Evaluation of Resistance Pattern to Fenpyroximate and Pyridaben in Tetranychus Urticae collected from Ggreenhouses and Apple Orchards using Lethal Concentration-slope Relationship

This study aimed to monitor the present and future developments of the resistance of Tetranychus urticae Koch to fenpyroximate and pyridaben, using the relationship of the LC₅₀ and slope of the concentration-mortality line in a probit model, for the provision of reliable resistance management tactics. Tetranychus urticae populations were collected from 16 commercial greenhouses, where various crops were cultivated, as well as from 10 apple orchards throughout Korea. The resistance to fenpyroximate and pyridaben of each population was estimated by calculating the median lethal concentration (LC₅₀), resistance ratio (RR) and slope of the concentration-mortality regression. Most of the greenhouse populations exhibited moderate levels of resistance, whereas the apple orchard populations showed only low levels, indicating that T. urticae populations in greenhouses were more strongly selected than those in apple orchards. Four population groups were established based on either the habitats (greenhouse and apple orchard) or acaricides (fenpyroximate and pyridaben). To test the hypothesis, “the slope is greatest at low and high levels of resistance,” the slopes were regressed as a function of the LC₅₀, and fitted to a polynomial regression. The polynomial regression model explained this relationship well for the four population groups (p < 0.05), indicating that the development of resistance toward fenpyroximate or pyridaben was consistent with the gradient. A laboratory selection study agreed with the results from both acaricide field populations. These results suggest that the gradient was a good indicator of the susceptibility of T. urticae to genetic variations, which was related to the LC₅₀. The application of these findings is also discussed in relation to the resistance management of T. urticae.     

Biology, life table and predation of Feltiella acarisuga (Diptera: Cecidomyiidae) feeding on Tetranychus cinnabarinus eggs (Acari: Tetranychidae)

Feltiella acarisuga (Vallot) is a common predatory gall midge, which feeds on many species of spider mites. All major life history and life table parameters of F. acarisuga were determined using the carmine spider mite, Tetranychus cinnabarinus (Boisduval) eggs as prey under laboratory conditions [26.7 ± 2 °C, 75 ± 5% RH, and a photoperiod of l4:10 (L:D) h]. Developmental times of F. acarisuga were 2.6, 7.1, and 6.7 d for eggs, larvae, and pupae, respectively, with an average of 16.4 d from egg to adult emergence. Female immatures development took ≈1 d longer than male immatures did. Adult F. acarisuga lived an average of 12.8 d, and the female adults (13.3 d) lived significantly longer than male adults did (11.9 d). After an average of 1.5 d preoviposition period, each female laid an average of 27.3 eggs in its life span with an average of 2.1 eggs per day and an average of 2.8 eggs on each of its oviposition day. The raw data were analyzed using an age-stage, two-sex life table method that takes into consideration of the variable developmental rates among individuals and between sexes. The intrinsic rate of natural population increase (r), net reproductive rates (R_o), gross reproductive rate (∑m_x), generation time (T), and doubling time (DT), and the finite rate of increase (λ) of F. acarisuga were estimated using the age-stage, two-sex (male and female) life table analysis as 0.122 d⁻¹, 16.19 eggs per female, 20.81 eggs per female, 22.81 d, 1.1298 d, and 5.7 d⁻¹, respectively. Each of the first, second, and third instar larvae of F. acarisuga consumed an average of 35.5, 54.0 and 86.9 T. cinnabarinus eggs per day, respectively. Larvae of F. acarisuga could consume an average of 175.4, T. cinnabarinus eggs, and female larvae consumed 14% more spider mite eggs (187.6 eggs) than male larvae (165.1 eggs). The significance of other life table parameters related to the population and the potential of using F. acarisuga as a biological control agent are discussed.     

Olfactory response of Typhlodromus pyri (Acari: Phytoseiidae) to synthetic methyl salicylate in laboratory bioassays

The herbivore‐induced plant volatile (HIPV) methyl salicylate (MeSA) is widely present in the chemical profile of several plant species and is known to attract natural enemies, including predatory mites. In this study, the response of Typhlodromus pyri, a key predator of pest mites in west coast vineyards, to synthetically produced MeSA was tested using a Y‐tube olfactometer in laboratory bioassays. Six doses ranging from 0.002 to 200 μg of MeSA diluted in 0.1 ml hexane were tested. Significantly higher proportions of T. pyri preferred MeSA at doses 0.02, 0.2 and 20 μg. No differences in response to MeSA were detected at the highest (200 μg), intermediate (2 μg) and lowest (0.002 μg) doses. Mite response to MeSA was a function of dose when fitting polynomial and logistic regression models using dose and square of the log dose prediction factors. Results indicate that synthetic MeSA may be applied to attract predatory arthropod populations in vineyards to enhance biological control of pest mites.     

Functional morphology and ultrastructure of mouthparts in unfed water mite larvae Piona carnea (Koch, 1836) (Acariformes: Pionidae)

Mouthparts of unfed larvae Piona carnea (Koch, 1836) (Acariformes: Pionidae) were studied on whole-mount preparations, semi-thin sections and with TEM and SEM methods. The mouth apparatus is incorporated within the pseudotagma, gnathosoma, composed of the infracapitulum and of the chelicerae resting on the roof of the latter. The gnathosoma inclines to the long axis of the body and is inserted at its base into the idiosoma by the circumcapitular fold. The basal cheliceral segments are long and fused. An anterior projection, the proposed fused fixed digits, protrudes from the distal end of the basal cheliceral segment forward between the movable digits. The movable digits are always found in protruded position, strongly curved upward and show a groove on their inner sides. The ventral wall of the infracapitulum is made of the mentum posterior and the malapophyses anterior to the palp articulation. The malapophyses are squeezed between the large palps and envelope the distal portion of the chelicerae from the sides. The ventral portion of the fused malapophyses are provided with a characteristic ventral cuticular fork of unknown function. Each malapophysis terminates by a flexible lateral lip provided by several rigid jags looking posterad. The palps face downward and backward, and bear on the tibia the large curved palpal claws turned laterad. The palp femur bears on the ventral aspect a characteristic wide spade-like projection provided with its own muscles originating on the dorsal wall of the femur. The labrum is a thick cuticular arrow-like structure protruding forward into the preoral cavity, whereas the cervix is a thin weakly sclerotized plate. The particular labral valve projects forward from the dorsal basis of the labrum into the preoral cavity. The labrum and the cervix are provided by their own small labral and cervical muscles originating on the cervical apodemes. The pharynx is totally separated from the ventral wall of the infracapitulum and is devoid of ventral dilators. The dorsal pharyngeal dilators originate on the thick and sclerotized capitular apodeme and, posteriorly, on the paired cuticular branches, capitular apodemes, which end freely in the body cavity and are combined with the common salivary duct. The short sigmoid pieces serve for origin of the levator muscles of the chelicerae. Retraction of the gnathosoma and the chelicerae is mediated by several sets of muscles originating on the dorsal plate.     

中国蜡梅上的瘿螨二新种(蜱螨亚纲,瘿螨总科)

记述寄生在蜡梅Chimonanthus praecox(Linn.)Link.(蜡梅科Calycanthaceae)叶子上的瘿螨2新种:蜡梅离子瘿螨Leipothrix chimonae sp.nov.和蜡梅双羽爪瘿螨Diptacus praecoxsp.nov.。模式标本保存在河北大学博物馆。蜡梅离子瘿螨,新种Leipothrix chimonae sp.nov.(图1～5)正模♀,副模:25♀♀,2♂♂,2009-06-01,陕西省岚皋县蜡烛村,海拔600m,谢满超采。寄主为蜡梅Chimonanthuspraecox(Linn.)Link.(蜡梅科Calycanthaceae)。新种与悬钩子离子瘿螨Leipothrix yipingae Shi,2000相似,但新种背盾板具背中线,雌生殖盖片基部具纵线,端部饰有斜线,羽状爪3支,而悬钩子离子瘿螨L.yipingae背盾板上无背中线,雌生殖盖片饰有短线和粒点,羽状爪4支。蜡梅双羽爪瘿螨,新种Diptacus praecox sp.nov.(图6～12)正模♀,副模:8♀♀,7♂♂,2009-06-01,陕西省岚皋县蜡烛村,海拔600m,谢满超采。寄主为蜡梅Chimonanthuspraecox(Linn.)Link.(蜡梅科Calycanthaceae)。新种与臭樱双羽爪瘿螨Diptacus maddenis Song,Xue etHong,2007相似,但新种足Ⅰ基节间具胸线,基节饰有线条和粒点,雌生殖器盖片上饰有1排纵肋,而臭樱双羽爪瘿螨D.maddenis足Ⅰ基节间无胸线,基节饰有粒点,雌生殖器盖片基部饰有粒点。     

Life history of the predatory mite <Emphasis Type="Italic">Phytoseiulus fragariae</Emphasis> on <Emphasis Type="Italic">Tetranychus evansi</Emphasis> and <Emphasis Type="Italic">Tetranychus urticae</Emphasis> (Acari: Phytoseiidae,Tetranychidae) at five temperatures

Tetranychus evansi Baker and Pritchard and Tetranychus urticae Koch (Acari: Tetranychidae) are important pests of Solanaceae in many countries. Several studies have demonstrated that T. urticae is an acceptable prey to many predatory mites, although the suitability of this prey depends on the host plant. T. evansi, has been shown to be an unfavorable prey to most predatory mites that have been tested against it. The predator Phytoseiulus fragariae Denmark and Schicha (Acari: Phytoseiidae) has been found in association with the two species in Brazil. The objective of this work was to compare biological parameters of P. fragariae on T. evansi and on T. urticae as prey. The study was conducted under laboratory conditions at 10, 15, 20, 25 and 30°C. At all temperatures, survivorship was lower on T. evansi than on T. urticae. No predator reached adulthood at 10°C on the former species; even on the latter species, only about 36% of the predators reached adulthood at 10°C. For both prey, in general, duration of each life stage was shorter, total fecundity was lower and intrinsic rate of population increase (r _m ) was higher with increasing temperatures. The slower rate of development of P. fragariae on T. evansi resulted in a slightly higher thermal requirement (103.9 degree-days) on that prey than on T. urticae (97.1 degree-days). The values of net reproduction rate (R ₀), intrinsic rate of increase (r _m ) and finite rate of increase (λ) were significantly higher on T. urticae, indicating faster population increase of the predator on this prey species. The highest value of r _m of the predator was 0.154 and 0.337 female per female per day on T. evansi and on T. urticae, respectively. The results suggested that P. fragariae cannot be considered a good predator of T. evansi.     

Variation in social behavior within a spider mite genus, Stigmaeopsis (Acari: Tetranychidae)

The spider mites belonging to the genus Stigmaeopsis constructextremely dense oval woven roofs (web-nests) over depressionson the lower surface of host leaves and are known to have akind of sociality. The four species that occur on bamboo plantsin Japan show different nest areas. The nest area of Stigmaeopsislongus is the largest, followed by that of S. celarius, S. takahashii,and S. saharai in decreasing order. Smaller nests effectivelyprevent adults of several predator mite species from intruding.We hypothesized that variation in nest size reflects differentanti-intruder adaptations of this mite group in relation totheir sociality. The larger nest makers may adopt an alternativeanti-intruder strategy, namely, counterattack by a large group,so as to compensate for the disadvantage of large nests. S.longus and S. celarius adults effectively defended their largenests against potential predators, and the effects of nest defenseincreased with the number of individuals in a nest. S. takahashiiand S. saharai revealed no counterattack effect. Counterattackabilities that increase with the adult density, and thus, socialitymay compensate for the vulnerability of larger nests.     

防尘螨药物的实验室药效测试方法

建立防螨药物的药效测试装置与操作方法很有必要。由于尘螨形体微小 ,给防螨药效测试的操作带来诸多困难 ,作者利用螨虫的生物习性及特点 ,建立了布块集螨法、成螨自动分离与净化法、标定计数法 ,布块浸水计数法以及螨虫的驱避和杀灭效果的测试装置与测试方法。结果表明 ,采用成螨自动分离与净化法获得的成螨比例为 ( 94 0± 1 7) %;采用标定计数的精度 (成螨数 刻度 )为 ( 2 0 4± 6 6)只。标定计数 1 0 0 0只螨的实际回收率平均为 ( 75 9± 1 4 6) %,与手工计数无显著性差别 (P >0 0 5 )。实践表明 ,此技术与方法操作简便 ,结果可靠 ,使测试的速度及效果有明显提高     

施用EM堆肥对土壤螨群落结构的影响

对不同施肥条件下农田中的土壤螨进行调查,结果表明：（1）EM堆肥区土壤有机层加深,土壤螨垂直分布下限下移;（2）施用EM堆肥土壤螨数量多,物种丰富,分布均匀,长期施用EM堆肥可以形成多层次的食物网络,传统堆肥区土壤螨数量和种类较化肥区多,单纯施用化肥的农田,土壤螨数量和种类呈减少趋势,群落结构稳定性差,土壤生物间的联系向单一化方向发展。