| Predatory mite, Neoseiulus californicus (McGregor)(Acari: Phytoseiidae) is anew recorded species in China. In this paper, we investigated the dispersal and spatialpattern of this species and its prey, the main contents of the dissertation are asfollows:（1）The indoor ambulatory dispersal experiments about N. californicus shows:a negative correlation between the N. californicus crawling speed and its prey density,the higher prey density in its habitat reduce the ambulatory dispersal of N.californicus; the N. californicus crawling speed is related to its feeding experience,starved predators stayed longer in a prey patch than those that had not experiencedstarvation and the higher prey density due to a more obvious phenomenon: the higherdensity N. californicus stayed shorter in the original habitat compared with the lowerdensity N. californicus when it is in starvation, but when the prey density is lower, thephenomenon is not obvious, so the availability of food in the environment sloweddown dispersion; deutonymphs and adult females ambulatory dispersal speed are notobvious difference; the total prey consumption of predators appears to be related totheir longer residence time on source disks (correlation coefficient is0.713).(2) Spider mites and predation mites density changes in greenhouse: when spidermites released separately, the T. cinnabarinus population density had increasedrapidly over time to13.12fold of initial density within15days in the absence of N.californicus; when the predatory mites are separately released, the population densityis little changed, and the N. californicus population density maintains at initial levelin the absence of T. cinnabarinus, can be maintained for at least15days in thegreenhouse; when T. cinnabarinus and N. californicus released together, the preypopulation density is suppressed, the population prey density slowly climb upincreased slowly, reached a peak only1/20as high as that in the absence of predatorca.6-9days after release, and started to decrease. Predatory population showed asimilar changing pattern, with its peak3-6days later than that of the prey. The peak predator density was ca.3.67fold of release density, and then decline, and the densityreach its peak after6-9days investigation; within a certain range, when a lowerpredatory prey ratio, the prey population density decrease quickly and predation mitepopulation is growing rapidly.(3) Both species showed aggregated distribution pattern. During early bloomingstage, T. cinnabarinus population mainly gathered at lower parts of the plant in theabsence of predators. A slow upward moving trend was observed, with mediumpopulation height increased from3th leaf to4.8th, however, the relative mediumpopulation height, assuming the overall plant height, is1decreased from0.3to0.24.This result suggested the dispersal speed of T. cinnabarinus is slower than plantgrowth speed. During fruiting stage, medium population height (0.58) of T.cinnabarinus is higher than that of early flowering stage, which is consistent with theupward moving trend observed in early flowering stage. Later in the season, olderleaves at the bottom were not able to provide sufficient nutrient demand required by T.cinnabarinus population, especially when population density is high. Similardistribution pattern of T. cinnabarinus were observed when N. californicus were alsoreleased, only except for a slower upward moving trend possibly resulted from lowerT. cinnabarinus population density due to predation. With the relative mediumpopulation height is0.28(assuming the overall plant height being1), correspondingto the3rd-4th leaf from the bottom (ca.13leaves in total). An upward migration trendwas observed. In the absence of prey, N. californicus move upward immediately afterrelease, possibly due to its phototaxis feature, in early bloom stage, N. californicusrelative medium population height is ca.0.81, in fruiting stage, N. californicusrelative medium population height is ca.0.75. In contrast, when T. cinnabarinus wasalso released, its relative medium population height decreased to0.31and0.64inearly flowering stage and fruiting stage, respectively. A high correlation coefficient(0.75) was observed between medium population height of both species whenreleased together, suggesting strong capability of N. californicus to locate preys ongreenhouse cucumber. |
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