Caught on camera: Field imagery reveals the unexpected importance of vertebrates for biological control of the banana weevil (Cosmopolites sordidus Col. Curculionidae)

Abstract

Understanding of ecological interactions is necessary for the application of biological control. Banana is the second most produced fruit worldwide and the banana weevil (Cosmopolites sordidus) is the most important pest of banana and plantain. Its biological control remains challenging because of the robustness and cryptic behaviour of the adult and the hidden development of larval stages. Researchers therefore tend to favour conservation biological control of this pest. The commonly used methods for measuring the effects of natural enemies on the regulation of this pest focus on invertebrates and may underestimate the role of vertebrates on biological control. Using cameras, we recorded the predation of sentinel adult weevils in banana plots in La Réunion island that differed in weevil infestation levels and in animal biodiversity. To facilitate image analysis, we used background subtraction to isolate moving parts of image sequences and thus detect predators and predation events. Our cameras recorded only vertebrates as predators of adult banana weevils. The most important predator appeared to be the Asian shrew (Suncus murinus), which was responsible for 67% of the predation events. Other predators included the house mouse (Mus musculus), the oriental garden lizard (Calotes versicolor), and the guttural toad (Sclerophrys gutturalis). The exact time of predation events were determined from the images metadata. It was thus possible to identify predator foraging periods that coincided with activity of adult weevils. Our results confirm that images provide useful information for biological and ecological studies. Along with other recent studies, our results suggest that the role of vertebrates in biological control may be underestimated. Based on these results, we advocate for several management implications such as the installation of hedges, grasslands, and ponds to favour these vertebrate predators of the banana weevil, possibly also favouring other vertebrate and invertebrate natural enemies.

Stop me if you can: quantification of the effect of interfaces between plots on the dispersal of Cosmopolites sordidus

“…Recently, Tresson et al . (2022) showed that vertebrates such as shrew, lizards and toads can be efficient predators of adults of C. sordidus 42 . We can hypothesize that predation also play a role inside interfaces, especially in the case of larger interfaces.…”

“…For instance, it was demonstrated that insect predators, especially ants, 39,40 can be involved in the regulation of C. sordidus and that more complex plant communities tend to increase their abundance and their regulation rates. 41 Recently, Tresson et al (2022) showed that vertebrates such as shrew, lizards and toads can be efficient predators of adults of C. sordidus. 42 We can hypothesize that predation also play a role inside interfaces, especially in the case of larger interfaces.…”

“…41 Recently, Tresson et al (2022) showed that vertebrates such as shrew, lizards and toads can be efficient predators of adults of C. sordidus. 42 We can hypothesize that predation also play a role inside interfaces, especially in the case of larger interfaces. We can also imagine that combining interfaces would be an interesting option, for instance by putting together a ditch with water to stop dispersion and a hedgerow to enhance predation.…”

Simulated Soil Moisture and Planting Material Health on the Behaviour of Cosmopolites sordidus, Germar (Coleoptera: Curculionidae)

“…Recently Tresson et al (2021) have confirmed the challenges with the use of biological control in weevil control. Others have also employed modern technologies such as the use of cameras and concluded that vertebrates such as the Asian shrew, house mouse, oriental garden lizard and the guttural toad were promising predators of the weevil (Tresson et al, 2022). The farmer stage accessible agronomic practices adopted in this experiment influences weevil behaviour, hence amendments that improves soil moisture should be recommended.…”

Diversity of functional edaphic macrofauna in Musa acuminata x Musa balbisiana (AAB) agroecosystems

“…On the other hand, invertebrate pests attract a lot of attention, and they cost farmers and producers millions of dollars (Tresson et al, 2022;Velásquez et al, 2012;Alcaraván, 2003;Decaëns et al, 2004;Cardona et al, 1998). Brown et al (2001) and Pocasangre, Brown and Quesada (2009) show that limited physical-chemical elements and fertility can lead to population decline.…”