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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Entomologia experimentalis et applicata 71 (1994), S. 23-31 
    ISSN: 1570-7458
    Keywords: Brassica fruticulosa ; B. spinescens ; Brevicoryne brassicae ; host-plant resistance ; EPG ; glucosinolates ; artificial diets
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Feeding behaviour of the cabbage aphid,Brevicoryne brassicae, was monitored electronically on two resistantBrassica species,B. fruticulosa andB. spinescens, and compared with a susceptible controlB. oleracea var.capitata cv. Offenham Compacta. Aphids, monitored for 10 h on the under side of leaves, performed recognizable feeding behaviour on all species. Electrical Penetration Graphs (EPGs) of aphids on resistant and susceptible plants showed no difference in behaviour for aphids on resistantBrassica species compared to susceptible until stylets penetrated the phloem sieve elements when a large reduction in the duration of passive phloem uptake (E2 pattern) onB. fruticulosa was indicated. Although feeding behaviour on 6 week-old plants ofB. spinescens was similar to the susceptible controls, behaviour on 10 week-old plants was similar to that recorded forB. fruticulosa. The mechanism of resistance is thought to be located in the sieve element as the normal sieve element salivation (E1) signal was either quickly terminated by withdrawal of the stylets from the sieve element or continued as a disrupted E2 pattern. Analysis of secondary plant compounds in the threeBrassica species only identified significant differences in the glucosinolate profile. No reproducible differences were detected in the concentration of phenolics or anthocyanins. The major glucosinolate component ofB. fruticulosa andB. spinescens was gluconapin rather than glucobrassicin and glucoiberin as found in the susceptible host plant. However, both pure glucosinolates and glucosinolate extracts from all three species did not reduce aphid survival on chemically-defined artificial diets. These results suggest that the mechanism of resistance may be a mechanical blocking of the sieve element or stylets rather than a difference in the secondary plant chemistry of glucosinolates and phenolics.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1570-7458
    Keywords: Brassica fruticulosa ; Brassica spinescens ; Brevicoryne brassicae ; lectin ; host-plant resistance ; chitin ; artificial diets ; chitinase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A lectin, with a chitin-binding domain and chitinase activity, is present in significant quantities in the wild brassica speciesB. fruticulosa andB. spinescens but at low levels in cultivated cabbage cv. Offenham Compacta. The lectin, purified 〉1000 fold after binding to chitin, migrated on SDS-PAGE gels as a single band with a M r of 14.500. The amino acid composition of the lectin fromB. spinescens indicated high concentrations of asparagine/aspartic acid, glycine, leucine and serine in common with other chitin-binding lectins with insecticidal and antifungal activities. Brassica lectin and the closely related agglutinin from wheatgerm and nettle show significant insecticidal activity when presented toBrevicoryne brassicae in chemically-defined synthetic diets.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1570-7458
    Keywords: Brevicoryne brassicae ; Myzus persicae ; Brassica fruticulosa ; B. spinescens ; B. juncea ; B. nigra ; B. carinata. B. macrocarpa ; B. villosa var drepanensis ; B. oleracea ; B. napus ; B. campestris ; host-plant resistance ; glucosinolates ; amino acids ; leaf water potential ; generalist ; specialist ; aphids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract This paper describes an experiment to investigate the relative importance of glucosinolates and the availability of free amino acids in the phloem to the feeding behaviour and development of the specialist brassica aphid, Brevicoryne brassicae (L) (cabbage aphid) and the generalist, Myzus persicae, (Sultzer) (peach potato aphid). Aphid development was determined on brassica species and cultivated brassica varieties. Analysis of individual glucosinolates in the wild brassica species identified significant differences in their profiles and in their concentrations present in freeze dried leaves. Multiple regression analysis showed a significant correlation ( $$\left( {r = 0.83} \right)$$ ) between the intrinsic rate of increase of B. brassicae and glucosinolate concentrations; four glucosinolates, 2-OH-3-butenyl, and 2-propenylglucosinolate, 3-methoxyindolyl and 4-pentenylglucosinolates accounted for 79% of the variation. The intrinsic rate of increase of M. persicae was less correlated, though still significant ( $$\left( {r = 0.5} \right)$$ ); 3-indolyglucosinolate and 3-butenylglucosinolate accounted for 47% of the variation. Regression analysis also showed a correlation between phloem amino acid concentrations and the intrinsic rate of increase of B. brassicae ( $$\left( {r = 0.48} \right)$$ ) but not of M. persicae. The concentration of the important amino acids tyrosine, alanine, leucine and glutamic acid, accounted for 43% of the variation in intrinsic rate of increase. Leaf water potential of the Brassica species showed no relationship with the intrinsic rate of increase of either B. brassicae or M. persicae.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Entomologia experimentalis et applicata 85 (1997), S. 135-143 
    ISSN: 1570-7458
    Keywords: Brevicoryne brassicae ; Myzus persicae ; Brassica juncea ; B. nigra ; B. carinata ; B. macrocarpa ; B. villosa var. drepanensis ; B. oleracea ; B. campestris B. napus ; B. rapa ; host-plant resistance ; electronic monitoring
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Feeding behaviour of the specialist Brassicae aphid, Brevicoryne brassicae (L) (cabbage aphid) and the generalist, Myzus persicae, (Sulzer) (peach potato aphid) was monitored electronically on the susceptible cauliflower, Brassica oleracea var. botrytis cv Newton Seale, and a range of 17 Brassica species, B. carinata, B. juncea, B. nigra, B. macrocarpa, and B. villosa var. drepanensis and cultivated brassica varieties, B. oleracea, B. campestris and B. napus. Aphids, monitored for 10 h on the underside of leaves, performed recognisable feeding behaviour on all brassica species. The main differences in feeding behaviour, between M. persicae and B. brassicae, on the susceptible cauliflower Newton Seale, were fewer probes, shorter times to initially reach the phloem but longer times to establish sustained phloem ingestion and the longer times spent, by M. persicae, in xylem ingestion. Feeding behaviour on the range of brassica species tested indicated that generalist and specialist aphids are influenced differently by the host plant. A longer time spent in xylem ingestion was again the major difference in the feeding behaviour of the two aphids. In addition, rejection of passive phloem ingestion, by M. persicae, was not related so closely to increased time spent in non probing activities, as for B. brassicae. This observation indicates that M. persicae does not generally accept or reject brassica species due to the presence of phagostimulants, such as glucosinolates at the leaf surface or along the stylet pathway, unless the concentration is very high. Differences in feeding strategies employed by generalist and specialist aphids on the same plants are discussed.
    Type of Medium: Electronic Resource
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