Influence of pymetrozine on feeding behaviors of three rice planthoppers and a rice leafhopper using electrical penetration graphs

Pymetrozine reportedly inhibits feeding of plant sap-sucking insects, such as aphids and brown planthopper (Nilaparvata lugens (St?l)). By using electrical penetration graph (EPG), this study was conducted to investigate any differential effect of pymetrozine on the feeding behaviors of four major rice sap-sucking insect species, 1) N. lugens, 2) white-backed planthopper (Sogatella furcifera (Horváth)), 3) small brown planthopper (Laodelphax striatellus (Fallen)), and 4) green rice leafhopper (Nephotettix cincticeps Uhler). On pymetrozine-free TN1 rice plants, white-backed planthopper and small brown planthopper showed a significantly less activity in the phloem phases than brown planthopper or green rice leafhopper while green rice leafhopper engaged in relatively more xylem ingestion than brown planthopper, white-backed planthopper, and small brown planthopper. On the plants treated with 100 mg liter(-1) of pymetrozine, all four insect species showed significant increases, in total duration of nonprobing and significant decreases in the activities in phloem tissue, while all species showed similar feeding behavior during the pathway and xylem phases. This study revealed that, regardless of whether the insects on untreated plants spent more time feeding on phloem than xylem (brown planthopper) or more time on xylem than phloem (green rice leafhopper) or similar times on phloem and xylem (white-backed planthopper and small brown planthopper), their feeding behavior was disturbed by pymetrozine and exhibited similar patterns of sharp decline in activity in the phloem tissue and a significant increase the nonprobing.     

Feeding responses of an oligophagous bean aphid, Megoura crassicauda, to primary and secondary substances in Vicia angustifolia

The feeding behaviour of the aphid Megoura crassicauda Mordivilko (Homoptera: Aphididae), which feeds selectively on plants in the genus Vicia (Fabaceae), was studied. The aphids deposited proteinaceous stylet sheaths intercellularly towards the phloem tissues of host plants. Similar stylet sheaths were formed on a Parafilm membrane when host‐specific acylated flavonoid glycosides [two 2″‐O‐(E)‐p‐coumaroyl esters of quercetin 3‐O‐diglycosides] present in the extracts of the narrow vetch, Vicia angustifolia L., were supplied in the solution covered by the membrane. In contrast, their corresponding deacyl analogues, present more abundantly in the host plant tissues, were not stimulatory, which suggested specificity in the structural requirements of the probing stimulants. While the aphids imbibed an artificial diet composed of primary nutrients (e.g., sucrose and amino acids) and produced a large quantity of honeydew, acylated flavonoids alone and non‐acylated flavonoids supplied with the nutrients more or less suppressed honeydew production. These findings implied that the acylated flavonoids serve as a cue to navigate the stylet sheath towards the phloem prior to sap‐sucking, whereas non‐acylated flavonoids may serve as a negative stimulus to refrain from sucking during tissue penetration before tapping the phloem, although the distribution of these compounds in the plant tissues remains unknown. Thus, the feeding behaviour of M. crassicauda appears to be controlled by multiple chemical stimuli in the process of the settling on its host plant.     

二种稻飞虱对寄主及氮肥、密度适应性的比较研究

本试验采用二因素最优设计,研究了白背飞虱[Sogatellafurcifera（Horvath）]和褐飞虱[Nilaparvatalugens(Stal）]的种群数量同栽插密度及施氮水平的关系,并考察了它们对寄主品种的适应性。结果表明：二种飞虱对寄主品种的适应性除受到品种自身特性的影响外,还随寄主生育状况及管理水平对田间小气候的影响而变化,表现出时间状态的差异;并得出了二种稻飞虱种群数量同施氮水平和栽插密度关系的回归方程。     

芥子油苷在甘蓝蚜寄主部位选择行为中的作用

利用刺吸电位技术（EPG）记录甘蓝蚜Brevicoryne brassicae在芥菜Sinapis alba 不同部位上的取食行为,同时用高压液相色谱（HPLC）分析芥菜相应部位的芥子油苷(glucosinolates)含量,据此分析芥子油苷在甘蓝蚜对寄主部位偏好行为中的作用。选择芥菜三个部位进行取食行为记录和化学分析,即新出完全叶(第7片)的叶片、叶柄,以及花茎。相对于其它两个部位,甘蓝蚜的口针在花茎上用较少的刺探次数和较短的时间到达韧皮部;一旦口针进入韧皮部持续吸食阶段,蚜虫在三个部位的取食行为没有太大的差异。只在花茎的表皮和皮层中测定到较高含量的白芥子苷（glucosinalbin）。因此,本实验的结果证明,白芥子苷是甘蓝蚜寄主部位选择的关键信号化学物质或取食促进剂。     

Physiological responses to Nilaparvata lugens in susceptible and resistant rice varieties: allocation of assimilates between shoots and roots

Nilaparvata lugens (St?l) is a typical vascular feeder, primarily sucking the phloem sap of host plants. Its feeding on rice, Oryza sativa L., plants changes the pattern of allocation of assimilates between roots and shoots, and the root:shoot (R/S) ratio of assimilates is often measured as an index of physiological responses to N. lugens. The current study investigated changes in the R/S ratio of biomass, sucrose, and soluble sugar contents of rice plants in a susceptible variety (TN1) and a resistant variety (Xieyou 963). The results demonstrated that root and shoot biomasses in the two varieties linearly decreased with the increase of N. lugens infestation density. However, the relationship between changes in the R/ S ratio ofbiomass and N. lugens density differed between rice varieties, with the R/S increasing with infestation density in TN1 and decreasing in Xieyou 963. Sucrose and soluble sugar contents and their R/S values were also significantly different between the two varieties. Compared with the control that was not infested by N. lugens, the R/S values of sucrose and soluble sugar at 3 days after infestation (DAI) increased but decreased at 6 DAI in TN1. The R/S values of sucrose and soluble sugar were higher at 6 DAI than those at 3 DAI in TN1, whereas these values were lower at 6 DAI than at 3 DAI in Xieyou 963. These contrasting results suggest that physiological responses to N. lugens infestation differ between the susceptible and tolerant rice varieties.     

Acceptability of different species of Brassicaceae as hosts for the cabbage aphid

The probing and feeding behaviour of the cabbage aphid, Brevicoryne brassicae (L.), (Homoptera, Aphididae) was studied on several plant species that represented various levels of acceptability: Sinapis alba L. (a permanent host plant), Capsella bursa-pastoris (L.) Med., Thlaspi arvense L., Lunaria annua L., Erysimum cheiranthoides L. (accidental host plants), Vicia faba L. (a non-host plant), using the electrical penetration graph technique (EPG). B. brassicae on V. faba did not show any patterns related to penetration of phloem vessels. Stylet penetration was deterred on L. annua and E. cheiranthoides where non-penetration prevailed, the periods of sap ingestion were short or did not occur, the percentage of time spent in the phloem was consistently low (5–6%) and E1 salivation predominated. The pathway activities were not suppressed on C. bursa-pastoris and T. arvense and the aphids spent an average of 3 h in the phloem during the 8-h experiment. However, a considerable delay between finding and accepting the phloem and a substantial proportion of E1 salivation (20–30% of all phloem activities) indicated a deterrent factor in the sieve elements of these plants. Aphid probing and sap ingestion were rarely interrupted on S. alba. The results of this study suggest that the deterrent agents vary in activity and may hinder stylet penetration at different levels (epidermis, parenchymatous tissues and/or phloem elements), depending on the plant species.     

Antifeedant and insecticidal effects of mandelic acid on the brown planthopper Nilaparvata lugens Stål

To study the effects of mandelic acid (MA) on the brown planthopper (BPH), Nilaparvata lugens, the survival rate and behaviour of BPH fed on an artificial diet with different dosages of MA was observed. The survival rate of BPH decreased with the increase of the MA concentration and feeding time. In contrast to the control, the survival rate of BPH 72 h after feeding decreased significantly. Electrical penetration graph (EPG) data indicated that MA absorbed by the rice plant from Kimura B solution significantly affected the feeding behaviour of BPH. At the concentrations of 0.1, 0.5, and 1.0 mg/ml, duration of the phloem ingestion of BPH decreased from 115.34 min (control) to 30.41, 7.63, and 0.36 min, respectively. Periods of xylem ingestion of MA-treated BPH were significantly shorter than those of the control (50.44 min). Moreover, BPH spent more time walking around or being at rest on MA-treated rice plants, as well as in stylet activities. The GST (glutathione S-transferase) activity of BPH increased with the increasing MA concentration, while the GPX (glutathione peroxidases) activity did not change significantly. The results indicate that MA has an antifeedant and insecticidal effect on BPH.     

Host acceptance by aphids: probing and larviposition behaviour of the bird cherry-oat aphid, Rhopalosiphum padi on host and non-host plants

The probing and larviposition behaviour of the bird cherry-oat aphid, Rhopalosiphum padi on summer and winter host plants were investigated using electrical penetration graph (EPG) coupled with simultaneous video recording. In this way the precise probing history prior to parturition can be monitored and the location of possible reproductive stimulants identified. On the host plant, all gynoparae (autumn winged females that give birth to sexual females on bird cherry, Prunus padus, the primary host) and 55% of winged virginoparae (summer females which produce further virginoparae on barley, Hordeum vulgare, a secondary host) initiated larviposition before phloem contact. However, 90% of wingless virginoparae (on barley) contacted the phloem before first larviposition whilst 10% did not. Thus, phloem contact does not appear to be a pre-requisite for these aphid forms to initiate reproduction.     

Cucurbit aphid‐borne yellows virus (CABYV) modifies the alighting,settling and probing behaviour of its vector Aphis gossypii favouring its own spread

Plant pathogens are able to influence the behaviour and fitness of their vectors in such a way that changes in plant–pathogen–vector interactions can affect their transmission. Such influence can be direct or indirect, depending on whether it is mediated by the presence of the pathogen in the vector's body or by host changes as a consequence of pathogen infection. We report the effect that the persistently aphid‐transmitted Cucurbit aphid‐borne yellows virus (CABYV, Polerovirus) can induce on the alighting, settling and probing behaviour activities of its vector, the cotton aphid Aphis gossypii. Only minor direct changes on aphid feeding behaviour were observed when viruliferous aphids fed on non‐infected plants. However, the feeding behaviour of non‐viruliferous aphids was very different on CABYV‐infected than on non‐infected plants. Non‐viruliferous aphids spent longer time feeding from the phloem in CABYV‐infected plants compared to non‐infected plants, suggesting that CABYV indirectly manipulates aphid feeding behaviour through its shared host plant in order to favour viral acquisition. Viruliferous aphids showed a clear preference for non‐infected over CABYV‐infected plants at short and long time, while such behaviour was not observed for non‐viruliferous aphids. Overall, our results indicate that CABYV induces changes in its host plant that modifies aphid feeding behaviour in a way that virus acquisition from infected plants is enhanced. Once the aphids become viruliferous they prefer to settle on healthy plants, leading to optimise the transmission and spread of this phloem‐limited virus.     

Maternal reproductive decisions are independent of feeding in the black bean aphid,Aphis fabae

Aphids are phloem feeders and an important assumption has been that reproduction is initiated only after phloem ingestion. Here we investigate the plant tissue location of parturition cues in winged and wingless, summer virginoparae and autumn migrants (gynoparae) of the black bean aphid, Aphis fabae. These seasonal forms have different host preferences. Using electrical penetration graph (EPG: to observe activity of the mouthparts) and video-monitoring procedures we demonstrate that the time to first parturition after host-plant contact is significantly shorter than the time to first registered phloem contact in the summer winged form. In gynoparae, the time to first parturition does not significantly differ from time to first phloem contact but is shorter than time to first phloem ingestion. Times to first parturition, first registered phloem contact and first phloem ingestion do not differ significantly in the summer wingless form. Simultaneous EPG and video recording procedures show that a high proportion of individuals of all morphs (45-70%) initiate reproduction before sustained phloem activities (salivation/ingestion). The only behaviours that all individuals demonstrate before first parturition are ‘non-penetration’ (aphid on plant surface with mouthparts outside plant) and stylet ‘pathway activity’, including secretion of gelling saliva and penetration of the non-vascular (epidermis and mesophyll) cells. A short period of penetration of the peripheral plant tissues (five cell punctures per individual) by aphids tethered and monitored by EPG decreases the time to first parturition of the winged summer form when subsequently placed on a Parafilm sachet containing 15% sucrose solution. This treatment also significantly increases the incidence of reproduction and individual reproductive output of gynoparae over a 24-h period. No detectable effects of tissue penetration on subsequent reproductive output are observed in the wingless summer form. Additionally, EPGs reveal that a number of aphids of all morphs display xylem ingestion, which occurs predominantly before initiation of phloem feeding but is not necessary to initiate parturition. It is concluded that aphids are likely to detect parturition cues during stylet punctures of cells within peripheral tissue layers, before reaching the phloem vessels.     

A potent, morph-specific parturition stimulant in the overwintering host plant of the black bean aphid, Aphis fabae

Abstract. The black bean aphid, Aphis fabae Scopoli, has a host‐alternating life cycle. Winged female autumn migrants (gynoparae) develop on numerous summer host plants but as adults will only colonize the winter host (spindle, Euonymus europaeus L.). When stylet activities of gynoparae were electrically recorded during access to a spindle leaf, the insects spent the majority (75%) of the 6‐h experimental period penetrating the plant surface and a large proportion of it (44%) ingesting from either phloem or xylem vessels. Most (95%) gynoparae initiated reproduction on spindle, producing 4.15 ± 0.59 offspring per adult by the end of the experiment (mean ± SEM). By contrast, gynoparae placed on a seedling of their natal, summer host (broad bean, Vicia faba L.) penetrated the plant for only 39% of the available time, rarely ingested plant sap and never reproduced. The number of nymphs deposited on spindle leaves was not correlated with the occurrence or duration of ingestion from vascular tissues, suggesting that parturition stimulants are detected before feeding, probably during penetration of nonvascular cells. Presentation of an aqueous spindle extract to the aphids in artificial feeding chambers showed that water‐soluble spindle factors evoke stimulation of parturition by gynoparae in 72‐h bioassays. The stimulant was extremely potent, remaining active until the total extracted material was diluted to less than 10 p.p.m. Stylet activities and reproductive responses were also evaluated for summer winged females (alate virginoparae), which have a broad host range, and will colonize both bean and spindle under laboratory conditions. On both of these plant species, virginoparae often ingested plant sap and deposited nymphs during the 6‐h electrical recording experiment (producing 4.60 ± 0.48 offspring on bean; 2.70 ± 0.35 on spindle: mean ± SEM), but no significant correlations were found between reproduction and the occurrence or duration of particular stylet activities. Aqueous host‐plant extracts had no effect on the numbers of offspring deposited by virginoparae in artificial feeding chambers, showing that this form of the aphid is not responsive to the spindle‐derived parturition stimulant. The results highlight the need for more information on the factors determining host acceptance and parturition by polyphagous aphid phenotypes.     

Probing and feeding characteristics of the greenhouse whitefly in association with host-plant acceptance and whitefly strains

Host-plant and whitefly strain effects and their interactions on the probing and sap feeding of the greenhouse whitefly, Trialeurodes vaporariorum (Westwood), have been investigated in this study using the DC-EPG (Electrical Penetration Graph) technique. Whiteflies generally displayed fewer but longer probes on highly acceptable cucumber than on less acceptable tomato. Both whitefly strains, the T(omato)-strain and the C(ucumber)-strain, showed a significantly lower number of phloem phases on cucumber than on tomato. However, the duration of total phloem phases achieved by either of the whitefly strains on these two host plants was not significantly different. These data indicate that a more continuous phloem feeding has occurred on cucumber plants. Indeed, the percentage of phloem feeding time after the first sustained phloem phase (longer than 15 min) was higher on cucumber for the C-strain whiteflies. When comparing these two whitefly strains, the T-strain whiteflies probed less frequently but longer than the C-strain whiteflies did on both host plants. Also, the T-strain whiteflies displayed a longer duration of total phloem phases on tomato. An interaction between the whitefly strain and plant effects was detected on a parameter, which showed that whiteflies probed significantly longer before reaching the first phloem phase on the host plants that had been previously experienced. In conclusion, both plant species and whitefly strains affect whitefly's probing and feeding behaviour, though plant effects are much stronger.     

Co-localisation of host plant resistance QTLs affecting the performance and feeding behaviour of the aphid Myzus persicae in the peach tree

The architecture and action of quantitative trait loci (QTL) contributing to plant resistance mechanisms against aphids, the largest group of phloem-feeding insects, are not well understood. Comparative mapping of several components of resistance to the green peach aphid (Myzus persicae) was undertaken in Prunus davidiana, a wild species related to peach. An interspecific F(1) population of Prunus persica var. Summergrand × P. davidiana clone P1908 was scored for resistance (aphid colony development and foliar damage) and 17 aphid feeding behaviour traits monitored by means of the electrical penetration graph technique. Seven resistance QTLs were detected, individually explaining 6.1-43.1% of the phenotypic variation. Consistency was shown over several trials. Nine QTLs affecting aphid feeding behaviour were identified. All resistance QTLs except one co-located with QTLs underlying aphid feeding behaviour. A P. davidiana resistance allele at the major QTL was associated with drastic reductions in phloem sap ingestion by aphids, suggesting a phloem-based resistance mechanism. Resistance was also positively correlated with aphid salivation into sieve elements, suggesting an insect response to restore the appropriate conditions for ingestion after phloem occlusion. No significant QTL was found for traits characterising aphid mouthpart activity in plant tissues other than phloem vessels. Two QTLs with effects on aphid feeding behaviour but without effect on resistance were identified. SSR markers linked to the main QTLs involved in resistance are of potential use in marker-assisted selection for aphid resistance. Linking our results with the recent sequencing of the peach genome may help clarify the physiological resistance mechanisms.     

Phloem specific aphid resistance in Cucumis melo line AR 5: effects on feeding behaviour and performance of Aphis gossypii

The feeding behaviour, excretion rate, and life history traits of the cotton-melon aphid, Aphis gossypii (Glover) (Homoptera, Aphididae), were measured on a resistant melon, Cucumis melo L., breeding line, AR 5. The site of resistance detection by the aphids was determined using the electrical penetration graph (EPG) technique. EPG recordings showed that resistance is expressed within the host plant, rather than on its surface, because the time to first stylet penetration was not significantly different between AR 5 and the closely related susceptible breeding line, PMR 5. EPG patterns associated with stylet pathway activities of the aphids were not significantly different between the resistant and susceptible lines. Significant behavioural differences were observed only after stylets contacted phloem sieve elements. On AR 5, the duration of salivation after sieve element puncture (waveform E1) was significantly longer, and the number of aphids showing phloem sap ingestion (waveform E2) was significantly reduced. We conclude that the resistance mechanism producing the effects seen in this study acts within the phloem sieve elements. Monitoring of excretion rates on the two genotypes showed that aphid feeding was delayed and greatly reduced on the resistant genotype. Comparisons of aphid life history traits and population development between host plant genotypes showed that the effects of resistance act throughout aphid development and are highly effective at slowing down population increase.     

Feeding studies on gynoparae, males and apterous virginoparae of Myzus persicae on potato by electrical penetration graph

Abstract:  Feeding behaviour of parthenogenetic apterae, post-teneral gynoparae and males of a holocyclic parthenogenetic lineage of Myzus persicae (Sulzer) (Hem., Aphididae) was studied on potato plants, Solanum tuberosum L. (Solanaceae) by DC-electrical penetration graph recording. Differences were observed between morphs during the 7-h recordings, specifically in the first phase of subcuticular probing and in xylem and phloem-related activities. The time required for the first penetration and first cell puncture of the non-vascular tissues was shorter in apterae than in gynoparae and males. Apterae more often showed phloem activities and sustained sap ingestion (100%) than winged morphs ( ca. 25%). In addition, phloem ingestion was much longer in apterae than in winged morphs, 3458 s and 25–70 s respectively. In contrast, winged morphs spent 14–21% of the available time ingesting sap from xylem while in apterae xylem sap uptake was only for 2% of the time. Furthermore, the data showed that males perform in general all the feeding behaviours that other conspecific morphs exhibit. The differences in feeding behaviour among morphs of M. persicae are discussed in relation to host specialization and to their possible involvement in non-persistent transmission of viruses.     

植食性同翅目昆虫寻找和接受植物韧皮部过程中的细胞与化学探试(英文)

植食性同翅目昆虫在最终接受其宿主植物的过程中,将感受从叶表层直到韧皮部筛管途中存在的多种化学物质,并导致不同的刺探和取食行为。本文就植物叶表层存在的糖类和生物碱类物质,叶肉层的多糖类、酸碱度和酚类物质以及韧皮部内的氨基酸、蛋白质、碳水化合物和植物次生物质等对昆虫寻找及取食韧皮部行为的影响作一综述,并且还探讨了植物叶肉层的细胞结构对昆虫刺探及取食行为的可能影响。此外,结合刺探电位(electrical penetration graphs,EPGs)的研究结果,还讨论了昆虫感受植物叶组织内部的各种化学和细胞结构信息的可能机制。     

Plant penetration by pea aphids (Acyrthosiphon pisum) of different plant range

Plant penetration by the stylets of six clones of the pea aphid, Acyrthosiphon pisum, on Vicia faba (acceptable to all clones) and Pisum sativum (acceptable to 3/6 clones) was investigated by the DC electrical penetration graph technique. In a 10 h recording period, 93% of 144 aphids exhibited sustained feeding on phloem sap. Significant interclonal differences were observed for the incidence of potential drops (indicative of brief punctures of plant cells) and the duration of waveform E1 (insect salivation into a sieve element). In addition, the total duration of the sieve element phase and the duration of completed bouts of sustained feeding differed between the two test plants, in a fashion varying between clones. However, these differences could not be related to the acceptability of plants to the different aphid clones. The duration of the stylet pathway phase preceding the first sustained feeding on phloem sap did not vary significantly with either aphid clone or plant. It is concluded that the resistance of P. sativum to certain A. pisum clones does not arise from factors impeding either stylet penetration through the plant tissues or the maintenance of feeding from the sieve elements. It is proposed that host plant affiliation of A. pisum may be mediated primarily by specific olfactory or gustatory cues, before the aphid initiates stylet penetration of the plant.     

CELLULAR AND CHEMICAL SAMPLING DURING PHLOEM FINDING AND HOST-PLANT ACCEPTANCE BY HOMOPTERAN INSECTS

Abstract The chemical compounds that exist in plant leaf tissue are of great importance for homopteran insects during the proccess of host-plant acceptance. From the leaf surface to the phloem tube, various groups of chemicals can be detected by insect's receptors which lead to different feeding responses. The effects of sugars and alkaloids in leaf surface; polysaccharides, pH gradients and phenolics in mesophyll; amino acids, proteins, carbohydrates and secondary substances in phloem tube on phloem finding and host-plant acceptance are reviewed respectively in this paper, which also includes the potential effects of mesophyll structures on insect's feeding preference. Furthermore the mechanism by which the insects perceive these chemical and mechanical cues, correlated with the EPG (electrical penetration graph) patterns (a series of visible signals showing the stylet activities in plant tissue) is also discussed.