Effect Of Photoperiod On Development Of Neoseiulus Barkeri (Hughes) And Its Applied Basic Research

Neoseiulus barkeri (Hughes) is the most abundant predatory mite in the citrus orchards in the south of Jiangxi province. Studies on the experimental population ecology of N. barkeri were systematically carried out.The main content and results were as follows:1. Effect of photoperiod on development of N.barkeri:Within different photoperiod, the development duration of different immature stages decreased in the L:D=4:20 to L:D=4:12 photoperiod,and increased in the L:D=12:12 to L:D=20:4 photoperiod, the total developmental duration from egg to adult varied from 5.43 to 8.55 days. Photoperiod had a significant effect on the hatching rate and survival rate of all immature stages of N.barkeri, but no significant effect on the sex ratio of N.barkeri.2. The experimental population life tables of N.barkeri were constructed at five different photoperiod:he results showed that N.barkeri had the longest female longevity (17.14 days) at L:D=20:4 photoperiod, At L:D=12:12 photoperod, mated females laid on average 1.43 eggs per day, respectively. The highest intrinsic rate of increase (rm=0.180) were obtained at L:D=12:12 photoperiod. The preoviposition and postoviposition period of N.barkeri all shortened as daylights increased in the L:D=4:20 to L:D=4:12 photoperiod, and lengthened as daylights decreased in the L:D=4:20 to L:D=4:12 photoperiod.The longest oviposition period was observed at L:D=12:12 with 11.89 days. However, the photoperiod didn't have a significant effect on sex ratio of N.barkeri.3. Study on spatial distribution type and sampling technique of N.barkeri: Several aggregation indices,Taylor power law and liner regression equation of Iwao were used to determine tha spatial distribution type of N.barkeri, and the spatial distribution type was assembly distribution.Aggregation was caused by both N.barker's biological characteristics and the environmental factors when the average density is above 2.89. The aggregation was caused by the environmental factors when the average density is blow 2.89. 4. Selective toxicity of some acaricides commonly used in citrus orchards between N.barkeri and Panonychus citri:High toxic of dimethyl disulfide,Avermectin and Fenpropathrin to N.barkeri suggested that the acaricides should not be used in citrus orchards where N.barkeri released for biological control.5 acaricides have sequence of selective toxicity between N.barkeri and P.citri as follows:lime-sulfur＞pyridaben＞azocyclotin＞mixture of avermectin and propargite＞propargite. The selective toxicity ratios of Lime-sulfur and pyridaben were 230.522 and 144.806, respectively, which ranged from 100 to 1000, showed strong positive regulation. It indicated that pyridaben and lime-sulfur were good agents to coordinate biochemical control and bio-control of pest mites in citrus orchards.