-associated group. Overall, primary host populations have a higher level of genetic diversity than secondary host populations. Several populations associated with secondary hosts such as spiderwort, madder, and Korean lettuce were considerably differentiated in the result of principle component analysis, which nearly showed the species level difference similar to Aphis glycines Matsumura and Aphis sp. ex Rhamnus. Thus, there could be reproductively isolated by the loss of primary hosts, and might be already speciated from A. gossypii

The cotton aphid, Aphis gossypii (Glover), is one of the most serious pest in the cultivation of various vegetables. A highly imidacloprid-resistant field population (CA-L) was collected from cucumber at Gangwha island in 4th August 2011. Even though neonicotinoid insecticides especially imidacloprid were sprayed six times during June and July, aphid density was too high to be counted. IEF and 2DE analyses revealed that general esterase isozyme (pI. 5) in CA-L were dramatically overexpressed and more isozyme spots identified in CA-L compared to susceptible (CA-S) strain. To identify differentially expressed genes in CA-L, comparative transcriptome analyses based on GS-FLX were conducted with total RNA extracted from CA-L, which generated ca. 143 Mb reads. Previously reported, comparative transcriptome analyses performed in imidacloprid resistant (CA-IR) and CA-S. The comparative transcriptome analyses re-investigated after all data sets were combined together. As previously reported, seven ATP-binding cassette (ABC) transporter genes were newly identified in A. gossypii, among which only ABCC9 gene was highly expressed in CA-IR and L. These results suggested that ABCC subfamily associated with imidacloprid resistance in A. gossypii.

After pea aphid Acyrthosiphon pisum genome project, hologenome concept was applied to pea aphid and symbioant such as Buchnera aphidicola. Here we screened symbiotic microorganism in four lab strains (two genetically different insecticide susceptible strains, host plant: cucumber and two different host adopted imiacloprid resistance strains, host plants: cucumber and potato) and four field populations (Jeju, Goryeong, Gimjae and Muju, host plant: potato) of cotton aphid based on GS-FLX pyrosequencing which were conducted with universal primer amplified partial fragments of 16S rRNA from total DNA which was extracted from each strain and population. B. aphidicola occupied over 90% of all identified prokaryotic microorganisms which all tested samples. It’s interesting that the ratio of B. aphidicola occupied over 99% in all of the tested lab strains. However, specific enterobacteriaceae occupied six to seven percents of all field populations which closely related endosymbiont of Glycaspis brimblecombei. That means B. aphidicola occupied only 91~92% of all identified prokaryotic microorganisms. Futhermore, other actinobacteridae and bacillaceae also were detected in field populations. The results obtained for these ratios suggested that there has some interaction between symbioant and environment NOT in imidacloprid resistance.