Repellent effects of five monoterpenoid odours against Tribolium castaneum (Herbst) and Rhyzopertha dominica (F.) in Calabar, Nigeria

Secondary plant compounds are recognised as important components of plant defence system against herbivores and pathogens. Five monoterpenoids, (R)-linalool, 1,8-cineole, (S)-2-heptyl acetate, (S)-2-heptanol and citral, which are natural components of the essential oils of Aframomum melegueta (K. Schum) and Zingiber officinale (Roscoe), were tested at the ratios in which they occur naturally for repellent activity against Tribolium castaneum (Herbst.) and Rhyzopertha dominica (F.) in a 4-way olfactometer. The results showed the repellent properties of the compounds as both beetles spent less time in the olfactometer arm containing the test stimuli. (R)-linalool and (S)-2-heptanol were stronger repellent compounds than the others. Linalool showed good repellent activity against T. castaneum (P = 0.001) as the insect spent 1.22 min in the test arm compared to the control arms (2.78 min), and R. dominica (P = 0.001) with 0.89 min in the test arm compared to 2.87 min in the control arms. With (S)-2-heptanol, T. castaneum spent 1.23 min in the test arm compared to 2.83 min in the control arms. R. dominica spent 1.61 min in the test arm and 2.69 min in the control arms. For the number of entries or visits made, while both insects were significantly repelled (P < 0.05) by the linalool-treated arm than the control, only R. dominica was repelled by the (S)-2-heptanol-treated arm (P = 0.038) compared to the control arms. The results indicate that A. melegueta and Z. officinale essential oils and their components could be suitable as safer repellents or fumigants against T. castaneum and R. dominica.     

茶梢和茶花信息物引诱有翅茶蚜效应的研究

用四臂嗅觉仪和昆虫触角电位仪（EAG）研究了新鲜茶梢和茶花的15种单一挥发性组分对有翅茶蚜的引诱效应。结果表明其中的顺-3-己烯-1-醇、反-2-己烯醛、水杨酸甲酯、芳樟醇、正辛醇和己醛等组分,及茶花主要香气组分橙花醇和烯丙基异硫氰酸酯显著引诱有翅茶蚜。在嗅觉仪生测中,15种组分的10^-4βg/ml和10^-2βg/ml两种剂量引诱蚜数的差异明显。EAG反应还表明：①新鲜芽下第一叶气味引出的EAG值最大;②用10^-2βg/ml的正己醇、正戊醇、1-戊烯-3-醇、2-戊烯-1-醇、反-2-己烯醛、顺-3-己烯-1-醇和乙酸顺-3-己烯酯按1∶1∶1∶1∶1∶1∶1比例组成“绿叶气味”,也可引起有翅蚜强烈的EAG反应;③蚜害茶梢嫩茎的气味忌避有翅蚜。认为新梢和茶花释放的绿叶气味和水杨酸甲酯可引导有翅茶蚜朝茶梢定位,严重遭受蚜害的茶梢可能释放忌避有翅蚜的信息物质。     

3种植物对椰心叶甲及椰心叶甲啮小蜂选择行为的影响

[目的]阐明3种植物的挥发物对椰心叶甲及椰心叶甲啮小蜂的引诱作用。[方法]利用四臂嗅觉仪在室内测试了椰子、大王棕和槟榔3种植物的挥发物对椰心叶甲雌成虫选择行为的影响,同时采用Y型嗅觉仪测试椰心叶甲啮小蜂对这3种植物受害前后挥发物的行为反应。[结果]3种植物的老叶和心叶的挥发物对椰心叶甲具有显著的引诱作用,对椰心叶甲啮小蜂无引诱作用,但当3种植物的心叶在遭受椰心叶甲幼虫为害后及为害后的去虫叶,其挥发物对椰心叶甲啮小蜂具有显著的引诱作用;3种植物受幼虫为害的心叶的挥发物之间对椰心叶甲啮小蜂的引诱作用均无显著差异。[结论]在椰心叶甲幼虫为害寄主植物心叶后可引诱椰心叶甲啮小蜂主动搜索和识别寄主。     

锈色粒肩天牛对植物的选择效应

[目的]探讨锈色粒肩天牛对三门峡市不同寄主植物的选择效应。[方法]采用"Y"形嗅觉仪法和风洞法研究锈色粒肩天牛对国槐、龙爪槐、栾树、垂柳、榆树、旱柳、雪松、桧柏、侧柏、刺柏、紫藤这些寄主植物的选择性。[结果]国槐对锈色粒肩天牛有明显的招引,龙爪槐、栾树、紫藤可能成为其潜在的危害对象,垂柳、榆树、旱柳、雪松、桧柏、侧柏、刺柏不会成为锈色粒肩天牛的危害和寄主对象。[结论]国槐的挥发物质对锈色粒肩天牛有显著的招引效应。     

松大蚜对植物选择效应研究

[目的]探讨松大蚜成蚜和3龄若蚜对鲁山不同寄主植物的选择效应。[方法]采用"Y"形嗅觉仪测试方法研究松大蚜对油松的松针、嫩枝、鲜球果、干果主干以及黑松、白皮松、赤松、刺槐、胡枝子、侧柏、合欢、黄荆这些寄主植物的选择性。[结果]成蚜和3龄若蚜试验结果一致,油松和白皮松对松大蚜有明显的招引,赤松和黑松可能成为其潜在的危害对象,侧柏、刺槐、胡枝子、合欢、黄荆不会成为松大蚜的危害和寄主对象。[结论]油松的嫩枝挥发物质对松大蚜有显著的招引效应。     

用选择性嗅觉仪测定棉铃虫对植物气味反应的研究

发展了一种选择性嗅觉仪 ,用这种嗅觉仪测定了棉铃虫成虫对萎蔫的枫杨叶、新鲜的棉花叶、棉花花蕾、玉米叶及玉米花丝气味的反应。结果表明 :萎蔫的枫杨叶的气味对棉铃虫处女雌蛾具有引诱作用 ,对雄蛾和已交配过的雌蛾无引诱作用 ;棉铃虫雌、雄蛾不受新鲜棉花气味的引诱 ;玉米叶的气味对棉铃虫成虫无引诱作用 ,但玉米花丝对棉铃虫处女雌蛾具有较强的引诱作用。讨论了生测方法在研究昆虫与植物气味关系中的作用以及萎蔫的枫杨叶气味引诱棉铃虫的生物学意义     

Olfactory cues associated with fungal grazing intensity and secondary metabolite pathway modulate Collembola foraging behaviour

Fungal secondary compounds play an important role for springtail food choice and fitness. Little is known, however, on the role of olfactory cues for Collembola foraging behaviour and whether Collembola can olfactorily perceive volatiles associated with fungal secondary metabolite pathways. We investigated the ability of three species of Collembola (Folsomia candida, Heteromurus nitidus and Supraphorura furcifera) to use olfactory cues for discriminating between fungi of different phylogenetic affiliation (Aspergillus nidulans, Cladosporium cladosporioides, Ascomycota; Laccaria bicolor, Basidiomycota) and toxicity using fungal strains of A. nidulans with reduced secondary metabolite production. Furthermore, we studied if olfactory cues from hyphae injured by grazing affect the foraging behaviour of Collembola. We hypothesized that (i) Collembola are able to olfactorily perceive and respond to fungal species/strains with different secondary metabolite pathways and that (ii) Collembola are able to sense fungal mycelia injured by grazing. Each of the Collembola species studied preferentially oriented their foraging towards fungal strains of A. nidulans with suppressed secondary metabolites, and in particular towards the mutant where the global regulator for secondary metabolites (ΔlaeA) has been silenced. Two of the three Collembola species (H. nitidus and S. furcifera) sensed olfactory cues of previously grazed fungi and moved towards ungrazed fungi, however, the response of S. furcifera was restricted to fungi extensively exposed to grazing (5 days) suggesting that the response varies between Collembola species.Overall, the results support the first and second hypothesis indicating that Collembola (1) are able to olfactorily differentiate fungi of different toxicity and move towards more palatable fungi, and (2) showed a lesser preference for fungi previously exposed to grazing.     

刺槐突瓣细蛾对植物的选择效应

[目的]探讨刺槐突瓣细蛾对徂徕山不同寄主植物的选择效应。[方法]采用"Y"形嗅觉仪法和风洞法研究刺槐突瓣细蛾对刺槐、国槐、紫藤、紫荆、胡枝子、合欢、侧柏、油松、板栗、核桃这些寄主植物的选择性。[结果]刺槐对刺槐突瓣细蛾有明显的招引效应,国槐、胡枝子可能成为其潜在的危害对象,紫藤、紫荆、合欢、侧柏、油松、板栗、核桃不会成为刺槐突瓣细蛾的危害和寄主对象。[结论]刺槐的挥发物质对刺槐突瓣细蛾有显著的招引效应。     

Calling behaviour and male response towards sex pheromone of poplar moth <Emphasis Type="Italic">Condylorrhiza vestigialis</Emphasis> (Lepidoptera: Crambidae)

The calling behaviour of virgin females Condylorrhiza vestigialis Guenée, 1854 (Lepidoptera: Crambidae) and the female pheromone gland extract activity were studied under laboratory conditions. Most of the females started calling from their first scotophase period after emergence. Maximum calling occurred between the seventh and tenth hours of the scotophase period. The length of the calling increased with age until the fourth scotophase, but the onset of calling time did not differ with age. The number of calling bouts increased significantly with age, but the mean duration of each calling bout (20.8 min) did not vary with age. Extracts of pheromone glands evaluated in a Y-tube olfactometer attracted significantly more males than control, 70 and 30%, respectively. Gas chromatographic–electroantennogram detection (GC–EAD) analysis of these extracts indicated the presence of a single EAD-active peak, the putative sex pheromone of the species. This pheromone compound may be suitable for monitoring populations densities of C. vestigialis, and for detection of the onset of the seasonal flight period. An efficient pheromone is of importance also with respect to current attempts to develop new control methods for this important pest of Populus spp. in Brazil.