Flight behaviour of the black bean aphid, Aphis fabae, and the cabbage aphid, Brevicoryne brassicae, in host and non-host plant odour

Abstract. Walking alate virginoparae of Brevicoryne brassicae (L.) and Aphis fabae Scopoli were presented with odours of steam-distilled extracts of the non-host plants summer savoury ( Satureja hortensis L.) and tansy ( Tanacetum vulgare L.) in an olfactometer. No effects of the extracts were observed on B. brassicae. However, A.fabae were repelled by summer savoury and tansy odour; both extracts also masked an attractant response to bean (host plant) odour. In a flight chamber, air permeated with odour from host or non-host plants was blown over flying alates of both species, with a green, plant-mimicking target presented once a minute. The incidence of targeted (host-responsive) flight of B.brassicae was not affected by odour from a growing host plant ( Brassica oleoracea ) or a non-host plant tansy. Host plant ( Vicia faba ) odour did not affect the initial rate of climb or the incidence of targeted flight of A.fabae , but when the bean odour was alternated with odour from non-host tansy plants a greater number of targeted flights occurred in the host plant odour. The volatile extracts of tansy and summer savoury were also presented to flying A.fabae. Aphids flying in air permeated with tansy odour at 450g plant equivalents initiated fewer targeted flights than when flying in clean air. However, no differences in flight behaviour were observed with summer savoury extract. In a horizontal wind tunnel the tansy extract at 90 g plant equivalents blown across the surface of yellow targets reduced the numbers of alate A.fabae landing. The results indicate that plant odours can affect flight and landing of aphids.     

Antixenosis resistance to Aphis fabae Scopoli (Hemiptera:Aphididae) in bean cultivars

Aphis fabae Scopoli (Hemiptera: Aphididae) is heteroecious and polyphagous that is harmful on secondary hosts such as many important agricultural products like beet, common bean, faba bean, potato and other products. This aphid is the cause of more than 33 viral transition. One of the mechanisms of plant resistance is antixenosis. This mechanism influences on placement and nutrition of pests that result in less damage. In this study, antixenosis resistance mechanism of 12 varieties of bean was tested. Experiment was on completely randomised design with 12 treatments and 6 replications. Bean varieties include of white bean, kidney bean and wax bean, and each replication includes one pot, and then, pots were placed under the isolated room that were filled with winged adult aphids in circular form. After 24 and 48?h, aphids and level of nymph production were counted. The lowest number of adult aphids was observed on Sayad variety among 12 varieties (during 24?h). The least number of produced nymphs was in Daneshkade variety. In Sayad variety, the frequency of matured insects and produced nymphs was minimum.     

Rapid accumulation of trihydroxy oxylipins and resistance to the bean rust pathogen Uromyces fabae following wounding in Vicia faba

BACKGROUND AND AIMS: Insect damage to plants leads to wound-activated responses directed to healing of damaged tissues, as well as activation of defences to prevent further insect damage. Negative cross-talk exists between the jasmonic acid-based signalling system that is activated upon insect attack and the salicylic acid-based system frequently activated following pathogen infection. Thus, insect attack may compromise the ability of the plant to defend itself against pathogens and vice versa. However, insect herbivory and mechanical wounding have been shown to reduce fungal infections on some plants, although the underlying mechanisms remain to be defined. This work examines the effects of mechanical wounding on rust infection both locally and systemically in the broad bean, Vicia faba and follows changes in oxylipins in wounded leaves and unwounded leaves on wounded plants. METHODS: The lamina of first leaves was wounded by crushing with forceps, and first and second leaves were then inoculated, separately, with the rust Uromyces fabae at various times over a 24 h period. Wounded first leaves and unwounded second leaves were harvested at intervals over a 24 h period and used for analysis of oxylipin profiles. KEY RESULTS Mechanical wounding of first leaves of broad bean led to significantly reduced rust infection in the wounded first leaf as well as the unwounded second leaf. Increased resistance to infection was induced in plants inoculated with rust just 1 h after wounding and was accompanied by rapid and significant accumulation of jasmonic acid and two trihydroxy oxylipins in both wounded first leaves and unwounded second leaves. The two trihydroxy oxylipins were found to possess antifungal properties, reducing germination of rust spores. CONCLUSIONS: These results demonstrate the rapidity with which resistance to pathogen infection can be induced following wounding and provides a possible mechanism by which pathogen infection might be halted.     

Phenotypic plasticity in host-plant specialisation in Aphis fabae

Abstract.  1. The study of phenotypic plasticity in host utilisation is crucial for predicting evolutionary patterns of insect – plant interactions. The presence of sufficient variation in plasticity may facilitate host race formation and sympatric speciation.
2.  Aphis fabae genotypes showed high levels of phenotypic plasticity in the intrinsic rate of natural increase ( r _m), relative growth rate (RGR), birth weight (BW), adult weight (AW), fecundity ( F ), and development time (1/ d ).
3. Thirteen A. fabae genotypes reared both on broad bean and nasturtium exhibited statistically significant genotypic variability in phenotypic plasticity.
4. Some genotypes displayed fitness improvement on novel host plants.
5. Differences in genotypic correlation among fitness components between the two hosts and increased variance on nasturtium indicated different genomic expression on nasturtium.
6. The results indicated that phenotypic plasticity in a novel environment may be a major determinant of the evolutionary trajectory of a parasitic species and might support the idea that speciation starts with phenotypic plasticity.     

Interaction between plant resistance and predation of Aphis fabae (Homoptera: Aphididae) by Coccinella septempunctata (Coleoptera: Coccinellidae)

We investigated the compatibility of host plant resistance to the black bean aphid in the faba bean crop with the use of the predatory ladybird beetle for biological control under laboratory and greenhouse conditions. Greenhouse experiments indicated that apteriform Aphis fabae reproduced on Vicia faba major (susceptible) and on 79S4 (partially resistant) cultivars at different rates. During the entire experimental period, aphids built up higher populations on V. faba major than on 79S4 cultivar. Aphid numbers on 79S4 were about 37% of those on V. faba major after 14 days. Release of a newly hatched Coccinella septempunctata larva onto each plant significantly reduced aphid density to 32.8% and 57.2% on V. faba major and 79S4 on day 14, respectively. Partial resistance combined with predation was more effective in lessening aphid numbers on faba bean than either the predator or the plant resistance alone. Laboratory tests showed that prey, A.   fabae , raised on susceptible cultivar was more suitable for the predator as food source, enhancing the development rate and fecundity than aphids fed on the partially resistant cultivar. Consumption of aphids reared on susceptible cultivar significantly increased the female fecundity and fertility of C. septempunctata by 37.7% and 33.2%, respectively, more than those fed with aphids from partially resistant cultivar. Pre-oviposition time was shortened by 4.5 days, and oviposition period was extended by 11.4 days. Feeding the predator on aphids from the partially resistant cultivar prolonged the embryonic larval developmental time and the time required from egg laying to adult emergence by 19.8, 10.1 and 32.5 h, respectively. Adult longevity was not influenced by the aphid source. The results are discussed in relation to the compatible utilisation of host plant resistance and biological control in the integrated management of aphids.     

Photoperiodic induction of winged females in the black bean aphid. Aphis fabae

Abstract. The Photoperiodic of winged females (alatae) in the black bean aphid, Aphis fabae Scop. (Homopetera: Aphididae), is investigated in detail with emphasis on the interaction of the maternal and embryonic/young larval photoperiodic clocks. Previous work had shown that in uncrowded conditions the induction of gynoparae (winged females that produce sexual females) requires both prenatal and postnatal exposure to long-night (12 h) Photoperidic cycles: present results show that sole postantal exposure to long nights of any lenght does not induce wing formation in early-born aphids.
When aphids were exposed to experimental light-dark cycles postanatally only, their daughters developed as alate in long nights and as apterae in short nights: the critical night lenght (CNL) was 11:1 h. Additional prenatal exposure to experimental regimes resulted in a significantly shorter CNL (10.6 h). This difference could be accounted for by the fact that more experimental light-dark cycles were experienced in the latter case.
Apterous aphids transferred from LD 16:8 h to LD 12:12 h as either third-or fourth-stadium larvae, or young adults, switched for aptera-production to alata-production. The transition form aptera- to alata-production was rather abrupt in third-stadium transfers but more gradual when transfers occurred as fourth-stadium larvae and adults. Moreover, s the number of days required for 50% of the aphids to become alata-producers increased from 7–8 in third-stadium transfers, to 9–10 and 11–12 in the later transfers.     

Climate effects on life cycle variation and population genetic architecture of the black bean aphid, Aphis fabae

Aphid species may exhibit different reproductive modes ranging from cyclical to obligate parthenogenesis. The distribution of life cycle variation in aphids is generally determined by ecological forces, mainly climate, because only sexually produced diapausing eggs can survive harsh winters or periods of absence of suitable host plants. Aphids are thus interesting models to investigate intrinsic and environmental factors shaping the competition among sexual and asexual lineages. We conducted a Europe-wide sampling of black bean aphids, Aphis fabae, and combined population genetic analyses based on microsatellite data with an experimental determination of life cycle strategies. Aphids were collected from broad beans (Vicia faba) as well as some Chenopodiaceae, but we detected no genetic differentiation between aphids from different host plants. Consistent with model predictions, life cycle variation was related to climate, with aphids from areas with cold winters investing more in sexual reproduction than aphids from areas with mild winters. Accordingly, only populations from mild areas exhibited a clear genetic signature of clonal reproduction. These differences arise despite substantial gene flow over large distances, which was evident from a very low geographic population structure and a lack of isolation-by-distance among 18 sites across distances of more than 1000 km. There was virtually no genetic differentiation between aphids with different reproductive modes, suggesting that new asexual lineages are formed continuously. Indeed, a surprising number of A. fabae genotypes even from colder climates produced some parthenogenetic offspring under simulated winter conditions. From this we predict that a shift to predominantly asexual reproduction could take place rapidly under climate warming.     

Effect of black bean aphid, Aphis fabae, on transpiration, stomatal conductance and crude protein content of faba bean

This study was initiated to investigate effects of damage by 0, 5 and 10 aphids/plant on the physiology of faba bean plants throughout different feeding periods and at two plant development stages. Immediately following removal of Aphis fabae, measurements showed 84–229% increase in transpiration rate. These changes were proportional to the number of aphids and infestation duration. Injury by A. fabae caused the stomatal conductance to be much higher in the leaves of infested plants. Leaf stomatal conductance of the infested plants increased significantly by 51–224% depending on initial aphid densities and feeding intervals. This increase was proportional to the infestation level for each date. Length of infestation period and plant growth stage seemed to have no clear effect on stomatal apertures. Aphid feeding caused a damage of about 7–33% of crude protein levels in the leaf tissue. This reduction increased with increasing infestation levels and time, except for 28‐day‐old plants on 28 days. The physiological effects of aphid feeding on water vapour and chemical composition of damaged leaves are particularly serious when the population is high.     

寄主龄期对可疑柄瘤蚜茧蜂寄生及其后代适合度的影响

采用单选试验,观察了可疑柄瘤蚜茧蜂（Tysiphlebus anbiguus）对不同发育时期黑豆蚜的寄生选择及其后代生长发育适合度相关特征,以检验寄主大小与其质量是否存在正相关关系。结果表明,黑豆蚜（Aphis fabae）1～4龄和成蚜均被寄生,但对2龄若蚜的寄生率最高（35．25％）,对成蚜寄生率最低（14．75％）;寄生低龄蚜虫的羽化率显著高于高龄若蚜和成蚜。寄生2龄若蚜的发育历期（8．4d）最短,而寄生1龄若蚜最长（9．3d）;寄生2～4龄蚜虫的后代蜂体型显著大于寄生1龄和成蚜;寄生4龄若蚜的后代中,雌蜂比例（75．74％）显著高于1龄若蚜（62．89％）和成蚜（65．19％）,但与寄生2～3龄若蚜无显著差异。寄主黑豆蚜的质量从高至低依次为2龄〉3龄=4龄〉成蚜〉1龄,因此,对可疑柄瘤蚜茧蜂而言。寄主大小与其质量并非存在正相关性。     

A study on common bean cultivars to identify sources of resistance against the black bean aphid,Aphis fabae Scopoli (Hemiptera: Aphididae)

Black bean aphid is an important common bean pest in the world. Aphids damage crops both directly by their feeding and by spreading viruses. Also, they indirectly damages with excretion honeydew and smokes moulds growth through some physiological processes and transmission of viruses. Resistant cultivars application is the main strategy to control Aphis fabae Scopoli. In this experiment, different lines and cultivars were infested with five wingless adult aphids. After 7 and 14?days, plants were evaluated and aphid population was counted and recorded. After 45?days when plants reached to the flowering stage, test was repeated. Result showed that there was a significant difference among cultivars in number of adult aphid in two-leaf stage. Most of the number of adult at the first week in two-leaf stage observed on Goynok cultivar that had significant difference to other lines and cultivars. Number of adults and nymphs among the line and cultivar at flowering stage did not show significant difference. Number of deployed aphids after two weeks was significantly higher than the first week that observed in all cultivars. Totally, the most resistant cultivar was Sayad and the most susceptible cultivar was Goynok.     

Action of beta radiation on the black bean aphid Aphis fabae Scop. (Aphididae, Homoptera)

A study was made of the effect of direct single exposure to beta-radiation of 0.5, 5, 10, 20, 30, and 50 Gy on development and reproduction of Aphis fabae Scop. (Aphididae, Homoptera). The numbers of bean aphid are prognosticated with regard to the radiation dose applied.     

Aphid responses to non-host epicuticular lipids

Initiation of stylet penetration by aphids depends on the sensory assessment of a number of plant surface features including colour, texture and phytochemicals (volatile and non-volatile). Video recording behaviour of the black bean aphid, Aphis fabae, showed that these insects rapidly inserted their stylets following contact with host plants (beans), but were reluctant to penetrate non-hosts (oats). However, when epicuticular waxes were stripped from oats, using cellulose acetate, aphids penetrated the plant surface significantly earlier than on oats with the wax layer intact. Chloroform extraction of epicuticular lipids, followed by coupled gas chromatography-mass spectrometry, revealed a complex blend of wax components on beans, whereas one compound (1-hexacosanol) predominated on oats. Epicuticular lipids were applied to artificial (glass) substrates in order to investigate their behavioural activity. Initiation of a stylet penetration attempt by A. fabae was delayed when the oat extract or pure 1-hexacosanol were applied, but the bean extract had no behavioural effect. The results suggest that epicuticular lipids play an important role in the early stages of host-plant selection by A. fabae.     

Effect of soft electron treatment on adzuki bean weevil, Callosobruchus chinensis (L.) (Col., Bruchidae)

Abstract:  Laboratory experiments were conducted to study the effect of soft electron (low-energy electron) treatment on adzuki bean weevil, Callosobruchus chinensis (L.), a major pest of stored legume seeds. Adzuki bean ( Vigna angularis ) seeds containing weevils of different ages (0, 2, 4, 6, 8, 10, 12, 14, 16 and 18 days), were exposed to electrons at an acceleration voltage of 170 kV for 20 min (10 kGy). The radiation sensitivity of the insect decreased with increasing age. The egg stage was highly susceptible to electron radiation whereas the 18-day-old stage (fully developed adults ready for emergence) was the most tolerant, and treatment at a higher energy (200 kV equal to 10 kGy) was necessary to achieve an 80% mortality of this stage. However, the longevity, fecundity and fertility of the surviving adult insects were adversely affected by the electron treatment and they failed to complete their life cycle. The sex ratio of weevils was not significantly affected by the electron treatment, suggesting an equal vulnerability of both sexes. Electron treatment did not affect the germination capacity of adzuki bean seeds, so soft electron irradiation represents a safer method for the disinfestation of adzuki beans.     

Yield loss of faba bean (Vicia faba) due to chocolate spot (Botrytis fabae) in sole and mixed cropping systems in Ethiopia

Two field experiments were conducted during 2004 and 2005 cropping seasons at Adet Agricultural Research Center, Ethiopia to assess yield losses caused by chocolate spot(Botrytis fabae) of faba bean in sole and mixed cropping systems using two cultivars. Cropping systems were sole faba bean (FB), faba bean mixed with field pea (FB: FP), barley (FB: BA) and maize (FB: MA). Mancozeb was sprayed at the rate of 2.5 kg a.i/ha at 7-, 14- and 21-day interval to generate different levels of chocolate spot disease in all the four cropping systems, and unsprayed control was also included. The treatments were arranged in a randomised complete block design (RCBD) with four replications. FB: MA mixed cropping significantly reduced disease severity and the area under disease progress curve (AUDPC) and increased faba bean grain yield. The highest faba bean grain yield among the three mixed croppings under different spray schedules was obtained from FB: MA mixed cropping in both 2004 and 2005 (2.56 and 3.74 t/ha, respectively) cropping seasons. There were highly significant yield differences (P < 0.05) among the spray intervals of mancozeb in both seasons. The highest grain yield (4.9 t/h) was recorded from the 7-day spray interval in 2005. The unsprayed faba bean had a lower grain yield (1.9 t/ha in 2004 and 2.3 t/ha in 2005) compared to the sprayed plots. The highest relative yield loss (67.5%) was calculated in 2005 from FB: FP mixed cropping in unsprayed plots. The relative yield losses in the unsprayed plots were in the range of 35.8–41.5% in 2004 and 52.6–67.5% in the 2005 cropping season. Severity and AUDPC were inversely correlated with faba bean grain yield. Significant differences were recorded in the 100-seed weight and days to maturity (DM). The unsprayed plots had shorter DM ranging from 126 to 128.5 day (except FB: MA mixed cropping) in 2004 and 122–123.9 days in 2005. In the sprayed plots DM was relatively longer than the unsprayed plots. A higher seed weight was recorded in the sole FB (56 g) and FB: MA (55 g) mixed cropping, and the lowest value of 100-seed weight was recorded from FB: FP (53 g) mixed cropping. The productivity of the mixed cropping evaluated by land equivalent ratio (LER) exceeded that of sole cropping. Faba bean grain yield was highly influenced by the severity of chocolate spot. The disease affects the DM, forcing early maturing of the plants.     

Insecticide‐mediated behavioral avoidance by bean bug,Riptortus pedestris (Heteroptera: Alydidae)

Bean bug, Riptortus pedestris (Fabricius) (Heteroptera: Alydidae), is an economically important pest of soybean and tree fruit. Behavioral responses of R. pedestris to olfactory cues from insecticide‐treated foliage were assessed in a Y‐tube olfactometer. Ten insecticides were applied to kidney bean plants at the recommended dosage, and then bug avoidance was assessed at 0, 3, 5, 7 and 13 days after treatment (DAT). Each bug was allowed 5 min to choose one of the olfactometer's arms. Even though the degree of avoidance was variable to the insecticides tested, bean bugs significantly avoided the insecticide‐treated leaf. The pyrethroid bifenthrin was the most avoided of the insecticides tested. In all treatments, avoidance decreased as DAT increased. Also, the movement speed was higher to the untreated leaf than to the insecticide‐treated leaf. The degree of avoidance was positively correlated to the vapor pressure of the chemical; this finding implies the interaction of the treated chemicals and plant volatiles may be used as cues for bean bug selection of the host‐plant.     

氯虫苯甲酰胺对黑肩绿盲蝽实验种群的影响

采取稻茎浸渍法测定了氯虫苯甲酰胺对黑肩绿盲蝽毒力,利用生命表技术研究了氯虫苯甲酰胺对黑肩绿盲蝽实验种群的影响,为协调水稻害虫的化学防治和生物防治提供参考。结果表明,氯虫苯甲酰胺对黑肩绿盲蝽若虫LC50和LC10分别为83.5mg/L和61.3 mg/L,氯虫苯甲酰胺对黑肩绿盲蝽成虫LC50和LC10分别为64.3 mg/L和39.0 mg/L。氯虫苯甲酰胺对黑肩绿盲蝽若虫和成虫的LC10分别大于和接近于大田使用剂量40mg/L。以大田使用剂量40 mg/L氯虫苯甲酰胺稻茎浸渍法处理黑肩绿盲蝽3龄若虫后,其产卵期、寿命和产卵量降低了4.3 d、3.0 d和22.0粒,与对照相比差异显著,表明氯虫苯甲酰胺对当代成虫寿命与生殖力影响较大;药剂处理后次代种群的成虫前期延长了2.3 d;存活率、平均日产卵量跟对照相比明显降低;种群净增值率、周限增长率、内禀增长率跟对照相比明显降低,分别为21.0(对照63.3)、18.8(对照19.2)、0.16(对照0.22),而种群加倍时间延长为4.3(对照3.2);这些结果表明,在40 mg/L浓度下,氯虫苯甲酰胺能够降低黑肩绿盲蝽种群的增长。     

Polymorphic microsatellites loci in the black Aphid,Aphis fabae Scopoli, 1763 (Hemiptera,Aphididae)

Aphis fabae is a widespread pest in Europe. This species includes four morphological cryptic subspecies which are mostly identified by their partially distinct secondary host range. To determine the extent of gene flow and isolation between these four taxa, we isolated and characterized eight microsatellite loci from A. fabae fabae and tested them on the three other subspecies. Polymorphism ranged from five to 35 alleles on the 138 individuals collected. When analysing each taxon separately, significant deviations from Hardy‐Weinberg (HW) equilibrum were observed. This could have different explanations, including the presence of null alleles, or the Wahlund effect or the mating system.     

On the processes shaping reproductive isolation in aphids of the Aphis fabae (Scop.) complex (Aphididae: Homoptera)

Models of sympatric speciation for phytophagous insects are based on the premise that ecological specialization on different host plants can indirectly result in significant reproductive isolation. A candidate example of host plant shift is provided by the partially reproductively-isolated aphids Aphis fabae fabae and A. f. mordwilkoi , which utilize different hosts for sexual reproduction. However, unexpected isolation based on mating behaviour was found for these two aphids. In olfactometer trials, males responded to the pheromones of females of both subspecies when presented a subspecies in isolation but preferentially to females of the same subspecies in choice tests. On contact, the incidence or duration of between-subspecies copulations was significantly lower than same-subspecies copulations, and spermatozoa were transferred during 88% of the same-subspecies copulations, but only 19% of between-subspecies copulations. These data are indicative of strong pre-zygotic isolation between the subspecies. Complementary restriction analysis of mitochondrial DNA and a plasmid (pAFE/eu) in an obligate symbiotic bacterium (Buchnera) revealed a paraphyletic relationship among four subspecies of A. fabae (A. f. fabae, A. f mordwilkoi, A. f cirsiiacanthoidis and A. f. solanella). We discuss how the lack of clear genetic differentiation between A. f. fabae and A. f. mordwilkoi , despite substantial pre-zygotic isolation, may be a consequence of reinforcement.     

The influence of black bean aphid, Aphis fabae Scop., and its honeydew on the photosynthesis of sugar beet

The effect of black bean aphids on the photosynthesis of sugar beet plants was studied under glasshouse and field conditions. The presence of up to several hundred aphids per leaf had no significant effect on CO₂ exchange rates over a range of light intensities between complete darkness and light saturation. Artificially prepared honeydew, sprayed onto leaves in the same amounts and composition as was found on severely aphid-infested plants, covered 30% of the stomata on the upper epidermis but did not significantly alter the rate of photosynthesis of these leaves in the light or the rate of respiration in the dark. The stomata on the lower epidermis were uncovered and functional. High pressure liquid chromatography of aphid-produced honeydew detected 20 different amino-acids. Three amino-acids, aspartic acid, glutamic acid and gluta-mine, made up the bulk of the amino-acid weight in the honeydew produced on young plants, up till the 8 leaf-stage. In the 10 to 12 leaf-stage, several different amino-acids occurred in substantial amounts. The amino-acids to sugars ratio of the honeydew produced by the aphids decreased strongly as the sugar beet plants aged: from 1:6 in plants with 3 or 4 leaves to 1:25 in plants having 10 to 12 leaves.     

Talisia esculenta lectin and larval development of Callosobruchus maculatus and Zabrotes subfasciatus (Coleoptera: Bruchidae)

Bruchid larvae cause major losses in grain legume crops throughout the world. Some bruchid species, such as the cowpea weevil and the Mexican bean weevil, are pests that damage stored seeds. Plant lectins have been implicated as antibiosis factors against insects, particularly the cowpea weevil, Callosobruchus maculatus. Talisia esculenta lectin (TEL) was tested for anti-insect activity against C. maculatus and Zabrotes subfasciatus larvae. TEL produced ca. 90% mortality to these bruchids when incorporated in an artificial diet at a level of 2% (w/w). The LD(50) and ED(50) for TEL was ca. 1% (w/w) for both insects. TEL was not digested by midgut preparations of C. maculatus and Z. subfasciatus. The transformation of the genes coding for this lectin could be useful in the development of insect resistance in important agricultural crops.