Plants respond to biotic stresses by releasing defence chemicals comprised of volatile organic compounds (VOCs) and non-volatiles that can influence the interaction with herbivores. The degree of interaction with herbivores can vary depending upon the plant species, genotype and plant stage, and the nature and potency of the biotic stress. The African citrus triozid, Trioza erytreae Del Guercio (Hemiptera: Triozidae) and citrus greening disease (CGD) vectored by this insect, have been heavily associated with a continuous decline in citrus production wherever they occur. We hypothesized that induction of volatiles in citrus plants in response to biotic stress would enhance attraction in adult T. erytreae. To test this hypothesis, we investigated the interaction between T. erytreae and one of its preferred host plants, Citrus jambhiri (lemon). We compared responses of adults of the hemipteran to healthy, T. erytreae egg- and nymph-infested and citrus greening bacteria, Candidatus Liberibacter africanus (CLaf) infected-plants to controls. We found that volatiles of healthy lemon plants dominated by monoterpenes attracted adult T. erytreae. However, egg- and nymph-infested lemon plants induced the biosynthesis of volatiles dominated by methyl esters that reduced attraction in adult T. erytreae. On the other hand, bacteria-infected plants induced biosynthesis of sesquiterpenes that enhanced attraction in triozids. Our results reveal that induced defensive responses in lemon plant varies with the biotic stress, releasing attractive and aversive compounds, which can be exploited in attract-and-kill and push-pull approaches for T. erytreae management.

Constitutive, herbivore- and microbe-induced Citrus jambhiri (lemon) volatiles differentially influence African citrus triozid Trioza erytreae behavior

2019 Fall National Meeting

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