Study On The Oviposition Attractant Of Culex Pipiens Pallens And Aedes Albopictus

There is a close relationship between mosquitoes and human life.In many parts of the world their biting is a considerable nuisance.More importantly,they can transmit several tropical diseases,including malaria,filariases,and numerous viral diseases,such as dengue, Japanese encephalitis and yellow fever.Traditionally,control of adult mosquitoes has relied almost exclusively on the use of chemical insecticides.This strict reliance on chemical insecticides has resulted in increased public apprehension about exposure to these insecticides, environmental concern,and increased reports of mosquito species developing resistance to a dwindling number of chemical insecticides approved for mosquito control.This reliance also has led to an increased interest over the past two decades in developing alternative mosquito control technologies.Identification of suitable ovipositional sites by mosquitoes is a critical feature of their life history,because it ultimately influences the survival of their progeny.The attractiveness of these sites to ovipositing mosquitoes is dependent upon a number of physical and chemical factors. Ovitraps have been widely employed to monitor and control populations of mosquitoes in recent years.In this paper,we mainly determined the effect of different types of nutrients and chemicals to oviposition behavior of two important vectors in China,Culex pipiens pallens and Aedes albopictus in the laboratory,semifield and field experiments.Major research results are as follows:(1)The responses of gravid Cx.pipiens pallens and Ae.albopictus to waters with different nutrients in the laboratoryThe oviposition of gravid Cx.pipiens pallens females and Ae.albopictus females in water with sugars,or vitamins,proteins and amino acids was evaluated under laboratory conditions. The results indicated that the gravid Cx.pipiens palIens females preferred to lay eggs in the 100 mg/L and 1000 mg/L of glucose solutions and 1000 mg/L of sucrose solutions,the gravid Ae. albopictus females had no clear preference to the sugar solutions tested compared to the tap water.Among the tested proteins,the gravid Cx.pipiens pallens females attracted clearly to oviposit in the 100 mg/L and 1000 mg/L of fish peptone solution and in the 1000 mg/L of yeast extraction solution compared to the tap water,and the gravid Ae.albopictus females attracted significantly to lay eggs in the 10 mg/L of fish peptone compared with the tap water.Most of vitamin solutions tested showed no attractive effect on the oviposition of Cx.pipiens pallens and Ae.albopictus exception for the 100 mg/L of VB₁ solutions and VC solutions and 10 mg/L of VB₁ solutions to the gravid Cx.pipiens palIens females and 10 mg/L of VB₁ solutions to the gravid Ae.albopictus females.Among 20 amino acids tested,the 10 mg/L～1000 mg/L of phenylalanine solutions showed significant attractive roles on oviposition of gravid females of Cx.pipiens pallens and Ae.albopictus.(2)The optimum attraction concentration and combined effect of different nutrients to gravid Cx.pipiens pallens and Ae.albopictus females in the laboratoryThe optimum concentrations of different nutrients dissolved with tap water and pond water respectively attracting gravid Cx.pipiens pallens and Ae.albopictus females were determined in the laboratory.When the tap water as solvent,100 mg/L of VB₁ solution and fish peptone solution elicited significantly oviposition behavior of gravid Cx.pipiens pallens and 100 mg/L of fish peptone solution and 1 mg/L of phenylalanine attracted significantly to lay eggs by gravid Ae.albopictus.When the pond water as solvent,the gravid Cx.pipiens pallens females attracted clearly to oviposit in the 1000 mg/L of glucose solution and fish pep(?)ne solution compared to the pond water.No synergistic effect was observed on oviposition of gravid Cx. pipiens pallens and Ae.albopictus females when these nutrients were mixed.(3)The combined effect of different nutrients acted with other factors influencing oviposition behavior to gravid Cx.pipienspallens and Ae.albopictus females in the laboratoryLaboratory studies were cofiducted on the oviposition behaviour of gravid Cx.pipiens pallens and Ae.albopictus females in response to different water types,colors and oviposition attractants.The pond water elicited significantly more oviposition of gravid.Cx.pipiens pallens and Ae.albopictus than the distilled water and the tap water.Blue was found to be the most preferred color for the gravid Cx.pipiens pallens and Ae.albopictus females.The compounds 3-methylindole(skatole)and 4-methylphenol elicited significantly oviposition behavior of gravid Cx.pipiens pallens and Ae.albopictus respectively.Exception of glucose and 4-methylphenol,no synergistic effect was observed on oviposition of gravid Cx.pipiens pallens and Ae.albopictus females when these nutrients were dissolved with pond water together with dye or 3-methylindole/4-methylphenol.(4)The oviposifion attraction of different nutrients to mosquitoes in field experimentsThe oviposition attractivity of different nutrients was conducted on the ovipositior behaviour of gravid mosquitoes under field conditions.The results showed that 1000 mg/L,100 mg/L and 10 mg/L of VB₁ solution dissolved with tap water displayed a negative effect on oviposition behavior of mosquitoes after treated 3～4 days,and 0.1 mg/L of phenylalanine solution dissolved with pond water showed a positive effect on oviposition behavior of mosquitoes after 3 day treatemnt.(5)The oviposition responses of gravid Cx.pipiens pallens and Ae.albopictus females to different Compounds in the laboratory and semifield experimentsAmong the 10 compounds tested in the laboratory,acetic acid(0.1 mg/L),ethyl acetate(10 mg/L and 0.1 mg/L)and dimethyl disulfide(10 mg/L)solution showed significant oviposition attraction to gravid Cx.pipiens pallens than the distilled water as control.Acetic acid(0.001 mg/L),propionic acid and ethyl acetate(0.01 mg/L)and 1-octen-3-ol(1 mg/L,0.1 mg/L and 0.01 mg/L)showed significant oviposition attraction to gravid Ae.albopictus females than the distilled water as control.In semifield(green house)experiments,only ethyl acetate(1 mg/L) and 1-octen-3-ol(10 mg/L)attracted significantly more oviposition behavior on gravid Cx. pipiens pallens and Ae.albopictus females,respectively.