Abstract

Pearl bodies are produced by some plant species as food reward for ants and in exchange, ants defend these plants against insect pests. Sap-sucking pests such as aphids also excrete honeydew as food reward for ants, leading to potential conflict where ants could preferentially defend either the plant or the aphid. How pest insects might influence plant pearl body production, is yet to be investigated. Okra is a widely consumed vegetable worldwide and is attacked by the ant-tended cotton aphid. The plants produce pearl bodies, which are predominantly found on the underside of the leaves and formed from epidermal cells. We conducted a set of field and greenhouse experiments to explore plant-aphid-ant interactions, their influence on pearl body production and resulting performance of okra plants, across okra varieties. We found that ants of Pheidole genus, which are dominant in okra fields, preferred pearl bodies over aphid honeydew; although, their highest abundance was recorded in presence of both these food rewards, and on one okra variety. Removal of pearl bodies from the plants increased their production; however, plant growth and chlorophyll content were negatively associated with pearl body replenishment. Potentially to mitigate this resource cost, plants developed such a novel defense response because we found that aphid presence reduced pearl body production, but only when there were no ants. Finally, aphids negatively affected plant performance, but only at very high densities. As aphids also attract ants, plants may tolerate their presence at low densities to attract higher ant abundances. Our study highlights that plants can adapt their defense strategies in pest presence for efficient resource use. We suggest that understanding pearl body associated interactions in crop plants can assist in using such traits for pest management.

Highlights

  • Plants have evolved numerous defense traits against herbivorous pests that reduce pest growth (Walling, 2000; Mithöfer and Boland, 2012)

  • We investigated the following questions: (a) Does okra pearl body production vary across okra varieties? (b) Do ants prefer okra pearl bodies over aphid honeydew, and does this vary across okra varieties? (c) Does aphid presence and pearl body removal affect okra pearl body replenishment, and does this vary across okra varieties? We have further explained okra pearl body morphology in the current study as it has not been described before

  • Our study shows that pearl body production and its variation across okra varieties can alter ant-plant interactions in the field

Read more

Summary

Introduction

Plants have evolved numerous defense traits against herbivorous pests that reduce pest growth (Walling, 2000; Mithöfer and Boland, 2012). One defense trait is the production of food rewards that plants produce as a nutrient resource to attract other species (Heil and McKey, 2003; Heil, 2015). Ants in particular have been shown to protect plants from herbivores in exchange for food rewards (Rosumek et al, 2009; Mayer et al, 2014). Ants can form mutualistic associations with the herbivores; e.g., ants tend aphids for their honeydew reward, and in return protect aphids from their natural enemies (Buckley, 1987; Völkl et al, 1990; Kaplan and Eubanks, 2005). Benefits and costs for plants through such mutualistic ant-aphid interactions is unclear as plants can benefit indirectly from these interactions (Styrsky and Eubanks, 2007; Singh et al, 2016). In the presence of ant-tended aphids, plants may develop different strategies to promote plant defense

Methods
Results
Conclusion

Talk to us

Join us for a 30 min session where you can share your feedback and ask us any queries you have

Schedule a call

Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.