| Cassava（Manihot esculenta Crantz）is an important food,feed,industrial raw material and biomass energy crop in the world.It is also a crop for mountain protection and famine relief in tropical and subtropical forest areas of China.Papaya mealybug（Paracoccus marginatus Williams and Granara de Willink）is not only one of worldwide dangerous quarantine pests in agriculture and forestry,but also is one of the four important pests that seriously threaten the sustainable development of agriculture and forestry industry and the safety of ecological environment in the mountainous cassava planting area in China.To investigate the host selection of P.marginatus could provide an important theoretical basis for the effective monitoring and ecological control of P.marginatus.In this study,15 representative cassava germplasms planted in mountainous areas of Hainan,Yunnan,Guangxi,Guangdong,Fujian,Jiangxi and Hunan provinces were used as experimental materials,furthermore,by analyzing their different effects on the growth,development,reproduction,as well as the activities of digestive enzymes,detoxification enzymes and antioxidant enzymes of P.marginatus,the host selection and the response mechanism of P.marginatus to 15 cassava germplasms were clarified.The main research results are as follows:1.The suitable and unsuitable cassava hosts were identified,and the vitality and fecundity-based host selection were illustrated by analyzing the different effects of cassava germplasm on mortality,development and reproduction of P.marginatus.The cassava cultivars BRA900 and C1115 were used as suitable and unsuitable references cultivars,respectively.Compared with BRA900,there were significant（P<0.05）and extremely significant（P<0.01）differences in the mortality of female adults after feeding on C1115 for 1 and 4 d,which indicated that 1 and 4 d were the inflection points of the mortalities.Moreover,compared with those feeding on BRA900,Bread Bassava,SC205,ZM9066,Swiss T7,Glutinous Rice cassava,SC6068 and GR5,female adults of F0generation feeding on J1301,Dongguan Hongwei,SC11,SC8002,SC8,Myanmar and C1115 for 1 and 4 d showed significantly higher mortalities（P<0.05）,significantly prolonged development durations（P<0.05）,significantly lower number of eggs per female as well as hatching rates（P<0.05）and significantly lower female percentages（P<0.05）.The results showed that Bread Cassava,SC205,ZM9066,Swiss T7,Glutinous Rice Cassava,SC6068,GR5 were the suitable hosts,while J1301,Dongguan Hongwei,SC11,SC8002,SC8 and Myanmar were the unsuitable hosts of P.marginatus.After statistical difference analysis,the order of the suitability of different cassava germplasms for the development and reproduction of P.marginatus were clusterd as:suitable cassava reference cultivar BRA900,Bread Cassava,SC205>ZM9066,Swiss T7,Glutinous Rice Cassava,SC6068,GR5>J1301,Dongguan Hongwei,SC11,SC8002>SC8,Myanmar species,unsuitable cassava reference cultivar C1115.2.Unsuitable cassava germplasms significantly inhibited the activities of digestive enzymes of P.marginatus,which preliminarily elucidated the digestive enzymes response-based host selection of P.marginatus to different cassava germplasms.Compared with those feeding on suitable cassava reference cultivar BRA900,Bread Bassava,SC205,ZM9066,Swiss T7,Glutinous Rice cassava,SC6068 and GR5,the activities of digestive enzymes such as amylase,sucrase and lipase were significantly decreased in F0generation female adults after feeding on unsuitable cassava reference cultivar C1115 and J1301,Dongguan Hongwei,SC11,SC8002,SC8 and Myanmar Species for 1 and 4 d,which indicated that the unsuitable cassava germplasms can significantly inhibit the activities of digestive enzymes of P.marginatus.3.Unsuitable cassava germplasms significantly inhibited the activities of detoxification enzymes of P.marginatus,which preliminarily elucidated the detoxification enzymes response-based host selection of P.marginatus to different cassava germplasms.Compared with those feeding on suitable cassava reference cultivar BRA900,Bread Bassava,SC205,ZM9066,Swiss T7,Glutinous Rice cassava,SC6068and GR5,the activities of detoxification enzymes such as Car E and GSTs were significantly decreased in F0generation female adults after feeding on unsuitable cassava reference cultivar C1115 and J1301,Dongguan Hongwei,SC11,SC8002,SC8 and Myanmar Species for 1 and 4 d,which indicated that the unsuitable cassava germplasms can significantly inhibit the activities of detoxification enzymes of P.marginatus.4.Unsuitable cassava germplasms significantly inhibited the activities of antioxidant enzymes of P.marginatus,which preliminarily elucidated the antioxidant enzymes response-based host selection of P.marginatus to different cassava germplasms.Compared with those feeding on suitable cassava reference cultivar BRA900,Bread Bassava,SC205,ZM9066,Swiss T7,Glutinous Rice cassava,SC6068 and GR5,the activities of antioxidant enzymes such as SOD,CAT,POD and PPO were significantly decreased in F0generation female adults after feeding on unsuitable cassava reference cultivar C1115 and J1301,Dongguan Hongwei,SC11,SC8002,SC8 and Myanmar Species for 1 and 4 d,which indicated that the unsuitable cassava germplasms can significantly inhibit the activities of antioxidant enzymes of P.marginatus.In present study,the host selection of P.marginatus to the 15 representative cassava germplasms was clarified,and the vitality and fecundity-based host selection together with the response mechanism of digestive enzyme,detoxification enzyme and antioxidant enzyme were illustrated.This study can provide theoretical basis and test materials for further exploration of the molecular mechanism of the host selection,the creation of new insect resistant cassava germplasms,and the development of green control strategy. |
