Effect of long-term cold storage of the predatory mite Neoseiulus californicus at high relative humidity on post-storage biological traits

The present study investigated whether long-term cold storage at high relative humidity (RH) affected the quality of the predatory mite Neoseiulus californicus (McGregor) (Acari: Phytoseiidae) in terms of its survival and reproduction. For this purpose, we examined biological traits at the end of storage and during the post-storage period. Mated females three?days after adult emergence were stored individually in 1.5-ml vials for 15, 30, 45, 60, or 75?days at 5.0?±?0.3°C and RH of 99?±?0.1% under continuous darkness. At the end of the storage period, 94–100% of females had survived when the storage period was ≤30?days, but percent survival decreased with longer storage. After storage, female survival and oviposition rates were equivalent to un-stored females at 24?±?1°C, RH of 93?±?2%, and a photoperiod of LD 16:8?h. The quality of progeny (hatchability, survival to adulthood, and sex ratio) of stored females was not affected by storage periods as long as 60?days. These results indicate that storage using the tested method can preserve N. californicus for at least 30?days without any degradation.     

Cold storage of the predatory mite Neoseiulus californicus is improved by pre-storage feeding on the diapausing spider mite Tetranychus urticae

Low air temperature accompanied with high humidity is effective for long-term cold storage of the predatory mite Neoseiulus californicus (McGregor) (Acari: Phytoseiidae). To further improve this storage method, we investigated the effect of pre-storage nutrition on survival during storage and on post-storage quality in terms of survival, oviposition, and progeny viability. The predatory mite was fed from the egg to adult stage on the diapausing two-spotted spider mite, Tetranychus urticae Koch (Acari: Tetranychidae), non-diapausing spider mites, or Japanese pear pollen, Pyrus pyrifolia Nakai. Newly emerged N. californicus adult females and males were mated, and then both were stored at 7.5 °C and a vapor pressure deficit of 0.0 kPa for up to 75 days. Survival during storage and post-storage quality was significantly better with the diapausing spider mite diet than with the other diets. No effects on the survival or sex ratio of the progeny of the stored adults were observed, regardless of diet or storage duration. Providing diapausing spider mites as a pre-storage diet therefore significantly improves the long-term storage of N. californicus. We discuss the possibility that ingestion of the cryoprotectants, antioxidants, and energy reserves that are present in rich amounts in diapausing spider mites mitigates chilling injury.     

Rapid cold hardening in the predatory mite Euseius (Amblyseius) finlandicus (Acari: Phytoseiidae)

A rapid cold hardening response was studied in diapause and non-diapause females of the predatory mite Euseius finlandicus. When laboratory reared diapause and non-diapause females were transferred and maintained from the rearing temperature of 20 degrees C for 2 h to -11.5 degrees C and -10 degrees C, 10 to 20% survived respectively. However, conditioning of diapause females for 4 h at a range of temperatures from 0 to 10 degrees C before their exposure for 2 h to -11.5 degrees C, increased survival to approximately 90%. Similarly, conditioning of non-diapause females for 4 h at 5 degrees C before their exposure for 2 h to -10 degrees C increased survival to 90%. A similar rapid cold hardening response in both diapause and non-diapause females was also induced through gradual cooling of the mites, at a rate of approximately 0.4 degrees C per min. The rapid increase in cold tolerance after prior conditioning of the mites to low temperatures, was rapidly lost when they returned to a higher temperature of 20 degrees C. Rapid cold hardening extended the survival time of diapause and non-diapause females at sub-zero temperatures. The cost of rapid cold hardening in reproductive potential after diapause termination was negligible. In non-diapause females, however, the increase in cold tolerance gained through gradual cooling could not prevent cold shock injuries, as both fecundity and survival were reduced.     

Evaluation of dry-adapted strains of the predatory mite Neoseiulus californicus for spider mite control on cucumber, strawberry and pepper

The goal of this study was to evaluate spider mite control efficacy of two dry-adapted strains of Neoseiulus californicus. Performance of these strains were compared to a commercial strain of Phytoseiulus persimilis on whole cucumber, pepper and strawberry plants infested with Tetranychus urticae at 50 +/- 5% RH. Under these dry conditions predators' performance was very different on each host plant. On cucumber, spider mite suppression was not attained by any of the three predators, plants 'burnt out' within 4 weeks of spider mite infestation. On strawberry, all predators satisfactorily suppressed spider mites yet they differed in short term efficacy and persistence. Phytoseiulus persimilis suppressed the spider mites more rapidly than did the BOKU and SI N. californicus strains. Both N. californicus strains persisted longer than did P. persimilis. The BOKU strain was superior to SI in population density reached, efficacy in spider mite suppression and persistence. On pepper, in the first 2 weeks of the experiment the BOKU strain was similar to P. persimilis and more efficacious in spider mite suppression than strain SI. Four weeks into the experiment the efficacy of P. persimilis dropped dramatically and was inferior to the SI and BOKU strains. Overall, mean predator density was highest on plants harbouring the BOKU strain, lowest on plants with P. persimilis and intermediate on plants with the SI strain. Implications for biocontrol of spider mites using phytoseiid species under dry conditions are discussed.     

Molecular and morphological boundaries of the predatory mite Neoseiulus californicus (McGregor) (Acari: Phytoseiidae)

Neoseiulus californicus (McGregor) is a natural enemy of pest mites used worldwide in many crops. Its correct identification is thus essential to ensure biological control success. The present study aimed to characterize molecular and morphological intraspecific variations for assisting in the diagnosis of the species and to build baseline information about expected variations within a commercially important phytoseiid species. Morphological and molecular [12S rRNA, cytochrome b mitochondrial (mt)DNA, and internal transcribed spacer] analyses were carried out on fourteen populations collected worldwide and on one mass‐reared strain. The genetic distances between the specimens of N. californicus and another related species were high and no overlap was observed, sustaining the reliability of such molecular methods for assisting a specific diagnosis. Furthermore, the genetic distances between populations of N. californicus were very low and overlap between intra‐ and interpopulations distances was observed, except for two populations collected in France (Marsillargues and Midi‐Pyrénées). The high mitochondrial differentiation between these two latter populations and the others questions their specific status: do they belong to the species N. californicus or to another cryptic species? However, using nuclear DNA marker analyses, no distinct differences were observed. Furthermore, even if significant morphological differences were observed between the populations, these differences were very small and the standard errors within each population were very low. We thus concluded that all the populations studied belong to the species N. californicus, despite unexpected high mitochondrial variations. The present study thus displays the importance of an integrative taxonomic approach for avoiding misidentifications. A discussion on morphological and mtDNA variations in relation to diagnostic reliability is developped. © 2011 The Linnean Society of London, Biological Journal of the Linnean Society, 2011, 104 , 393–406.     

Diet‐dependent intraguild predation between the predatory mites Neoseiulus californicus and Neoseiulus cucumeris

Based on the hypothesis that matching diets of intraguild (IG) predator and prey indicate strong food competition and thus intensify intraguild predation (IGP) as compared to non‐matching diets, we scrutinized diet‐dependent mutual IGP between the predatory mites Neoseiulus cucumeris and N. californicus. Both are natural enemies of herbivorous mites and insects and used in biological control of spider mites and thrips in various agricultural crops. Both are generalist predators that may also feed on plant‐derived substances such as pollen. Irrespective of diet (pollen or spider mites), N. cucumeris females had higher predation and oviposition rates and shorter attack latencies on IG prey than N. californicus. Predation rates on larvae were unaffected by diet but larvae from pollen‐fed mothers were a more profitable prey than those from spider‐mite fed mothers resulting in higher oviposition rates of IG predator females. Pollen‐fed protonymphs were earlier attacked by IG predator females than spider‐mite fed protonymphs. Spider mite‐fed N. californicus females attacked protonymphs earlier than did pollen‐fed N. californicus females. Overall, our study suggests that predator and prey diet may exert subtle influences on mutual IGP between bio‐control agents. Matching diets did not intensify IGP between N. californicus and N. cucumeris but predator and prey diets proximately influenced IGP through changes in behaviour and/or stoichiometry.     

Integration of the predatory mite Neoseiulus californicus with petroleum spray oil treatments for control of Tetranychus marianae on eggplant

The red spider mite, Tetranychus marianae McGregor (Acari: Tetranychidae), a pest of several vegetable crops and perennials, is widespread in the Pacific Islands, like the Mariana Islands, where it was first reported. Recently, T. marianae has become a serious pest, particularly affecting eggplant. Efforts were therefore made to develop an integrated approach to control of T. marianae. First, indoor experiments on eggplant, Solanum melongena L. (Solanaceae), determined the optimal combination of petroleum spray oil (PSO; Volck® oil spray) with release of Neoseiulus californicus (McGregor) (Acari: Phytoseiidae) for the management of T. marianae. Additionally, studies evaluated the viability of the predatory mites on Guam. The combination of N. californicus with PSOs produced significant control of T. marianae and did not affect the survival of N. californicus. Although dicofol and carbaryl reduced populations of T. marianae, they caused high mortality of N. californicus. Integrating PSO with N. californicus yielded better control of T. marianae than did N. californicus alone. The release of N. californicus at 200 individuals per plant reduced populations of T. marianae more than did other release rates. In addition, N. californicus was able to survive and become established after being released on Guam.     

The effects of prestarvation diet on starvation tolerance of the predatory mite Neoseiulus californicus (Acari: Phytoseiidae)

Understanding the factors affecting stress tolerance in phytoseiid mites is critical for their integration into biological control programs. In the present study, the effects of diet (varying in prey species, physiological status and phenotype) are examined on the future starvation tolerance of the predatory mite Neoseiulus californicus McGregor (Acari: Phytoseiidae). The predators are fed from egg to adulthood on diapausing or nondiapausing Tetranychus urticae, Tetranychus kanzawai (wild and albino strains) or the nondiapausing species Panonychus citri (wild and albino strains). Thereafter, 3‐day‐old mated adult females are held without food at 25 ± 1 °C and a relative humidity of 98 ± 2%. The survival of these starved females is observed daily until all females have died. The survival curves and mean survival times of N. californicus are found to vary among prey types and are significantly longer when the predator is fed with diapausing prey. This enhanced survival is consistent with high concentrations of glycogen and triacylglyceride in the body of the predator at the onset of starvation. The predators fed nondiapausing prey have shorter survival times, and the glycogen and triacylglyceride contents in their bodies are low or undetectable. The protein contents of the predator's body are similar after consuming different prey types, except for a high concentration when fed the albino strain of P. citri. Protein content is unlikely to play a direct role in starvation tolerance, although it may affect the response to varying glycogen and triacylglyceride levels. These findings indicate that nutritional value of prey has a strong impact on the starvation tolerance of N. californicus.     

双尾新小绥螨的形态特征及捕食性功能

【目的】通过对新疆本地捕食螨双尾新小绥螨Neoseiulus bicaudus Wainstein的形态学特征观察及其对新疆农作物上两种重要害螨的捕食量测定,为该捕食螨的保护、研究、扩繁和释放提供理论基础。【方法】在实验室(26±1)℃,RH60%,16L︰8D条件下,借助显微成像系统观察其各个螨态形态特征及生物学习性;定量小室饲养技术对不同密度下对新疆两种重要害螨各螨态的捕食量进行研究。【结果】双尾新小绥螨有卵、幼螨、第一若螨、第二若螨和成螨5个螨态,嗜好阴暗条件,活动范围小,通过有性生殖进行繁殖,有多次交配行为,产卵方式为单产;单头双尾新小绥螨雌成螨每日对截形叶螨Tetranychus truncatus卵和幼螨的捕食量(106.8粒/日·雌和45.4头/日·雌)要显著大于土耳其斯坦叶螨Tetranychus turkestani(64.4粒/日·雌和39.4头/日·雌),而对两种叶螨的若螨和成螨捕食量无明显差异。【结论】本研究表明双尾新小绥螨对土耳其斯坦叶螨和截形叶螨的卵和幼螨的捕食较对若螨和成螨的效果好,对新疆害螨有一定控制能力。     

Effect of temperature on life history of the predatory mite Amblyseius (Neoseiulus) californicus (Acari: Phytoseiidae)

Amblyseius (Neoseiulus) californicus is an indigenous mite in Japan that feeds on many spider mite species. We evaluated the development, survivorship and life-history parameters of A. californicus on a diet of eggs of Tetranychus urticae (red form). More than 97.3% of A. californicus eggs hatched and more than 81.6% of newly hatched larvae attained maturity at temperatures between 15 and 35 degrees C. Females oviposited at 37.5 degrees C, but no eggs hatched. At 40 degrees C, no females laid eggs. The lower threshold temperature from egg to oviposition was 10.3 degrees C and the thermal constant was 86.2 degree-days. Based on these data, the maximum number of generations that could complete development in a year under field conditions in Ibaraki, central Japan, would be between 21 and 28. At 25 degrees C, females laid a mean of 41.6 eggs during a mean oviposition period of 19.4 days. The intrinsic rates of natural increase (rm) were 0.173 at 20 degrees C, 0.274 at 25 degrees C and 0.340 at 30 degrees C.     

Effect of hexythiazox and spiromesifen resistance on the life cycle of the predatory mite Neoseiulus californicus (Acari: Phytoseiidae)

Neoseiulus californicus (McGregor) (Acari: Phytoseiidae) is one of the most important and effective predators of Tetranychus spp. (Acari: Tetranychidae). This study analyzed the effects of hexythiazox and spiromesifen resistance on biological characteristics of N. californicus. Pre-oviposition, oviposition, post-oviposition times, adult lifespan, total number of eggs laid per female, net reproductive rate (R₀), intrinsic rate of increase (r_m), doubling time (DT), mean generation time (T) and finite rate of increase (λ) were compared among three populations: 63.9-fold hexythiazox resistant (HEX14), 53.6-fold spiromesifen resistant (SPR13) and a susceptible base population. Pre-oviposition and oviposition times, mean number of eggs/female, adult lifespan, R₀ and r_m values were all significantly higher for the two resistant populations than for the susceptible population. Life tables of HEX14, SPR13 and the susceptible population showed that R₀ was 35.0, 26.5 and 19.4 (females/female generation), r_m was 0.35, 0.32 and 0.30 (females/female/day), DT was 1.92, 2.07 and 2.27 days, T was 9.8, 9.8 and 9.7 days, and λ was 1.43, 1.39 and 1.35 (individuals/female/day), respectively.     

Rearing of coconut mite Aceria guerreronis and the predatory mite Neoseiulus baraki in the laboratory

A method was developed for the rearing of coconut mite, Aceria guerreronis Keifer (Acari: Eriophyidae), and its predatory mite Neoseiulus baraki (Athias-Henriot) (Acari: Phytoseiidae) on embryo culture seedlings of coconut (Cocos nucifera) in the laboratory. Seedlings in the ages of <2, 2–4 and 4–6 months were infested with 75 field-collected coconut mites and the population growth was determined up to six weeks after introduction. The populations of coconut mites increased exponentially up to five weeks after introduction and declined thereafter on seedlings of all ages with significant differences among the three groups of seedlings occurring over time. At week 5, a significantly higher mean number (±SE) of coconut mites (20,098 ± 3,465) was bred on 4–6-month-old seedlings than on smaller seedlings, and on the largest seedlings the numbers were highest at all time intervals, except at week 2. Neoseiulus baraki was reared on embryo culture seedlings of the three age groups infested with coconut mites, by introduction of five female deutonymphs and one male, three weeks after introducing coconut mites. Predator numbers progressed significantly over time, but the size of seedlings did not significantly influence the numbers. On all groups of seedlings, the mean number of N. baraki increased up to two weeks after introduction on to seedlings and then declined. Many coconut mites were successfully reared in the laboratory for a longer period by this method and it could also be used as an alternative method to rear N. baraki. Development of this method may contribute to the progress of studies on the biology and ecology of coconut mite and its interactions with natural enemies.     

巴氏新小绥螨对猎物搜寻能力的研究

巴氏新小绥螨Neoseiulus barkeri(Hughes)是一种多食性捕食螨,主要捕食叶螨和蓟马等。因其捕食范围广,捕食量相对较大,且易人工繁殖,因此,被广泛应用于农业生物防治中。本文利用温室的释放-回收实验研究了巴氏新小绥螨对截形叶螨Tetranychus truncatus和西花蓟马Frankliniella occidentalis(Pergande)的搜寻能力。实验共设3个处理:(1)叶螨为害植株与清洁植株;(2)蓟马虫害植株与清洁植株;(3)蓟马、叶螨混合为害植株与清洁植株。当捕食螨释放于清洁黄瓜植株和虫(螨)害黄瓜植株交替排列的六角结构的中心时,2种害虫(螨)不论是单独危害还是混合危害,巴氏新小绥螨回收比例随着时间的延长逐渐趋于平缓。释放后1 d之内,叶螨、蓟马及混合猎物处理中回收到的捕食螨分别占释放总量的65.25%±1.61%、62.75%±1.31%和81.75%±2.14%,并且虫(螨)害植株上回收到的捕食螨数量明显比清洁植株多,叶螨、蓟马及混合猎物危害植株回收的捕食螨量分别占释放总量的53.5%±5.6%、49.5%±3.6%和74.0%±2.7%。因此,巴氏新小绥螨对这2种猎物及其混合物均有较强的搜寻能力,能够有效定位作物中有猎物的植株。同时对利用一种捕食螨生物防治温室中同时发生的2种害虫(螨)的可能性进行了讨论。     

Effects of air temperature and water vapor pressure deficit on storage of the predatory mite Neoseiulus californicus (Acari: Phytoseiidae)

To determine the optimum air temperature and water vapor pressure deficit (VPD) for the storage of the predatory mite, Neoseiulus californicus, 3-day-old mated females were stored at air temperatures of 0, 5, 10, or 15?°C and VPDs of 0.1, 0.3, or 0.5?kPa for 10, 20, or 30?days. At 10?°C and 0.1?kPa, 83?% of females survived after 30?days of storage; this percentage was the highest among all conditions. VPDs of 0.3 and 0.5?kPa regardless of air temperature, and an air temperature of 0?°C regardless of VPD were detrimental to the survival of the females during storage. Since the highest survival was observed at 10?°C and 0.1?kPa, the effect of the storage duration on the post-storage quality of the stored females and their progeny was investigated at 25?°C to evaluate the effectiveness of the storage condition. The oviposition ability of the stored females, hatchability, and sex ratio of their progeny were not affected even when the storage duration was extended to 30?days. Although a slight decrease in the survival during the immature stages of progeny was observed when the storage duration was ≥20?days, the population growth of N. californicus may not be affected when individuals stored in these conditions are applied to greenhouses and agricultural fields. The results indicate that mated N. californicus females can be stored at 10?°C and 0.1?kPa VPD for at least 30?days.     

Prey preference of the predatory mite Neoseiulus womersleyi Schicha is determined by spider mite webs

Abstract:  We experimentally verified a proximate cause for the preference of prey species by the predatory mite Neoseiulus womersleyi , which prefers the eggs of Amphitetranychus viennensis Zacher to those of Tetranychus urticae Koch. To separate the effects of spider mite eggs and spider mite webs on the prey preference of the predatory mite, we manipulated combinations of eggs and webs of the two prey species. The number of eggs consumed by adult female N. womersleyi was compared with respect to two factors: eggs of the same species under webs of the different species and eggs of different species under webs of the same species. The results revealed that the prey preference of N. womersleyi was determined by the webs, and not by the eggs.     

Factors affecting ambulatory dispersal in the predaceous mite Neoseiulus californicus (Acari: Phytoseiidae)

Experiments conducted in the laboratory showed that different biotic and abiotic factors affected the ambulatory dispersal behaviour of Neoseiulus californicus. The experimental set-up comprised dwarf alfalfa (Medicago polymorpha) infested or unifested by Tetranychus urticae. Temperatures were measured with thermocouples. Trials were performed at three temperatures, three prey densities, three light intensities, two relative humidities (RHs) and two vegetative states of alfalfa plants, turgid and withered. Deutonymphs were the most dispersive followed by young ovipositional females. High temperatures (35°C), high light intensities (40 000 lux) and drought-stressed alfalfa increased the dispersal of N. californicus. The availability of food in the environment and high moisture (80% RH) slowed down dispersion. The main factors which seem to elicit dispersal behaviour are the deprivation of food and high temperatures which result in an increase in the walking speed of the mite. In addition, other factors tested either increase or reduce the ambulatory dispersal of N. californicus. According to our results, individuals could move from ground cover into apple trees before spring. © Rapid Science Ltd. 1998     

Using high relative humidity and low air temperature as a long-term storage strategy for the predatory mite Neoseiulus californicus (Gamasida: Phytoseiidae)

The survival time of an indigenous Japanese strain of Neoseiulus californicus (McGregor) was investigated at high and low relative humidities (RHs) of approximately 100% and 80%, respectively, at an air temperature of 5 °C. Five life stages, larva, protonymph, deutonymph and unmated and mated adult female, were tested in 1.5-mL polypropylene vials, in which the RH was adjusted by either adding or omitting a water-saturated filter paper. The survival curves and median survival time (LT₅₀) were significantly different between high and low RHs, and the mean survival time (MST) was 1.6–2.3 times longer at high RH than that at low RH, except in larvae, in which tolerances to high RH and/or low air temperature were not well developed. At high RH, the MST of the mated adult females was 63.1 d and was 1.4 times longer than that of unmated adult females. These results indicate that the suitable water content in the body was probably maintained by increasing the RH at the low air temperature, which is considered to be a primary factor affecting the survival time of N. californicus. Moreover, the nutrient content in the body, such as eggs and male sperm in the mated adult females, could have positive effects on prolonging their survival time. These findings will help to construct an efficient long-term storage method for N. californicus.     

不同温度下双尾新小绥螨对西花蓟马的捕食功能反应

为明确双尾新小绥螨Neoseiulus bicaudus各螨态对西花蓟马Frankliniella occidentalis不同龄期若虫的捕食量及不同温度对其捕食量的影响。本研究通过测定不同温度下24 h内双尾新小绥螨各螨态对不同密度西花蓟马若虫的捕食情况(西花蓟马猎物密度分别为5、10、15、20和25头/室,温度分别设置为23、26、29、32和35℃)。研究结果表明,双尾新小绥螨各螨态对猎物的捕食量随猎物密度的升高而增加。当温度为29℃,雌成螨对西花蓟马1龄若虫捕食量最高,在猎物数为25头/室时,可达4.4头/日。23~32℃内,双尾新小绥螨的雌成螨的捕食量随温度的上升而增加,到达35℃时开始降低。29~32℃双尾新小绥螨的雌成螨对西花蓟马1龄若虫的捕食量最高,可达6.7头/日,最适于其捕食。结果表明双尾新小绥螨对西花蓟马若虫的捕食功能反应类型符合Holling II模型,其对西花蓟马有较好的捕食能力,可利用于西花蓟马的生物防治。