Specificity and success of oral-bait delivery to Eurasian wild boar in Mediterranean woodland habitats

Abstract

Eurasian wild boar (Sus scrofa) is an important reservoir host for pathogens affecting humans and domestic animals. The eradication of these diseases may require the development of control strategies that reduce pathogen transmission between wildlife and domestic animals. Baiting for oral vaccine delivery is often considered for wildlife disease control. The effective and efficient field vaccination of wildlife requires species-specific baits as delivery vehicles for oral vaccines and designing appropriate baiting strategies. The objective of this study was to determine the proportion of young and adult wild boar and non-target animals that consumed baits containing a chemical marker, iophenoxic acid (IPA), in delivery trials conducted in summer in four different sites in the Mediterranean region of Spain where wild boar are abundant. The proportion of wild boar showing IPA markers in serum in autumn ranged from 11.5% to 56.4%. When attending to age classes, 12.6% to 72.7% of young individuals presented IPA. The results evidenced that the percent of wild boar that ingested the baits varied among study sites and age classes. Placing baits inside selective cages (for juveniles) and under heavy pavel stones (for adults) contributed to improve age specificity in bait consumption. We suggest ways for improving the age specificity of bait delivery systems used for young and adult wild boar.

Assessment of an Oral Mycobacterium bovis BCG Vaccine and an Inactivated M. bovis Preparation for Wild Boar in Terms of Adverse Reactions, Vaccine Strain Survival, and Uptake by Nontarget Species

“…Meanwhile, the bait uptake results from this study make us confident that most vaccine capsules were actually consumed by the target wild boar piglets. This confirms the results of previous bait deployment experiments (32). Selective feeders allow targeted delivery of oral baits to wild boar piglets, at the preferred age for vaccination (31).…”

“…Some kinds of oral bait have been found to be highly palatable to different nontarget wild and domestic animals (28); thus, strategies ensuring that only target species gain access to the bait are necessary (31,32). More studies concerning bait deployment and BCG viability are in progress (8).…”

“…Target animals for vaccination are 3-to 4-month-old piglets (28,32) (an age usually achieved by early summer). The aim of this study was to assess, through data compiled from both published and unpublished studies, the potential risks of field deployment of orally administered BCG and the prototype inactivated M. bovis preparation for wild boar, considering adverse reactions in the target host, risks due to vaccine strain survival or excretion in vaccinated individuals, and bait uptake by nontarget species.…”

Monitoring wild pig populations: a review of methods

“…Depending on the marker substance, the mark may be detectable on internal tissues collected from hunted animals or in hair and whiskers (Ballesteros et al 2012;Fisher 1999). As an example, systemic markers such as ethyl-iophenoxic acid and analogs may be detected in the blood, muscle, and liver of hunted wild pigs (e.g., Ballesteros et al 2011;Massei et al 2009;Sage et al 2013) and may be used to provide information on temporal or spatial patterns of bait consumption. One potential source of bias is that there may be subjectivity in determining whether an individual actually is marked because indirect marking does not always produce clear-cut marks.…”

Attractants for wild pigs: current use, availability, needs, and future potential

“…While wild pigs are not generally territorial and do not actively defend an exclusive area, they do have mating and dominance behaviors similar to wild ungulates, which could make them susceptible to decoy use in hunting scenarios (Mayer and Brisbin 2009 Several extensive research efforts focusing on attractants for wild pigs have been conducted over the last few decades (Supplemental Tables 2 and 3) (Wathen et al 1988;Campbell and Long 2008;Snow et al 2016b); however, conclusive results defining the most effective attractants are lacking (Wathen et al 1988;Mitchell 1998;Hartin et al 2007;Campbell and Long 2008). Researchers in Spain have been working toward developing baits (consisting of grainy piglet feed, sodium chloride, sacarose, and cinnamon-truffle powder) and a deployment strategy for vaccinating susceptible young wild piglets against bovine tuberculosis (Ballesteros et al 2011). In Australia, researchers delivered antifertility agents to wild pigs, and corn was the preferred attractant (Supplemental Table 3) (Bengsen et al 2011).…”