Impact Of Insect-sourced Diets On Stratiolaelaps Scimitus And Its Alternative Prey Tyrophagus Putrescentiae

Stratiolaelaps scimitus is a polyphagous and soil-dwelling predatory mite that has been commercialized and widely used.It is an important predatory natural enemy for the control of small insect pests and acarine pest.The mass-production of predatory mite is the premise to realize its commercial production and application,the nutrient level of prey or diet is closely related to the growth,development and reproduction of predatory mites.Therefore,the reproductive capacity and biological characteristics of predatory mite can be enhanced by improving the nutritional level of prey or diet.In this study,the effects of different insect-sourced diets on the growth,development and reproduction of S.scimitus,as well as the population growth and the contents of soluble protein and soluble sugar in the alternative prey,Tyrophagus putrescentiae were studied in the laboratory.Finally,on the basis of mass rearing T.putrescentiae with different insect-sourced diets,the impact of different nutrient levels of T.putrescentiae on the growth,development and reproduction of S.scimitus were studied.By measuring the contents of crude protein,crude fat,amino acid and glucose in different diets to analyze the causes of the data difference between different treatments.These results provide fundamental data for the mass-production of the predatory mite,S.scimitus and its alternative prey T.putrescentiae.All the main results are as follows:1.Feeding S.scimitus on four kinds of insect-sourced diets:Locusta migratoria manilensis,Tenebrio molitor,Musca domestica and Hermetia illucens,the developmental duration of S.scimitus’s each stage was significantly longer compared with feeding S.scimitus on T.putrescentiae,and the probability of S.scimitus developing to the adult stage was very small,indicating that the four kinds of insect-sourced diets were not suitable as the food of S.scimitus.The biological parameters and population parameters of S.scimitus reared on L.migratoria manilensis were analyzed based on the theory of the age-stage,two-sex life table.When reared S.scimitus with L.migratoria manilensis,the protonymph,deutonymph and pre-adult were significantly longer than those fed on T.putrescentiae;the average fecundity（F）was only 0.67 eggs/female;the intrinsic rate of increase（r）was only-0.0700 d^-1;the net reproductive rate（R₀）was only 0.03;the mean generation time（T）was 48.13d.These results indicated that the development and reproduction of S.scimitus could not be completed by fed on L.migratoria manilensis.2.When fed T.putrescentiae on different diets for seven weeks,the population density of T.putrescentiae was the highest when reared on L.migratoria manilensis within six weeks.In the seventh week,the population density of T.putrescentiae fed on yeast exceeded that of T.putrescentiae fed on L.migratoria manilensis.When T.putrescentiae fed on yeast,L.migratoria manilensis,T.molitor,M.domestica and H.illucens,the population quantity was multiplied 89.73 times,73.67 times,34.14 times,33.91 times and 6.42 times,respectively.3.The soluble protein and soluble sugar content of T.putrescentiae were significantly different when fed on different diets,which were not positively correlated with the crude protein and glucose content of the diet.The content of soluble protein of L.migratoria manilensis group（a group of T.putrescentiae fed on L.migratoria manilensis）and Tenebrio molitor group（a group of T.putrescentiae fed on Tenebrio molitor）were lower than those in control group.The content of soluble sugar of L.migratoria manilensis group was not significantly different from that in control group,the content of soluble sugar of Tenebrio molitor group was significantly lower than that in control group.4.The biological parameters and population parameters of S.scimitus reared on T.putrescentiae with different nutrient levels were determined based on the theory of the age-stage,two-sex life table.There was no significant difference in the pre-adult,female adult longevity,APOP and TPOP when S.scimitus fed on three groups of T.putrescentiae with different nutritional levels.When reared S.scimitus with the L.migratoria manilensis group（a group of T.putrescentiae fed on L.migratoria manilensis）,yeast group（a group of T.putrescentiae fed on yeast）and Tenebrio molitor group（a group of T.putrescentiae fed on Tenebrio molitor）,the average fecundities（F）were 71.94,67.09 and 61.49 eggs/female,respectively;the intrinsic rates of increase（r）were 0.1666 d^-1,0.1543 d^-1and 0.1465 d^-1,respectively;the finite rates of increase（λ）were 1.1813 d^-1,1.1668 d^-1and 1.1577 d^-1,respectively;the net reproductive rates（R₀）were 62.51,41.93 and 46.69,respectively;the mean generation time（T）was 24.82 d,24.22 d and 26.24 d,respectively.Based on the above life table parameters and with 50 eggs as the benchmark,we simulated and predicted the population growth dynamics of S.scimitus in the next 90 d when fed it on three groups of T.putrescentiae.It was found that when S.scimitus fed on L.migratoria manilensis group,the population growth of other developmental stages of S.scimitus were faster than the other two groups of food except for male adult.These results indicated that L.migratoria manilensis group was more favorable to the growth,development and reproduction of S.scimitus.5.When fed S.scimitus on three groups of T.putrescentiae,there were significantly different in the length and width of the dorsal shield of the offspring female adults of S.scimitus,and width of the dorsal shield of the offspring male adults of S.scimitus,but no significant difference in the length of the dorsal shield of the offspring male adults of S.scimitus.The length and width of the dorsal shield of the offspring female adults of S.scimitus were 655.08μm and 368.01μm,respectively,when S.scimitus fed on L.migratoria manilensis group,which was not significantly different from that of yeast group（CK）,but significantly longer than that of Tenebrio molitor group.when S.scimitus fed on L.migratoria manilensis group,the width of the dorsal shield of the offspring male adults of S.scimitus was the longest（313.29μm）,which was significantly longer than that of yeast group（CK）and Tenebrio molitor group.These results showed that the L.migratoria manilensis group was more favorable to the development of S.scimitus’s offspring.When reared S.scimitus on the L.migratoria manilensis group,yeast group and Tenebrio molitor group,the proportions of female adult in offspring were 84.80%,84.02%and 77.17%,respectively.When reared S.scimitus on the L.migratoria manilensis group,the proportion of female adult in offspring was the largest,which was no significant difference of control group but significantly larger than that in Tenebrio molitor group.The results showed that the L.migratoria manilensis group and the control group could maintain a larger proportion of female adult in offspring,which was beneficial to the population breeding of predatory mite.