苹果绵蚜在苹果树上空间分布型的研究

采用6种空间分布型聚集度指标,测楚了苹果绵蚜在苹果树新梢、侧枝、树干(环剥处)和根部的空间分布型。结果表明均呈聚集分布,据此提出了适宜的调查取样技术。     

Genome mapping of three major resistance genes to woolly apple aphid (Eriosoma lanigerum Hausm.)

Woolly apple aphid (WAA; Eriosoma lanigerum Hausm.) can be a major economic problem to apple growers in most parts of the world, and resistance breeding provides a sustainable means to control this pest. We report molecular markers for three genes conferring WAA resistance and placing them on two linkage groups (LG) on the genetic map of apple. The Er1 and Er2 genes derived from ‘Northern Spy’ and ‘Robusta 5,’ respectively, are the two major genes that breeders have used to date to improve the resistance of apple rootstocks to this pest. The gene Er3, from ‘Aotea 1’ (an accession classified as Malus sieboldii), is a new major gene for WAA resistance. Genetic markers linked to the Er1 and Er3 genes were identified by screening random amplification of polymorphic deoxyribonucleic acid (DNA; RAPD) markers across DNA bulks from resistant and susceptible plants from populations segregating for these genes. The closest RAPD markers were converted into sequence-characterized amplified region markers and the genome location of these two genes was assigned to LG 08 by aligning the maps around the genes with a reference map of ‘Discovery’ using microsatellite markers. The Er2 gene was located on LG 17 of ‘Robusta 5’ using a genetic map developed in a M.9 × ‘Robusta 5’ progeny. Markers for each of the genes were validated for their usefulness for marker-assisted selection in separate populations. The potential use of the genetic markers for these genes in the breeding of apple cultivars with durable resistance to WAA is discussed.     

Bionomics and population growth statistics of apterous virginoparae of woolly apple aphid, Eriosoma lanigerum, at constant temperatures

Development, survival, reproduction and population growth statistics of apterous virginoparae of woolly apple aphid, Eriosoma lanigerum (Hausmann) (Hemiptera: Aphididae) at constant temperatures of 10, 13, 15, 20, 25, 30 and 32°C are reported. The developmental times of all life stages were inversely related to temperature ranging from 10 to 30°C. Span of total development (time from birth to adulthood) decreased from 57.8 days at 10°C to 11.7 days at 30°C and increased to 16.8 days at 32°C. A good linear model fit (R²>0.96) between developmental rate and temperature in the range 10–25°C was observed for all life stages. The lower developmental threshold was estimated at 5.8°C for instar I, 4.8°C for instar II, 4.9° for instar III and 4.4°C for instar IV. The lower temperature threshold for total development was estimated at 5.2°C. The upper developmental limit was found to be 32°C. Mean degree-day accumulations required for completion of instars I, II, III, IV and total development were: 125.6, 51.0, 47.7, 50.7 and 267.6, respectively. Fecundity, larviposition period and adult longevity were reduced with increasing temperature. Net reproductive rate was greatest at 15°C whereas intrinsic rate of increase peaked at 25°C. Optimal performance, as measured by fecundity, survival and intrinsic rate of increase, ocurred in the range 13–25°C.     

鲁西南地区苹果绵蚜(Eriosoma lanigerum)及其天敌种群动态与群落结构特征

通过田间蚜块计数、黄色粘虫板诱集、室内镜检等方法统计苹果绵蚜Eriosoma lanigerum (Hausmann)及其寄生性天敌日光蜂Aphelinus mali Haldeman种群数量,分析比较了它们的消长动态.利用群落结构特征指数研究比较了不同时期苹果绵蚜及其天敌群落多样性.连续2a调查发现,苹果绵蚜种群在鲁西南地区全年发生两个高峰,其中5月中、下旬～7月上旬为第一高峰期,8月下旬～10月中旬为第二高峰期.有翅蚜发生在4月上旬～6月上旬和9月上旬～10月上旬.不同时期,苹果绵蚜在苹果树体不同部位的种群数量存在差异,上半年,苹果绵蚜在根、树干及主枝部位分布密集,发生危害较重;7月中、下旬之后,苹果绵蚜在根及树干部位基本不再发生或发生较轻,而在枝干部位,包括主枝、侧枝和新梢,发生危害较重.7月份之前,日光蜂滞后于苹果绵蚜的发生高峰,其控制作用不很明显,7月份以后日光蜂跟随现象才比较明显,与苹果绵蚜的第二个发生高峰前期基本吻合,可以很好地控制苹果绵蚜的危害.鲁西南地区苹果绵蚜及其天敌群落多样性低,群落稳定性差,发现天敌23种,捕食性天敌亚群落中七星瓢虫Coccinella septempunctata Linnaeus、二星瓢虫Adalia bipunctata (Linnaeus)和叶色草蛉Chrysopa phyllochroma Waesmael等为优势种,特别是4、5月份,七星瓢虫和叶色草蛉可以很好地弥补因日光蜂跟随滞后而对苹果绵蚜控制作用的影响.这为保护利用自然天敌、可持续控制苹果绵蚜危害奠定了理论基础.     

Feeding by sugarcane aphid,Melanaphis sacchari,on sugarcane cultivars with differential susceptibility and potential mechanism of resistance

Feeding behavior of Melanaphis sacchari Zehntner (Hemiptera: Aphididae) was studied on sugarcane, Saccharum spp. (Poaceae), cultivars HoCP 91‐555 (resistant), LCP 85‐384 (moderately resistant), and L 97‐128 (susceptible) using the electrical penetration graph (EPG) technique. Constitutive concentrations of total phenolics and available carbohydrates, water potential at the whole‐leaf tissue level, and free amino acids (FAAs) in phloem sap extracts, and in honeydew produced by aphids fed on L 97‐128 and HoCP 91‐555 were determined. Cultivar did not influence time for M. sacchari to access phloem sieve elements. Total time in sieve elements was ca. two‐fold greater on L 97‐128 than on HoCP 91‐555, whereas it did not differ from LCP 85‐384 in either cultivar. The mean duration of individual events associated with phloem sap ingestion was ca. 50% shorter on both HoCP 91‐555 and LCP 85‐384 than on L 97‐128. Although cultivar effects were not detected for levels of total phenolics, available carbohydrates, and water potential, two free essential amino acids, histidine and arginine, were absent from phloem sap in HoCP 91‐555. Two free essential amino acids, leucine and isoleucine, and two free non‐essential amino acids, tyrosine and proline, were absent from honeydew of aphids fed on HoCP 91‐555. These results suggest that despite apparent biosynthesis of some FAAs, the absence of important FAAs in the phloem sap of HoCP 91‐555 and the inability of M. sacchari and its endosymbionts (e.g., Buchnera) to derive specific free essential and non‐essential amino acids from other ingested molecules, possibly along with other unidentified factors, underlie the pest's decreased phloem sap ingestion and consequently reduced growth potential on HoCP 91‐555.