Among several insect pests in the potato fields, Liriomyza huidobrensis, pea leafminer, is emerging as a new threat to potato plants. Adult females damage the host mesophyll cells host due to ovipositor probing. After egg hatching, the eclosing larva also damage the leaf by mining the mesophyll and causing tissue death. Despite the importance of leafminer in potato production, there is no information available regarding its resistance level to potato cultivars in Korea. Using choice test, 21 potato cultivars consisting of 11 early-maturing, 6 mid-maturing and 4 late-maturing cultivars were evaluated the resistance to pea leafminer in the greenhouse and field condition. In this test, significant differences for resistance were observed. High levels of resistance to leafminers were obtained from cvs. Namsuh, Seohong, Jayoung and Superior. These resistant cultivars might be useful in future breeding programmes.

The pea leafminer fly, Liriomyza huidobrensis Blanchard (Diptera: Agromyzidae), is an emerging pest in Korea. High population and heavy damage of this pest were observed from potato fields in the southern part of Korea in 2012. Morphological and genetic evidence confirmed the species as L. huidobrensis. The infestation was expanding throughout the country and a rich complex of parasitoid was recognized. From the exclusion study, high density infestation of leafminers reduced yield among potato varieties (Chubeak, Seohong, Goun, Dejima, and Sumi). Higher leaf damage was evident in the lower part of plants. In olfactory bioassay and feeding preference tests, leafminers choosed the Goun variety most. Given the six constant temperatures, the developmental time from egg to adult significantly decreased with increment of temperatures. From the insecticide toxicity tests, abamectin and lepimectin and spinetoram were found effective against immature stages, while cartap hydrochlorid (Neonicotinoid) was against adult insects. Overall, these studies help to pave the ways for managing this new invasive pest.

Liriomyza leafminer flies comprise a pest group that causes both considerable economic losses and serious quarantine problems. To investigate Liriomyza spp. abundance and distribution along with natural enemies, we surveyed of leafminer (LM) species and its natural enemies (NE) on potato crop from 146 farmers’ field in the potato growing provinces during 2015. Sweeping (10 sweeps/ field) and visual inspection were employed within 5 minute-walking distance, and damaged leaflets (10 leaflets/ field) were collected in each field. Leafminer species were identified by morphological, and its NE was identified by morphological and molecular techniques. L. huidobrensis was the most dominant Liriomyza species. Distribution of L. huidobrensis on potato fields was expanding. Highest potato fields were infested with leafminer in southern parts of country. Highest rate (100%) field damage was recorded in Miryang, Namwon, Henam, and Boseong. Overall, NE species collected constituted of 4 families and 18 and 20 species in sweeping, and damaged samples respectively. There was a rich complex of parasitoid species including 20 species (13 species of Eulophidae family). The endoparasitoid, Braconid sp., Ganaspidium sp., and ectoparasitoid, Diglyphus isaea were dominant species in sweeping. While Diglyphus isaea, Hemiptarsenus varicornis, and the Braconid sp. were most dominant species collected from damaged samples. The number and diversity of parasitoid species in potato crop in Korea provides insight into the development of integrated control strategies of invasive LM pests in the field, and glasshouse crops.

To assess actual foliage damage due to potato leaf miner, Liriomyza huidobrensis (Blanchard), commercial potato pockets of Lalitpur, Kathmandu, Bhaktapur, Kavrepalanchwok, Sindhupalchwok and Makwanpur districts of Mid-Nepal were surveyed in 2009. Percent foliage damage analysis and ANOVA (with unbalanced frequency distribution) of multiple regressions of different factors were done to evaluate the level of damage and factors significantly influencing damage. Damage level was found more in lower altitudes (790-1568 meters above sea level) than in higher altitudes (1560-2610 meters above sea level). Similarly, lower leaves were more damaged than the upper ones. So, altitude and plant age were two factors influencing damage by test insect. Since the pest is becoming severe and can withstand chemical sprays, it is imperative to develop suitable IPM technique against this insect. Similarly, strict quarantine and awareness campaign against this insect pest are crucial to check its migration to virgin potato pockets.

The pea leafminer fly, Liriomyza huidobrensis (Blanchard) (Diptera: Agromyzidae), is a polyphagous pest attacking wide range of field and greenhouse crops and ornamental plants. Surprisingly, localized outbreaks with high population and heavy unique damage of leafminers were observed from the field survey of potato fields in the southern parts (Miryand and Goryeong) of Korea in 2012. L. huidobrensis was the responsible for those potato damages based on the morphological and genetic characteristics. Then after, it added a one more emerging species in Korean Liriomyza account. Infestation of L. huidobrensis was expanding and reported in major potato growing areas of the country. Genetic evidence showed the close relationship with Chinese L. huidobrensis population, so it might be invaded from China. As a new emerging pest, very few informations relative to this pest are available in Korean prospective. There is also significant potential for it to widen its distribution, as the Korean Peninsula is a hot spot of climate change, particularly global warming. There are a lot of challenges uprooting infront of researchers and growers. It is demanded to explore new secrets and to be ready to tackle of this invasive pest, L. huidobrensis.

The development of Liriomyza huidobrensis (Blanchard), an economic pest of wide range of field crops and ornamental plants, was studied under laboratory conditions at six constant temperatures (10, 15, 20, 25, 27 and 30oC). The total development period decreased with increasing temperatures between 15 and 27oC. In 10oC, eggs did not hatch and in 30oC, pupa did not survive. So, it may be assumed that these temperatures fall outside the development. Linear regression was used to describe the relationship between development rate and temperature. For total immature development (egg to adult) required 250 degree-days (DD) above the threshold of 9.75oC. The developmental data were fitted to a nonlinear temperature-dependent model (Lactin-1) for best described of development. Development rates of males and females did not differ in 20 and 25oC. High immature mortality was recorded in 27oC. Sex ratio of the surviving individuals was 0.62 from this study. Thermal requirements and temperature thresholds can be used to forecast the occurrence, number of generations and population dynamics of L. huidobrensis.

Liriomyza leafminer flies comprise a pest group that causes both considerable economic losses and serious quarantine problems. We reported for the first time of the infestation of field crops by this invasive leafminer L. huidobrensis in Korea in 2012. Distribution survey of leafminer flies and other insect pests on potato crops along with associated natural enemies was conducted from 378 farmers' field in most of the potato growing provinces during 2011, 2012 and 2013. Sweeping (10 sweeps/field) and visual inspection were employed within 5 minute-walking distance each field. For damage rate was also calculated for each field. Ten mined leaflets were investigated for parasitoid species identification. Leafminer flies were identified by morphologically and molecular. However, parasitoid species were only morphologically identified. All the leafminer flies collected were identified as L. huidobrensis. No leafminer flies infested fields were recorded in Boseong (Jeollanam-do) in 2011. L. huidobrensis infested fields with unique crop damage symptoms were found only in Miryang and Goryeong (Gyeongsangnam-do) in 2012. There was significant different in leafminer infested fields among the surveyed locations in 2012 (f=85.73, df=5, 127, P<0.0001). Higher damaged (100%) potato fields were recorded in Miryang. Similarly, the leafminer infested potato fields were significantly different among the surveyed locations in 2013 (f=36.77, df=19, 201, P<0.0001). Highest damaged rates (100%) were recorded in all the surveyed locations of Gyeongsangnam-do. Increasing distribution expansion pattern of L. huidobrensis was found. Distribution covers from southern parts to northern parts of the country. The study on rate of distribution and factors responsible in rapid distribution of L. huidobrensis in Korea are demanded.

Liriomyza species are the major pests of greenhouse and field crops. It was as minor pests in past, but the pest population increased rapidly such as L. trifolii, L. huidobresnsis and L. sativae during recent years is attributed to application of ineffective insecticides and developed insecticide resistance. This study was carried out to determine the efficacy of insecticides groups, Anthranilic diamide, Biopesticide, Carbamate, Neonicotinoid, Organophosphate, Pyrethroid and Oxadiazine, recommended for the control of leafminer species in Korea. Bioassay tests were done on first, third larval stages and adults under glasshouse and laboratory conditions respectively. The result showed significant differences in toxicity among the tested insecticides. The mortality of abamectin and lepimectin and spinosad were higher (>50%) in larvae stages. Etofenprox insecticide was not effective on larvae stage. The toxicity of Cartap hydrochlorid (Neonicotinoid) was higher (100%) in adult insects, followed by thiamethoxam, etofenprox and indoxacarb. Abamectin and lepimectin showed the decreasing toxicity level as insect stage developed. Abamectin showed least toxicity (26.67%) in adult stage. Spinetoram and emamectin benzoate showed higher toxicity (>50%) in all the insect stages tested. It could be suggested that abmectin and lepimectin have high efficiencies on control of larvae. However, spinosad and emamectin benzoate has higher potential on the control of both larvae and adult insects.

The potato leafminer fly, Liriomyza huidobrensis (Blanchard) (Diptera: Agromyzidae) is a polyphagous pest attacking many vegetables and ornamental plants. We found L. huidobrensis were infesting potato crop in Miryang and Goreyong in 2011. Five potato (Solanum tuberosum) varieties (Ghowun, Daeri, Sumi, Chubeak, and Seohong) were tested for the preference of L. huidobrensis. In the olfactormeter bioassay, leafminers chose the Ghowun variety most (55%) followed by Sumi (18%). Remaining 3 varieties were chosen less than 10%. When leafminers choose and move toward the preferred variety, movement speed was faster. In the plant choice test in the laboratory, as expected, Ghowon was the most chosen but the choice of the other 4 varieties was not different. The same pattern as found in the plant choice test conducted in the greenhouse. Feeding frequency was the highest in Ghowun variety followed by Sumi > Daeri = Seohong > Chubaek in the laboratory test but Ghowun > Sumi > Chubaek > Daeri = Seohong in greenhouse test. When measured in 2 weeks after release, plant damage rates and number of mines were in congruence to the preference results. Further study is needed to clarity the factor responsible for the choice of the plants and also the ways to manage this new pest.

Liriomyza leafminers comprise a pest group that causes both considerable economic losses and serious quarantine problems. In recent years, the pest status of Liriomyza sp. has changed in Korea, as well as other areas of the world. Potato field survey was conducted in 157 farmers’ field from five provinces during 2011 and 2012. Foliar insect monitoring was done within 5 minutes walking distance by visual inspection. Leafminer fly and parasitoids were collected by sweeping net (10 sweeps/field) in same field in each time. Overall, potato insect species collected constituted of 7 orders, 22 families and 42 species. Aphis gossypii was most abundant species in all the locations. However, Potato tuber moth, Pthorimaea operculella was only dominated species in Boesong (Jellanam-do). L. huidobrensis was the first record infesting the potato in Korea. Liriomyza huidobrensis was only found from Miryang (Gyeongsangnam-do) and Goreyong (Gyeongsangbuk-do). There is a rich complex of parasitoid species; 18 species of parasitoids were recorded. Most parasitoid species (11) belong to the Eulophidae family. The most abundant species were the ectoparasitoid, Diglyphus isaea and endoparasitoid, Ganaspidiumsp. The number and diversity of parasitoid species in potato crop in Korea provides insight into the development of integrated management strategies of leafminer pests.