Californicus Females Research Articles

Lethal and sublethal effects of carlina oxide on Tetranychus urticae (Acari: Tetranychidae) and Neoseiulus californicus (Acari: Phytoseiidae).

Tetranychus urticae Koch, is a polyphagous and damaging pest, presenting several resistant populations worldwide. Among new and more environmentally friendly control tools, botanical pesticides represent a valuable alternative to synthetic ones within integrated pest management strategies. Accordingly, we investigated the lethal and sublethal effects of carlina oxide isolated from Carlina acaulis (Asteraceae) roots on T. urticae and its natural enemy, the predatory mite, Neoseiulus californicus (McGregor). Carlina oxide (98.7% pure compound) was used for acaricidal tests on eggs, nymphs, and adult females of T. urticae (concentrations of 312.5, 625, 1250, 2500 and 5000 μL L-1 ), and eggs and females of N. californicus (1250 and 5000 μL L-1 on eggs and females, respectively). Behavioral two-choice tests were also conducted on phytoseiid females. Carlina oxide toxicity was higher on T. urticae females than nymphs (median lethal dose 1145 and 1825 μL L-1 , respectively), whereas egg mortality and mean hatching time were significantly affected by all tested concentrations. A decreasing daily oviposition rate for T. urticae was recorded with concentrations ranging from 625 to 5000 μL L-1 , whereas negative effects on the population growth rate were recorded only with the three higher concentrations (1250, 2500 and 5000 μL L-1 ). No toxic effect on N. californicus females was found, but a strong repellent activity lasting for 48 h from application was recorded. Carlina oxide reduced longevity and fecundity of T. urticae adults, but not of N. californicus. This selective property allows us to propose it as a novel active ingredient of ecofriendly acaricides for T. urticae management. © 2023 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Experienced generation-dependent functional and numerical responses of Neoseiulus californicus (Acari: Phytoseiidae) long-term reared on thorn apple pollen

The functional and numerical responses of the predatory mite Neoseiulus californicus (McGregor) (Phytoseiidae) females reared on thorn apple pollen (Datura stramonium L.) over 40 generations on different densities (2, 4, 8, 16, 32, 64 and 128) of deutonymphs of Tetranychus urticae Koch (Trombidiformes: Tetranychidae) were determined. The results indicated a type II functional response for N. californicus on T. urticae in generations of G0 (no rearing on pollen as control), G10, G20, G30, and G40. The attack rate (α) for N. californicus females increased as the number of generations increased from G0 (0.079 h<sup>-1</sup>) to G20 (0.182 h<sup>-1</sup>), then decreased in G30 and G40. The longest and shortest handling time (T<sub>h</sub>) was observed in G0 (1.670 h) and G40 (0.890 h), respectively. The highest value of maximum attack rate (T/T<sub>h</sub>) was estimated in G40 (26.96 prey/day). The equation of the regression line showed that the relationship between the prey density and the number of eggs laid was significant in G0, G10 and G40, and the number of eggs deposited by N. californicus increased with increasing the density of prey. The relationship between the prey density and ECI (the efficiency of conversion of ingested food) was not significant in tested generations. Our findings show that long-term rearing on thorn apple pollen did not affect the type of functional response and efficiency of N. californicus by confirming this predator is an effective biological control agent against T. urticae.

Biocontrol Potential of Neoseiulus californicus (Mesostigmata : Phytoseiidae) Against Oligonychus punicae (Acari: Tetranychidae) in Avocado.

Oligonychus punicae (Hirst) (Trombidiformes: Tetranychidae) is a common pest in Mexican avocado orchards. Neoseiulus californicus (McGregor) (Mesostigmata: Phytoseiidae) is frequently found associated with avocado orchards in Mexico and may be an important aid for controlling O. punicae. Given the lack of information in the scientific literature, this study evaluated the predation and oviposition of N. californicus when fed O. punicae at different developmental stages in a no-choice experiment. We also assessed fluctuations in the population size of O. punicae and N. californicus in commercial avocado orchards; correlations among mite density and air temperature, humidity, and precipitation in commercial avocado orchards; and the correlations between prey and predator populations. The no-choice test revealed that N. californicus adult females fed on O. punicae of all developmental stages, with higher levels of predation being recorded for eggs, followed by larvae. The highest oviposition values of N. californicus females were observed when females were fed O. punicae eggs. In orchards, the populations of both mites increased between February and June. The populations peaked during the warmest months of the year, with O. punicae populations peaking between June and July and N. californicus peaking in August. In addition, the population size of N. californicus was significantly and positively correlated with rainfall, air temperature, and the population densities of O. punicae. Meanwhile, O. punicae population size was positively correlated with air temperature, and the population of its predator N. californicus.

Intraguild predation in three generalist predatory mites of the family Phytoseiidae (Acari: Phytoseiidae)

BackgroundThe predatory mites, Neoseiulus californicus (McGregor), N. barkeri (Hughes), and Amblyseius swirskii Athias-Henriot, are important predators attacking many insect and mite pests. They can coexist in the same habitat and engage in intraguild predation (IGP).Main bodyIGP was assessed among the exotic one N. californicus and the native species N. barkeri and A. swirskii as Intraguild predator (IG-predator)/intraguild prey (IG-prey) in either absence or presence of extra-guild prey Tetranychus urticae Koch (EG-prey). In the laboratory, the physiological parameters, longevity, fecundity, and predation rate of these predatory mites’ females, fed on EG-prey, were evaluated, where phytoseiid larvae are considered as (IG-prey) or combined IG-prey with EG-prey. All predatory species consumed larval stages of each other’s, but in case of N. californicus, females failed to sustain oviposition on N. barkeri larvae. Also, it was noticed that N. californicus females killed 3 times more A. swirskii larvae than N. barkeri larvae, whereas A. swirskii consumed more N. californicus than N. barkeri larvae, respectively. Neoseiulus californicus lived longer on T. urticae and A. swirskii larvae than on N. barkeri, while the latter survived longer on T. urticae only than on the other prey or with combinations with T. urticae. Amblyseius swirskii lived shorter when fed exclusively on T. urticae or IG-prey than on EG-prey combined with IG-prey. In choice experiments, N. californicus showed a higher preference to consume more T. urticae than any of phytoseiid larvae. The comparison between T. urticae and IG-prey diets definite the higher influence of T. urticae on the fecundity in N. californicus and N. barkeri than on IG-prey, whereas in A. swirskii fecundity was as equal on T. urticae as on IG-prey N. californicus larvae.ConclusionA. swirskii seemed to be the strongest IG-predator.

Strawberry pollen as a source of UV-B protection ingredients for the phytoseiid mite Neoseiulus californicus (Acari: Phytoseiidae).

A new physical control method using ultraviolet-B (UV-B) lamps and light-reflecting sheets (UV method) significantly suppressed a spider mite population on greenhouse strawberries. Although UV-B radiation may adversely affect the survival of phytoseiid mites, previous research has suggested that Neoseiulus californicus can improve its survival on exposure to UV-B irradiation by consuming antioxidants contained in tea and peach pollen. In this study, we evaluated strawberry pollen as an alternative food source for N. californicus and examined whether antioxidants in the pollen mitigated UV-B damage to N. californicus. The fecundity of N. californicus females reared on Tetranychus urticae decreased on shifting their diet to pollen. By contrast, females reared continuously on strawberry pollen produced as many eggs as females reared continuously on T. urticae. Survival and fecundity after UV-B irradiation were higher in females on the pollen diet. Oxygen radical absorbance capacity analysis revealed that the high antioxidant activity of strawberry pollen was due to four hydroxycinnamoyl spermidine derivatives. Strawberry pollen was an adequate alternative food source for N. californicus. Feeding on strawberry pollen, which contains spermidine derivatives with high antioxidant activity, mitigated UV-B damage. This shows the potential of combining the UV-method with N. californicus for controlling T. urticae in strawberries.

Survival time and size of Neoseiulus californicus (Mesostigmata: Phytoseiidae) reared on different prey species and prey life stages

Neoseiulus californicus (McGregor) (Mesostigmata: Phytoseiidae) is among the most commonly used predatory mites in biological control programs. Tetranychus urticae Koch (Trombidiformes: Tetranychidae) and Polyphagotarsonemus latus (Banks) (Trombidiformes: Tarsonemidae) are the important pest mite species in many agricultural crops worldwide. In the present study, the effect of diet (varying in prey species, prey stage) on the future starvation tolerance and body size at maturity of N. californicus were investigated. The diets used for N. californicus were the mixed stages of P. latus, mixed stages of T. urticae, T. urticae eggs and T. urticae actives (larvae, protonyph and deutonymph). 1–2-day-old mated adult females were held without food and water at 25 ± 1 °C, 65 ± 5% relative humidity and 16:8 h light/dark photoperiod. The survival times of predators were recorded twice a day at 12-h intervals until they died. The dorsal shield lengths and widths of N. californicus females reared on the four different diets were separately measured. The results confirm that the starvation time and dorsal shield size of N. californicus females were influenced by diet type. The N. californicus females reared on active only or eggs only of T. urticae lived longer under no-food and no-water conditions than those of females reared on the mixed stages of T. urticae only or P. latus only. They were also longer than those females on the mixed stages of T. urticae only or P. latus only. Additionally, the females on T. urticae mixed stages only were larger than those of females on P. latus mixed stages only.

The impact of pesticides used in greenhouses, on the predatory mite neoseiulus californicus (parasitiformes, phytoseiidae)

Nine commercial pesticides currently used in Russian greenhouses against pests (aphids, thrips, whiteflies) were selected to determine their toxicity to predatory mite Neoseiulus californicus McGregor in order to find out the potential use him affected by chemical treatments Vertimec (abamectin), Fitoverm (aversectin C), Clipper (bifenthrin), Novaction (malation), Oberon (spiromesifen), Bitoxibacillin (Bacillus thuringiensis var. thuringiensis), Actara (tiametoxam), Admiral (piriproxifen), Confidor (imidacloprid), Mospilan (acetamiprid). The recommended concentration of the preparation (T), half the concentration (1/2T), and a double concentration (2T) were used on the female mite in the experiments. The side effects of the pesticides applied to the predator mite were determined one, three, and five days after the application. The recommended concentration of the preparation of Vertimec, Fitoverm and Clipper showed a higher toxic effect on N. californicus femails (mortality rate 100%). The obtained data reveals the impossibility of their joint application with the release of N. californicus. The toxic effects of Mospilan, Confidor, Admiral, Actara, Bitoxibacillin and Novaktion on N. californicus females were a low level (mortality of females 0-16,6%). The present study confirms that the use of predatory mite N. californicus in combination with these pesticides prospectively in Integrated Pest Management in Russian greenhouse conditions.

Continuous rearing of the predatory mite Neoseiulus californicus on an artificial diet

Neoseiulus californicus (McGregor) (Acari: Phytoseiidae) is one of the most efficient biological control agents of tetranychid mites and is commercially used in various countries around the world. In this study, four artificial diets were tested as an alternative food source for rearing N. californicus, and life table studies were performed to evaluate the nutritional value of the diets. Further, the performance of N. californicus reared for seven consecutive generations on the artificial diet enriched with Ephestia kuehniella Zeller eggs was assessed. The egg and larval periods of N. californicus did not differ among the natural prey (Tetranychus urticae Koch) and artificial diets, but the developmental times of the nymphal stages were significantly longer on any of the artificial diets than on the natural prey. The total fecundity of N. californicus was reduced when the predator was fed on any of the artificial diets as compared with T. urticae (54.33 eggs per female). Among the artificial diets, fecundity of N. californicus was best on a basic artificial diet enriched with E. kuehniella (AD2) (41.32 eggs per female). Moreover, AD2 did not significantly affect the longevity and reproduction of N. californicus females after long-term rearing on this artificial diet. The predation and reproduction capacities of N. californicus reared on AD2 for up to four generations were significantly reduced when the predator was switched to natural prey on the first day, but generally improved from the second to third day on. In conclusion, artificial diets supplemented with an extract of E. kuehniella eggs (20%) may have potential for use in the mass rearing of N. californicus.

Biological Aspects and Life Table Parameters of the Predatory Mite, Neoseiulus californicus McGregor (Acari: Phytoseiidae) Reared on Different Diets

The predator mite Neoseiulus californicus McGregor is an effective predator that is used to control the invasion of Tetranychus urticae Koch on crop plants. Experiments for rearing N. californicus on different food sources were carried out under laboratory condition (25±2oC, 75+5 % RH). N. californicus was reared on three different food types; two types of phytophagous mites (Tetranychus urticae and Brevipalpus phoenicis Geijskes) and date palm pollens. In response to food type, the periods of N. californicus immature stages were 4.79, 8.14, and 11.79 days for females and 3.93, 6.71, and 10.71 days for males when fed on T. urticae, B. phoenicis, and date palm pollen, respectively.The developmental periods (life cycle) of both female and male individuals were longer when they fed on date palm pollen (14.07, 12.86 days for females and males respectively) compared with 6.93, 5.79 days for females and males in case of feeding on T. urticae and 10.29, 8.79 days for those reared on B. phoenicis.N. californicus males completed their developmental stages on the studied food types successfully ,however, N. californicus females were significantly affected by the type of food, which recorded the highest number of eggs per each female when fed on T. urticae (32.14 eggs), followed by females that fed on B. phoenicis and date palm pollen (13.29 and 3.86 eggs, respectively). Obtained results provide alternatives of T. urticae to rear N. californicus for mass production although the efficiency was not the same.

Innate and acquired response of Neoseiulus barkeri and Neoseiulus californicus (Acari: Phytoseiidae) to spider mite induced plant volatiles

Predators may adjust their foraging behavior according to herbivore induced plant volatiles innately or through learning. Here, first we investigated whether the phytoseiid predatory mites, Neoseiulus californicus and N. barkeri were innately able to respond to odors related to Tetranychus urticae infested bean leaves. The naive predator females were reared on washed T. urticae as prey on filter paper with no experience of SIPV. The olfactory experiments showed that both N. barkeri and N. californicus significantly moved towards T. urticae infested bean leaves rather than clean air. Neoseiulus californicus significant preference of T. urticae infested bean leaves rather than clean tomato (as unfamiliar environment) confirmed the innate response in this species, while N. barkeri could not differentiate the latter odor sources so that its innate response considered weak. In a separate set of experiments, naive N. californicus females with no preference towards SIPV were experienced by receiving odors related to T. urticae infested bean leaves. The changed response (significant preference) of the experienced individuals showed the predator ability for acquired response. As the predator paired the odor with food absence/presence, associated learning was suggested as the mechanism. No acquired response was recorded for N. barkeri.

Anoxia treatment for selectively controlling spider mites Tetranychus urticae and Panonychus citri with little impact on the predatory mite Neoseiulus californicus

ABSTRACTAnoxia treatment with a deoxidant consisting of iron, calcium chloride and silicon dioxide was evaluated at different temperatures for pest spider mites (Tetranychus urticae and Panonychus citri) and their natural enemy, the predatory mite Neoseiulus californicus. No spider mite eggs survived when exposed to anoxia for 18 h at 20°C or for 12 h at 25°C, whereas the survival of N. californicus eggs under these conditions was 53% and 72%, respectively. No adult female spider mites survived when exposed to anoxia for 15 h at 20°C or for 8 h at 25°C, whereas >95% of adult N. californicus females survived under these conditions. These results indicate that anoxia has potential as a selective method for controlling pest mites, such as T. urticae and P. citri, but has little impact on their natural enemy, N. californicus.

Intraguild interactions among three spider mite predators: predation preference and effects on juvenile development and oviposition.

A first step to evaluate potential negative effects of intraguild predation (IGP) when using multiple predators against a pest species is the determination of the predation behavior of the predators and the nutritional value of intraguild (IG) prey in terms of development and oviposition. Here, we investigated the predation preference of the female predatory mites Neoseiulus californicus, Typhlodromus bagdasarjani and Phytoseius plumifer, when having choice between larvae of the two other predatory mite species (IG prey) with and without extraguild prey, the spider mite Tetranychus urticae (EG prey). Additionally, we evaluated the juvenile development and oviposition of the three predator species when provided with larvae from each other species. Irrespective of EG prey, IG prey species affected neither the first attack nor attack times of the three female IG predator species. The IG predation rates of the predator females, however, were influenced by prey species in the absence of EG prey. Neoseiulus californicus females killed more P. plumifer than T. bagdasarjani larvae, whereas T. bagdasarjani and P. plumifer females killed more N. californicus than P. plumifer and T. bagdasarjani larvae, respectively. All IG predator species consumed significantly more EG than IG prey. IG prey species did not influence juvenile and adult survival probabilities of the IG predators. We conclude that IGP is a weak force among the three predators and the potential consequences of IGP should not result in the elimination of one by another tested predatory mite species at least in the presence of spider mites.

Interdependent effects of male and female body size plasticity on mating behaviour of predatory mites

The adaptive canalization hypothesis predicts that traits with low phenotypic plasticity are more fitness relevant, because they have been canalized via strong past selection, than traits with high phenotypic plasticity. Based on differing male body size plasticities of the predatory mites Phytoseiulus persimilis (low plasticity) and Neoseiulus californicus (high plasticity), we accordingly hypothesized that small male body size entails higher costs in female choice and male–male competition in P. persimilis than N. californicus. Males of both species are highly polygynous but females differ in the level of polyandry (low level in P. persimilis; medium level in N. californicus). We videotaped the mating interactions in triplets of either P. persimilis or N. californicus, consisting of a virgin female (small or standard-sized) and a small and a standard-sized male. Mating by both small and standard-sized P. persimilis females was biased towards standard-sized males, resulting from the interplay between female preference for standard-sized males and the inferiority of small males in male–male competition. In contrast, mating by N. californicus females was equally balanced between small and standard-sized males. Small N. californicus males were more aggressive (‘Napoleon complex’) in male–male competition, reducing the likelihood of encounter between the standard-sized male and the female, and thus counterbalancing female preference for standard-sized males. Our results support the hypothesis that male body size is more important to fitness in the low-level polyandrous P. persimilis than in the medium-level polyandrous N. californicus and provide a key example of the implications of sexually selected body size plasticity on mating behaviour.

Spectrum-Specific Uv Egg Damage and Dispersal Responses in the Phytoseiid Predatory MiteNeoseiulus californicus(Acari: Phytoseiidae)

Solar ultraviolet-B (UVB) radiation is deleterious to plant-dwelling mites. Neoseiulus californicus (McGregor) is a predominant predator of agriculturally important pest species of spider mite. However, phytoseiid mites are more vulnerable to UVB radiation than spider mites. Thus, the UVB radiation may influence decision making in foraging phytoseiid mites whether disperse or not. We tested the difference in impact and behavioral response among wavelengths of monochromatic UV radiation using a spectroscopic light source in N. californicus in the laboratory. We also examined whether the behavioral responses of N. californicus females to UV radiation varied based on the presence of prey (Tetranychus urticae Koch) eggs and residues (webs and excreta of T. urticae: foraging cue). The impact of UV radiation on the N. californicus egg hatchability varied drastically between wavelengths of ≤300 nm (0%) and ≥310 nm (100%). The N. californicus females escaped from UV radiation more quickly when they were irradiated with UV at shorter wavelength. Presence of T. urticae eggs had no effects arresting the escape of phytoseiid mites. In contrast, prey residues (including eggs) markedly detained N. californicus females from escaping under UV irradiation at ≥310 nm. However, N. californicus females quickly escaped when irradiated with UV at harmful 300 nm wavelength, regardless of prey cues. This indicates that the eyeless phytoseiid mite is capable of perceiving UV radiation, and whether escape or not is determined on the basis of harmful/harmless UV wavelength and presence/absence of foraging cues.

Effect of hot-water treatment on the two-spotted spider mite, Tetranychus urticae, and its predator, Neoseiulus californicus (Acari: Tetranychidae, Phytoseiidae)

Hot-water treatment has been used on various kinds of plants to control plant diseases and pests. Here, we determined the lethal times (LT50 and LT100) for various temperatures for the two-spotted spider mite, Tetranychus urticae, and the predatory mite, Neoseiulus californicus (Spical®). Mites were placed on strawberry leaf discs that were dipped in hot water. For T. urticae eggs, LT50 ranged from 250 s at 47.5°C to 1 s at 57°C, while LT100 ranged from 600 s at 47.5°C to 7 s at 57°C. For T. urticae females, LT50 ranged from 380 s at 47.5°C to 4 s at 57°C, while LT100 ranged from 1200 s at 47.5°C to 9 s at 57°C. For N. californicus eggs, LT50 ranged from 68 s at 45°C to 7 s at 50°C, while LT100 ranged from 300 s at 45°C to 6 s at 52.5°C. For N. californicus females, LT50 ranged from 107 s at 45°C to 6 s at 50°C, while LT100 ranged from 180 s at 45°C to 6 s at 52.5°C. LT50s for N. californicus eggs and females were 4–10 and 13–32 times shorter than those of T. urticae, respectively. The strawberry leaves did not appear to be damaged (i.e., they did not show significant wilting) when treated for 150 s at 50°C, 30 s at 55°C or 20 s at 57°C. Together, these results suggest that hot-water treatment can be used to control spider mites on strawberry, without much damage to the plants, but predatory mites may need to be replaced due to their sensitivity to hot water.

Predation, oviposition and conversion rates of the predacious mite, Neoseiulus californicus (McGregor) consuming different densities of Tetranychus urticae Koch, Bemisia tabaci (Genn.) and Thrips tabaci Lind.

Rates of prey consumption, egg production and prey conversion by the predacious mite, Neoseiulus californicus (McGregor) were estimated at different densities of Tetranychus urticae Koch, Bemisia tabaci (Genn.) and Thrips tabaci Lind. in the laboratory. N. californicus females functionally and numerically responded to the increasing densities of T. urticae nymphs, B. tabaci nymphs and T. tabaci larvae showing Holling’s type II. The maximum mean predation and oviposition rates by the predator females devouring T. urticae, B. tabaci and T. tabaci occurred at 15, 10 and 10 prey individuals/day, respectively, followed by the plateau levels at higher prey densities. N. californicus females exhibited the highest feeding and oviposition on T. urticae nymphs, followed by T. tabaci larvae and B. tabaci nymphs. The predator females showed the highest efficiency in converting the prey into egg progeny at 5 individuals/day of the previous prey species, respectively. T. urticae was the most favourable for N. californicus females, followed by T. tabaci and B. tabaci.

Alternating temperatures affect life table parameters of Phytoseiulus persimilis, Neoseiulus californicus (Acari: Phytoseiidae) and their prey Tetranychus urticae (Acari: Tetranychidae)

Increasing energy costs force glasshouse growers to switch to energy saving strategies. In the temperature integration approach, considerable daily temperature variations are allowed, which not only have an important influence on plant growth but also on the development rate of arthropods in the crop. Therefore, we examined the influence of two constant temperature regimes (15 °C/15 °C and 20 °C/20 °C) and one alternating temperature regime (20 °C/5 °C, with an average of 15 °C) on life table parameters of Phytoseiulus persimilis and Neoseiulus californicus and their target pest, the two-spotted spider mite Tetranychus urticae at a 16:8 (L:D) h photoperiod and 65 ± 5 % RH. For females of both predatory mites the alternating temperature regime resulted in a 25-30 % shorter developmental time as compared to the corresponding mean constant temperature regime of 15 °C/15 °C. The immature development of female spider mites was prolonged for 7 days at 15 °C/15 °C as compared to 20 °C/5 °C. With a daytime temperature of 20 °C, no differences in lifetime fecundity were observed between a nighttime temperature of 20 and 5 °C for P. persimilis and T. urticae. The two latter species did show a higher lifetime fecundity at 20 °C/5 °C than at 15 °C/15 °C, and their daily fecundity at the alternating regime was about 30 % higher than at the corresponding mean constant temperature. P. persimilis and T. urticae showed no differences in sex ratio between the three temperature regimes, whereas the proportion of N. californicus females at 15 °C/15 °C (54.2 %) was significantly lower than that at 20 °C/5 °C (69.4 %) and 20 °C/20 °C (67.2 %). Intrinsic rates of increase were higher at the alternating temperature than at the corresponding mean constant temperature for both pest and predators. Our results indicate that thermal responses of the studied phytoseiid predators to alternating temperature regimes used in energy saving strategies in glasshouse crops may have consequences for their efficacy in biological control programs.

Survival, fecundity and reproductive recovery period of Neoseiulus californicus (McGregor) during long-term preservation on maize pollen and after switch to Tetranychus urticae Koch

Immature stages of the predacious mite, Neoseiulus californicus (McGregor) were reared on eggs of Tetranychus urticae Koch and gravid females were preserved on pollen of maize, Zea mays L. for 30, 45, 60 and 80 days. Afterwards, pollen was shifted to prey eggs for 15 days to evaluate their survival, fecundity and reproductive recovery period. All adult females of N. californicus survived the different maintenance periods and the following 15 days after pollen switch to the prey. Furthermore, predator females consuming pollen produced relatively few eggs during the preservation experiments, while they laid the majority of eggs during 15 days after pollen change to T. urticae without a second mating. The fecundity during the conservation periods significantly increased with increasing the maintenance period, whereas the reverse occurred subsequent to the shift to the prey. Moreover, the reproductive recovery period after the switch to T. urticae was inversely associated with the preservation period. Therefore, maize pollen is a useful alternative food for long-term survival and for maintaining fecundity of N. californicus females to exhibit an adequate numerical response to T. urticae at a subsequent time.

Biological aspects and life table parameters of the predacious mite, Neoseiulus californicus (McGregor) (Acari: Phytoseiidae) consuming food types during immature stages and after adult emergence

To investigate the effect of food types on biological aspects and life table parameters of the predacious mite, Neoseiulus californicus (McGregor), immature stages were fed on pollen of maize, Zea mays L. and eggs of Tetranychus urticae Koch, while adult females were offered the same foods and the alternate shift of each food. All individuals of predator females reached adulthood when reared on maize pollen and prey eggs, but their life cycle was significantly longer on pollen than on prey. The shortest preoviposition period of N. californicus occurred after continuous feeding on T. urticae eggs, whereas the longest happened when fed on prey eggs switched to maize pollen. Continuous consuming of maize pollen showed the longest ovipositoin period for the predator, while rearing on maize pollen shifted to prey eggs exhibited the shortest duration. The longest longevity and highest sex ratio of females to total in N. californicus were recorded when continuously utilised pollen, whereas the shortest longevity and lowest sex ratio were noted when continuously consumed prey. On the contrary, the egg production and life table values of the predator were the highest by continuous feeding on prey eggs, while they were the lowest by continuous rearing on maize pollen. Therefore, feeding juveniles on prey eggs and adult females on maize pollen is better for long-term preservation of N. californicus females than continuous feeding on maize pollen due to a shorter developmental duration, a higher egg production and more favourable life table values.

Humidity‐controlled cold storage of Neoseiulus californicus (Acari: Phytoseiidae): effects on male survival and reproductive ability

AbstractHumidification can suppress water loss from an organism and has great potential for improving the cold storage of short‐lived arthropods, such as predatory mites. The effectiveness of humidity‐controlled cold storage was recently verified for Neoseiulus californicus (McGregor) females but was not examined for males. Combining both males and females in one storage protocol might increase the predator population because it would enhance the opportunity for multiple mating, which is necessary for females to maximize their egg production. Newly emerged adult males were stored at an air temperature of 5°C and relative humidity (RH) of 100% or 80%. The median survival time (LT50) was 32 days at 100% RH and 14 days at 80% RH; the survival curves differed significantly. Males stored at 100% RH for 0, 10, 20 and 30 days were introduced to virgin females for mating at 25°C to evaluate their reproductive ability. The pre‐oviposition period was significantly prolonged in the females mated with males stored for ≥20 days. No negative effects of storage were observed on the oviposition period, total number of eggs or net reproduction rate (R0) in the females mated with males stored for ≤20 days or on the mean generation time (T) for those stored for 30 days. A slight decrease in the intrinsic rate of increase (rm) was observed in the females mated with males stored for ≥20 days. Our storage method can preserve N. californicus males for 20 days with only a minor reduction in their survival and reproductive ability.