Bożena Kordan

European yellow lupine, Lupinus luteus, and narrow‐leaf lupine, Lupinus angustifolius, as hosts for the pea aphid, Acyrthosiphon pisum

The pea aphid, Acyrthosiphon pisum Harris (Homoptera: Aphididae), fed, developed, and reproduced on yellow lupine, Lupinus luteus L. (Fabaceae: Genisteae). No clear preferences for any variety within L. luteus were found. Acyrthosiphon pisum showed negative values of relative growth rate and no aphid completed development on any variety of narrow‐leaf lupine Lupinus angustifolius L. Aphids did not ingest phloem sap while probing on L. angustifolius and the probes were very short. All varieties of L. angustifolius were rejected by aphids during an early stage of probing in peripheral tissues, that is, epidermis or mesophyll. There were qualitative and quantitative differences in alkaloid and soluble sugar content between the two lupine species. Within species, the relative content of individual compounds differed among the varieties. Lupinus angustifolius contained four quinolizidine alkaloids (13‐hydroxylupanine, dehydrolupanine, lupanine, and angustifoline), while L. luteus contained two (lupanine and sparteine). Lupanine occurred in all varieties of both lupine species. The total content of soluble carbohydrates was similar in L. luteus and L. angustifolius. The following cyclitols were found in both lupine species: myo‐inositol, D‐ononitol, and D‐pinitol. Lupinus angustifolius also contained D‐chiro‐inositol. The study of aphid probing behaviour, development, and reproduction demonstrated that L. luteus is a suitable host plant for A. pisum while L. angustifolius is not. It is likely that the rejection of L. angustifolius by A. pisum was caused by chemical factors detected by aphids at the epidermis and mesophyll level.

Systemic deterrence of aphid probing and feeding by novel β-damascone analogues

Abstractβ-Damascone appeared a weak attractant close to not active to Myzus persicae, but modifications of its structure caused the avoidance of treated leaves by aphids during settling and reluctance to probe in simple choice- and no-choice experiments in previous studies. Here, the electrical penetration graph (EPG) technique, which allows monitoring of aphid probing within plant tissues, was applied to explore the biological background and localisation in plant tissues of the deterrent activities of β-damascone and its analogues. Activity of β-damascone and β-damascone-derived compounds depended on their substituents, which was manifested in the variation in the potency of the behavioural effect and differences in aphid probing phases that were affected. β-Damascone appeared a behaviourally inactive compound. The moderately active β-damascone ester affected aphid activities only during the phloem phase. The highly active deterrents—dihydro-β-damascol, β-damascone acetate, δ-bromo-γ-lactone, and unsaturated γ-lactone—affected pre-phloem and phloem aphid probing activities. The most effective structural modification that evoked the strongest negative response from M. persicae was the transformation of β-damascone into δ-bromo-γ-lactone. The behavioural effect of this transformation was demonstrated in frequent interruption of probing in peripheral tissues, which caused repeated failures in finding sieve elements, and reduction in the ingestion time during the phloem phase in favour of watery salivation. The inhibition of aphid probing at both the pre-phloem and phloem levels reveals the passage of the compounds studied through the plant surface and their distribution within plant tissues in a systemic way, which may reduce the risk of the transmission of non-persistent and persistent viruses.

Behavioral sensitivity of Myzus persicae to volatile isoprenoids in plant tissues

Volatile isoprenoids (VIPs) are low‐molecular isoprene‐derived compounds that are produced and emitted by plants as a protection against and in response to various biotic and abiotic stresses. They also participate in direct and indirect plant defense against herbivores. Foliar VIPs may accumulate in mesophyll cells, which makes them detectable for foraging aphids. In this study, probing behavior of the peach potato aphid, Myzus persicae (Sulzer) (Hemiptera: Aphididae), was monitored using the electrical penetration graph (EPG) technique, following the exogenous application of camphene, α‐ and β‐ionones, and linalool to its host plant Brassica rapa subsp. pekinensis (Lour.) Hanelt (Brassicaceae). None of the VIPs studied affected M. persicae propensity to probe: aphids spent at least 75% of the experimental time penetrating plant tissues. The application of α‐ionone and linalool did not alter M. persicae behavior relative to control individuals. In contrast, on camphene‐ and β‐ionone‐treated plants, the proportion of non‐probing relative to other stylet activities was high, the success rate in reaching sieve elements and feeding was low, and the proportion of salivation in phloem phase was high. The aphid reluctance to continue probing and feeding due to the exogenously applied VIPs may be considered as means for the limitation of transmission of semi‐persistent and persistent viruses.

Susceptibility of forage legumes to infestation by the pea aphid Acyrthosiphon pisum (Harris) (Hemiptera: Aphididae)

Abstract. The small-seeded legumes are important forage crops for grazing animals and contribute nitrogen to succeeding crops in crop rotation systems. However, the susceptibility of several of the forage legumes to the specialist pea aphid Acyrthosiphon pisum (Harris) has never been investigated. The present study on aphid probing behaviour using the Electrical Penetration Graph technique revealed that the forage legumes studied were (i) highly acceptable (common vetch Vicia sativa L.), (ii) acceptable (wooly vetch Vicia villosa Roth), (iii) moderately acceptable (fodder galega Galega orientalis Lam., crimson clover Trifolium incarnatum L., Persian clover Trifolium resupinatum L., white clover Trifolium repens L.), (iv) barely acceptable (common bird’s-foot-trefoil Lotus corniculatus L., yellow lucerne Medicago falcata L., alfalfa Medicago sativa L., sand lucerne Medicago × varia Martyn, common bird’s-foot Ornithopus sativus Brot., alsike clover Trifolium hybridum L., red clover Trifolium pratense L., common sainfoin Onobrychis viciifolia Scop.), and (v) unacceptable (white melilot Melilotus albus Medik.) to the pea aphid. On (i) plants, probing occupied 85% of experimental time, all aphids (100%) succeeded in feeding on phloem sap, phloem phase occupied 50% of probing time, sap ingestion periods were long (mean duration: 100.8 ± 28.2 min.) and engaged 97% of the phloem phase. On (ii) plants, probing occupied 73% of exp. time, feeding activity occurred in 66.7% of aphids, phloem phase occupied 30% of probing time, sap ingestion periods were long (mean duration: 115.5 ± 46.7 min) and engaged 80% of the phloem phase. On (iii) plants, probing ranged from 53% of exp. time on T. repens to 70% on T. incarnatum and T. resuspinatum, feeding occurred in 35.3% of aphids on T. resuspinatum up to 54.5% on T. incarnatum, phloem phase occupied 10% of exp. time on G. orientalis, T. incarnatum, and T. resuspinatum and 20% on T. repens, sap ingestion periods were from 9.8 ± 1.8 min. on G. orientalis to 51.9 ± 20.7 min. long on T. resuspinatum and engaged from 30% of phloem phase on G. orientalis to 80% on T. incarnatum. On (iv) plants, probing occupied 25% of exp. time on O. viciifolia up to 38% on O. sativus and T. hybridum, feeding occurred in 6.7% of aphids on T. hybridum to 28% on O. sativus, phloem phase occupied less than 1% of probing time on all plants except O. viciifolia (4%) and O. sativus (5%) and it consisted mainly of salivation. On M. albus (v), probing occupied 22% of experimental time, the probes were short (1.8 ± 0.3 min), and no aphid on M. albus showed feeding on phloem sap. M. albus can be recommended for intercropping, ‘push-pull’ strategies, or as a barrier crop against A. pisum in sustainable agricultural practices.

Fenugreek Trigonella foenum-graceum L. as a feeding deterent to the pea aphidAcyrthosiphon pisum Harris.Ocena kozieradki pospolitej Trigonella foenum-graceum L. jako deterenta pokarmowego mszycy grochowej Acyrthosiphon pisum Harris.

The aim of the study was to evaluate the effect of the fenugreek Trigonella foenum-graceum L. on the feeding of the pea aphid Acyrthosiphon pisum Harris on peas Pisum sativum L. The parameters derived from 8-hour EPG (Electrical Penetration Graph) recordings were analysed. The following combinations were studied: peas covered with the extract from the fine ground seeds of the fenugreek, peas watered with the extract from fenugreek seeds, peas grown together with fenugreek, and peas grown in the soil with the addition of the fenugreek ground seeds. The results have shown that the fenugreek did not reduce the feeding of the pea aphid on peas. The phloem sap ingestion predominated in aphid activities in almost all combinations. The penetration of extra-phloem tissues prevailed only on plants grown together with the fenugreek. The longest time spent on phloem sap ingestion by A. pisum was found on control plants and plants watered or covered with the fenugreek seed extract.