Role of visual and olfactory cues from agricultural hedgerows in the orientation behavior of multicolored Asian lady beetle (Coleoptera: Coccinellidae)

Harmonia axyridis Pallas is an introduced lady beetle common in eastern North American agroecosystems. Two-choice behavioral bioassays were performed to determine whether visual and olfactory stimuli from prey and host habitats could elicit taxis in wild-collected H. axyridis adults and whether beetles exhibit a preference among stimuli. Soybean aphid (Aphis glycines Matsumura) spends much of the year in agricultural hedgerows residing on buckthorn (Rhamnus cathartica L), and H. axyridis is frequently observed feeding on aphids in this habitat. Olfactory bioassays were performed in a Y-tube olfactometer and tested the response of beetles to the odor of buckthorn leaves, apple leaves (Malus domestica Borkh.), and buckthorn leaves both naturally and artificially infested with A. glycines. No differences were observed between the numbers of beetles moving toward the odor of buckthorn artificially infested with A. glycines and uninfested buckthorn, but more beetles preferred naturally infested buckthorn over uninfested buckthorn. Visual bioassays were performed in an acrylic tube arena,and tested beetle response to silhouettes and to apple and buckhorn leaves. Beetles were significantly more likely to choose silhouettes over blank space in visual trials. Significantly more beetles moved toward buckthorn leaves than blank space, but beetles did not discern between apple and buckthorn until olfactory cues were also included. This study lays the foundation for future work examining the response of H. axyridis to visual and olfactory cues in Ontario agroecosystems, which could help enhance effectiveness of H. axyridis as a biological control and mitigate its impacts as a pest species.     

Effects of plant odor on oviposition by the black swallowtail butterfly,Papilio polyxenes (Lepidoptera: Papilionidae)

Black swallowtail females laid more eggs on plant models treated with contact stimulants and volatiles from carrot leaves than on models treated only with contact stimulants. The volatiles enhanced landing rates and females alighted more frequently on artificial leaves treated with host volatiles than on adjacent control leaves. Volatiles from cabbage, a nonhost, inhibited landing rates on artificial leaves treated with carrot contact stimulants. Examination of antennae revealed two major types of sensilla, believed to be olfactory in function. Electroantennogram preparations responded more strongly to carrot volatiles than to cabbage volatiles and several shared responses at particular retention times to carrot volatile components eluting from a gas chromatograph. Our results are consistent with a long-standing hypothesis that behavioral responses to essential oil components characteristic of the larval food plants have facilitated host shifts in the genus Papilio.     

Selection on olfactory response to semiochemicals from a plant-host complex in a parasitic wasp

Parasitic wasps (parasitoids) use volatiles from the plants infested by phytophagous insects to locate host herbivores, but their behavioural response to such semiochemicals is highly variable. Bi-directional selection on Cotesia glomerata (Hymenoptera: Braconidae) was conducted to investigate the importance of genetic variation in the olfactory response of parasitoids. Female wasps were assessed for flight orientation and landing success in response to the hexane extract from a plant-host complex in a wind tunnel. After the first generation of selection, two strains significantly differentiated in both flight orientation and landing success, and their divergence continued with further selection. The two selected strains genetically differentiated in olfactory perception rather than upwind flight ability. The realized heritability was estimated as 0.248 for flight orientation and 0.216 for landing success. The selection experiment further demonstrated that a prior exposure to the semiochemicals significantly enhanced the subsequent response of female wasps, independent of genetic differences. These results suggest that both genetic component and environmental conditioning have played an important role in the evolution of host selection and utilization by the parasitoid in a tritrophic system.     

Rhythms of volatile release from female and male sea buckthorn plants and electrophysiological response of sea buckthorn carpenter moths

The sea buckthorn, Hippophae rhamnoides L., is a thorny, nitrogen-fixing, dioecious, and deciduous shrub which has been attacked by a catastrophic outbreak of Holcocerus hippophaecolus in the ‘Three North Areas’ of China recently. The behavioral responses of female individuals to their dioecious host sea buckthorn, H. rhamnoides ssp. sinensis, were tested by Y-tube bioassay, and intraspecific emission variations and the circadian rhythm of male and female sea buckthorn plants were compared, together with the electrophysiological responses of sea buckthorn carpenter moths to these parameters. Y-tube olfactometry indicated that mated female H. hippophaecolus individuals did not display a significant preference for either sex of sea buckthorns. Additionally, no unique chemical compound was found. Female antennae significantly responded to 1-octene, methyl salicylate, and (Z)-3-Hexen-1-ol acetate, among which methyl salicylate was more abundant in females than in males. In addition, the circadian variation of (Z)-3-Hexen-1-ol acetate suggested that it was an effective compound for host location.     

How do Pieris rapae search for Brassicaceae host plants?

Pieris rapae curucivora Boisduval is a major cause of damage to important Brassicaceae vegetable crops. The method of host landing plant selection by adult females was investigated by covering cabbage (host) and lettuce (non-host) plants to block visual and/or olfactory signals, and also by using volatile extracts of both plants.     

Genetic structure in the seabuckthorn carpenter moth (Holcocerus hippophaecolus) in China: the role of outbreak events, geographical and host factors

Understanding factors responsible for structuring genetic diversity is of fundamental importance in evolutionary biology. The seabuckthorn carpenter moth (Holcocerus hippophaecolus Hua) is a native species throughout the north of China and is considered the main threat to seabuckthorn, Hippophae rhamnoides L. We assessed the influence of outbreaks, environmental factors and host species in shaping the genetic variation and structure of H. hippophaecolus by using Amplified Fragment Length Polymorphism (AFLP) markers. We rejected the hypothesis that outbreak-associated genetic divergence exist, as evidenced by genetic clusters containing a combination of populations from historical outbreak areas, as well as non-outbreak areas. Although a small number of markers (4 of 933 loci) were identified as candidates under selection in response to population densities. H. hippophaecolus also did not follow an isolation-by-distance pattern. We rejected the hypothesis that outbreak and drought events were driving the genetic structure of H. hippophaecolus. Rather, the genetic structure appears to be influenced by various confounding bio-geographical factors. There were detectable genetic differences between H. hippophaecolus occupying different host trees from within the same geographic location. Host-associated genetic divergence should be confirmed by further investigation.     

锰胁迫和性别竞争交互处理下沙棘雌雄幼苗生理响应特征

沙棘(Hippophae rhamnoides)是重要的雌雄异株人工林防护树种,但对其环境胁迫的性别响应差异研究不足,性别竞争与胁迫因子的交互效应响应特征尚不清楚。为了探讨锰胁迫和性别竞争交互处理下沙棘雌雄植株的生理响应特征和耐受能力,旨在为沙棘修复土壤重金属污染提供实践指导,该文研究了锰胁迫(4 000 mg·kg^-1)和3种不同性别组合模式(雌雄、雌雌、雄雄)处理下沙棘的生理响应,分别测定雌雄沙棘叶片中叶绿素、过氧化物酶(peroxidase,POD)、超氧化物歧化酶(superoxide dismutase,SOD)、丙二醛(malondialdehyde,MDA)、总酚(total phenols, TP)、游离脯氨酸(free proline,Pro)、可溶性糖(soluble sugar,SS)、甜菜碱(glycine betaine, GB)以及锰含量。结果表明:(1)锰胁迫下,在所有竞争组合中,性间竞争的雄株(M/FM)SOD活性最高,而MDA含量与对照相比未有明显升高,表明雄株的抗氧化能力更好,膜氧化损伤程度更小。(2)锰胁迫时M/FM积累了更多的游离脯氨酸,表现出更好的渗透调节能力和耐受能力。(3)交互效应分析显示性别互作和锰胁迫交互处理显著影响了沙棘雌雄叶片的光合色素、抗氧化酶活性和渗透调节能力; 主成分分析显示SOD、POD、MDA、叶绿素b(chlorophyll b, Chlb)、SS、Pro可作为重要的生理响应指示参数。该研究结果对于利用沙棘修复土壤重金属污染可提供一定的参考。     

烟粉虱(Bemisia tabaci)的寄主选择性

通过田间系统调查、实验室嗅觉测定、笼内和培养皿内自由扩散观察,对烟粉虱的寄主选择性进行了研究.结果表明,在田间,烟粉虱对不同的寄主植物存在明显的寄主选择性,其中对茄子、花椰菜、黄瓜等植物具有较强的嗜性,而对蕹菜、芹菜、苋菜等植物的嗜性较差;烟粉虱对同一植物的不同品种也有明显的选择性.烟粉虱对寄主植物颜色有明显的选择性,选择结果与烟粉虱对这些寄主的嗜性趋势基本一致.烟粉虱对单株寄主植物的嗅觉反应不敏感,但对植物叶片的乙醇抽提物有明显的嗅觉反应,并表现出较强的寄主选择性.在养虫笼内,烟粉虱从虫源皿向寄主植物自由扩散的过程中,在不同寄主植物和同一植物的不同品种上着落的成虫数量不同,并且在一定的时间范围内,着落在寄主叶片上的虫量还会不断的发生变化.     

云斑天牛对补充营养寄主的选择性

通过林间调查和室内选择性试验,研究云斑天牛Batocera horsfieldi(Hope)成虫在补充营养阶段对多种寄主植物的选择性。林间调查结果表明,云斑天牛成虫对法国冬青(V.awabuki)和光皮桦(B.luninifera)有较强的嗜食性,林间最高取食选择率分别为100%和92.4%。利用"Y"型嗅觉仪测定云斑天牛成虫对法国冬青、核桃(Jugians regia L.)、光皮桦和杨树(Populus tomentosa)等寄主挥发物的行为反应,生测结果与林间调查及室内选择结果一致,法国冬青和光皮桦的挥发物对云斑天牛引诱效果明显,并且枝条挥发物引诱力高于叶片挥发物,引诱效果最佳的组合为:采用蒸馏法,用二氯甲烷提取的冬青枝叶粗提物;采用浸提法,用乙醚提取的冬青和光皮桦枝叶粗提物和二氯甲烷分别提取的冬青枝和叶的粗提物。     

Bioassays on selection and feeding responses of Holotrichia oblita adults to different plant species

Bioassays on selection and feeding responses of Holotrichia oblita adults to different plant species were conducted both in laboratory and under field conditions. The selection response bioassay showed that the adults were significantly attracted to Ricinus communis. In paired tests of the field cages, more than 60% adults were attracted to R. communis plants, while only 35.55%, 34.45%, 33.35%, and 26.65% were attracted to plants of Glycine max, Arachis hypogaea, Ipomoea batatas, and Gossypium hirsutum, respectively. In the laboratory, the selection response percentage of the adults to R. communis leaves reached up to 93% in the presence of other host plant leaves and still arrived at 70% in the absence of other host plant leaves. Feeding deterrence bioassay showed that the adults preferred to I. batatas leaves with 229.90 ± 4.25 mg leaf consumption and 41.30 ± 5.19 mg faeces excretion after 12 h, followed by the leaves of G. hirsutum and A. hypogaea. The adult did not prefer leaves of R. communi with only 7.10 ± 0.23 mg leaf consumption and corresponding 4.00 ± 0.84 mg fecal excretion. In summary, all experimental results suggested that the attraction of H. oblita adults to R. communi is not triggered for feeding.     

Bioassays on selection and feeding responses of Holotrichia oblita adults to different plant species

Bioassays on selection and feeding responses of Holotrichia oblita adults to different plant species were conducted both in laboratory and under field conditions. The selection response bioassay showed that the adults were significantly attracted to Ricinus communis. In paired tests of the field cages, more than 60% adults were attracted to R. communis plants, while only 35.55%, 34.45%, 33.35%, and 26.65% were attracted to plants of Glycine max, Arachis hypogaea, Ipomoea batatas, and Gossypium hirsutum, respectively. In the laboratory, the selection response percentage of the adults to R. communis leaves reached up to 93% in the presence of other host plant leaves and still arrived at 70% in the absence of other host plant leaves. Feeding deterrence bioassay showed that the adults preferred to I. batatas leaves with 229.90 ± 4.25 mg leaf consumption and 41.30 ± 5.19 mg faeces excretion after 12 h, followed by the leaves of G. hirsutum and A. hypogaea. The adult did not prefer leaves of R. communi with only 7.10 ± 0.23 mg leaf consumption and corresponding 4.00 ± 0.84 mg fecal excretion. In summary, all experimental results suggested that the attraction of H. oblita adults to R. communi is not triggered for feeding.     

Volatiles released from foliar extract of host plant enhance landing rates of gravid Polygonia c‐album females,but do not stimulate oviposition

The role of olfactory cues for host search is much less investigated in day‐active butterflies than in their relatives, the nocturnal moths. The goal of this study was to investigate whether host‐plant volatiles from foliar extracts of hop, Humulus lupulus L. (Cannabaceae), evoke electroantennographic (EAG) responses, increase landing rates, and stimulate egg‐laying behavior of gravid Polygonia c‐album L. (Lepidoptera: Nymphalidae) females. Eighty‐nine volatile compounds were detected in a non‐concentrated methanol extract of hop by gas chromatography–mass spectrometry, 11 of which elicited an EAG response. Concentration of the crude extract significantly reduced landing rates on artificial leaves treated with the sample due to loss of volatile compounds, but after landing the oviposition response of gravid females was not affected. A mixture of eight commercially available EAG‐active volatiles increased the landing rate of gravid females to their source but did not act as oviposition stimulants. Dividing the volatile compounds into two groups – consisting of (1) hexanal, (E)‐2‐hexenal, octanal, nonanal, and decanal, and (2) sulcatone, humulene, and benzyl alcohol – obliterated effectiveness, revealing synergism between compounds. Although volatiles did not stimulate oviposition, they significantly contributed to the distribution of eggs by increasing the landing rates on treated artificial leaves.     

寄主植物物理性状及营养物质对地红蝽寄主选择性的影响

【目的】地红蝽Pyrrhocoris tibialis是一种重要的农业植食性害虫,寄主范围广泛。本研究测定地红蝽对不同植物的取食偏好及分析寄主植物物理性状和营养物质在地红蝽成虫寄主选择行为中的作用,以期从寄主理化性状的角度来探讨地红蝽寄主选择行为机制,为指导作物抗虫育种提供依据。【方法】通过自由选择方法研究地红蝽成虫对5种寄主植物(谷子Setaria italica、高粱Sorghum bicolor、绿豆Vigna radiata、大豆Glycine max和玉米Zea mays)叶片的取食选择性;使用Y型嗅觉仪进一步检测地红蝽对5种植物叶片气味的趋性反应;测定分析5种植物叶片物理性状及主要营养物质含量与地红蝽取食选择性的相关性。【结果】地红蝽成虫对5种寄主植物叶片的取食选择率存在显著性差异,依次为谷子＞高粱＞绿豆＝大豆＞玉米,与对这5种寄主植物叶片气味的趋性反应百分率结果一致。相关性分析表明,地红蝽成虫的取食选择性与叶片长宽比、含水量和背面茸毛密度呈显著正相关,相关系数分别为0.881, 0.884和0.906,而与地红蝽成虫取食前后寄主植物叶片可溶性糖含量变化和总蛋白质含量变化呈显著负相关,相关系数分别为-0.915和-0.951。通径分析表明,寄主植物叶片背面茸毛密度和总蛋白质含量变化是地红蝽寄主选择性的重要决定因素。【结论】地红蝽成虫对不同寄主植物存在取食选择和趋向性差异,地红蝽成虫取食选择与寄主植物叶片长宽比、背面茸毛密度、含水量以及可溶性糖和总蛋白质含量变化有关。     

The role of visual and olfactory plant cues in aphid behaviour and the development of non-persistent virus management strategies

Non-persistent viruses are transmitted by aphids in short feeding probes during the initial stages of aphid host plant selection behaviour. To control the transmission of these viruses, farmers rely on pesticides and cultural control practices, with varying success rates. As a result, there is a need for novel management practices that are more robust and specific to reducing aphid landing rates in crops. Aphid–plant–virus interactions involve a number of behaviours and processes to ensure survival of the insect vector and virus. So far, virus management tactics focused on reducing immigrating aphids in crops have emphasized the manipulation of visual rather than olfactory stimuli. An improved understanding of the synergistic or additive effects in which aphids use visual and olfactory stimuli to locate host plants could be used to improve on current non-persistent virus management tactics and develop novel strategies. The aim of this review is to evaluate current understanding of aphid vector behaviour and the ways that these behaviours have been exploited to develop management strategies, and to identify areas of research needed to further improve virus management.     

Cross-modal effect of natal habitat experience increases receptivity to non-natal habitat cues in generalist parasitic wasps

Exposure to natal habitats induces preferences in individual organism for foraging cues that originate from their developmental habitat. However, the natal experience of habitat generalists may play a different role in their habitat selection, since they use a broad range of foraging cues in a non-natal habitat. In this study, the effects of natal habitat experiences on the responses of females of the generalist parasitoid Aphidius gifuensis Ashmead to cues from natal or non-natal habitats were investigated. The landing rates on plant-host complexes (PHCs) and undamaged plants (UDPs) of natal (wheat) and non-natal (broad bean) plant systems in a wind tunnel increased after encounters with host aphids on the wheat-PHCs when the wasps had previously been exposed to wheat-UDPs. However, without the previous exposure to wheat-UDPs, the landing rate on the broad bean-PHCs was not increased. Similar increase found in responses to green paper disc dummies suggested involvement of visual stimuli in the reinforcement. In olfactometer tests, preferences for broad bean-UDPs over broad bean-PHCs were found but wasps with previous exposure to wheat-UDPs and host encounter on wheat-PHCs did not show the preference. These results suggest that the early exposure to natal habitat plants modified later learning and response to visual cues from potential non-natal habitat plants, and olfactory learning might be involved in the modification. This cross-modal effect of early natal experience would compensate for the loss of host-searching efficiency due to uncertain information of potential non-natal habitats.     

Characterization and identification of ISSR markers associated with resistance to dried-shrink disease in sea buckthorn

Sea buckthorn (Hippophae L.) is an economically important, globally distributed shrub with unique biochemical properties. This long-juvenile and long-lived woody plant can be more difficult to cultivate than other crop plants. Dried-shrink disease is a dangerous pathogen that destroys sea buckthorn and halts commercial production. We estimated variability of ISSR molecular markers in 52 accessions of 16 sea buckthorn varieties and lines to seek markers associated with dried-shrink resistance and help identify potential breeding varieties and lines. Fifteen ISSR primers generated 346 bands, with an average of 23 bands per primer. Genetic similarities (Jaccard coefficient) between pairs of accessions ranged from 0.216 to 0.781. At a Jaccard coefficient of 0.39, the dendrogram generated with 342 polymorphic bands clustered 51 accessions of H. rhamnoides into five groups and one H. salicifolia isolate. Four ISSR markers (887₁₉₀, 835₇₀₀, 809₂₉₀, and 811₂₈₀) were significantly correlated with resistance to dried-shrink disease (P < 0.001). These markers provide a potential method for breeding programs that select lineages resistant to dried-shrink disease, especially when no other genetic information such as linkage maps and Quantitative Trait Loci are available.     

寄主挥发物、叶色在B型烟粉虱寄主选择中的作用

在室温条件下,研究B型烟粉虱Bemisia tabaci(Gennadius)对不同寄主植物和颜色的行为趋性。笼罩实验的结果显示,烟粉虱雌虫对共存的5种寄主植物偏好存在显著差异,总体上表现为对番茄的趋性最强(35·0%),甘蓝次之(27·7%),烟草和棉花再次之,辣椒最低(7·1%);且随着时间的延长,烟粉虱数量在番茄上逐渐增加,在甘蓝上呈下降趋势,在烟草、棉花和辣椒上变动幅度不大,但数量总体上仍是番茄(48·8%)>甘蓝(18·4%)>烟草、棉花>辣椒(3·4%)。但烟粉虱在不同寄主植物上的产卵量则表现为:甘蓝>番茄>棉花、烟草>辣椒;其中甘蓝和番茄上卵量分别占总卵量的56·8%和28·2%;而烟草、棉花和辣椒上的卵量均不到总卵量的6·0%。"Y"型嗅觉仪进一步测定表明:寄主植物番茄和甘蓝气味对烟粉虱具有显著引诱作用,且表现为番茄>甘蓝,辣椒不具引诱作用;烟粉虱对3种植物(番茄、甘蓝、辣椒)的叶片颜色均有显著趋性,选择率在75%左右,但在三者之间的趋性差异不明显;烟粉虱雌虫对黄色和绿色均具有显著趋性,且对黄色的趋性显著大于对绿色的趋性,但对红色无趋性。综合分析表明,在对寄主定向和定位过程中,B型烟粉虱的视觉和嗅觉均起作用,但在对同种颜色(绿色)的寄主进行选择和定位的过程中,嗅觉起主要作用,而对不同种颜色(红、黄、绿)的选择和定位时,其视觉起决定作用。     

Integration of Visual and Olfactory Cues in Host Plant Identification by the Asian Longhorned Beetle,Anoplophora glabripennis (Motschulsky) (Coleoptera: Cerambycidae)

Some insects use host and mate cues, including odor, color, and shape, to locate and recognize their preferred hosts and mates. Previous research has shown that the Asian longicorn beetle, Anoplophora glabripennis (Motschulsky), uses olfactory cues to locate host plants and differentiate them from non-host plants. However, whether A. glabripennis adults use visual cues or a combination of visual and olfactory cues remains unclear. In this study, we tested the host location and recognition behavior in A. glabripennis, which infests a number of hardwood species and causes considerable economic losses in North America, Europe and Asia. We determined the relative importance of visual and olfactory cues from Acer negundo in host plant location and recognition, as well as in the discrimination of non-host plants (Sabina chinensis and Pinus bungeana), by female and male A. glabripennis. Visual and olfactory cues from the host plants (A. negundo), alone and combined, attracted significantly more females and males than equivalent cues from non-host plants (S. chinensis and P. bungeana). Furthermore, the combination of visual and olfactory cues of host plants attracted more adults than either cue alone, and visual cues alone attracted significantly more adults than olfactory cues alone. This finding suggests that adult A. glabripennis has an innate preference for the visual and/or olfactory cues of its host plants (A. negundo) over those of the non-host plant and visual cues are initially more important than olfactory cues for orientation; furthermore, this finding also suggests that adults integrate visual and olfactory cues to find their host plants. Our results indicate that different modalities of host plant cues should be considered together to understand fully the communication between host plants and Asian longhorned beetles.     

Population dynamics ofHemisarcoptes coccophagus Meyer (Astigmata: Hemisarcoptidae) attacking three species of armored scale insects (Homoptera: Diaspididae)

The parasitic miteHemisarcoptes coccophagus Meyer (Astigmata: Hemisarcoptidae) feeds on armored scale insects (Homoptera: Diaspididae). Three host scales were studied: chaff scale (Parlatoria pergandii Comstock andP. cinerea Hadden) infesting citrus (grapefruit and orange) orchards, latania scale [Hemiberlesia lataniae (Signoret)] and olcander scale (Aspidiotus nerii Bouche) occurring on acacia (Acacia cyanophylla) branches and leaves. The overall dynamics of mite populations were similar on the different scale species, although the level of attack on each sampled diaspidid host was different. Rates of young mite stages were highly variable on all three hosts throughout the sampling period while adult rates were stable, constituting around 20% of all mites. No oviposition by mites occurred in mid-winter on any scale species, on any plants or parts, at all sampling sites. Of the three diaspidids, highest mite prevalence (parasitization rate) occurred on latania scale. Mite prevalence on oleander scale infesting mature leaves was higher than on young leaves.H. coccophagus apparently first attacks latania scale on branches, it then disperses to the same host inhabiting mature leaves, from there to co-occurring oleander scale and finally to oleander scale infesting young leaves. Mite prevalence on chaff scale was influenced by host plants and climatic regions: in the Negev it was higher than in the coastal plain, with scales on grapefruit being more heavily attacked at the former site but not on coastal plain. Our data suggest thatH. coccophagus prefers ovipositing scale females. The decreasing order of preference for other scale stages was: young females immature males, 2nd-instar nymphs females.