Abstract
Simple SummaryResistance of a Pisum fulvum and five Pisum sativum genotypes to Acyrthosiphon pisum pea and alfalfa-adapted biotypes was evaluated by measuring aphid body mass, confirming the variable resistance level of these genotypes. The feeding behavior of the aphids on the Pisum genotypes was then examined by electropenetrography (EPG). The EPG results suggested that the resistance of Pisum genotypes to non-adapted A. pisum resides in mesophyll and phloem tissues while the resistance variation of P. sativum to pea adapted aphids may be influenced by the quality of phloem sap.Resistant genotypes of crops have emerged as an alternative and sustainable solution to pesticide use against pest insects. The resistance depends on the genetic diversity of the host plant and the pest species and can cause an alteration of the insect behavior. The aim of this work was to characterize the resistance level of different Pisum genotypes (one P. fulvum and five P. sativum genotypes) to two biotypes of the aphid Acyrthosiphon pisum, respectively adapted to pea and alfalfa, by measuring the individual aphid weight and analyzing aphid feeding behavior by electropenetrography (EPG). Aphid body mass was influenced by Pisum genotypes reflecting variation in their resistance level. P. fulvum was the most resistant to the A. pisum pea biotype (ArPo28 clone) and showed intermediate resistance to the A. pisum alfalfa biotype (LSR1 clone). The resistance levels of the five P. sativum genotypes to the two aphid biotypes were variable and more pronounced for the alfalfa biotype. EPG data showed that ArPo28 on P. fulvum and LSR1 on all the Pisum genotypes spent shorter time phloem feeding compared to ArPo28 on P. sativum genotypes, indicating that the resistance of Pisum genotypes to non-adapted A. pisum resides in mesophyll and phloem cells. In the meantime, ArPo28 on P. sativum genotypes with a different level of resistance spent a similar length of time phloem feeding, indicating that the quality of phloem sap of the resistance genotypes may not be optimal for the aphid. The study indicated that the resistance of Pisum genotypes to the two A. pisum biotypes involves different genetic factors and mechanisms that affect the aphid differently.
Highlights
IntroductionAphids are sapfeeding pests of many crops and are mainly controlled by a range of insecticides; due to the toxicity of the pesticides to beneficial insects, the recurrent development of insecticide resistance and the current EU moratorium on the use of certain insecticides, more environmentally sound pest control strategies are required
We focused on the interactions between the Pisum species and the pea aphid, Acyrthosiphon pisum
Significant differences were found in the larval weight of the A. pisum pea biotype clone) reared on the different Pisum genotypes (Figure 1)
Summary
Aphids are sapfeeding pests of many crops and are mainly controlled by a range of insecticides; due to the toxicity of the pesticides to beneficial insects, the recurrent development of insecticide resistance and the current EU moratorium on the use of certain insecticides, more environmentally sound pest control strategies are required. The deployment of insect-resistant crops has great potential to reduce pesticide use, the mechanisms of plant resistance to aphids are not well understood. The only cloned and characterized genes known to confer resistance against aphids encode NBS-LRR Vat in melon [1] and Mi in tomato [2]. One approach to characterize plant barriers responsible for aphid resistance lies in the electrical penetration graph (EPG), which tracks aphid feeding behavior during interaction with the plant [3,4].
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