Asymmetric Interaction between Aphis spiraecola and Toxoptera citricida on Sweet Orange Induced by Pre-Infestation

Abstract

<jats:p>Indirect interactions between herbivorous insects that share the same host have been focused on insects feeding on herbaceous plants, while few studies investigate similar interactions on woody plants. We investigated performance and feeding behavior of two citrus aphids, Aphis spiraecola Patch and Toxoptera citricida Kirkaldy, on sweet orange as affected by prior infestation of conspecifics and heterospecifics. Results showed that pre-infestation-induced interactions between A. spiraecola and T. citricida were asymmetric, with A. spiraecola gaining more fitness. In detail, pre-infestation by A. spiraecola decreased adult weight, enhanced survival rate and accelerated phloem sap acceptance of conspecifics. However, A. spiraecola pre-infestation did not affect performance or feeding behavior of T. citricida. In another infestation sequence, the pre-infestation of T. citricida did not affect conspecifics, but positively affected heterospecifics, indicated as a decreased pre-reproductive period, enhanced survival rate, adult weight, fecundity, and feeding efficiency, i.e., faster access and acceptance of phloem sap, and longer phloem sap ingestion duration. Furthermore, we found A. spiraecola pre-infestation enhanced amino acid concentration, amino acid to sugar ratio, activated salicylic acid and jasmonic acid marker gene expression, while T. citricida pre-infestation only depressed jasmonic acid marker gene expression. Changes in nutrient and phytohormone-dependent defense probably underlie the asymmetric effect.</jats:p>

Aphis spiraecola and Aphis (Toxoptera) citricidus differently manipulate plant metabolism to gain fitness in terms of population abundance or dispersal

“…Previously, we found that A. spiraecola infestation induced phytohormone-based SA and JA signaling defenses, whereas A. citricidus did not affect SA and inhibited JA signaling (Gao et al, 2020), implying that A. spiraecola may encounter more difficulty in ingesting plant nutrients than A. citricidus. However, how the plant defenses induced by citrus aphids change during infestation is unknown.…”

“…Second, leaf curling may provide a sheltered micro-environment that protects A. spiraecola from natural enemies and other threats (Goggin, 2007). Third, the plant-mediated indirect interaction between the two citrus aphids favors A. spiraecola as a superior competitor (Gao et al, 2020).…”

“…Wingless adult aphids of both aphid species starved for 8 h were used according to methods previously reported (Gao et al, 2020). Prior to recording, aphids were connected to gold wire with silver glue attached on its dorsal side.…”

Vermicompost Amendments Disrupt Feeding Behavior of Diaphorina citri Kuwayama and Boost Activities of Salicylic Acid and Jasmonic Acid Pathway-Related Enzymes in Citrus

“…Similarly, a reduced phloem sap ingestion duration was observed on D. citri feeding on citrus plants drenched with the insecticides thiamethoxam and imidacloprid [ 26 ]. Previously, the duration of phloem sap was linked to the performance of piercing–sucking insects [ 30 , 31 , 32 ]. Therefore, our findings help to explain the negative effect of vermicompost on piercing–sucking insects from the aspect of feeding behavior.…”