Functional responses of two species of predatory mites (Acari: Phytoseiidae) to eggs and first-instar nymphs of Bactericera Gobica Logniova (Homoptera: Psyllidae).

The goji berry psyllid, Bactericera gobica Logniova (Homoptera: Psyllidae), is one of the most important pests on goji berry plants (Lycium barbarum L.), whose fruits are widely used in traditional Chinese medicine and food. However, chemical control is still the predominant control strategy of this pest. Recently, two species of predatory mites, Neoseiulus setarius Ma, Meng & Fan and Neoseiulus barkeri Hughes were found to be associated with B. gobica in China. To assess their predation potential against B. gobica, the functional responses of these two phytoseiid species feeding on different densities (2, 4, 8, 12, 16, 24 and 32 individuals) of B. gobica eggs and 1st instar nymphs were compared at a temperature of 25ºC ± 1º C. Logistic regression analysis revealed that both predatory mite species exhibited type Holling-II functional responses on eggs and 1st instar nymphs of B. gobica, with the predation number increased for both predators as the density of prey increased. Overall, N. setarius consumed more prey compared to N. barkeri across all levels of prey densities. Meanwhile, the highest attack rate (α = 0.0283), the lowest handling time (Th = 1.1324 h prey- 1), and the highest estimated maximum predation rate (T/Th = 21.19 prey day- 1) were all observed for N. setarius fed with 1st instar nymphs of B. gobica. These findings suggest that it is worthy considering utilizing N. setarius and N. barkeri as candidate biocontrol agents of B. gobica, with N. setarius appearing to be a more effective predator than N. barkeri.

[Analgesic effect of buccal acupuncture on patients after lumbar spinal fusion: a randomized controlled trial].

OBJECTIVE: To observe the effect of buccal acupuncture on pain after lumbar spinal fusion. METHODS: Sixty patients undergoing lumbar spinal fusion were randomly divided into an observation group (30 cases, 1 case dropped off) and a control group (30 cases, 1 case was eliminated). The patients in the control group were treated with routine anesthesia. On the basis of the control group, the patients in the observation group were treated with buccal acupuncture at bilateral back point, waist point, and sacral point for 30 min per treatment. The first acupuncture was given before anesthesia induction, and then once a day postoperation for two days, totally 3 treatments. The dosage of sufentanil, the number of remedial analgesia, and the incidence of nausea and vomiting within 48 h after surgery were compared between the two groups; rest and motion visual analogue scale (VAS) scores at 2 (T1), 8 (T2), 12 (T3), 24 (T4), and 48 (T5) h after surgery were observed; the quality of recovery-15 scale (QoR-15) at 24 and 48 h after surgery were evaluated. RESULTS: The dosage of sufentanil and the number of remedial analgesia within 48 h after surgery in the observation group were lower than those in the control group (P<0.01). There was no significant statistically difference in rest and motion VAS scores between the two groups in T1, T2, T3, T4 and T5 (P>0.05). The QoR-15 scores in the observation group at 24 and 48 h after surgery were higher than those in the control group (P<0.01). The incidence of nausea in the observation group was lower than that in the control group (P<0.05). CONCLUSION: Buccal acupuncture could reduce the amount of postoperative analgesic drugs of patients after lumbar spinal fusion, and promote early postoperative recovery.

Rapid cold hardening response of the phytoseiid mite Neoseiulus striatus: increased cold tolerance but not reduced predation.

The predatory mite Neoseiulus striatus (Wu) (Acari: Phytoseiidae), which has been found on maize plants in Inner Mongolia, is regarded as a promising biological control agent of small sucking pests, especially Tetranychid mites. Temperature is an important abiotic factor, and a sudden drop in temperature may affect its performance when released in areas with big circadian temperature differences. Rapid cold hardening is a type of phenotypic plasticity that allows ectotherms to quickly enhance their cold tolerance in response to a brief chilling exposure. However, it is not clear whether N. striatus possesses such plasticity. To understand how this species of phytoseiid mite copes with short-term low-temperature stress, its rapid cold hardening response was studied in the laboratory by first exploring its critical temperature. Then, the effects of exposure to a series of temperatures (0, 5, 10, 15, and 20 °C) for different durations on the survival of N. striatus were investigated to determine the optimal temperature and duration for cold hardening. Moreover, the effect of cold hardening on the consumption of Tetranychus urticae by N. striatus was also investigated, as was the response of immature stages. The critical temperature for N. striatus was - 15 °C, at which its survival dropped below 10%. An exposure to 5 °C for 2 h was optimal for rapid cold hardening, efficiently increasing survival in N. striatus. Rapid cold hardening was found in all developmental stages of N. striatus, and there was no significant effect of exposure on the consumption of spider mites. Our study shows that exposure to low temperatures during a limited period can enhance the cold hardiness but not reduce predation by N. striatus, which will be advantageous to its field applications during a period of large diurnal temperature fluctuations.

Effects of Beauveria bassiana on predation and behavior of the predatory mite Phytoseiulus persimilis.

Determination of intraguild interactions between entomopathogens and predators is important when attempting to use a combination of these two natural enemy groups for biological control of their shared arthropod pest species. This study assessed the effects of Beauveria bassiana on the predation and associated behavior of the predatory mite, Phytoseiulus persimilis, against Tetranychus urticae. The functional response tests showed that P. persimilis exhibited a Holling type II response on the spider mite, Tetranychus urticae, when treated with either a B. bassiana or Tween-80 suspension. There were no significant differences between the treatments in the number of T. urticae consumed. The laboratory choice test indicated that P. persimilis displayed a significant avoidance response to B. bassiana on bean leaves immediately following spray application. They also spent significantly longer time in self-grooming behavior on leaf disks sprayed with fungal conidia than on discs treated with Tween-80. There were no significant differences in the predation rates on T. urticae eggs between the different treatments. The potted plant investigations indicated that P. persimilis showed significant aversion behavior to the initial fungal spray, but gradually dispersed over the entire bean plants. Observations using scanning electron microscopy revealed that fungal conidia were attached to the body of P. persimilis after mounting the leaf disk treated with B. bassiana, which would account for its varied behavioral responses. Our study suggests that fungal spray did not affect the predation capability of P. persimilis and poses a negligible risk to their behavior.

Limited predator-induced dispersal in whiteflies.

Whereas prey are known to avoid habitats with their predators, it is less well established whether they are triggered to emigrate to new habitats when exposed to predators in their current habitat. We studied plant-to-plant dispersal of adult whiteflies in response to the presence of predatory mites on the plant on which the whiteflies were released. These predators attack whitefly eggs and crawlers, but not the adults, which can fly to other plants and can learn to avoid plants with predators. Being tiny and wingless, the predatory mites are slow dispersers compared to adult whiteflies. This offers the whiteflies the opportunity to escape from plants with predatory mites to plants without predators, thus avoiding predation of their offspring. To test for this escape response, a greenhouse experiment was carried out, where whiteflies were released on the first of a row of 5 cucumber plants, 0.6 m or 2 m apart, and predators either on the same plant, on the next plant, or nowhere (control). Adult whiteflies dispersed significantly faster from plants with predatory mites onto neighbouring plants when the plants were 0.6 m apart, but not when plants were 2 m apart. However, the final numbers of whiteflies that had successfully dispersed at the end of the experiments did not differ significantly for either of the two interplant distances. Overall, the proportion of whiteflies that did disperse was low, suggesting that adult whiteflies were apparently reluctant to disperse, even from plants with predators. Our results suggest that this reluctance increases with the distance between the plants, so most likely depends on the uncertainty to find a new plant. Thus, whiteflies do not always venture to fly even when they can easily bridge the distance to another plant.

[Relationships between host preference of Liriomyza huidobrensis (Blanchard) and nutrient and chlorophyll contents in host foliage].

The laboratory study with no free choice means showed that the host preference of Liriomyza huidobrensis (Blanchard) adult differed significantly with test plants. Phaseolus vulgaris, Chrysanthemum coronarium and Cucurbita pepo were the most preferred, while Lycopersicum esculenturn and Brassica oleracea were the least. Correlative analysis indicated that the host preference of L. huidobrensis adult had a significant positive correlation with the content of soluble sugar, but less correlation with soluble protein and chlorophyll contents in host foliage.

Previous and present diets of mite predators affect antipredator behaviour of whitefly prey.

Predator diet is known to influence antipredator behaviour in prey. Yet, it is not clear how antipredator behaviour is affected by diet changes of the predator. We studied the effect of previous and present diet of a predatory mite Typhlodromips swirskii on the antipredator response of its prey, the whitefly Bemisia tabaci. An earlier study showed that adult female whiteflies that had experienced predators, had learned to avoid ovipositing on plants with predators whose previous and present diet consisted of whitefly eggs and immatures. Here, we investigate whether adult whiteflies also avoid plants with predators whose present and/or previous diet consisted of a non-whitefly food source. Adult whiteflies were found not to avoid plants with predators whose present diet consisted of pollen and whose previous diet had consisted of either pollen or whitefly eggs and larvae. They did avoid plants with predators whose present diet consisted of whiteflies and whose previous diet had consisted of pollen, but to a lesser extent than when previous and present diet consisted of whiteflies. In a choice experiment, whiteflies discriminated between plants with predators whose present diet consisted of whiteflies, but that differed in previous diet. Our results show that both previous and present diets of predators are important in eliciting antipredator behaviour.

How predatory mites find plants with whitefly prey.

We investigated the searching behaviour of two species of predatory mites, Typhlodromips swirskii (Athias-Henriot) and Euseius scutalis (Athias-Henriot), both known to feed on immature stages of the whitefly Bemisia tabaci Gennadius. When released in a greenhouse inside a circle of cucumber plants that were alternatingly clean or infested with immature whiteflies, the mites took several days to find plants. Both species were recaptured significantly more on plants with whiteflies. This suggests that the mites are able to discriminate between plants with and without whiteflies. The predators may either have been attracted to plants with whiteflies from a distance or arrested on plants with whiteflies. Typhlodromips swirskii that had previously fed on whitefly immatures on cucumber leaves were significantly attracted by volatiles from cucumber plants with whiteflies in a Y-tube olfactometer. This suggests that the mites use volatile cues to discriminate between infested and clean plants. However, this response waned rapidly; if predators, experienced as above, were starved for 3-4 h in absence of cucumber leaves, they no longer preferred volatiles of infested plants to clean plants. Furthermore, T. swirskii that had no experience with immature whiteflies on cucumber plants also did not prefer odours of infested plants to those of clean plants. Because the release experiment with this species in the greenhouse was done with inexperienced predators, this suggests that the aggregation of mites on plants with whiteflies was mainly caused by differential arrestment of mites on plants with prey and clean plants. For T. swirskii, this was in agreement with the finding that the fraction of predators on plants with prey increased with time to levels higher than 70%. A less clear trend was found for E. scutalis, for which the fraction of predators on plants with prey stabilized soon after release to levels from 54-70%. Hence, the predatory mites may find plants with prey by random searching, but they are subsequently arrested on these plants. An earlier study showed that 87% of all whiteflies released in a set-up as used here were recaptured within 1 day. Hence, the effectiveness with which predatory mites locate plants with whiteflies is low compared with that of their prey. We expect this to generate spatial patterns in the dynamics of predator and prey and this may have consequences for biological control of whiteflies with predatory mites.