Studies On The Experimental Population Ecology Of Neoseiulus Dinghushanensis(Acari: Phytoseiidae)

Predatory mite, Neoseiulus dinghushanensis (Acari: Phytoseiidae) is newly identified as phytoseiidspecies in China.The preliminary experiment showed that N. dinghushanensis has high consumptionrate and high fecundity when spider mites were supplied as food. In order to estimated whether N.dinghushanensis could be used as a biological control agent of spider mites, studies on the experimentalpopulation ecology of N. dinghushanensis were systematically carried out.The main content and resultswere as follows:The prey preference and functional response of the predatory mite, N. dinghushanensis on different developmentalstages of T. cinnabarinus were studied in251℃,805%RH, and a16:8h L: D photoperiod. Its functional responseto spider mites was also compared with another predatory mite, Amblyseius pseudolongispinosus. Theresults showed that N. dinghushanensis preferred consuming nymph than larva of spider mite, whileeggs were the least preferred stage. When more than20eggs or15nymphs of spider mites weresupplied, N. dinghushanensis preyed more than A. pseudolongispinosus did. Functional response fortwo species on each stage (egg, larva or nymph) of T. cinnabarinus could be described by the HollingⅡtype. The suppression (a’/Th) of these three developmental stages of T. cinnabarinus by N.dinghushanensis was greater than that by A. pseudolongispinosus. When eggs or nymphs of T.cinnabarinus were supplied, N. dinghushanensis preyed35.0or37.1%more than A.pseudolongispinosus did in the daily maximum theoretic number of prey consumed. However,8.0%lessthan the latter when the larva of T. cinnabarinus was supplied.The effect of six constant temperatures (15,20,25,20,32and35℃) on the development, survivaland reproduction of N. dinghushanensis fed on T. cinnabarinus was examined in the laboratory. Theresults indicated that within the range of15-30℃, the development duration of egg, larva, protonymph,deutonymph shortened with temperature increased, the total developmental duration from egg to adultvaried from11.2to3.6days. The development time of egg, larva, protonymph, deutonymph didn’tshorten and even extend when the temperature is higher than32℃. At35℃, the predatory mite coulddevelop, but its mortality rate was more than54%, and fertilized female mite couldn’t spawn normally.The lower threshold for development and thermal constant from egg to adult were6.37℃and99.00degree-days. The logistic model accurately described the effect of temperature on developmental rate ofN. dinghushanensis. The oviposition duration and the mean lifetime decreased with the temperatureincreased, whereas daily fecundity was inversely related to temperature. The lifetime fecundity had nosignificant correlation at constant different temperatures, which reached an average of fifty. Both sexratios (71%,73%) and net reproductive rate (R0) were the highest (38.58,38.80) at20℃and25℃.The effect of relative humidity on development of eggs and larva for N. dinghushanensis wasstudied at25℃, The results indicated that the egg could not hatch normally when relative humiditywas34.97%. The hatching rate of egg increased as the relative humidity increased with the relativehumidity range from57.11to66%. When relative humidity was more than66%, the hatching rate ofegg did not increase significantly. The larva could not survival when relative humidity was less than57.11%. The survival rate of egg increased as the relative humidity increased with the relative humidity range from57.11to93%. Higher relative humidity is a propitious environment for N. dinghushanensisto develop.The life table of experimental population of N. dinghushanensis living on Carpoglyphus lactis wasstudied in251℃,805%RH, and a16:8h L: D photoperiod: When fed with C. lactis, the developmentalduration of N.dinghushanensis was5.7d, which increased by23.9%than fed with T. cinnabarinus. Allthe lifetime fecundity, oviposition duration and daily fecundity were decreased significantly, theproportion of N. dinghushanensis female off springs is shortened from72.8to56.57%. The lifetimefecundity had no significant correlation when fed with C. lactis or T. cinnabarinus. Mean generationtime was increased by4.7d, the net reproductive rate (R0) is shorten from38.58to5.70, higher intrinsicincrease rates is shorten from0.25to0.09. When C. lactis was provided as prey, N. dinghushanensiscould keep the individual development but it could not keep the population growth rapidly.