卵形异绒螨对梨二叉蚜的控制作用

卵形异绒螨（Allothrombium ovatum)是蚜虫的重要天敌，其对果树蚜虫的控制效果，之前尚无报道。经笔者多年在徐州市果树站试验基地的研究发现，在长期利用绒螨及其它无公害措施进行病虫害防治的生防园，早期蚜虫不需要进行化学防治，利用生防措施就能控制其危害，而常规对照园期间需喷两次药。2003年的试验表明，在生防园用5％溴氰菊酯1500倍防治梨二叉蚜(Schizaphis piricola Matsumura)，虽然药后1天防效达95．1％，但20天后只有71．7％，这时生防园地控制效果达96．7％。经几年的试验表明，化防容易引起蚜虫产生抗性，费时费工，增加了成本，果面残留农药多，对环境污染严重，且树上种群数量的消长变化猛增猛减，极不稳定。而生防园的害虫种群数处于低水平之下，不会对果树造成伤害。同时，利用自然天敌控制害虫，成本低，不污染环境，无副作用。     

杨陵地区麦二叉蚜在小麦品种Amigo上的抗性鉴定

根据麦三叉蚜种下生物型分化特性，设计了小麦品种Amigo的抗蚜性和麦二叉蚜生物型鉴定试验。分析了自然条件下小麦品种Amigo对麦二叉蚜的出生率、死亡率和内秉增长度的影响，组建了自然条件下麦二叉蚜在小麦品种Amigo上的生命表。以生命表中的内秉增长度和稳定年龄组配为指标进行生物型鉴定分析。结果表明：①麦二叉蚜在Amigo上的生存曲线、繁殖曲线同麦二叉蚜在其它品种上的表现一致，分别为B型和偏峰曲线；②平均世代时间为11.7670d，周限增长率为1.1453；③种群的瞬时出生率为0.3220，瞬时死亡率为0.1846；④内秉增长率为0.1357；⑤稳定年龄期组配成蚜比例为37.64%，若蚜为62.37%，与二叉蚜在其它小麦品种上的参数差异不显著。参数分析表明，在Amigo品种上的麦二叉蚜种群发展趋势是上升的，种群数量是增长的，可见杨陵地区麦二叉蚜既非A、B，也非C生物型，品种Amigo不抗本地区麦二叉蚜。     

红梨园梨二叉蚜种群空间格局与抽样技术研究

运用5种聚集度指标与2种回归分析方法对红梨园梨二叉蚜（Schizaphis piricola Matsumura）种群空间格局进行了研究。结果表明,在整个调查期间内,红梨园梨二叉蚜均呈聚集分布,且种群处于扩散和聚集交替进行的动态过程中。利用Iwao法确定了红梨园梨二叉蚜不同种群密度下的田间理论抽样数。     

麦二叉蚜在10个小麦品种(系)室内苗期生物学反应及抗性分析

为了评价不同小麦品种(系)对麦二叉蚜的抗性,应用每株麦苗上接1头蚜虫的方法,在温室内用5个指标(发育历期D_D、成虫与幼虫的体重差W_D、成虫在与发育历期相等时间内的产子数F、相对日均体重增长量MRGR和成虫在与发育历期相等时间内的日均产仔数R_m)测定了10个小麦品种对麦二叉蚜的抗性,并以此为基础用多元方差分析法、多目标综合判别法和聚类分析法评价了这10个小麦品种(系)对麦二叉蚜的抗性,结果表明,Amigo最不适于麦二叉蚜在其上取食,抗性最好,Batis抗性较好,其他品种抗性较弱。     

不同燕麦品种(系)对麦二叉蚜生命参数的影响

为比较具有不同抗蚜性的燕麦品种对麦二叉蚜连续2个世代若蚜和成蚜主要生命参数的影响,在室内22℃条件下,采用网罩法对UFRGS105064-3等8个具有不同抗蚜性的燕麦品种(系)上的若蚜发育历期、存活率和成虫寿命、生殖力等生命参数进行了观测,组建了麦二叉蚜实验种群生命表。结果表明,不同燕麦品种(系)对麦二叉蚜若蚜发育历期和成蚜生殖力有显著影响,在抗蚜性强的品种(系)上,麦二叉蚜若蚜发育历期延长,成蚜产仔量减少;以内禀增长率作为测定抗生性的指标,供试燕麦品种(系)中,UFRGS105064-3、燕2007和白燕2号的抗生性最强,其次为MF9715,QO245-7、OA1251-1、108C105和UFRGS097018-3抗生性较差。通过对比不同世代的蚜虫生物学参数发现,抗蚜品种(系)对蚜虫下世代抗生性的影响存在加重现象,抗生性在蚜虫世代间可能存在累加效应,并且这种影响随着燕麦抗性的升高而加重。     

Differentiating greenbug resistance genes in barley

The greenbug [Schizaphis graminum (Rondani)] is an extremely damaging pest of barley (Hordeum vulgare L), particularly in the southern Great Plains of the USA. Two greenbug resistance genes, Rsg1a (in ‘Post 90’) and Rsg2b (in PI 426756), available for developing resistant barley cultivars, have similar phenotypes when challenged by various greenbug biotypes. This study was conducted to separate these two resistance genes via differential plant reactions to a recently collected field isolate of greenbug. Four barley entries and one wheat germplasm were challenged with two greenbug isolates and damage ratings were recorded for each combination. One greenbug isolate used in this study (TX1) was able to differentiate Rsg1a from Rsg2b through dramatically different plant responses (Rsg2b conferred resistance, Rsg1a did not). The results indicate the potential vulnerability of greenbug resistance genes in barley. Based on these and other reported results, we propose that gene symbol designations for greenbug resistance in barley be changed from Rsg1a to Rsg1 and Rsg2b to Rsg2.     

Screening for Greenbug Resistance in Hordeum chilense Roem et Schult.

Schizaphis graminum (Rondani) is a serious pest of cultivated wheat (Triticum aestivum L.) and resistance is only available in other related species such as Hordeum chilense. Amphiploids between H. chilense and Triticum spp. have been obtained, and addition lines of H. chilense in wheat have been developed. Thirty-five accessions of H. chilense were screened to identify greenbug antixenosis, antibiosis and tolerance. Antixenosis was determined in a conventional host free choice test; antibiosis was measured by aphid life cycle and fecundity rate, and tolerance was tested in a conventional infestation test of 4 weeks. Two commercial barley cultivars were used as susceptible and resistant controls. Eight H. chilense accessions showed higher degrees of antixenosis than the resistant check, 19 were similar and the rest were lower. All accessions were more resistant than the susceptible check. Measured by aphid life cycle, 22 H. chilense accessions showed higher antibiosis than the resistant cv., and all exhibited a higher antibiotic effect on fecundity rates than the control. A similar degree of tolerance to that of the resistant control was observed in six accessions, the remaining entries ranged between the controls. The presence of one mechanism did not exclude the existence of other mechanisms in the same entry and therefore, independence of the different mechanisms is proposed. Most of the accessions showed higher variability than both controls for the three mechanisms, and it appears to be genetic variability within entries for the three mechanisms.     

Multigenic inheritance of biotype-E greenbug resistance in wheat

Relatively little is known about host-plant insect-resistance genes. Near-isogenic lines (NILs) can be a useful tool in evaluating such genes and their mechanisms of action. Through backcrossing and single-seed selection, NILs have been produced in wheat (Triticum aestivum L.) for resistance/susceptibility to biotype-E greenbug, Schizaphis graminum (Rondani). Crosses among several resistant and susceptible NILs produced segregation patterns in the F₂ generation that were inconsistent with simple monogenic inheritance. The simplest genetic hypothesis consistent with the data would involve two independently segregating loci, requiring complementary expression of multiple resistance alleles. F₃ segregation data were also consistent with the proposed genetic hypothesis. Multiple alleles are required to account for the observed variation, although the source of the multiple alleles is unknown. Direct comparison of specific resistant/susceptible pairs of NIL's, as well as bulked segregant analysis, should permit elucidation of resistance mechanisms. Based on the segregation data presented, new designations for the resistance loci studied are proposed.