Do pollen beetles need pollen? The effect of pollen on oviposition,survival, and development of a flower‐feeding herbivore

Abstract.  1. Pollen is considered to be an important dietary component for many species of flower-feeding herbivores. Its influence on oviposition site selection by the pollen beetle Meligethes aeneus , and on the development of its larvae was investigated.
2. The effects of pollen presence and absence on adult, egg, and larval incidence in the field, and on larval development in the laboratory were compared through the use of Synergy, a composite hybrid oilseed rape Brassica napus variety comprising male-fertile (with pollen) and male-sterile (without pollen) plants.
3. In the field, adult females were more abundant on male-fertile plants during flowering, and a greater proportion of male-fertile than male-sterile buds were accepted for oviposition. These data indicate a possible role of pollen in oviposition site selection by female pollen beetles.
4. The numbers of first instar larvae on the two plant lines did not differ; however, more second instars were found on male-fertile than on male-sterile flowers. This suggests a greater larval survival on male-fertile plants, possibly due to the more readily available food resources and better nutrition afforded by the presence of pollen.
5. Laboratory experiments confirmed that a diet which included pollen improved survival to adulthood and resulted in heavier pupae and adults; however, pollen was not obligatory for larval survival and development.
6. The pollen beetle, previously thought to be an obligate pollen feeder, is therefore more generalist in its requirements for development. These findings may relate to the nutritional and behavioural ecology of other flower-feeding herbivores.     

甘蓝型油菜芥酸和二十碳烯酸含量的基因效应

以甘蓝型油菜的4种纯合芥酸基因型之间所有可能的6个杂交组合的P_1、P_2、F_1、P_2、B_1和B_2世代为材料,用生统遗传学方法研究了芥酸和二十碳烯酸的基因作用形式及效应。发现无论亲本是单基因差异还是二基因差异,F_1和F_2代的芥酸含量都接近中亲值,F_1略大于中亲值和F_(20)世代均值分析表明,芥酸含量的遗传符合加性显性模型,加性效应占绝对优势,显性效应不显著。用数量遗传学方法估计的芥酸基因数与已知的结果相近。     

Identification of potentially embryogenic microspores in Brassica napus

Studies were undertaken with Brassica napus L. cv. Topas to identify buds containing microspores predisposed to embryogenesis in vitro and to investigate bud and microspore development in relation to this process. No significant correlation was found between the final embryo number and bud components. There appears to be a developmental window of less than 8 h duration during which microspores are very likely to form embryos: over 70% of the microspores can undergo division and up to 70% of these can form embryos. Embryos were mainly obtained from late uninuucleate to early binucleate microspores: the former contained mainly a G2 or M phase nucleus located at the microspore periphery and the latter a generative nucleus (associated with the intine) and a vegetative nucleus. Observations indicated that only the vegetative nucleus contributed to embryo formation. The first embryogenic division occurred between 8 and 16 h for uninucleate- and between 8 and 48 h for binucleate-derived embryos.     

水稻、小麦、油菜和烟草细胞质雄性不育系统中组分Ⅰ蛋白的比较分析

组分Ⅰ蛋白(RuBP羧化酶/加氧酶)的生物合成系由叶绿体基因和细胞核基因共同控制,所以,被作为研究细胞质遗传的标记。本实验用免疫化学和氨基酸成分分析等方法,对水稻(珍汕97)、小麦(繁7)、油菜(湘矮早)和烟草(G28)的细胞质雄性不育系及其保持系的组分Ⅰ蛋白作了比较,同时对不同作物的组分Ⅰ蛋白也作了免疫鉴定。结果表明,细胞质雄性不育系及其保持系的组分Ⅰ蛋白差异不大,但是,四种不同作物的组分Ⅰ蛋白之间有明显差异。     

Effects of the triazole plant growth retardant BAS 111¨W on gibberellin levels in oilseed rape, Brassica napus

Three-week-old shoots of the spring oilseed rape cv. Petranova ( Brassica napus L. ssp. napus ) were found by combined gas chromatography-mass spectrometry to contain GA₁, GA₈, GA₁₅, GA₁₇, GA₁₉, GA₂₀, GA₂₄, GA₂₉, 3-epi-GA₁ and a previously uncharacterised C₁₉ dicarboxylic acid that is probably structurally related to GA₂₄. Shoots of the winter cultivar Belinda, harvested at the early flowering stage, contained the same GAs with the exception of the C₁₉ dicarboxylic acid and, in addition, GA₃₄ and GA₅₁ were identified. All material contained higher levels of GA₂₀ than of GA₁; the ratio of GA₁ to GA₂₀ was highest in shoots containing the largest proportion of young immature tissues. Soil treatment of cv. Petranova seedlings with the growth retardant BAS 111¨W [1-phenoxy-5,5-dimethyl-3-(1,2,4-triazol-1-yl)-hexan-4-ol] caused 80% reduction in height 18 days after treatment and the levels of all GAs were 20% or less that of control plants. Foliar treatment at the same dosage reduced height by 50% and caused an 85% or greater reduction in the concentrations of the GA₁ precursors GA₂₀, GA₁₉ and GA₄₄. However, the levels of GA₁, GA₈ and GA₂₉ were affected to a much smaller extent. Foliar application of BAS 111¨W to cv. Belinda 1 month after sowing resulted in only a 20% height reduction at flowering, but no uniform decrease in the concentrations of endogenous GAs at this stage.