Breeding And Predation Evaluating Of Longevity Population Of Neoseiulus Californicus(McGregor)

Neoseiulus californicus（Mc Gregor）belongs to the family Phytoseiidae,a predator mite group with biocontrol potential against small agricultural pests such as spider mites,thrips,and whiteflies.At present,the improvement and upgrading of the existing products and objects of predatory mites is one of the important contents of the industrialization of natural enemies.In the pest-predator mite system,the lifespan of predator mite is a very important factor affecting the offspring population and the duration of pest mite control.Prolonging its lifespan is of positive significance to enhance sustainable control of spider mites.Plant pollen is rich in sugar,lipid,protein,flavonoids,and other nutrients,which have special significance in regulating the growth and development,fecundity and life span of insects and mites.Pollens,as alternative foods,can prolong the life span of predatory mites to a certain extent,compared with feeding only on natural prey.In this study,five kinds of pollen such as pear,plum,apple,peach and almond were used as the food of N.californicus to select long-lifespan population based on the age-stage two-sex life table,and the nutrients of these pollen were measured.Alternative food pollen was selected to prolong its lifespan,and its lifespan and predation ability were evaluated after multiple generations of feeding.The main results are as follows:1 Construction the age-stage two-sex life table of N.californicus fed on five pollens as alternative foodThe N.californicus mites reared with pollens of five plant species（five pollens in short bellow）,pear,plum,apple,peach and almond,and the prey Tetranychus urticae could complete their growth,development,and reproduction.The five pollens could therefore be used as alternative foods to maintain the population of N.californicus.The average life span of N.californicus adults fed on apple pollen and almond pollen was the longest,the lifespan of female adult was 40.18 d and 37.31 d,and that of male adult mite was 37.21 d and 34.63 d,respectively.The adult life span of all populations of N.californicus fed on five pollens was longer than that of adult mites fed on T.urticae only.The intrinsic growth rate（r）of N.californicus raised by the five pollens and T.urticae was of 0.23 to 0.28.Although the intrinsic growth rate of N.californicus fed on apple pollen was the lowest（0.23）,but its net proliferation rate（R₀）and fecundity（F）had no differences from that of the fed on natural prey,and its life span was the longest among all the tested populations.Eating apple pollen as an alternative food can complete the population breeding and prolong the lifespan of N.californicus.2 Determination of main nutrients in five kinds of pollenThe contents of sugars（glucose,fructose,sucrose and polysaccharide）,lipid,protein and flavonoids of the five pollens were different.The protein contents of the five pollens,285.46-327.67 mg/g,were significantly higher than that of other nutrients,and the protein content of apple pollen was the highest,327.67mg/g.The content of lipid in the five pollen was 13-5.5 mg/g,the highest in apple pollen,which was significantly lower than that in other pollen.Among sugar nutrients,the content of sucrose in the five pollens was the highest,80.03-101.93 mg/g,and among which that of peach pollen was the highest,101.93mg/g;The fructose of the five pollens was11.80-24.19mg/g,the glucose was 21.57-33.00mg/g,and the polysaccharide was14.71-19.61mg/g.The content of flavonoids in the five pollens was 8.75-22.57mg/g,and the highest was that of plum pollen.The contents of protein and lipid in pollen may be the factors effecting the lifespan of N.californicus.3 Evaluation of lifespan of N.californicus reared continuously with alternative foodAfter 12 generations of continuous rearing of N.californicus on apple pollen as a alternative food,there was no significant difference in the adult preovipositional period,ovipositional period and fecundity among the tested generations.The differences were measured more or less in female adult mite life,male adult mite life and late oviposition among the tested generations.From G1 to G3,life spans of the female and male adult mites,and female spawning period were significantly prolonged;then in G3 to G12,the life span of female and male adults and late spawning period had a shortening trend to a certain extent,but there was no significant difference.Therefore,after rearing on apple pollen as an alternative food for several generations,the N.californicus can still maintain a long lifespan and normal fecundity.4 Evaluation of predation functional response of N.californicus reared continuously with alternative foodUnder the two conditions of providing T.urticae eggs and T.urticae eggs+pollen,the predatory functional response of the N.californicus fed on apple pollen in G1-G12 generations to T.urticae eggs conformed to Holling type II disk equation.The predation ability of G1 generation was the strongest,and a/T_hvalues of the two treatments were 53.61 and 51.64 respectively;The predation ability declined from G3generation,and a/T_hvalues of the two treatments were 45.1 and 37.87 in G12respectively.In addition,the predation ability of N.californicus,throughout the generations feeding on pollen,would be weakened to a certain extent,but N.californicus could not lose predation ability to natural prey.Although alternative foods such as pollen may lead the depression of predation ability of predatory mites,the pollens are conducive to maintain the population of predatory mites and have advantages in the integrated control of harmful mites.In general,the study clarified that apple pollen could significantly prolong the lifespan of N.californicus.The content of protein and lipid in pollen might be important factors affecting the lifespan of N.californicus.After multiple generations fed on apple pollen,the N.californicus still had long life,good fecundity,and predation ability though which was weakened in some ways.The results are of theoretical and practical significance for understanding the ability of predatory mites and making efficient and reasonable control measures for continuous control of spider mites.