Research Progress of Occurrence and Comprehensive Control of Oriental Fruit Fly [Bactrocera dorsalis (Hendel)]

The paper summarizes the research progress of occurrence and comprehensive control of oriental fruit fly in the following aspects ： biological and ecological characteristics, assessment of the risk and suitability, dynamic monitoring and control index, and comprehensive control methods.

Analysis on Suitable Distribution Area of Oriental Fruit Fly (Bactrocera dorsalis) Based on GARP Ecological Niche Model

[Objective] The paper was to provide the scientific basis for effective monitoring and early warning on oriental fruit fly in Jiangxi Province.[Method] Using the distribution data and environmental factor data of oriental fruit fly,the potential distribution area of oriental fruit fly in Jiangxi Province was predicted by GARP ecological niche model.[Result]The total suitable area for oriental fruit fly in Jiangxi province was over two thirds of the whole province.Most areas in southern Jiangxi basin ranged from 24° to 26° N were the high suitable area for oriental fruit fly,where the annual average temperature was 19-20℃.Part areas in north Ganzhou and small areas in southwest Ji＇an,Wuzhou,Yingtan,southeast Shangrao ranged from 26° to 27° N were the moderate suitable areas for oriental fruit fly,where the annual average temperature was 18-19℃.The low suitable area was ranged from 26° to 30° N including Binhu,Ganjiang River,Wuhe,Yuanshui area and Southwestern Mountain of Jiangxi Province,where the annual average temperature was 17-18℃.Northeast and northwest areas in Jiangxi Province and coastal areas along the Yangtze River was predicted to be non-suitable area for oriental fruit fly,where the annual average temperature was 16-17℃.[Conclusion] The results showed that the actual distribution of oriental fruit fly basically was consistent with the distribution predicted by GARP.

Study on Integrated Control against Oriental Fruit Fly[Bactrocera dorsalis(Hendel)] in Guava Orchard

[ Objective ] The paper was to explore the damage, occurrence pattern and integrated control methods of oriental fruit fly [ Bactrocera dorsalis （ Hen- del） ] in Nanning region of Guangxi Province. [ Method ] Using fixed system survey method, with fruit fly attractants as the materials, the occurrence dynamic of oriental fruit fly adult in guava orchard was investigated. The control effects of the methods such as fruit fly attractants, fruit bagging, cleaning park to pick up fallen fruit and timely spraying pesticide against the pest were also studied. [ Result] Oriental fruit fly had two damage peak periods in Nanning region of Guangxi Prov- ince （May to June, August to September）. Through the integrated control measures of trapping agent for male flies, timely spraying, fruit bagging and cleaning park to pick up fallen fruit, the population density in guava orchard dropped significantly. The fruit damage rates of guava in research base were only 6.67% -7.33% during the peak period of oriental fruit fly in June 2008, while they were 90.53% -98.00% in control area, obtaining good control effect against the pest. [ Con- dttalon ] The method used in the study preliminarily restored the yield losses of guava, which also provided basis for the preparation of overall strategy against orien- tal fruit fly in the region.

Population Quantity Variations of Oriental Fruit Fly (Bactrocera dorsalis Hendel) on the Basis of Stepwise Regression Analysis

[Objective] The research aimed to study the significant influence factors of the population variations of oriental fruit fly. [Method] Using stepwise regression analysis, the population variations law of oriental fruit fly in Jianshui County of Yunnan province and the meteorological factors that caused its occurrence were analyzed. And the regression model was built. Finally, the regression model was tested on the basis of the data in Jianshui County of Yunnan Province during 2004-2006.[Result] The main meteorological factors that influenced the occurrence of oriental fruit fly were relative humidity, the lowest monthly temperature and rainfall. [Conclusion] This study will provide certain reference for the prediction researches on the time, quantity and occurrence peak of oriental fruit fly.

Relationship between Population Fluctuation of Oriental Fruit Fly Bactrocera dorsalis Hendel and Abiotic Factors in Yezin, Myanmar

Population fluctuation of oriental fruit fly, Bactrocera dorsalis （Hendel） （Diptera： Tephritidae）, was monitored by using methyl eugenol traps during May, 2011 to December, 2011 and May, 2016 to December, 2016 in mango orchard farms of Department of Agricultural Research in Yezin, Myanmar. In 2011, the highest mean number of male oriental fruit flies/trap/day （241.42 ± 11.79） was recorded in June and the lowest （2.21 ± 0.40） in December. The highest mean number of male oriental frui t flies/trap/day （388.95 ± 8.56） was recorded in the month of June and the lowest （2.33 ± 0.20） in December, 2016. Population data were correlated with meteorological data including temperature, duration of sunshine, and rainfall. Population fluctuation of male fruit flies was positively correlated with temperature and rainfall, and negatively correlated with the duration of sunshine.

Population dynamics of the oriental fruit fly, Bactrocera dorsalis （Diptera： Tephritidae） in the Kunming area,southwestern China

Population dynamics of Bactrocera dorsalis Hendel （Diptera： Tephritidae） were studied through pheromone trapping over 4 years （1997, 1999, 2000, 2003） in the Kunming region, a high plateau area in southwestern China. B. dorsalis immigrates from southern Yunnan to Kunming each year, and occurs during early May through November. Annual trap captures recorded an increase in the B. dorsalis populations from May to July, when they peaked in abundance, and a decline until November. No flies were detected from November to April. The fruit flies had two generations. There was considerable overlapping due to the continuous arrival of immigrating flies during the summer months. Annual capture rates were significantly related to numbers of flies caught in July when peak captures were recorded; whereas the peak captures, in turn, positively depended on numbers of flies recorded in May, the first month of fly appearance in the current year. It suggested that the annual population abundance was mainly dependent on the size of the initial emigrating population. A daily average temperature of 18℃ was probably the threshold temperature required for the flies to undertake long-range dispersal, which partially explained the start of the fly in May each year on this high plateau. Under field conditions, the fruit flies can withstand 13℃ as a daily average temperature. No flies were recorded in any of the study years at a daily temperature colder than 10 ℃.

Living Habits of Orient Fruit Fly in Taihu Area

[ Objective] The aim was to supply technical basis for developing quarantine and control techniques for orient fruit fly. [ Method] By utilizing facilities including rearing chamber and rearing cage, the population of orient fruit fly was established and sustained by using the methods of artificial feeding and fruit culture, and the continuous indoor biological observation was carried out. The isolated enclosure equipped with temperature and humidity recorder was established in Dongshan area of Taihu for cultivating various species of host plants, then the living habits of orient fruit fly were observed everyday. [ Result] Through feeding and observation in lab, the living habit of adult, larva, pupa and eggs of orient fruit fly were studied; the impact of soil depth on the emergence rate of pupa were conducted, and the result indicated that when the soil layer depth increased to 40 cm, there were still adults appeared and their emergence rate was 80%. The results of indoor trend test showed that the selectivity of orient fruit fly on fruits produced in Suzhou was sequenced from high to low as follows： tangerine, dates, pomegranate, peach, orange, pear and persimmon. While the sequence of fruit tree species were tangerine, dates, pomegranate, pears and persimmons according to damage rates of orient fruit fly from high to low under field isolation rearing conditions. In the local tangerine varieties, the damage rate from high to low were Dongting manda- rin, eady tangerine, Wen orange, Huangpi, Zaohong, Liaohong. [ Conclusion] Orient fruit fly artificial rearing facility was established, which laid the foundation for carrvina out bioloaical characteristics observation and biolooical exoeriments

Cloning and functional characterization of two peptidoglycan recognition protein isoforms (PGRP-LC) in Bactrocera dorsalis (Diptera: Tephritidae)

The innate immune system of insects is the front line of self-defense against pathogen invasion. Peptidoglycan recognition proteins (PGRPs) are important components and play key roles in insect immune systems by recognizing peptidoglycan (PGN) in bacterial cell walls. We characterized two isoforms of the PGRP-LC gene, BdPGRP-LCa and BdPGRP-LCb, from Bactrocera dorsalis (Hendel), an important fruit and vegetable pest worldwide. These two isoforms contain an open reading frames of 1 668 bp and 1 731 bp, encoding a protein of 555 and 576 amino acids, respectively. Quantitative real-time PCR results showed that both transcripts were prominently expressed in midgut and fat body of B. dorsalis adult. Inoculation of pathogens showed that both isoforms actively responded to Escherichia coli PGN. We also observed a light response to Staphylococcus aureus PGN. Upon Beauveria bassiana inoculation, the expression of BdPGRP-LCa was enhanced, but the expression of BdPGRP-LCb was suppressed. Suppression of both transcripts by RNA interference led to increased mortality of flies challenged by E. coli, indicating that the two isoforms are involved in sensing Gram-negative bacterial infections.

CRISPR-mediated mutagenesis of the odorant receptor co-receptor(Orco)gene disrupts olfaction-mediated behaviors in Bactrocera dorsalis

Olfaction plays an essential role in insect behavior such as host location,foraging,mating,and oviposition.The odorant receptor co-receptor(Orco)is an obligatory odorant receptor and indispensable in odor perception.Here,we characterized the Orco gene from the oriental fruit fly,Bactrocera dorsalis(Hendel),a notorious agriculture pest.The olfactory deficiency mutants were generated by editing the BdorOrco gene using the CRISPR/Cas9 system.Electroantennograms(EAG)and olfactory preference assays confirmed that BdorOrco^(−/−)mutant flies had reduced perception of methyl eugenol,β-caryophyllene,and ethyl acetate.Oviposition bioassays showed that the eggs laid by BdorOrco^(−/−)females mediated by benzothiazole and 1-octen-3-ol were significantly decreased.In addition,BdorOrco^(−/−)mutant flies took a significantly longer time to locate the food source compared with wild type(WT)flies.Altogether,our data indicated that Orco is essential for multiple physiological processes in B.dorsalis,and it expands our understanding of the function of insect Orco.

Small GTPase Rab40C is upregulated by 20-hydroxyecdysone and insulin pathways to regulate ovarian development and fecundity

The insulin and 20-hydroxyecdysone(20E)pathways coordinately regulate in-sect vitellogenesis and ovarian development.However,the detailed molecular mechanisms such as the genes mediating the cooperation of the interaction of these 2 pathways in reg-ulating insect reproductive development are not well understood.In the present study,a small GTPase,Rab4oC,was identified from the notorious agricultural pest Bactrocera dorsalis.In addition to the well-known RAB domain,it also has a unique SOCS-box do-main,which is different from other Rab-GTPases.Moreover,we found that Rab40C was enriched in the ovaries of sexually mature females.RNA interference(RNAi)-mediated knockdown of BdRab40C resulted in a decrease in vitellogenin synthesis,underdevel-oped ovaries,and low fertility.Furthermore,depletion of insulin receptor InR or the het-erodimer receptor of 20E(EcRor USP)by RNAi significantlydecreased the transcription of BdRab40C and resulted in lower fecundity.Further studies revealed that the transcrip-tion of BdRab40C could be upregulated by the injection of insulin or 20E.These results indicate that Rab40C participates in the insulin and 20E pathways to coordinately regulate reproduction in B.dorsalis.Our results not only provide new insights into the insulin-and 20E-stimulated regulatory pathways controlling female reproduction in insects but also contribute to the development of potential eco-friendly strategies for pest control.