The selective sequestration of glucosinolates by the cabbage aphid severely impacts a predatory lacewing

The cabbage aphid Brevicoryne brassicae is a notorious agricultural pest that specializes on plants of the Brassicaceae family, which are chemically defended by glucosinolates. By sequestering glucosinolates from its host plants and producing its own activating enzyme (myrosinase), this aphid employs a self-defense system against enemies paralleling that in plants. However, we know little about the metabolic fate of individual glucosinolates during aphid sequestration and activation and about the biochemical effects of this defense on aphid enemies. Here, we probed these questions focusing on B. brassicae and a predatory lacewing, Chrysoperla carnea. We found that distinct glucosinolates were accumulated by B. brassicae at different rates, with aliphatic glucosinolates being taken up more quickly than indolic ones. B. brassicae myrosinase enzymatic activities toward different glucosinolates were strongly correlated to their rates of accumulation in vivo. Surprisingly, after simulated predation, the production of toxic isothiocyanate products (ITCs) was quantitatively outweighed by less toxic products such as nitriles and ITC-conjugates. Nevertheless, the defensive cocktails significantly impaired C. carnea development. Tissue-specific quantification of glucosinolate metabolites revealed that the lacewings employ both conjugation and mobilization to reduce the toxicity of aliphatic ITCs, but these strategies were only partially effective. These results clarify the metabolic fates of glucosinolates after sequestration by an aphid herbivore and further in a higher trophic level, as well as the consequences for predator survival and development, and might be instructive for integrative pest management approaches targeting the cabbage aphid.

     

Identification and Characterization of Two “Sensory Neuron Membrane Proteins” (SNMPs) of the Desert Locust,Schistocerca gregaria (Orthoptera: Acrididae)

Pheromone-responsive neurons of insects not only require specific receptors but in addition several auxiliary components, including the “sensory neuron membrane protein,” SNMP. Accordingly, SNMP is considered as a marker for neurons responding to pheromones. For the desert locust Schistocerca gregaria, it is known that the behavior, including aggregation behavior and courtship inhibition, is largely controlled by pheromones. However, little is known about pheromones, their receptors, and the pheromone-responsive cells in locusts. In this study, we have identified two SNMP subtypes, SNMP1 and SNMP2, and compared their phylogenetic relationship and primary structure motifs with SNMPs from other species. Both SNMPs were found in chemosensory tissues, especially the antennae. Employing double in situ hybridization, we identified and localized the SNMP-expressing cells in the antennae. Cells expressing SNMP1 were localized to sensilla trichodea but also to sensilla basiconica, which in locust respond to pheromones. One or a few cells express SNMP1 within the multineuron clusters from sensilla basiconica, whereas the SNMP2 subtype was expressed in cells surrounding the neuron clusters, possibly supporting cells. Based on the finding that SNMP1 is expressed in distinct neurons under chemosensory sensilla, it is conceivable that these cells may represent pheromone-responsive neurons of the desert locust.     

春播夏谷子品系农艺性状的相关性和聚类分析

为了明确谷子品系的适应性,为杂交亲本选配提供实验依据,以引进的夏谷子品系和自选品系为材料,利用SPSS 22.0和Microsoft Excel 2007软件对其农艺性状进行变异、聚类、相关和双关联分析,结果表明,(1)供试品系质量性状遗传多样性指数在0~1.910之间,由大到小依次为穗形>穗茎姿态>刚毛长度>刚毛颜色>颖果颜色>籽粒形状>籽粒颜色>植株颜色>叶姿;数量性状变异系数变幅为8.11%~20.29%,依次分别是穗粒重>亩产量>穗颈长度>单穗重>茎秆长度>穗长>千粒重>穗粗>茎秆粗度。(2)亩产量与穗茎姿态、穗形、千粒重、穗粒重、穗码个数、单码籽粒数、单穗重、穗粗、穗长、穗茎长度、倒二叶宽呈极显著正相关,与茎秆粗度呈极显著负相关。(3)在欧式距离4.0将供试材料聚为六大类:第一类包括11份,均为夏谷子品系,亩产量约为400 kg,茎秆较矮且粗,叶姿半上冲,刚毛黄较短,纺锤型穗;第二类只有2015137-2Ⅱ-4-1,叶姿半上冲,刚毛中等为紫色,穗茎姿态为勾形,圆锥型穗,株高较高,亩产为387.71 kg;第三类6份均为夏谷品系,刚毛短为黄或紫色,穗茎姿态为强弯,纺锤型穗,茎秆较矮且粗,亩产在287~340 kg之间;第四类包括2016025♀-2-4(大同29系选后代)等6份高产品系,叶姿半上冲,刚毛中或短为黄色,穗茎姿态为勾形,穗形为纺锤型、猫爪型或圆锥型,株高适中,亩产量均在529 kg以上;第五类包括2015053Ⅰ-2Ⅰ-5-1(济谷13系选后代)等5份品系,叶姿半上冲,亩产约489 kg。第六类包括2015(07)-4-10和2015137-2Ⅱ-5-1等2份品系,叶姿半上冲,猫爪型或圆锥型穗,亩产约501 kg。综合分析得出8份产量较高的品系,分别为2015(07)-4-10、2015(07)-4-11、2015053Ⅰ-2Ⅰ-4-2、2015053Ⅰ-2Ⅱ-1-1、2015137-2Ⅱ-5-1、16C227-2-2、2016025♀-2-4和2016025♀-2-5。