Fundamental Study On Adult Control Of Bactrocera Minax (Enderlein)

Bactrocera minax?Enderlein?,a major citrus pest in China,is mainly controlled by trapping and SIT in adult stage.The optimum trapping period,the distribution inside and outside of the orchard,the physiological function of proteins on adult,the cool temperature starage of pupae,and the quality of erradiated adults of the fly were study to improve the trapped accuracy and effect in field,to solve the apply of SIT limitted by lack of insects.In order to monitor the adult dynamics and predict its optimal trapping period in the orchards,we compared the dynamics of adult eclosion and field trapping in Yidu,and calculated the interval of the peak period between eclosion and capture.Meanwhile,the environmental factors during the interval,including the temperature,humidity,and rainfall were analyzed.The results showed that the interval was relatively stable between eclosion and trapping.The interval of the beginning,apex and ending of the adult peak period between eclosion and trapping were 15�1.35 days,18.5�1.32days and 22.5�1.55 days,respectively.There was no significant correlation between the interval days and the temperature,humidity,and rainfall during the interval.In the way to monitor dynamics of eclosion at normal temperature,and then foreseeing the optimum trapping period of B.minax in orchard,this study can provide the basis for enhancing the accuracy of trapping.The distribution characteristics of Chinese citrus fruit flies,B minax,in the orchard on the side of wood were different from the non-forest side according to the population density.When the density of adults population were low?rate of maggot fruit at 2%-4%?,adults was much more in the wood side than that in the non-wood side.But,when at higher densities?rate of maggot fruit at 20%?,there was no significant difference with adults in both sides.There was a coincidence with the females,males and total adults distributed in both sides,and there was no significant difference with females and males.From the occurrence dynamics of adults inside and outside the orange orchard,the citrus fruit fly has a peak in the orange orchard in which the adult density was higher in the internal orchard than that of external orchard.There are two peaks occurring to external orchard that the first peak coincided with the peak of internal orchard and the second peak is after the internal.During the start and end of trapping period of adults,the population density of external orchard was greater than that of external.The pre-infesting period was mainly distributed at 20 m outside the orchard.The peak period was mainly distributed at 50 m and 10 m inside the orchard and the end period was mainly distributed at 10 m outside the orchard.In the initial field occurrence,adults was mainly distributed in the adjacent wood and then after once inward diffusion,then distributed inside and outside of the orange orchard.The occurrence of peak period maintained the similar distribution in the internal and external orchard.Finally,after one outward and one inward diffusion,adults were gradually move towards the external orchard at the end of occurrence period.Whether the inward or outward diffusion of adults,it was mostly that females went firstly and males followed.The eggs,larvae and pupae of Chinese citrus fruit fly are very hard to find due to their shielding in fruit or in soil and therefore,baits spray for adults is the main management method in the field?baits trapping??Baits spray is based on characteristic behavior of adult flies that displays a strong propensity to sugar and protein.However,the main weakness with this method is that the trapping period is commonly against the mature adults and little knowledges are known about the feeding selectivity of the early age of adult flies,such as newly-emerged infants.In this study,we investigated the feeding selectivity of newly-emerged B.minax for diets,by observing the number of infantile fruit flies to imbibe on water or honey,honey with or without protein,honey with or without antiseptics?sorbic acid or nipagin?,and honeys from different habitats,respectively.The results showed that there were no significant effects on the feeding selectivity between water and honey,although females at the 2nd and 3rd day and males at the 4th day after eclosion had displayed clearly feeding preferences to the water than honey.The feeding selectivity of honey after adding protein became visibly weakened for newly-emerged females not males.And the feeding selectivity of female infants to honey was greatly reduced with adding nipagin and sorbic acid,and that of male infants to honey significantly reduced only with adding nipagin in honey.In addition,for males,they fed gallnut honey from tree and shrub habitat more selectively than both motherwort honey and rape honey from herb habitat and honeysuckle honey from vine habitat,and more jujube honey from tree and shrub habitat than motherwort honey from herb habitat,but,there were no significant effects on feeding selectivity to these honeys from diverse habitats for females.The study provided us new thoughts for pest management of B.minax by the way of aiming at the newly-emerged adults,keeping baits effective and active,and set proper trapping station.Artificial rearing technology of B.minax adult is not well documented to date.In this study,we tried to determine if supplementing proteins to the adult diet could result in the enhancement of some fitness parameters of B.minax.Four feeds with varying protein source were provided as F0?water?,F1?sucrose?,F2?sucrose+yeast?,F3?sucrose+peptone?.F0 and F1 being the control,F2 and F3 were protein food types.The results showed that adults fed by F2 and F3 lived longer with 40.1 days and 32.8 days,respectively,had reduced death rates?death peaks were delayed for 5.6 days and 4.3 days,respectively?,increased mating frequencies?8.1 and 5.3 per females,4.7and 7.3 per males,respectively?,and longer mating durations?with 42days and 34 days?.In addition,females recorded an increased adult ovary development,more egg load?with 94.8 and 77.3 brood eggs per ovary?and to greater oviposition rates of 63.2 eggs/female and 19.3 eggs/female.Feed with F1,although there were eggs developed in ovary,but no eggs laid outside,and content of carbohydrates and threhalose were higher inside adult of B.minax.Based on our results,protein supplements enhanced B.minax survival,mating and fecundity.This study does not only provide basic knowledge to implement artificial rearing of B.minax,but also deepens our understanding on its physiology that could be used to enhance the management of the pest.Temperature is the main factor on eclosion of B minax pupae.Pupae preserve is one main manner to gain enough B.minax for SIT or studing on control continuous.How low temperature effect on the fruit fly must be clear when pupae preserve were done.1)Development delay effects of 1-4grade pupae with 0-grade pupae storage at 10?for different duration were studied.The results showed that:storage with 0-grade pupae at 10?,when the cold duration shorter than 40d,the eclosions had no significant difference with control.If cold storage duration exactly be 35d,the delay duration of pupae development peak in 1-grade,2-grade,3-grade and 4-grade were 15d,18d,24d and 15d.the delay duration of eclosion peak were11d.2)Survival level were evaluate by deal 1-4 grade pupae with25?-25?-25?,25?-20?-25?,25?-15?-25?,25?-10?-25?low temperature regime in short-time.Results showed that:1-grade pupae exposed to 25?-20?-25?,25?-15?-25?for 2h,4h and 8h could lead to more eclosion.The same as 2-3 grade pupae exposed to 25?-15?-25?,25?-10?-25?for 4h or 8h,4-grade pupae exposed to 25?-20?-25?,25?-15?-25?,25?-10?-25?for 2h,4h or 8h.when 1,2,3 or 4 grade pupae exopsed to special short time regime will benefit to the survival.3)To demonstrate the trade-off effects on constant temperature cost of the 1-4st stages pupae of B.minax,the 1-4st stages pupae were exposed to series lower temperature?10?,15?,20?,based on constant temperature of25??for 2h,4h and 8h and the adult eclosion growth were calculated.The results showed that:The eclosion growth rate,were 14%-47%when the 1st stage pupae were exposed to 15?or 20?for 2h,4h and 8h,were 2%-45%when the 2-3st stages pupae were exposed to 10 or 15?for 2h,4h and 8h and 20?for 4h,were 28%-46%when the 4th stage pupae were exposed to10?,15?or 20?for 2h,4h,8h,with the positive growth.It indicated that there were recover effects on the constant temperature cost.The recover effects of the 4th stage pupae exposed to 10?,15?and 20?for2h and 8h was higher significantly than these of the 2-3st stages pupae.It was concluded that certain stage pupae exposed to exact lower temperature with particular exposure time can produce recover effects on constant temperature cost and there be significantly recover difference between different stage pupae.The results could be referenced for the B.minax pupae preserve in laboratory and adult population forecasting in the field with rapid warm in early spring or cold spell in later spring.Aim to break the adult amount and quality restriction of SIT applied in field,the suitability of irradiated pupae stage and effect of higher sterility dose on B.minax were studied.Results showed that:1)Irradiated by⁶⁰Co?ray at 1-grade,2-grade and 3-grade papae stage,the eclosion rate,eclosion peak have no difference singnicantly with the index of 4-grade or no irradiate natural flies.The mating frequence and mating duration have no singnicant difference except females from 3-grade irradiated pupae.So,for the apply in field,the suitable stage of irradiated could be at the peak of 2-3 grade pupae?mixed with 1-4 grade pupae?.2)irradiated by100Gy?110Gy⁶⁰Co?ray on 1-4 grade pupae,mortality rates of male and female have no difference with natural male's and female's.although there are advance or delay of death peak,but no death peak occurred exceed 10 ages.Correct mortality rates?24.53%,39.62%?of irradiated males were higher significantly than females.In totally,the survival of adults from 1-4grade pupae irradiated by 100Gy?110Gy⁶⁰Co?ray were no influenced.