Effects Of Environmental Factors On Growth,development And Reproduction Of Diaphania Angustalis(Snellen)

Diaphania angust.alis(Snellen),belonging to Lepidoptera:Pyralidae,is a main pest for Alstonia scholaris(L.)in China.As an important medicinal plant and an excellent greening tree species,A scholaris is damaged by D.angustalis,then the medicinal value and greening function decreased seriously.The system studied the effects of temperature,photoperiod,Leaves with different maturity,larval density,pupation site and supplementary nutrition on the growth,development and reproduction of D.angustali.s.The results not only help to clarify the growth and reproduction characteristics of D.angustalis,but also provide a scientific basis for further research on its prediction and forecasting techniques.The main findings are as follows:(1)Temperature(20±0.1?,25±0.1?,3010.1??35±0.1?)had significant effects on the growth,development and reproduction of D.angustalis.The developmental duration while the temperature was increased from 20-30?.The survival rate of each insect stage decreased with the increase of temperature.The pupa survival rate was the highest at 25?C,which was 96.11%.The longevity of adults of D.angustalis decreased with the increase of temperature at 20-30?,and there was no significant difference between males and females.Excessive or low temperature had an effect on the oviposition of adults.The average number of eggs laid per female was 656.96,and the longest oviposition period was 6.3 d at 25?.The results showed that the optimum temperature for the growth and reproduction of D.angustalis was 25?.(2)The photoperiod had a significant effect on the reproduction of the adults.The longest oviposition period was 8.28 d at 14L:10D.The average oviposition per female was 638.92,and the longevity of the female was 15.58 d.The photoperiod 14L:10D was the optimum photoperiod for the reproduction of the adults.(3)Food had a significant effect on the growth and development of the larvae of D.angustalis.The development duration of larvae feeding on mature leaves is the shortest,for example,the development duration of 4th instar larvae is 2.39 d,2.27 d and 2.58 d,respectively,and the pupal stage shortens with the increase of leaf maturity.The survival rate of 1-4 instar larvae decreased with the increase of leaf maturity.The number of female borers was the highest under the mature leaves.The male and female pupae were the heaviest when feeding on young leaves,171.9 mg and 186.5 mg,respectively.(4)The larval feeding density(1 larvae/box,10 larvae/box,20 larvae/box,30 larvae/box and 40 larvae/box)had significant effects on the growth and development of larvae and the reproduction of adults,except for no significant difference in the proportion of male to female,the average number of eggs laid per female and the hatching rate.The larval development duration was the shortest at 30 larvae/box density.The larval survival rate was the highest at 1 larvae/box density 88.33%and the adult longest spawning period was the longest at 10 larvae/box density.Although the weight of female pupae was the smallest when the density was the highest(40 larvae/box),there was no significant change in the average number of eggs laid per female.The ratio of male to female was the highest at 10 larvae/box density.The results showed that there was a close relationship between population density and the growth and reproduction of D.angustalis.(5)The pupation of the D.angustalis silk borer in four pupation sites(white paper trough,kraft paper,leaves and soil)was studied.The results showed that pupation sites had significant effects oin the survival rate,pre-pupa stage,pupa stage and pupa weight of D.a,ngustalis.The survival rate of mature larvae was 95.56%in the white paper trough,and the shortest pre-pupae period was 3.63 d in the white paper trough.In soil,pupa stage is the shortest and the pupa weight is the smallest.(6)Supplementary nutrition had a significant effect on the reproduction of the adults.When adults fed 15-5%honey water,the pre-oviposition period prolonged with the decrease of honey water concentration,while the oviposition period shortened.Adults cannot reproduce when they are hungry or feed on distilled water.When adults feed on 10%honey water,the average number of eggs laid per female is the highest and the longest life span of adults is the longest.