Invasive ant (Anoplolepis gracilipes) disrupts pollination in pumpkin
Yellow crazy ant (Anoplolepis gracilipes (F. Smith); “YCA”) is known for its aggressive predatory ability and ability to exert exploitation competition on both native and other invasive ants via floral nectar. We argue that YCA invasion can exert both interference and exploitation competition on legitimate pollinators. In pumpkin fields (Cucurbita maxima L.) of south India, YCA infested the flowers, particularly the pistillate flowers, for nectar foraging. Pumpkin is a honey bee-mediated cross-pollinated monoecious plant that produces disproportionately very few pistillate flowers. We hypothesize that YCA presence in the flowers can affect the visitation rate and foraging time of honey bees in the flowers, the fruit set in pumpkins, and can exert predatory pressure on the honey bees if the bees linger in ant-colonized flowers. Both YCA and honey bees preferred to forage on the limited pistillate flowers in the plants. After colonizing the flowers, YCA did not retreat for hours, even upon disturbance by competitors, such as honey bees. Both the visitation frequency and the foraging time of honey bees were drastically reduced in ant-colonized flowers, and none of the ant-colonized flowers developed into fruits, suggesting that the YCA exert both an ecological and evolutionary pressure on pumpkin. The ants preyed upon about 17% of the honey bees that lingered in ant-colonized flowers, and the time the bees spent foraging predicted the fate of the bees. Exploitation competition exerted by the YCA on pumpkin may have far-reaching consequences for the pollination and productivity of this cash crop.
KeywordsInvasive species Competition Mutualism Pollination Pollination crisis Honey bee Crop production
We thank the two anonymous reviewers and the subject editor for their constructive comments on the previous versions of the manuscript. We also thank Judith Bronstein for the comments on the original version of the manuscript. We thank Sangeetha Varma for sampling ants in the study sites using pitfall traps in the 2016–2017 cultivation period. PAS would like to thank the committee for the Conservation, Research, and Exploration of National Geographic Society and Kerala State Economic and Planning Affairs for the grants that supported this research. PAS also thanks University Grants Commission (New Delhi) for awarding the Raman Fellowship for Post-Doctoral Studies at the University of Arizona. We thank all the farmers who cooperated in our research and bore the loss incurred due to our research. We thank Kayla Sale for proof reading the revised manuscripts.
VCS studied the effect of yellow crazy ant on honey bee visits; TVJ studied the effect of yellow crazy ant on fruit set in pumpkin; MVN, KSR, and PPM took the census of staminate and pistillate flowers in eighteen pumpkin fields; PAS studied the predation pressure of yellow crazy ant on honey bees, analyzed the data, and wrote the manuscript.
Compliance with ethical standards
Conflict of interest
The authors declare that they have no conflict of interest.
- Ali M, Saeed S, Sajjad A, Bashir MA (2014) Exploring the best native pollinators for pumpkin (Cucurbita pepo) production in Punjab, Pakistan. Pakistan J Zool 46:531–539Google Scholar
- Anonymous (2015) Agricultural statistics 2013–2014. Department of Economics and Statistics. Government of Kerala. www.ecostat.kerala.gov.in/docs/pdf/reports/agristat/1314/agristat1314.pdf. Accessed 10 March 2017
- Anonymous (2016) Horticultural statistics at a glance 2015. Government of India. Oxford University Press, New DelhiGoogle Scholar
- Baker G (1972) The role of Anoplolepis longipes Jerdon (Hymenoptera: Formicidae) in the entomology of cacao in the Northern district of Papua New Guinea. In: International congress of entomology, Abstracts, p. 327, CanberraGoogle Scholar
- Bates DM, Maechler M, Bolker BM, Walker S (2014) Lme4: linear mixed-effects models using Eigen and S4. R packageGoogle Scholar
- Lowe S, Browne S, Boudlejas S, De Poorter M (2004) 100 of the world’s worst invasive alien species. Invasive species specialist group, IUCN. www.issg.org/booklet.pdf
- Matsumoto T, Yamazaki K (2013) Distance from migratory honey bee apiary effects on community of insects visiting flowers of pumpkin. Bull Insectol 66:103–108Google Scholar
- NeSmith DS, Hoogenboom G, Groff DW (1994) Staminate and pistillate flower production of summer squash in response to planting date. HortScience 29:256–257Google Scholar
- Rai M, Pandey S, Kumar S (2008) Cucurbit research in India: a retrospect. In: Pitrat M (ed) Proceedings of the IX EUCARPIA meeting on genetics and breeding of Cucurbitaceae. INRA, Avignon, pp 285–294Google Scholar
- Rajesh TP, Manoj K, PrashanthBallulaya U, Surendran P, Sinu PA (2017) Ants indicate urbanization pressure in sacred groves of southwest India: a pilot study. Curr Sci (in press)Google Scholar
- R Core Team (2014) R: a language and environment for statistical computing. R Foundation for statistical computing, Vienna. http://www.R-project.org
- Veeresh GK, Gubbaiah (1984) A report on the ‘Crazy ant’ (Anoplolepis longipes Jerdon) menace in Karnataka. J Soil Biol Ecol 4:65–73Google Scholar
- Visser D, Wright MG, Giliomee JH (1996) The effect of the Argentine ant, Linepithema humile (Mayr) (Hymenoptera: Formicidae), on flower-visiting insects of Protea nitida Mill. (Proteaceae). Afr Entomol 4:285–287Google Scholar
- Walters SA, Taylor BH (2006) Effects of honey bee pollination on Pumpkin fruit and seed yield. HortScience 41:370–373Google Scholar
- Wetterer JK (2005) Worldwide distribution and potential spread of the long- legged ant, Anoplolepis gracilipes (Hymenoptera: Formicidae). Sociobiology 45:1–21Google Scholar