| Blattisocius dentriticus （Berlese） is an important parasitoid of the major stored-product mite,Tyrophagus putrescentiae （Schrank）,and plays an important role in the natural control of T. putrescentiae. This paper studied the biology and ecology of B. dentriticus feeding on T. putrescentiae and its application. The main contents and conclusions are as follows:Biology of B. dentriticusB. dentriticus could feed on T. putrescentiae,Panonychus citri （McGrigor） and Oligonychus hainanensis Ma,Yuan & Lin. The predatory mites would cannibalize when the food was deficient. The predatory action of B. dentriticus on T. putrescentiae could be divided into five sections: searching,catching,sucking,cleaning and resting. Satiated female of B. dentriticus spent 9.47% of its time budget in feeding with T. putrescentiae. It was significantly lower than that of starved female,which spent 21.68% of its time on feeding. Satiated female spent 14.28%,29.93% and 48.12% of its time in cleaning,resting and searching,respectively,while starved female spent 8.47%,16.90% and 55.47% of its time in cleaning,resting and searching,respectively. Different instar stages had strong capacity for hunger,the adult mite could endure 7.17d on average,the longest time for hunger reached 12d. It reproduced 40 generations in a year in Guangzhou and had no hibernation and aestivation phenomenon. The reproduction style of the B. dentriticus was amphigenesis. At 29℃,one female adult could at most laid 70 eggs in one generation and average 4 eggs in one day,the sex ratio （♀:♂） was 13:7. The intrinsic rate of natural increase （rm） of B. dentriticus was 0.22. The net reproduction rate （R0） was 21.11. The finite rate of natural increase （λ） was 1.58.Ecology of B. dentriticusThe effects of different constant temperatures on development and survivorship of B. dentriticus were studied. Among the range of temperature 20℃to 29℃,the development period for each stage of egg to adult of B. dentriticus decreased as the temperature increased. But over 29℃,the development period for each stage of egg to adult of B. dentriticus increased gradually with increasing temperature. By the method of priority law,the developmental threshold temperature is 12.87℃and the effective accumulative temperature of development periods is 147.19℃·d. The preoviposition periods of B. dentriticus shortened with temperature increasing at the range of 20℃～29℃. But over 29℃, the preoviposition periods of B. dentriticus prolonged significantly as the temperature increased. The generation survival rates of B. dentriticus were 100% at the range of 23℃～32℃. At 20℃,the generation survival rate of B. dentriticus was 90%. At 35℃,the generation survival rate of B. dentriticus was 85%.Dispersal ability of B. dentriticusThe dispersal ability of B. dentriticus adults was studied in the greenhouse by mark-recapture method. Based on the Data of experiment,the dispersal models were built. The average distance of diffusion between different plants is 28.67cm an hour. The results indicated that the dispersal density of B. dentriticus was correlated with the reciprocal of dispersal distance.Feeding habit on plant pollens of B. dentriticusPollens of 12 plants were used as foods for feeding habit study of B. dentriticus,the result showed that 7 species of them （Zea mays,Ipomoea plamata,Ricinus communis,L. cylindrica,Hibiscus sinensis,Musa nana and Canna indica） were ingested by B. dentriticus and the mites could deposit eggs,while the others （Citrus roticulata,Bauhinia variegata,Nicotiana tabacum,Bauhinia blakeana and Amylis vittata） were no eggs. The mite reared with L. cylindrica pollen and Canna indica pollen had faster development, longer longevity,higher egg deposition and higher population tendency index. Therefore,these two pollens were suggested as alternative food to feed B. dentriticus in the laboratory.The experiments on controlling effect of B. dentriticus on T. putrescentiaeThere are distinct differences in the favorite level for the different stage of T. putrescentiae. Larva is the preferable prey. Following are egg and nymph,adult is distasted.In this experiment,HollingⅡNa= （1.0186×Nt）/（1+1.0186×0.0102×Nt） fit the formula of the functional response that the female predacious mites of B. dentriticus prey on the egg of T. putrescentiae. The size of the habitat and starvation could affect the parameter of the functional response,but could not change the category of formula. The results indicated that starvation could increase the searching efficiency of the female predacious mites under 24～48 hours,but would decrease when it was beyond. Temperature also affected the functional response. Among the range of temperature 17℃to 29℃,the handling time （Th） shortened and the instantaneous search rate （a） of female of B. dentriticus increased with increasing temperature. But over 29℃,the instantaneous search rate （a） of the females of B. dentriticus decreased significantly as the temperature increased.Laboratory experiment was conducted to assess the effectiveness of B. dentriticus for suppressing populations of T. putrescentiae. The results indicated that the best biological control was obtained when the predator was released at the ratio of predator:prey as 1:4. The result of the releasing experiment suggested that B. dentriticus could work well in biological control program on T. putrescentiae.The experiments on controlling effect of B. dentriticus on B. obovatusIn this experiment, HollingⅡNa= （0.7461×Nt）/（1+0.7462×0.0126×Nt） fit the formula of the functional response of B. dentriticus on the egg of B. obovatus. It shows that there are distinct differences in the favorite level for the different stage of B. obovatus. Egg is the preferable prey. Following are nymph and adult, larva is distasted. The result supposed that HollingⅡis better fitting the functional response that B. dentriticus prey on the egg of B. obovatus. The size of the habitat and starvation can affect the parameter of the functional response, but do not change the category of formula. The result of the interference response supposes that the predacious rate of B. dentriticus will decrease with the increase of predator density. With the further increase of the density of predator, searching efficiency will decrease quickly.The experiments on controlling effect of B. dentriticus on P. citriThe potential of B. dentriticus to control P. citri was studied in the greenhouse. B. dentriticus demonstrated a satisfactory Agent to control P. citri in the greenhouse release experiment. Non-significant difference of control effect was obtained when the predators were released at the ratios of predator:prey as 1:3,1:5 and 1:8. The ratio of predator: prey as 1:8 was suggested as the best chose for control based on the controlling cost... |
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