不同寄主植物对山楂叶螨生长发育和繁殖的影响

室内采用叶碟饲养的方法研究了苹果、桃、李、樱桃和杏等不同果树对山楂叶螨Tetrancychusvienensis生长发育和繁殖的影响。结果表明,在李树上山楂叶螨的发育历期短、生殖力强、存活率高,rm值大,而在樱桃和杏树上该螨的发育历期长、生殖力弱、存活率低、rm值小。寄主转换试验结果表明,当山楂叶螨由苹果转移至樱桃和杏树时,其生长发育的历期显著延长,rm值大幅度降低;而由苹果转移至桃树和李树时,其生长发育的历期虽也有所延长,但差异不显著,rm值则明显降低。表明山楂叶螨对新寄主的适应因不同寄主而异,在桃和李上经历1代后即可适应,而在杏和樱桃上经历2代后才能适应新的寄主。     

Polymorphisms of VEGF,TGFβ1, TGFβR2 and conotruncal heart defects in a Chinese population

Genetic variants may determine susceptibility of congenital heart disease (CHD). To evaluate the impact of transforming growth factor-β1 (TGFβ1), TGFβ receptor II (TGFβR2) and vascular endothelial growth factor (VEGF) polymorphisms on conotruncal heart defects susceptibility, we genotyped six functional polymorphisms TGFβ1 rs1800469 C>T, TGFβR2 rs3087465 G>A, VEGF ?2578C>A, ?1498T>C, ?634G>C and +936C>T in a hospital based case–control study of 244 conotruncal heart defects cases and 136 non-CHD controls in a Chinese population. Logistic regression analyses revealed that if the TGFβ1 rs1800469 CC homozygote genotype was used as the reference group, subjects carrying the CT variant heterozygote had a significant 0.48-fold decreased risk of conotruncal heart defects [odds ratio (OR) = 0.52; 95 % confidence interval (CI) = 0.30–0.88], subjects carrying the TT variant homozygote had a significant 0.47-fold decreased risk of conotruncal heart defects (OR 0.53; 95 % CI 0.28–1.00). In stratification analyses, the TGFβ1 rs1800469 C>T genotype was associated with a decreased risk for tetralogy of fallot in homozygote comparisons (OR 0.47; 95 % CI 0.22–0.99), a decreased risk for transposition of great artery in the dominant genetic model (OR 0.49; 95 % CI 0.28–0.87) and heterozygote comparisons (OR 0.45; 95 % CI 0.24–0.83). Our findings suggest that TGFβ1 rs1800469 C>T polymorphism was significantly associated with decreased risk of conotruncal heart defects. TGFβR2 rs3087465 G>A, VEGF ?2578C>A, ?1498T>C, ?634G>C and +936C>T polymorphisms may not play a role in the susceptibility of conotruncal heart defects.     

Assessment of Sublethal Effects of Clofentezine on Life-table Parameters in Hawthorn Spider Mite (Tetranychus viennensis)

A leaf disc bioassay was employed in the laboratory to assess the population responses of Tetranychus viennensis Zacher to clofentezine at three concentrations (LC₁₀, LC₂₅ and LC₅₀) in three successive generations. Life-table parameters were calculated in each acaricide exposure regime and compared by jackknife procedures. Clofentezine treatments in the juvenile stages significantly delayed development of the mites, and this delay increased with increasing dose but decreased as the mites developed. Exposure to clofentezine reduced the net reproduction rate (R₀) in a concentration-dependent manner. The LC₅₀ treatment had strong effects on the hatchability of eggs produced by surviving females. Hatch rate dropped from 0.83 in the untreated control to 0.51 in the third generation. When exposed to constant concentrations of clofentezine in three successive generations, the intrinsic rate of increase and R₀ of the mites decreased significantly, but they increased significantly when exposed to decreasing concentrations. Unexposed offspring of the exposed mother also displayed increases in R₀ and the jackknife procedures indicated no significant differences in R₀ between LC₁₀ and LC₂₅ offspring and their mothers vs. the control, while R₀ in unexposed LC₅₀ offspring was significantly higher than their mother’s, but lower than that in the control. These changing patterns of r_m reveal that acaricide effects at the population level strongly depend on the life-history characteristics of T. viennensis and the chemical mode of action.     

塔六点蓟马对山楂叶螨的功能反应

室内采用叶碟饲养的方法研究了苹果园塔六点蓟马Scolothrips takahashii各发育阶段对山楂叶螨Tetranychus viennensis各虫态的功能反应,结果表明,塔六点蓟马成虫、幼虫对叶螨的卵、幼若螨及成螨的功能反应均为Holling-Ⅱ型;随着蓟马个体的不断生长,其捕食量逐渐增大,雌成虫的捕食量显著大于雄虫,但其捕食的猎物数量随着叶螨个体的不断生长而减少;温度对蓟马成虫的功能反应有明显的影响,在20～35℃范围内,随着温度的升高其处置时间缩短、捕食能力明显增强;蓟马成虫的日龄对其功能反应也有明显影响,雌虫在日龄在12d之后,捕食能力逐渐减弱,15d日龄的雌虫对螨卵的处置时间显著长于3～6d日龄,雄虫则在9d日龄时对螨卵的处置时间已显著延长.     

Male age and sexual experience affect male mating behavior in the hawthorn spider mite,Amphitetranychus viennensis

As is reported, in species with first-male sperm precedence, male age and previous sexual experience play crucial roles in male mating behavior. In the hawthorn spider mite, Amphitetranychus viennensis Zacher, previous studies showed that only females that copulated for the first time could achieve fertilization. Based on this, the effects of male age and mating history on male mate choice and male mate competition were investigated. It was confirmed that males could distinguish virgins from fertilized females but they were unable to discriminate between virgins and unfertilized females. Interestingly, the copulation duration of males mated with fertilized females was much shorter than that of males mated with virgins or unfertilized females. Additionally, for male mating choice, males of all ages and more experienced males preferred 5-day-old virgin females, whereas only less experienced males preferred 1-day-old virgin females. In male-male competition, 3-day-old males were more competitive and obtained more copulations compared with others. Copula duration was closely related to male age. Though no significant differences were observed in mating competition between virgin and mated males, copula duration of males in first copulation was the longest and gradually shortened in subsequent copulations. In all, this investigation demonstrated that male age and sexual experience affected male mate choice and male-male competition, leading to further insight into the influences of male age and sexual experience on the reproductive fitness of both sexes.

     

Effect of host plants on developmental time and life table parameters of Carposina sasakii (Lepidoptera: Carposinidae) under laboratory conditions

Studies were designed to examine the effects of host plants (apricot, Prunus armeniaca L.; plum, Prunus salicina L.; peach, Prunus persica L.; jujube, Zizyphus jujuba Will.; apple, Malus domestica Mill.; and pear, Pyrus sorotina Will) on the development and life table parameters of the peach fruit moth, Carposina sasakii Matsumura (Lepidoptera: Carposinidae) under laboratory conditions. Peach fruit moth developed faster (12.48 d) and had the highest preimaginal survival rate (50.54%) on plum compared with the other host plants. Adult longevity was significantly longer on jujube for both female and male moths. Adult females from larvae reared on jujube and peach laid significantly greater numbers of eggs (214.50 and 197.94 eggs per female, respectively) compared with those reared on the other four host plants. Life-table parameters were calculated for each host plant and compared by jackknife procedures. The intrinsic rate of natural increase (r(m)) was significantly greatest on plum (0.1294 eggs per female per d), followed by jujube and apricot (0.1201 and 0.1128 eggs per female per d), respectively. Implications of the various measures of population performance are discussed.