Population dynamics and density of Bactrocera dorsalis( Hendel) in different habitats

Although different researches related to the population dynamics of orient fruit fly [Bactrocera dorsalis( Hendel) ]have already been conducted by many Chinese scholars,the systematic researches related to the population dynamics of B. dorsalis in different habitats have not yet been conducted. In order to reveal the effect of different habitats on the population dynamic of B. dorsalis,the population dynamics of B. dorsalis was monitored by using sex induction agents during 2008—2009 in each monitoring point in Fuzhou,Fujian,China. The study objects are displayed as follows. The first one is population dynamics and density of B. dorsalis in different orchards,including guava,carambola,grape,luffa, cucumber citrus,grapefuit and mixture orchard. The second one is population dynamics and density in orchard and its surroundings jungles. The third one is population dynamics and density in different geographical environment in orchard, including ridge and valley,along river and not. And the last one is population dynamics and density in city and countryside. The result shows,first,that the population of B. dorsalis reaches peak when the fruit ripening in each type of orchard. Second,the population density in mixed orchard is obviously higher than the orchards of single species. Third,the population density in orchard was higher than surrounding jungles during the fruit ripening while the case was contrary to former after the fruit ripening in the orchard. Forth,the population level in valley was higher than ridge while the number along river was higher than that not along river. Fifth,the population period in city subdivision is earlier than in countryside and the population density in city is also higher than in countryside. Last,some useful and effective methods for improving control of this pest were also proposed,and drawbacks of this study and the future researches were presented. Based on our results,we suggest,first,that trying to avoid mixed cultivation with all kind of fruits in the agricultural production because of the population density in the orchard of single species is much lower than mixed orchard. Second,the field microclimate should be taken into account in pest forecasting and prevention. Third,the population changing of B. dorsalis in city should be emphasized by government and quarantine department. Because the population period in city subdivision is earlier than in countryside and the former population density is also higher than later. Next,based on the limitations of this study,some suggestions for further research are presented. Insufficient number of monitoring points is the mainly limitation in this study. For example,space-time dynamic characteristic between city subdivision and countryside has not yet been reflected because of insufficient number of monitoring points. So the characteristic of space-time dynamics between city and countryside be done in future research. Moreover,the cause of the difference of B. dorsalis populations in different habitats will be revealed in future study,especially the reasons of the difference of B. dorsalis populations in different orchards,the causes of the population dynamics between orchard and its surrounding jungles and the reasons of population dynamics between city and countryside.