Studies On The Experimental Population Ecology Of Amblyseius Barkeri (Hughes) (Acarina: Phytoseiidae)

Amblyseius barkeri(Hughes) is the most abundant predatory m(?)te in the c(?)s orchards in the south of Jiangxi province.Studies on tbe experimental population ecology of A.barkeri were systematically carried out.The main content and results were as follows:1.Effect of temperature on development of A.barkeri:Within the temperature range from 16 to 32℃,the development duration of different immature stages decreased with the increasing temperature,the total developmental duration from egg to adalt varied from 4.98 to 17.51 days.Temperature had a significant effect on the development of A.barkeri.The lower thermal threshold for development and the thermal constant from egg to adult were 7.85℃and 115.33 degree-days.The Logistic model accurately described the effec(?) of temperature on developmental rate of A barkeri.2.Effect of relative humidity on development of A.barkeri:Within the relative humidity range from 50%to 90%,the developmental time of egg increased as the relative humidity increased,while the developmental time of larva,protonymph and deutonymph shortened as the relative humidity increased.Higher relative humidity is a propitious environment for A.barkeri to develop.Relative humidity had a significant effect on the hatching rate and survival rate of all immature stages of A. barkeri,but no significant effect on the sex ratio of A.barkeri.3.The experimental population life tables of A.barkeri were constructed at 16, 20,24,28and 32℃.The results showed that A.barkeri had the longest female longevity(48.10 days) at 16℃,but no eggs were laid at the temperature.At 20,24, 28 and 32℃,mated females laid on average 0.65,1.53,1.64 and 1.47 eggs per day, respectively.Both the maximum fecundity(30.85 eggs per female) and the highest intrinsic rate of increase(r_m=0.166) were obtained at 28℃.The preoviposition, postoviposition period and female longevity of A.barkeri all shortened as temperature increased.The longest oviposition period was observed at 24℃with 20.39 days.However,the temperature didn't have a significant effect on sex ratio of A.barkeri4.Functional responses of A.barkeri towards A.ovatus and P.citri:At five constant temperatures(16,20,24,28 and 32℃),A.barkeri exhibited strong predacity to A.ovatus and P.ci(?).The functional responses of A.barkeri on A.ovatus and P.citri approximated Holling typeⅡ.Over the full range of temperatures tested, the a/T_h value increased with increasing temperature,and peaked at 28℃.Adult female had the strongest predacity to A.ovatus and P.citri,while adult male had the poorest predacity.With a fixed number of preys available,predatory rate per predator decreased with increasing predator density due to mutual competition and interference.A.barkeri consumed significantly more larvae and nymphs than other stages of the prey P.citri.