Plant Volatiles Influence the African Weaver Ant-Cashew Tree Mutualism

Abstract

Plant volatiles influence virtually all forms of ant-plant symbioses. However, little is known about their role in the mutualistic relationship between the African weaver ant and the cashew tree. In this study, we tested the hypothesis that cashew tree volatiles from plant parts most vulnerable to herbivory viz. inflorescence, leaves, and fruits, are attractive to weaver ants. Using behavioral assays, we show that these volatiles attract weaver ants but without significant difference in preference for any of the odors. These same plant parts are associated with extra floral nectaries (EFNs') and therefore we evaluated the possibility that the ants associate the volatiles with food rewards. We found that perception of the odors was followed by a searching response that led the ants to non-volatile sugar rewards. More importantly, we observed that weaver ants spent significantly more time around the odor when it was paired to a reward. Chemical analysis of volatiles showed that the plant parts shared similarities in chemical composition, dominated by monoterpenes and sesquiterpenes. Additionally, we evaluated the attractiveness of a synthetic blend of three ocimene isomers ((E)-β-ocimene, (Z)-β-ocimene and allo-ocimene) identified in cashew leaf odor and shown to constitute a candidate kairomone for the cashew pest Pseudotheraptus wayi. We found that the attractiveness of the blend was dose dependent, and the response of the ants was not significantly different to that established with the crude volatiles from plant tissues. These results present new and interesting possibilities for improving weaver ant performance in cashew pest management.

Volatile and Phenolic Compounds In The Resistance of The Melon to The Vegetable Leafminer, Liriomyza Sativae Blanchard (Diptera: Agromyzidae)

“…These results suggest that the presence of linalool, alloocimene, and neo-allo-ocimene, whether alone or in double or triple combinations, is positively associated with attractiveness to L. sativae. This possibility is supported by Egonyu et al (2013) and Wanjiku et al (2014), who also identi ed the compounds allo-ocimene and neo-allo-ocimene in cashew leaves, and showed, using behavioural bioassays, that as mixtures these compounds are attractive to the insect-pest Pseudotheraptus wayi (Heteroptera: Coreidae) and their natural enemy Oecophylla longinoda (Latreille) (Hymenoptera: Formicidae). In addition, olfactometry studies Guohui et al (2005) have found that the isolated linalool attracted adult females of L. sativae.…”

“…Andrade et al 2016, Egonyu et al, 2013, Wanjiku et al 2014, and is present in considerable quantities in the genotypes of Citrus sp. less preferred by the psyllid Diaphorina citri, Kuwayama (Hemiptera: Psylidae)(Andrade et al 2016).…”

The Odorant Binding Protein, SiOBP5, Mediates Alarm Pheromone Olfactory Recognition in the Red Imported Fire Ant, Solenopsis invicta

“…Unfortunately, the ants fed with dsRNA SiOBPs, and Orco did not show any effects on the transcription and EAG levels at all. Feeding with dsRNA was reported to be a successful method for RNAi in some sap-sucking insects, such as the pea aphid ( A. pisum ) [ 21 , 22 ], white fly, ( Bemisia tabaci ) [ 23 ], and triatomine bug ( Rhodnius prolixus ) [ 24 ]. Even in S. invicta , the effect of the regulation of the pheromone-biosynthesis-activating neuropeptide (PBAN) on S. invicta survival has been investigated using RNAi.…”

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“…Embora a produção e liberação de COVs sejam comuns no reino vegetal, os perfis quantitativos e qualitativos das misturas desses voláteis são distintos e dependem da espécie, cultivar e idade/estágio de desenvolvimento da planta (Niederbacher;Winkler;Schnitzler, 2015). Em cajueiro, embora alguns COVs tenham sido identificados (Egonyu et al, 2013;Wanjiku et al, 2014;Fancelli et al, 2018), estudos visando caracterizar esses compostos em diferentes genótipos ainda não foram realizados.…”