Developing Snail Management Programs in Florida Citrus

By Lauren Diepenbrock and Nicole Quinn

In recent years, a new pest has been added to the ever-evolving scope of pest management in Florida citrus: Bulimulus bonariensis snails. These snails, also referred to as ghost snails or peanut snails, were reported to be clogging irrigation jets in Central Florida in 2020 in limited locations. Now, in 2025, they have spread throughout Florida and much of the southeastern United States. They impact a broad array of agricultural commodities and are becoming problematic in residential areas as well.

In citrus, the primary impacts documented to date include microjet clogging (Figure 1), defoliation within individual protective covers (IPCs) and occasional trunk damage to green stems (Figure 2). Additionally, the snails have been noted to feed at sites of previous canker lesions on fruit (Figure 3) and under bark after freeze damage (Figure 4).

Because this snail is a recently established pest, there is much that is not known about its biology or the best management options. As such, this article serves to share the information that University of Florida Institute of Food and Agricultural Sciences (UF/IFAS) researchers are developing about B. bonariensis snails in citrus to help growers make informed management decisions.

SEASONAL BIOLOGY

While B. bonariensis snails can be found throughout much of the year, their presence is most obvious in groves in late spring/early summer before the rainy season starts. The snails are not only abundant on tree trunks at this time, but they also tend to cluster on microjets, which leads to reduced irrigation efficiency. This can have severe ramifications on HLB-affected trees by impacting the ability of both water and nutrients to reach roots.

Researchers have been using a series of traps to document relative snail populations within groves. Activity is seen throughout much of the year, with notable increases in trap captures from March up until the seasonal rains begin in June or July. Snails are more readily captured by traps in the dry periods as they seek refuge from the hot, dry grove soil surfaces.

Once rain events begin, usually in mid to late June, snails move away from the traps and are often not found impeding microjets during the rainy period. Similar patterns throughout the year suggest that moisture and/or ground temperature may be the driving force for snail movement either across the ground (wet, cooler periods) or up tree trunks and microjets (dry, hot periods). This statement is largely based on observations and data obtained through trapping. Researchers will further document this behavior throughout 2025.

FEEDING PREFERENCES

While feeding damage to citrus has been documented, until recently it was not clear if citrus is a main food resource for B. bonariensis snails or if the feeding damage to citrus occurred because it was the only option, such as when snails become trapped within IPCs. To better understand their feeding preferences, snails were collected from groves. Snail guts were dissected and subjected to molecular analysis to describe their contents. Preliminary data from this research shows that most of the foods consumed by these snails consist of weeds that are commonly found in groves. Citrus comprised less than 1% of species detected.

Weeds clearly play an important role in the life cycle of B. bonariensis. What is unclear right now is how weed management would impact these snails. Would increasing vegetation in row middles reduce impacts on irrigation? Or would modifying ground cover reduce overall snail populations? UF/IFAS will explore this further in the summer of 2025.

CHEMICAL MANAGEMENT OPTIONS

Pesticides exist for managing snails, mostly in the form of molluscicidal baits. Baits registered for use in citrus, along with two baits under development for use in citrus, were evaluated in semi-field assays to determine their efficacy on B. bonariensis (Figure 5). Of the baits that are commercially available, Deadline GT, Ferroxx AQ, Deadline M-Ps and Slugger Ultra consistently showed mortality of 90% or greater. Additionally, one of the baits under development had 100% mortality of B. bonariensis. This bait has a narrower range of potential non-target pests. With further testing, it is anticipated that this material will be available for growers in the coming years.

In addition to molluscicides, other pesticides including insecticides, herbicides and fungicides have been found to be efficacious toward the management of snails in other production systems. Using the same semi-field assays, researchers evaluated several commonly used insecticides to determine if any had potential to impact this pest (Figure 6). While these chemistries are not currently registered for snails, future label expansions may occur with proper supporting data. From this screening, products containing abamectin had the highest mortality rates. This chemistry has been found to have mortality for a limited spectrum of snails in other regions and may be a tool for use in management plans. Potential deterrents, which could prevent snails from clogging irrigation jets in the first place, are also being evaluated.

WHAT’S NEXT?

UF/IFAS continues to evaluate chemical tools for use toward the management of B. bonariensis. At the same time, researchers are seeking predators, documenting field populations and will soon be using tracking technology to follow snails and document what elements of a grove habitat influence where they move within the field (e.g., ground temperature, moisture availability and shade availability).

Lauren Diepenbrock is an assistant professor at the UF/IFAS Citrus Research and Education center in Lake Alfred. Nicole Quinn is an assistant professor at the UF/IFAS Indian River Research and Education Center in Fort Pierce.