Experimental Design and Placement of Dispensers

The baits were administered in both areas using the same experimental design. The products, attached to the appropriate pegs, were placed in dispensers in pairs, with 2 blocks per product positioned alternately (e.g., ABAB). Each pair represented a direct comparison between two products, or trials. The pairs were arranged so that the six possible combinations were equally represented. Based on this design, each individual trial was replicated 8 times, and each formulation was administered in a total of 24 dispensers.

The dispensers were placed opportunistically at points deemed suitable or indicated by the site personnel (e.g., along riverbanks, inside sheds with feed or grains, near stables, etc.). In each area, 12 points were selected, and at each point, 2 dispensers were placed 1-10 meters apart, arranged so that all 4 products were available at each point (for example, around point 1, a dispenser with products AB was placed and another with products CD).

Temporal Schedule and Control Protocol

The dispensers were checked every other day for 5 times (plus an initial “0” check for 12 dispensers to confirm the presence of rodents; Table 2).

At each check, a dispenser was defined as “visited” when clear signs of consumption were present (reduction of the bait, clear incisor marks) or rodent droppings were found inside (Fig. 2). The remaining bait was weighed using a spring scale (accuracy 1 g) to quantify consumption, calculated as the difference in weight compared to the previous check. Bait blocks consumed by more than half of their weight were replaced to ensure a greater availability of product. Finally, the position of the bait inside the dispensers was reversed at each check to exclude any effects due to position and/or rodent experience (for example, if at the first check the products were positioned in the ABAB scheme, at the next check their position was reversed, according to the BABA scheme).

Data Analysis

The data were analyzed at different levels:

1. Visits to dispensers: In this phase, the probability of a visit to the dispensers was analyzed (1 = visit, 0 = no visit), regardless of the amount of bait consumed. The results are therefore related to the attractiveness of the baits to the rodents, who are prompted to enter the dispenser and possibly taste the product.

Statistical analysis: Binomial models using the glmer function (lme4 package) on the open access R software. Error structure: random = 1 | dispenser/control.

2. Rodenticide bait consumption: This data reflects the rodent’s preference for the baits. Once inside the dispenser, the rodent will tend to consume more of the bait that is more appealing. This analysis was performed at the level of:

– Total consumption, obtained by summing the total consumption over the 10-day duration of the test. The results give a measure of how much the products were consumed overall, in comparison with each other, over multiple days of administration.

Results and Discussion: Species Detected

Feces and signs of consumption attributable to both rats (Rattus sp.) and mice (Mus musculus) were found in the dispensers, with a higher abundance of rat signs in the area of the Riding School. A direct finding of a dead specimen of Rattus sp. (likely R. norvegicus) was reported near a dispenser located by the riverbank at the riding school.

In the riding school area, the presence of mice was also directly observed following the escape of individuals that were inside the dispensers during the inspection. The same direct sighting of mice during the inspection occurred in the agricultural area, where a dead specimen of M. musculus was also found inside one of the dispensers.

Results and Discussion: Visits to the Dispensers

During the 10 days of administration, 37 out of 48 dispensers (77%) were visited at least once, with 18 in the agricultural area and 19 in the riding school area. For unidentified reasons, 11 dispensers were never visited and were therefore excluded from the consumption analysis.

Visits to the dispensers were generally more frequent in the riding school area, but they gradually decreased over the course of the 5 inspections. In the agricultural area, visits to the dispensers remained at lower but more consistent levels over time.

Visits to dispensers containing different products seemed to follow the same general pattern over time, except for the dispensers containing product B, where, after an initial increase, visits seemed to decrease more rapidly.

Results and Discussion: Consumption Trends

Total consumption (the sum of all dispensers’ consumption) followed a similar pattern in both areas, with an initial increase at the second inspection followed by a gradual decrease. This trend, which mirrors the visits to the dispensers, is likely due to rodents overcoming their initial hesitation, followed by progressive death due to the consumption of the baits.

Overall, the consumption data reveals a clear pattern, similar in both areas, where product D, Notrac Blox by Bell, was the most consumed, and product B was the least consumed. This result did not differ between the two areas.

Results and Conclusions

• A peak in visits to the dispensers and consumption was observed at the second inspection, followed by a gradual decrease over time (likely due to overcoming initial hesitation, followed by death from rodenticide ingestion).

• There does not appear to be a product that induces rodents to visit a dispenser more frequently or earlier than the others.

• The product that shows the highest attractiveness, both overall and when compared individually with other products, is Notrac Blox.

• The differences between the products are consistent regardless of the area or inspection, demonstrating the general validity of the test results.

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