# Ant-mealybug interactions in pineapple cropping systems in Reunion Island

Marie Bourel, Eva Faustin, Philippe Tixier, Bernard Raymond Abufera, Dominique Carval

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Marie Bourel, Eva Faustin, Philippe Tixier, Bernard Raymond Abufera, Dominique Carval. Ant-mealybug interactions in pineapple cropping systems in Reunion Island. European Congress of Entomology (ECE 2023), Oct 2023, Heraklion, Greece. Hellenic Entomological Society, 1 p., 2023. [hal-05181826]

HAL Id: hal-05181826

https://hal.science/hal-05181826v1

Submitted on 23 Jul 2025

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# Ant-mealybug interactions in pineapple cropping systems in Reunion Island

## INTRODUCTION

In Reunion Island, pineapple cultivation is largely impacted by the **Wilt virus complex**, transmitted by mealybugs of the **Dysmicoccus brevipes** (Hemiptera) species. However, other species such as **ants** (Hymenoptera) are involved in this complex pathosystem. Ants usually **nurture** and **protect** the mealybugs from predators<fnref n="1" />, while the latter provide **honeydew** to the ants.

* Which ant species are present and tend on mealybugs in pineapple cropping systems in Reunion Island ?

* How can sugar provisioning impact the mutualism between ants and mealybugs ?

<figure><img src="image_3.png" /><figcaption>© M. Bourel
Wilt symptoms</figcaption></figure>

## ANT & MEALYBUG COMMUNITIES IN PINEAPPLE CROPPING SYSTEMS

Pineapple plants were collected from **10 plots** in the south of the island, for a total of **144 plants** sampled. The plants were dissected to count the **number of mealybugs** and **ants** per species.

<table><caption>Table 1: Occurrence and abundance of species collected on plants</caption><thead><tr><th>Species</th><th>Occurrence<br>(/144 plants)</th><th>Abundance<br>(Total)</th></tr></thead><tbody><tr><td><i>Dysmicoccus brevipes</i> (Cockerell)</td><td>84</td><td>4976</td></tr><tr><td><i>Brachymyrmex cordemoyi</i> (Forel)*</td><td>53</td><td>352</td></tr><tr><td><i>Solenopsis geminata</i> (Fabricius)*</td><td>50</td><td>4643</td></tr><tr><td><i>Pheidole megacephala</i> (Fabricius)*</td><td>24</td><td>601</td></tr><tr><td><i>Tetramorium bicarinatum</i> (Nylander)</td><td>9</td><td>71</td></tr><tr><td><i>Tapinoma melanocephalum</i> (Fabricius)</td><td>6</td><td>240</td></tr><tr><td><i>Hypoponera punctatissima</i> (Roger)</td><td>4</td><td>5</td></tr><tr><td><i>Technomyrmex spp.</i> (Mayr)</td><td>4</td><td>5</td></tr><tr><td><i>Nylanderia bourbonica</i> (Forel)</td><td>4</td><td>237</td></tr><tr><td><i>Technomyrmex difficilis</i> (Forel)</td><td>4</td><td>236</td></tr><tr><td><i>Paratrechina longicornis</i> (Latreille)</td><td>3</td><td>22</td></tr><tr><td><i>Technomyrmex albipes</i> (Fr. Smith)</td><td>3</td><td>3</td></tr><tr><td><i>Hypoponera eduardi</i> (Forel)</td><td>3</td><td>7</td></tr><tr><td><i>Strumigenys rogeri</i> (Emery)</td><td>1</td><td>2</td></tr></tbody></table>

* Observation(s) of interactions with *D. brevipes*

We used a negative binomial generalized linear mixed model to analyse the effect of the 3 more frequent **ants** abundances on *D. brevipes* abundance. The plot effect was considered as a random effect.

<figure><img src="image_4.png" /><figcaption>Figure 1: Prediction plot of the model</figcaption></figure>

Plot effect

*S. geminata*
Marginal R² = 0,21

<figure><img src="image_5.png" /></figure>

Only the abundance of *S. geminata* was **positively** correlated with the abundance of *D. brevipes* in our plants.

## ANT DOMINANCE

We used an **imagery approach** to facilitate the detection of ant species and study their **dominance** on a honey bait.

<figure><img src="image_6.png" /><figcaption>Figure 2: Probability of bait control after deposition of the bait</figcaption></figure>

A multinomial analysis was performed in order to analyse the effect of (i) the **time** after deposition of the bait and (ii) the **Day/Night** effect on the relative **probability of control** of the bait. Both had a significant influence on the **probabilities of bait control**. The effects **differed** depending on the **species**.

## SUGAR PROVISIONING

Colonies of *P. megacephala* and *D. brevipes* were captured and maintained in a climatic chamber (Temperature = 22°C, Relative Humidity = 64%). We tested the **effect** of adding a **sugary resource** on the **tending** of mealybugs by ants in terms of simple and prolonged contacts.

<figure><img src="image_7.png" /></figure>

<figure><img src="image_8.png" /><figcaption>Figure 3: Effect of a sugary resource on ant tending</figcaption></figure>

Ants **tended** mealybugs significantly **less** when provided with a **sugary resource**, in both simple and prolonged contacts.

## CONCLUSION & PERSPECTIVES

In Reunion Island, **3 ant species** were found to be **dominant** and **involved** in the mutualism with mealybugs.

**Sugar providing** appears to be an effective lever for **reducing** the **attractiveness** of mealybugs to *P. megacephala*. Future studies, especially on *S. geminata*, need to be carried out to clarify the **long term** effects of this alternative resource on mealybug attendance in the lab and **in the field**.

<figure><img src="image_9.png" /><figcaption>© M. Bourel
*S. geminata* worker</figcaption></figure>

<figure><img src="image_10.png" /></figure>

<footnote n="1">¹Offenberg, J. (2001). Balancing between mutualism and exploitation: The symbiotic interaction between Lasius ants and aphids. Behavioral Ecology and Sociobiology, 49(4), 304–310. https://doi.org/10.1007/s002650000303</footnote>