| Insects of the families Sciaridae and Scatopsidae in the order Diptera are major pests attacking mushroom cultures.In the past years,concerns have been raised due to pollution caused by overuse of chemical controls.Previous studies found that predatory mites of the families Macrochelidae and Laelapidae have ability to control Diptera insects.The aim of this study was to screen out some native predatory mites and evaluate their potential to control Diptera insects in mushroom farms in Fujian province.The main results were as follows:1.Twenty one subterranean predatory mites were collected.Among them,Macrocheles glaber,Macrocheles merdarius,Stratiolaelaps scimitus and Proctolaelaps sp.nr.fiseri were tested to determine whether they were predators of Lycoriella sp.and Cobolidia fuscipes.Furthermore,M.glaber and S.scimitus were successfully reared in lab.For each of these four species,the microstructures of olfactory receptors were examined.2.The four predator mites' attraction to C.fuscipes(Diptera),Lycoriella sp.(Diptera),Drosophila sp.(Diptera)and Carpoglyphus lactis(Acari:Astigmata)was first determined using a Y-tube olfactometer with one species and ambient air.The main results showed that:(1)M.glaber was only attracted by C.fuscipes;(2)M.merdarius preferred C.lactis and Drosophila sp.;(3)S.scimitus was attracted to the three Diptera insects,and(4)P.sp.nr.fiseri showed no attraction at all to any insects.When two preys were tested for preference in the olfactometer,the results showed that:(1)M.glaber significantly preferred Drosophila sp.over Lycoriella sp.;(2)M.merdarius was attracted by both Drosophila sp.and C.fuscipes similarly;(3)S.scimitus was significantly attracted to Drosophila sp.then,C.fuscipes and then Lycoriella sp.;and(4)P.fiseri did not prefer any species specifically.3.The average predation numbers of M.glaber and S.scimitus on larvae of C.fuscipes were 3.74 individuals/d and 3.05 individuals/d.The predation models for M.glaber and S.scimitus were Na=20/(1+e2.203-0.045t)and Na=20/(1+e2.576-0.051t),respectively.The relationship between predation rate and time period was described by equation of v=.861-1.549X+0.403X2-0.032X3 for M.glaber and V=1.433-1.206X+0.325X2-0.027X3 for S.scimitus.The daily predation number of M.glaber was significantly higher than S.scimitus.Interestingly,there was no significant difference in the predation rate between treatments.4.The age-stage two-sex life tables of the experimental populations of M.glaber and S.scimitus were compared.M.glaber and S.scimitus were fed with C.fuscipes at 25±10C,80-90%RH and under darkness.The results showed that S.scimitus had a significantly longer developmental time before pre-adult,oviposition period and life longevity than M.glaber.S.scimitus fecundity was significantly higher than M.glaber.The sex ratio((?))of M.glaber was 1.6:lwhich was lower than that of S.scimitus(3.11:1).In general,S.scimitus had a pre-adult development time longer than the adulthood with these phases being longer than M glaber,as well as the presence of a more stable age distribution suggest a greater population growth potential for S.scimitus than M.glaber.The intrinsic rate of increase(?),finite rate of increase(?)and net reproductive rate(Ro)of S.scimitus were significantly higher and the mean generation time(T)shorter than M.glaber.5.The control effectiveness of S.scimitus and M.glaber on Lycoriella sp.was tested on a culture of mushroom,Agrocybe cylindracea.The treatments included Lycoriella sp.+M.glaber(T1),Lycoriella sp.+M.glaber+S.scimitus(T2),Lycoriella sp.+S.scimitus(T3),Lycoriella sp.(T4),and a control with no pest or predator(CK).The results showed that Lycoriella sp.population was the best controlled under T3,followed by T2,and finally T1.These results were due to the fact that S.scimitus population grew faster than M.glaber,which hardly increased in population size during the 10 weeks of release.The number of mushroom-budding and mushroom yield was significantly higher in T3 and CK than other treatments. |
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