• Korean journal of applied entomology
• /
• v.58 no.3
• /
• pp.233-238
• /
• 2019

For greenhouse crops, thrips is one of the major insect pests, but its control is difficult owing to short generation time, rapid escaping behavior, and development of pesticide resistance. Stratiolaelaps scimitus (Womersley) is a soil-dwelling predatory mite attacking various soil invertebrate species, including thrips. Using the method by growers' self-production, we mass-reared S. scimitus colony and investigated thrips control in the greenhouse chrysanthemum. The initial density of thrips was six individuals/flower. The treatment with one S. scimitus box in the greenhouse was estimated to be $1,000individuals/m^2$. From August to September 2018, the greenhouse was released with a total of 10 boxes of S. scimitus. The density of thrips in the untreated and the treated cultivar was $53.7{\pm}7.0$ and $13.5{\pm}1.7$ on the late September, respectively, which indicated a reduction of 74.9% in the treated cultivar. Our results suggest that S. scimitus was highly effective for the control of thrips in the greenhouse chrysanthemum although temperature is very high during the summer season.

• Korean Journal of Organic Agriculture
• /
• v.26 no.4
• /
• pp.707-717
• /
• 2018

The acaricidal activity of extracts of Gleditsia japonica var. koraiensis, Camellia sinensis, Cinnamomum cassia, Lantana camara and their mixtures against the tea red spider mite, Tetranychus kanzawai was evaluated. Treatments with mixtures 3 and 1 were effective against the adult females of T. kanzawai and yielded 82.0% and 77.3% adulticidal activities at 7 days after treatment, respectively. Treatment with mixture 2 revealed 68.0% adulticidal activity. Generally, the acaricidal activity of the single treatment of each plant extract was lower than the mixtures. The adult females of T. kanzawai treated with mixtures 3 and 1 produced only 24.0~29.6% as many eggs as control females did. The residue of the plant extracts tested had low adulticidal activity (16.7~31.3% at 7 days after treatment). All the plant extracts tested exhibited no remarkable toxic effect to the eggs of T. kanzawai. Treatments of mixtures 3 and 1 were effective against nymphs of T. kanzawai and led to emergence rates of 16.7 and 22.0%, respectively. These results suggest that mixtures 3 and 1 might be used for the control of T. kanzawai in tea fields.

• Korean journal of applied entomology
• /
• v.57 no.4
• /
• pp.253-260
• /
• 2018

A mass-rearing method for a soil-dwelling predatory mite Stratiolaelaps scimitus (Womersley) was developed using the double box system. The rearing box consists of two, outer (22 L, $54{\times}36{\times}18cm^3$) and inner (6.5 L, $31{\times}22{\times}11cm^3$), plastic boxes. Inner box was filled with chaff (rice husks) which is used as the shelter of the predatory mites. Outer box contained 1 L of water and the inner box, then covered with a lid. This system prevents the predatory mites from escaping as well as keeping moisture of the shelter. In addition, Tyrophagus putrescentiae (Schrank), as prey mites of S. scimitus, was reared on the rice bran as a food source using the same double box system. The both mites were reared at $25{\pm}1^{\circ}C$, $60{\pm}10%$ relative humidity condition. The prey mites were provided once a week. The density of predatory mites increased three times for four weeks and the final population was approximately 120,000 individuals/box (4 L). This is a simple mass-raring technique of S. scimitus and helpful for the biological control of soil pests.

• Korean journal of applied entomology
• /
• v.59 no.4
• /
• pp.421-425
• /
• 2020

We investigated an ecologically-sensitive method to control Polyphagotarsonemus latus in a green perilla polyvinyl house using concentrated pyrethrum. The survival rates of Polyphagotarsonemus latus nymphs and adults to 2%, 4%, and 6% pyrethrum 3 days after spraying were 58.1%, 27.5%, and 22.7% respectively, and 73.4%, 37.3%, and 30.6% at 5 days after spraying. These results show that the most effective control occurred using 6% pyrethrum. To investigating the densities of P. latus on a 1 cm diameter leaf-disk of green perilla, we sprayed the leaf every 10 days from May 10 with 6% pyrethrum 1,000 times and milbemectin EC 2% 1,000 times. The period chosen was one where the incidence of P. latus could be predicted. The density was kept low during the treatment period. However, if leaf damage had already occurred from P. latus, the density could not be decreased by spraying 1 or 2 times each week where milbemectin EC 2% was used, but the population could be reduced when sprayed 3 times. Therefore, in order to effectively control P. latus in green perilla greenhouses, it is important to begin treatment at an early stage when P. latus are first observed.

• Parasites, Hosts and Diseases
• /
• v.59 no.6
• /
• pp.625-634
• /
• 2021

Based on the field investigations in 91 investigation sites (counties) in southwest China between 2001 and 2019, the present paper reported the chigger mites on A. agrarius mice in southwest China for the first time by using a series of statistical methods. From 715 striped field mice captured in 28 of 91 investigated sites, only 255 chiggers were collected, and they were identified as 14 species, 6 genera in 3 subfamilies under 2 families. Of 715 A. agrarius mice, only 24 of them were infested with chigger mites with low overall prevalence (P_M=3.4%), overall mean abundance (M_A=0.36 mites/host) and overall mean intensity (M_I=10.63 mites/host). The species diversity and infestation of chiggers on A. agrarius were much lower than those previously reported on some other rodents in southwest China. On a certain species of rodent, A. agrarius mouse in southwest China seems to have a very low susceptibility to chigger infestations than in other geographical regions. Of 14 chigger species, there were 3 dominant species, Leptotrombidium sialkotense, L. rupestre and Schoengastiella novoconfuciana, which were of aggregated distribution among different individuals of A. agrarius hosts. L. sialkotense, one of 6 main vectors of scrub typhus in China, was the first dominant on A. agrarius. The species similarity of chigger mites on male and female hosts was low with C_SS=0.25, and this reflects the sex-bias of different genders of A. agrarius mice in harboring different chigger species.

• Korean journal of applied entomology
• /
• v.61 no.1
• /
• pp.255-266
• /
• 2022

This study was conducted to examine the effects of grass vegetation (W: manual weeding, NW: herbicide sprays) and pyrethroid spray (P: pyrethroid spray, NP: no pyrethroid spray) on the population dynamics of Panonychus citri and natural enemies in citrus orchards. Two essential hypothesis were made to test the population dynamics: 1) weed planting promotes natural enemies by offering habitat and alternative food sources, resulting in the reduction of P. citri populations, and 2) pyrethroid spray removes natural enemies by its non-selective toxicity, resulting in the increasement of P. citri populations. The observed natural enemy populations (mainly Phytoseiids and Agistemus sp.) were not different largely from the expected values in the hypothesis, which assumes more abundant natural enemies in weeds and no pyrethroid plots. Although some discrepancy was occurred in NW+NP and W+NP plots in 2011, the observed values were almost same with expected values in 2012. In overall, pesticide effect was strongly significant and pyrthroids removed largely natural enemies. Although habitat (weeds) effect showed a conflict result, natural enemy population increased in plots allowing weed growth, when considering the increased autumn population relatively compared to that of spring-summer population. The decreased abnormal P. citri populations in pyrethroid plots could be explained under the assumption of a strong repellent behavior of P. citri to the pyrethroids.

• Korean Journal of Environment and Ecology
• /
• v.21 no.6
• /
• pp.536-543
• /
• 2007

This research was conducted every month from June 1994 until August 1996 with the aim to understand the ecosystem structure through the analysis of oribatid mite community structure in soil subsequent to environmental difference of its habitats located at northward & southward slopes adjacent to each other at an altitude of 1,000 meters of Mt.Jumbong, which is a natural reserved forest, remaining intact. There appeared a significant difference [t-test, p<0.06] in comparison of the number of the species and individuals of Oribatid mite species which were collected and identified at two survey areas. The mean density and the number of the species collected and identified at the northward slopes, and southward slopes were $99.2{\pm}17.6,\;234.2{\pm}62.6$ and $24.7{\pm}3.0,\;40.8{\pm}5.8$, respectively. Species diversity index(H') was higher at the southward slopes($3.09{\pm}0.11$) than at the northward slopes($2.71{\pm}0.13$). The population size of Oribatid mite species was found by the percentage of each species density as against the whole density and classified into dominant species, influent species, and recessive species according to the percentage; as a result, O. nova and Suctobelbella naginata was found to be a dominant species at both survey slopes while Trichogalumna nipponica was found to be a dominant species, at southward but it wasn't collected at the northward slopes at all. The feeding habit of the dominant species at two survey slopes was found to be microphytophagous- eating soil microbe. There appeared a conspicuous difference in compositions of the number of the species, individuals and dominant species at the southward/northward slopes adjoining each other at an attitude of 1,000 meters and less similarity between the two survey slopes. Conclusively, It was found that the heterogeneity of microhabitat has a great effect on Oribatid mite's community characteristics.

• Journal of Mushroom
• /
• v.10 no.4
• /
• pp.184-190
• /
• 2012

Monitorings and management experiment of adult Lycoriella ingenua (Diptera: Sciaridae) in artificial sawdust grown shiitake mushroom cultivation were carried out by using yellow sticky traps and Hypoaspis aculeifer (Acari: Laelapidae) at Hwaseong, Buyeo and Cheongwon in 2012. The larvae of L. ingenua reduced commercial value of the mushroom by direct eating or retarding the growth of mushroom by spongifying the sawdust medium. The number of L. ingenua caught by traps showed the highest peak in late september resulting in 127.5~1,025.7, 87.4~743.6 and 133.7~650.4 individuals per trap in Hwaseong, Buyeo and Cheongwon, respectively. Damage rate of fruiting bodies in shiitake mushroom by L. ingenua were 7.7~30.3% in Hwaseong, 6.7~25.3% in Buyeo and 5.3~26.0% in Cheongwon and showed the highest peak in late september. L. ingenua were effectively controlled when 30.3 individuals of H. aculeifer per $m^2$ inoculated for three time with 7 to 14 days of interval. In Hwaseong, Buyeo and Cheongwon, density of L. ingenua which were caught on the yellow sticky traps were 168.2, 126.1, 132.5 individuals, respectively. And, damage rate of fruiting bodies by L. ingenua were 5.9%, 5.5% and 5.4% respectively. Both of the L. ingenua density and damage rate of mushroom reduced more than 60% in all experimental site in contrast to the control treatment.

• Korean Journal of Environmental Agriculture
• /
• v.28 no.2
• /
• pp.125-130
• /
• 2009

The aim of this study was to investigate whether differences in the distribution of soil invertebrates among different vegetation types (forest, reservoir, and crop land types) in rural area. A total of 18 orders and 137 species were collected by pitfall traps. Species numbers were the lowest (33 species) at the Chamaecyparis obtusa plantation (St. 6). On the forest sites, the individual number of Hymenoptera was the most abundant, and Acari and Coleoptera was the relatively more abundant than the other sites. On the reservoir sites (Salix chaenomeloides community), the individual number of Collembola was the most abundant, and Diptera was the relatively more abundant than the other sites. On the crop land sites, the individual numbers of Collembola, Hymenoptera, and Araneae were the relatively more abundant than the other orders. The density of Araneae was higher in the reservoir and crop land sites than in the forest sites. From a point of view of biodiversity, although the diversity index(H') was the highest in the mixed broad-leaved forest type (St. 2) with Quercus serrata and Q. acutissima, and the lowest in the upland levee of crop land(St. 11), there was no significant difference among the habitat or vegetation types. According to the community analysis, the soil invertebrates could be divided into 4 groups, the mixed broad-leaved forest type (A group), the plantation or pure forest type (B group), the reservoir type (C group), and the crop land type (D group).

• Korean journal of applied entomology
• /
• v.50 no.3
• /
• pp.235-245
• /
• 2011

Temperature-related parameters of Panonychus citri (McGregor) (Acarina: Tetranychidae) development were estimated and a stage-structured matrix model was developed. The lower threshold temperatures were estimated as $8.4^{\circ}C$ for eggs, $9.9^{\circ}C$ for larvae, $9.2^{\circ}C$ for protonymphs, and $10.9^{\circ}C$ for deutonymphs. Thermal constants were 113.6, 29.1, 29.8, and 33.4 degree days for eggs, larvae, protonymphs, and deutonymphs, respectively. Non-linear development models were established for each stage of P. citri. In addition, temperature-dependent total fecundity, age-specific oviposition rate, and age-specific survival rate models were developed for the construction of an oviposition model. P. citri age was categorized into five stages to construct a matrix model: eggs, larvae, protonymphs, deutonymphs and adults. For the elements in the projection matrix, transition probabilities from an age class to the next age class or the probabilities of remaining in an age class were obtained from development rate function of each stage (age classes). Also, the fecundity coefficients of adult population were expressed as the products of adult longevity completion rate (1/longevity) by temperature-dependent total fecundity. To evaluate the predictability of the matrix model, model outputs were compared with actual field data in a cool early season and hot mid to late season in 2004. The model outputs closely matched the actual field patterns within 30 d after the model was run in both the early and mid to late seasons. Therefore, the developed matrix model can be used to estimate the population density of P. citri for a period of 30 d in citrus orchards.