Characterisation of bird cherry‐oat aphid (Rhopalosiphum padi L.) behaviour and aphid host preference in relation to partially resistant and susceptible wheat landraces

Abstract

The bird cherry‐oat aphid ( Rhopalosiphum padi L.) is a major pest of wheat ( Triticum aestivum L.) and can cause up to 30% yield losses. Heritable plant resistance to aphids is both an economically and ecologically sound method for managing aphids. Here we report how the behaviour and performance of R. padi differs on two resistant, one susceptible wheat landrace and a susceptible elite wheat variety. Feeding behaviour differed among the genotypes, with aphids on resistant lines spending longer in the pathway phase and less time phloem feeding. These behaviours suggest that both inter‐ and intracellular factors encountered during pathway and phloem feeding phases could be linked to the observed aphid resistance. Locomotion and antennal positioning choice tests also revealed a clear preference for susceptible lines. Although feeding studies revealed differences in the first probe indicating that the resistance factors might also be located in the peripheral layers of the plant tissue, scanning electron microscopy revealed no difference in trichrome length and density on the surface of leaves. Aphids are phloem feeders and limiting the nutrient uptake by the aphids may negatively affect their growth and development as shown here in lower weight and survival of nymphs on resistant genotypes and decreased reproductive potential, with lowest mean numbers of nymphs produced by aphids on W064 (54.8) compared to Solstice (71.9). The results indicate that resistant lines markedly alter the behaviour, reproduction and development potential of R. padi and possess both antixenosis and antibiosis type of resistance.

Volatile interactions between specific undamaged barley cultivars affect aphid feeding behavior and performance

“…Both constitutive and induced resistance to aphids can be located in specific plant tissues, and monitoring aphid stylet activity by electrical penetration graph (EPG) technique has been used for the identification of plant tissues where resistance factors against aphids are expressed (Tjallingii 2006). Constitutive resistance factors located in the peripheral layers of the plant tissues make R. padi probed slower on resistant than on susceptible genotypes of Triticum aestivum L. (Singh et al 2020). In the present study, volatile interactions between undamaged barley cultivars triggered a similar probing behavior in R. padi.…”

“…Plant susceptibility to aphids can depend on the morphological characteristics of plant tissues. It has been shown that large intercellular space appearing with a smaller number of mesophyll cells, thinner leaves and thinner guard cells in vascular bundles could make plants more susceptible to aphids (Singh et al 2020).…”

Identifying aphid resistance in the ancestral wheat Triticum monococcum under field conditions

“…No commercial varieties have been bred specifically for R. padi, S. avenae or M. dirhodum resistance to date, but partial resistance has been identified in a number of varieties, including resistance to R. padi in Watkins land race collections 27 , 28 , north-eastern European Gediflux collection 27 and S. avenae resistance in the ancestral diploid Triticum urartu (T.) and Triticum boeoticum (L.) 29 . The diploid ancestral Triticum monococcum (L.) (genome A m A m ) 30 , 31 was cultivated in the Neolithic age 32 , genotypes within this species have shown to confer resistance to R. padi 33 – 35 , S. avenae 29 , 31 , 35 – 37 and M. dirhodum 30 , 34 .…”