Life tables of the predatory mite Neoseiulus cucumeris (Acari: Phytoseiidae) on two pest mites as prey,Aculops lycopersici and Tetranychus urticae

Abstract

Studies on the life history and life table parameters of Neoseiulus cucumeris Oudemans (Acari: Phytoseiidae) were carried out under laboratory conditions of 25?±?1?°C and 65?±?5% RH; 30?±?1?°C and 60?±?5% RH; 35?±?1?°C and 55?±?5% RH. As prey, immature stages of tetranychid spider mite T. urticae Koch (Acari: Tetranychidae) and the moving stages of the Tomato Russet Mite A. lycopersici (Massee) (Acari: Eriophyideae) were selected. The predatory phytoseiid mite, Neoseiulus cucumeris (Oudemans) was able to develop successfully from egg to adult stage through the entire life history on both preys. The higher of different temperatures and relative humidities shortened the development and increased reproduction and prey consumption and vice versa. The maximum reproduction (3.91, and 3.09 eggs/♀/day) was recorded at 35?°C and 65% RH, while the minimum (2.12, and 1.90 eggs/♀/day) was at 25?±?1?°C and 55?±?5% RH. when N. cucumeris fed on A. lycopersici and T. urticae, respectively. The reproductive rate on eriophyid was significantly higher than previously recorded on tetranychid. Life table parameters indicated that feeding of phytoseiid mite N. cucumeris on tomato russet mite A. lycopersici led to the highest reproduction rate (rm?=?0.268, 0.232 and 0.211 females/female/day), while feeding on T.urticae gave the lowest reproduction rate (rm?=?0.159, 0.143 and 0.131) at 35?°C and 55% RH, 30?°C and 60% RH and 25?°C and 65% RH, respectively. The population of N. cucumeris multiplied (36.81, 28.71 and 20.47) and (24.60, 19.58 and 14.62 times) in a generation time of (20.10, 23.20 and 25.14) and (22.35, 25.36 and 27.79 days) when a predator fed on A. lycopersici and T. urticae at the same temperature above mentioned, respectively. These results suggest that the two mites, particularly A. lycopersici, proved to be suitable prey for N.cucumeris, as a facultative predator.     

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.     

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.     

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.     

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.     

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.     

Acaricidal and biological activities of Titanium dioxide and Zinc oxide nanoparticles on the two-spotted spider mite,Tetranychus urticae Koch (Acari: Tetranychidae) and their side effects on the predatory mite,Neoseiulus californicus (Acari: Phytoseiidae)

The excessive application of pesticides raises environmental pollution levels, necessitating the need to identify alternative substances that do not cause ecological damage. In this context, the toxicity and residual efficacy of titanium dioxide (TiO₂) and zinc oxide (ZnO) nanoparticles (NPs) compared to abamectin against adult females of T. urticae was evaluated under laboratory and greenhouse conditions. In addition, the effects of tested NPs on the biological parameters of T. urticae as well as their side effects on the predatory mite, Neoseiulus californicus were examined. In laboratory bioassays, LC₅₀ values of TiO₂ and ZnO NPs were 5.82 and 7.09 mg L^–1, respectively, compared to 4.90 mg L^–1 in abamectin 72 hr post-treatment. TiO₂ and ZnO NPs had a prolongation effect on both the developmental and reproductive durations with mean life spans of 33.18 ± 0.72 days and 30.53 ± 0.82 days in the case of TiO₂ and ZnO NPs, respectively, compared to 24.65 ± 0.53 days in the normal case. Treated T. urticae females produced lesser fecundities (10–22 eggs less than the normal mean) and decreased hatchability rates. The highest mortality percentages in T. urticae populations were 92.4 % and 90.0 % after 24 h of spraying with TiO₂ and ZnO NPs, respectively, compared to 98.4 % in abamectin. In contrast, tested NPs demonstrated less toxicity in N. californicus populations with no phytotoxicity on treated leaves. This study is the first in Egypt to investigate the NPs control of T. urticae mites infesting cucumber plants and the effects on their biology and natural enemies.     

Side-effects of three pesticides on the predatory mite, Phytoseiulus persimilis (Acari: Phytoseiidae)

Side-effects of three commonly used pesticides in Iran were evaluated on an introduced strain of the predatory mite. Phytoseiulus persimilis Athias-Henriot, reared for about 10 years without exposure to any pesticides. Application of pesticides was carried out either to detached bean leaves using a Potter tower at 1 mg wet deposit per cm2 or by a hand sprayer on bean plants until run off. According to an EPPO decision making scheme, pirimiphos-methyl was found to be harmful (E=90.8%) and heptenophos harmless (E=-3.7%) to the predatory mite in the residual initial toxicity tests. For determination of the hazard class of malathion a field test was found to be necessary (E=59.8%). Categories of 1, 2, 3 were determined for heptenophos, malathion and primiphos-methyl, respectively, using IOBC classification. Despite being harmful, it is possible to use pirimiphos-methyl 10 days before release of P. persimilis. Investigation of the contribution of both lethal and sub-lethal effects to total impact indicated the dominance of lethality in the case of pirimiphos-methyl, while malathion acted by both mechanisms. Heptenophos did not have negative effects on fecundity of P. persimilis but rather caused a higher rate of fecundity in comparison with the control. The mortality found in the heptenophos test was not significantly different from the control.     

Taxonomy and biological control: Neoseiulus cucumeris (Acari: Phytoseiidae), a case study

The predatory mite Neoseiulus cucumeris (Oudemans) (Acari: Phytoseiidae) is an important biological control agent of thrips and other small pests worldwide. Yet, despite its economic importance, this species is poorly defined taxonomically and cannot be reliably separated from other species on the basis of morphology alone. Neoseiulus cucumeris has been reported from Australia, although considerable confusion exists as to whether the Australian material is actually N. cucumeris or a presumed endemic species, Neoseiulus bellinus (Womersley). A morphological investigation of N. bellinus and several geographical 'strains' of N. cucumeris demonstrated that: (i) N. bellinus is a distinct species, the males of which can be morphologically separated from those of N. cucumeris , using setal and cheliceral lengths and number of teeth on the fixed digit; and (ii) N. cucumeris , or a morphologically identical species, is present in Australia. Despite behavioural differences, there are no significant morphological differences between the 'strains' of N. cucumeris . Biosystematic research is a more reliable method of species separation, and such a method is suggested for future work with phytoseiid mites.     

How feeding on mixed pollens of cattail and saffron affects Neoseiulus cucumeris (Acari: Phytoseiidae) performance

Predatory phytoseiid mite, Neoseiulus cucumeris (Oudemans) is a commercially available biocontrol agent against various pests of greenhouse crops, and it can feed on different diets, including small arthropods and pollen. This generalist predatory mite was reared on the mixture of two different plant pollens including cattail (35%), and saffron (65%) for 10 generations. The effects of mixed diet on the biological parameters of N. cucumeris were evaluated under laboratory conditions at 25 ± 1 °C, 60 ± 5% RH, and a photoperiod of 16:8 (L: D) h every 5 generations (G1, G5, and G10). In addition, the predation ability of nymphs and adults of N. cucumeris encountering the natural prey, Tetranychus urticae Koch was evaluated after 10 generations. The results showed that the quality of mass-reared N. cucumeris on a mixed diet of cattail and saffron pollens did not decrease up to 10 generations of rearing. The intrinsic rate of increase (r) of the predator in G1, G5, and G10 was 0.180, 0.189, and 0.199 day⁻¹, respectively. In addition, the r value was 0.181 day⁻¹ after switching this predator to T. urticae, and it had a high potential of predation (513 prey/generation). The results of this study revealed that rearing N. cucumeris for 10 generations on a mixed diet of saffron and cattail pollens did not affect the performance of the predator negatively.     

Use of polypropylene bags for mass rearing Neoseiulus baraki (Acari: Phytoseiidae), a predatory mite of Aceria guerreronis Keifer (Acari: Eriophyidae)

An efficient, low cost and practicable mass rearing method for the predatory mite, Neoseiulus baraki Athias-Henriot (Acari: Phytoseiidae) was developed using a bag made of two-ply polypropylene (gauge 150, 24 cm × 36 cm) sheets. Introducing 20 N. baraki females into the bag produced a mean number 5218 ± 212.10 offspring in 6 weeks with a 260-fold increase of the initial population.     

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     

Factors determining species displacement of related predatory mite species (Acari: Phytoseiidae)

Neoseiulus womersleyi (Acari: Phytoseiidae) used to be the dominant species in fruit-tree orchards throughout Japan, but starting in the 1990s, N. womersleyi began to be displaced by Neoseiulus californicus in central and southwestern Japan. The present study was conducted to examine factors explaining the displacement of N. womersleyi by N. californicus. First, we confirmed under laboratory conditions that N. californicus could exclude N. womersleyi if they initially coexisted in a 1:1 ratio. During a 2-h continuous observation period, none of the heterospecific pairs had copulated and after 5 days together with heterospecific males, none of the females had laid eggs. When these females were placed with conspecific males, normal numbers of offspring were produced. Moreover, conspecific matings were not substantially disturbed in the presence of heterospecific males or females. Total fecundity was significantly lower in N. womersleyi than in N. californicus, but their r _m values did not differ from each other. On the other hand, the frequency of intraguild predation by N. californicus on N. womersleyi was significantly higher than vice versa. From these results, we concluded that not reproductive interference nor differential female fecundity but asymmetrical intraguild predation seemed to explain the competitive exclusion of N. womersleyi by N. californicus.     

Biological studies of the Australian predatory mite Typhlodromalus lailae (Schicha) (Acari: Phytoseiidae)

Abstract The biology of the Australian phytoseiid mite Typhlodromalus lailae is described from material collected in Western Australia and New South Wales in 1994. At 25°C, when fed on cumbungi ( Typha sp.) pollen, the life cycle is completed in approximately 6 days, with an intrinsic rate of natural increase ( r _m ), of 0.38. Female−male pairs produced a mean total of 44.6 eggs within 22 days of oviposition, with 39% of these females living in excess of 29 days. Females that were deprived of males after first mating stopped laying eggs after 4−9 days, but if another male was added they resumed egg laying and produced close to a full complement of eggs (mean 42 eggs). At 25°C, fecundity on a diet of cumbungi pollen or thrips larvae (first-instar Frankliniella schutzei Trybom) was high, averaging 3.71 and 3.33 eggs per day, respectively, over a 3-day period. The sex ratio was approximately 1.5 females to 1 male. Consumption rate of thrips was also high, with an average of approximately seven first-instar or two second-instar F. schultzei larvae eaten per day. The species was also observed to feed on broad mite, Polyphagotarsonemus latus (Banks), and tomato russet mite, Aculops lycopersici (Massee). No diapause was observed under conditions of 25°C 8 h light and 10°C 16 h dark. Eggs were sensitive to low humidity, with 50% failing to hatch below 71.1% relative humidity. This species is of interest as a candidate biological control agent for thrips, broad mite and tomato russet mite in protected crops.     

Functional response of Neoseiulus cucumeris (Oudemans) (Acari: Phytoseiidae) to Bemisia tabaci (Gennadius) on tomato leaves

Bemisia tabaci (Gennadius) is an important invasive pest of vegetables and other horticultural plants worldwide. In this study, the functional response of Neoseiulus cucumeris (Oudemans) to different stages of immature B. tabaci was evaluated under laboratory conditions. Predation experiments were conducted on tomato leaf discs (2.5?cm diameter) over a 24-h period at 26?±?1°C and 65?±?5% relative humidity with a L16:D8 photoperiod. The prey densities ranged from 5 to 90 immature stages (eggs and first- to fourth-instar nymphs) of B. tabaci per leaf disc. The results showed that the egg stage of B. tabaci was the most susceptible prey stage and that the mated female adult mite (3-day-old) was a more effective predator than the male adult mite. The functional response of adult N. cucumeris followed a Type II trend curve as shown in a logistic regression model. Adult N. cucumeris exhibited different predation tendencies towards prey in different stages of immaturity. The daily maximum number of eggs, first-, second- and third-instar nymphs of B. tabaci killed by a single female over a 24-h period (26?±?1°C, 65?±?5% RH and L16:D8 photoperiod) were 8.5, 5.2, 3.0 and 2.1, respectively, whereas the number killed by a single male was 6.0, 4.0, 2.3 and 1.8, respectively. The results of this study could help determine an effective B. tabaci biocontrol measure that employs a natural predator.     

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.     

Disease prevalence and transmission of Microsporidium phytoseiuli infecting the predatory mite, Phytoseiulus persimilis (Acari: Phytoseiidae)

Isolated colonies of the predatory mite, Phytoseiulus persimilis, were used to gain information regarding prevalence and transmission of Microsporidium phytoseiuli. Two colonies of P. persimilis were reared on spider mite (Tetranychus urticae)-infested bean plants in isolated cages. Disease prevalence of predators from Colony 1 remained relatively low (between 0 and 15%) over 57 weeks of observation whereas disease prevalence of predators from Colony 2 increased over 3 months (from 12 to 100%). Disease prevalence among predators from Colony 1 had increased to 100% 2 months after weekly sampling had ceased for this colony and periodic sampling confirmed that disease prevalence among individuals of both colonies remained at 100%. Microsporidian spores were not detected in randomly chosen samples of T. urticae prey mites that were removed and examined biweekly during this period. Although numerous microsporidian spores were observed in smear preparations of fecal pellets examined by light microscopy, spores were not observed on leaf surfaces or predator feces when examined by SEM. The latter appeared as intact aggregates composed of numerous dumbbell-shaped crystals and it is unlikely that spores are liberated from intact fecal pellets onto leaf surfaces. Vertical transmission of M. phytoseiuli was 100%; horizontal transmission was low (14.3%) and occurred only when immature P. persimilis were permitted to develop in contact with infected immature and adult predators. The mean number of eggs produced per mated pair was highest when uninfected females were mated with uninfected males (63.2 eggs per mated pair). Although mean egg production decreased when one or both parents were infected, not all differences were significant. Male predatory mites did not contribute to infection of their progeny. Results suggest that routine examination of P. persimilis for microsporidian spores is essential for the management of M. phytoseiuli within P. persimilis colonies. Low disease prevalence and lack of obvious disease signs or symptoms, as in the case of M. phytoseiuli, increase the probability that these pathogens will escape notice unless individuals are routinely examined for pathogens.