세계적인 침입해충 담배가루이 (Bemisia tabaci Gennadius)의 한국 계통과 중국 계통의 유연관계를 알아보기 위하여 2019년에 채집한 두 계통들의 biotype 분포, 살충제 반응, 바이러스 보독율을 조사하고 차이를 분석하였다. 미토콘드리아 COI 유전자 서열을 이용하여 집단 분석한 결과 국내는 모든 지역계통에서 Q biotype만 발견되었으며, 중국은 B biotype (14.3%)과 Q biotype (85.7%)이 동시에 발견되었다. 담배가루이 Q biotype의 haplotpye 구성도 중국은 모두 Q1 그룹만 관찰되었고 Q1H1 (79.8%), Q1H2 (20.2%)로 구성되어 있었으며, 한국은 Q1이 우세한 가운 데 Q2도 관찰되었으며 Q1 그룹의 구성도 Q1H1 (1.7%), Q1H2 (97.5%)로 중국과는 크게 달랐다. 15종 살충제에 대한 약제반응은 국내 계통은 일부 약제를 제외하고 대부분 약제에서 충분한 살충력 (mortality≥80%)을 보여주었으나 중국 계통은 40% 이하의 살충력을 보인 약제들이 다수 있었으며 한국보다는 높은 저항성을 갖고 있었다. 토마토 황화잎말림바이러스 (TYLCV)의 보독율은 국내 계통에서는 발견되지 않았으며 중국의 경우 0∼60% (평균 21.4%) 가 발견되었다. 따라서 한국와 중국의 담배가루이 계통 간에는 유전적 조성과 살충제 반응, 바이러스 보독율에 있어서 큰 차이를 보여주었으며 양국의 담배가루이가 서로 다른 유입 패턴을 갖고 있음을 알 수 있었다.

Bemisia tabaci biotype Q in China (Shandong) orginated from the western Mediterrenean regions. B. tabaci biotype Q was introduced into Shandong province of China in 2006 and has since displaced the previous well-established population of biotype B in the whole province. The populations of B. tabaci biotype Q in the field have a rapid genetic turnover. These findings will be helpful to the management of whitefly populations in the field.

This present study aimed at invasion process, cataleptic mechanism and monitoring basis of Bemisia tabaci biotype Q species. The main content are as follows: (1) The introduction of Bemisia tabaci biotype Q species into China was discovered for the first time. The fixed-point monitoring for 10 years indicated the invasion, formation, expansion and eruption process of BBemisia tabaci biotype Q species in China. (2) The rapid genetic evolution and the basis of ecological adaptability were emphasized from the level of individual/group. The ecological elements and mechanism influencing competitive advantage translocation of the biotype B/Q species were analyzed from the level of the relationship among the species. The synergistic and interactional effect between the biotype Q species and biological factor were also analyzed from the level of the community/system. (3) The quick and new technology to detect and monitor biotype Q species and the damages and variation of population were established, significant damages controlling methods using insecticide agent and RNA interference were also studied.

The tobacco whiteflies, Bemesia tabaci, infest the Oriental melon and give significant economic damage along with its virus-vectoring activity. Various biotypes of B. tabaci have been well known and are classified depending on the severity of crop damage and insecticide susceptibility. B. tabaci adults were collected in the melon fields and diagnosed with PCR molecular markers. In all 11 sampling sites, B. tabaci adults were diagnosed to be Q biotype. In contrast, B biotype was found in one sampling site. These results indicated that most B. tabaci occurring the Oriental melon fields in Andong is Q biotype.

Recently, the Q biotype of tobacco whitefly has been recognized as the most hazardous strain of worldwide because of increased resistance to some insecticide groups requiring alternative strategies for its control. We studied the susceptibility of this biotype of B. tabaci to 21 isolates of Beauveria bassiana, 3 isolates of Isaria spp., 1 isolate of P. cateni，3 isolates of Lecanicillium lecanii, 1 isolate of L. attenuatum and 1 isolate of Aschersonia aleyrodes. These isolates were evaluated on pruned egg plant seedlings, at a concentration of 108conidia/ml (deposited at 6000±586 conidia mm-2). The mortality based on mycosis varied from 18 to 97% after 6 days. An Isaria sp. isolate, two B. bassiana isolates and a L. lecanii isolate were found the most effective. Furthermore, five isolates were chosen for concentration-mortality response assays and compared to B. bassiana GHA as a standard. The numbers of nymphs infected by fungi were correlated with the spore concentration. A L. lecanii isolate and Isaria sp. had the short LT50 at 6000±586 conidia mm-2. Mortality reduced and LT50s were longer as the concentration of conidia was reduced. The LD50 values were differed in isolates from 87 to 269 conidia mm-2. These results indicated that the Q biotype of sweetpotato whitefly was susceptible to the five isolates of entomopathogenic fungi and these isolates have potential to be developed as a microbial pesticide for whitefly control.

In the previous study, the plant essential oils such as clove bud , thyme white and garlic oils gave potent toxicity with the range of 1.5 to 4.5×10-3 ul cm-3 of LC50 values against Bemisia tabaci. Based on the bio-assay results, three plant essential oils(clove bud, thyme white and garlic) were applied to 30% emulsion type. The 100, 200 and 400 fold dilution of these emulsions was showed mild toxicity under port scale treatment against Q biotype. At each fold dilution, clove bud showed 44, 26 and 14%, and thyme white produced 44, 39 and 27%, respectively. Of garlic emulsion, its toxicity was evaluated with 27, 26 and 11%, respectively. But, in case of clove bud and thyme white mixture, their toxicity was more good under the mixture than under the single treatment. Mixture with clove bud 200 fold dilution adding to thyme white 200 fold dilution showed potent activity with 86% mortality. And also 200 adding to 400, and 400 to 400 exhibited 61%, 76%, respectively. These essential oil mixtures showed similar strong toxicity against B biotype under port scale test. In particular, the mixture with clove bud 200 fold dilution adding to thyme white 200 fold dilution showed the highest synergistic effect. Toxicity to plants, except the 100 fold dilution of these emulsions was not observed.

Nymphal development of the B and Q biotypes of Bemisia tabaci was normal on all seven tomato varieties tested. However, their nymphal development was different on red pepper varieties. B biotype was not normally developed on nine red pepper varieties tested. On the contrary, Q biotype was normally developed, but its adult emergence rate was very low in Nokkwang variety than in other eight varieties. The EPG analysis of the feeding behavior of Bemisia tabaci showed that B and Q biotypes had different duration of phloem phases on red pepper. Q biotype showed longer phloem phases than B biotype. On Nokkwang variety, Q biotype had short phloem phases and did not prefer to feed on Nokkwang variety. Interestingly, Q biotype was found to have long duration of phloem phases on eight red pepper varieties, but B biotype did not prefer to feed on red pepper varieties. However, both biotypes did not show any difference in feeding time on tomato varieties.

Identifying effective chemical control agents of Bemisia tabaci biotype B and Q is an important step toward IPM strategy. Until 2008, only 10 chemical agents were registered for B. tabaci. From the laboratory screening of 60 insect- and acaricides, 18 chemicals for egg, 10 for nymph and 8 for adult stage were found effective (>90% mortality). Also ten chemicals were less toxic to B. tabaci. Among ten chemicals, some conventional insecticides need further careful resistance monitoring. Field trials with some of the selected chemicals open the possibility to chemical control of B. tabaci biotype Q. Further consideration of non-target effects and resistance development has to be exerted before registration process.

This study was done to evaluate the susceptibility, systemic effect, residual effect and control effect in each developmental stages of biotype Q of sweetpotato whitefly against insecticides, acetamiprid+spinetoram SC and dinotefuran SG. Two insecticides were showed similar activity against the eggs, and showed higher activity in acetamiprid+spinetoram SC against the nymph and adult. In systemic effect, two insecticides have a similar activity. It was showed higher activity in root zone systemic application than leaf zone systemic application. Residual effect was showed higher in acetamiprid+spinetoram SC (92%) than dinotefuran SG (44 %) at seven days after treatment. Control effect was showed all over 90 % activity at tree- and seven days after treatment. Therefore, these insecticides are expected to control the sweetpotato whitefly effectively.

This study was performed to investigate the feeding behavior of sweetpotato whitefly, Bemisia tabaci using the DC-EPG and the each developmental periods of biotype Q against nine varieties of red pepper. The result was showed that biotype Q did not feed and develop in the Nokkwang variety. In order to analyze the antifeedant, three feeding-preferred varieties (Cheongpungdaegun, Cheonyang, and Sannedeul) and non-preferred variety (Nokkwang) was tested for their sugar compounds using HPLC (ELSD Detector). The detected sugars were erythritol, xylose, xylitol, fructose, glucose, mannitol, and sucrose. In feeding-preferred varieties, the sugar such as erythritol, xylose, and xylitol were present at higher quantity than Nokkwang variety, however, fructose was existed lower quantity than Nokkwang variety. Subsequent bioassay for antifeedant activity, only xylitol showed repelled at lower concentration; however, attracted at higher concentration. Therefore, it is believed that xylitol may play a key role in the variety choice of red pepper by Q biotype of sweetpotato whitefly.

This study was performed to investigate the change of probing and feeding behavior of Q type of B. tabaci according to the decrease of residual effect of two insecticide, emamectin and pyridaben, using EPG technique. Examined the residual activity during 20 days, pyridaben is showed longer than emamectin benzoate. When treated two insecticides onto tomato leaves with the recommended concentration through 20 days, EPG waveforms of Q type of B. tabaci was recorded during three hours compare with the characteristic patterns of feeding behavior between two insecticides such as duration of first probing time, total duration of non-probing phase, total duration of probing phase and total duration of phloem phase. Recorded result from the change in total duration of probing activity to react the two insecticides, pyridaben was showed higher the time of probing activity, however, total duration of phloem phase was appeared low activity. Total duration of phloem phase with passage of days did not show until seven days, however, and gradually increased in emamectin benzoate after 10 days. In conclusion, residual effect between two insecticides was showed more rapidly decreased in emamectin benzoate, however, feeding behavior of Q type of B. tabaci was increased.

This study was performed to investigate the feeding behavior of Bemisia tabaci B- and Q-biotypes using EPG technique against seven tomato and eight red pepper commercial varieties. EPG waveforms was recorded during three hours compare with the characteristic patterns of feeding behaviors between two biotypes such as total duration of non-probing times, the time taken until stylet activities changed after reaction, number of probes, and total duration of phloem phase. In comparing the effect of the varieties between the two biotypes, biotype Q showed the feeding behavior against all pepper varieties in the total duration of phloem feeding. Daeshin variety has the longest feeding time. However in total duration of phloem feeding, biotype B was observed in hanyeoreumbigarim and Daeshin varieties, but feeding time was very short. Biotype B was longer in total duration of non-probing, and showed lower number of probes, and total duration of probing phase. However, biotype Q was shorter time in total duration of non-probing phase than biotype B, but showed more aggressive probing and stylet pathway pattern. These results suggest that biotype Q are more preferred the pepper host than biotype B. However, tomato varieties between the two biotypes did not show the difference.

Developmental periods of sweet potato whitefly, Bemisia tabaci(Gennaius) Q-biotype, were investigated on three host plants- sweet bell pepper (Capsicum annuum L.), eggplant(Solanum melongena L.) and oriental melon(Cucumis melo L. var. makuwa MAKINO). Egg and nymph development of B. tabaci were studied within temperature ranging of 15℃-35℃ by 2.5℃ under photoperiod 16:8(L:D). Egg period of B. tabaci was the shortest at 32.5℃ and nymphal period was shortest at 27.5℃ on sweet bell pepper. Nymphal period of B. tabaci on eggplant was the shortest at 27.5℃ as well. On the other hand, nymphal period of B. tabaci was shortest at 30℃ and 32.5℃. Lower temperature threshold and effective degree-day for completing egg development on sweet bell pepper were estimated as 13.11, 91.95, respectively. Lower threshold temperature of nymphal stage on sweet bell pepper, eggplant, oriental melon were estimated as 13.01, 13.39, 12.31,respectively. Degree-days required to complete nymphal stage on sweet bell pepper, eggplant, oriental melon were estimated as 191.22, 164.41, 190.34, respectively. The relationships between development rates of egg and nymph were well described by poikilothermal rate function and weibull function. The fitted curves will be used as input for a simulation model of the population dynamics of B. tabaci.

The feeding behaviors of 2 biotypes (type B and Q) of tobacco whitefly, Bemisia tabaci, were monitored using EPG technique on tomato and pepper plants treated 3 insecticides for controlling whiteflies, for examples, acetamiprid, spinosad and thiamethoxam. After treatment of three insecticides with recommended concentrations to tomato and pepper plants, EPG waveforms were recorded during 6 hours. The characteristic patterns of feeding behaviors investigated were as follows, time consumed by withdrawal of proboscis, total non-penetration time, total stylet pathway pattern time and total phloem feeding time. There was somewhat difference among 3 insecticides tested. As a result of investigation of total duration showed the stylet pathway activity due to the reaction against all tested insecticides, the Q biotype showed fewer time than those from the B biotype. The B biotype showed more frequent stylet pathway activity patterns during whole recording time and a shorter phloem ingestion time than those from the Q biotype. In result of prior np (non-penetration) time representing the reaction against the insecticide treated, the time of B biotype was more faster than that of the Q biotype, so it was considered that the B biotype was more sensitive to the tested insecticides. Therefore, our results revealed a clear difference in feeding behaviour between the Band Q biotypes of B. tabaci. Also, it was investigated that B biotype was susceptible to the 3 insecticides.