Background:Browsing repellents are widely used to deter large herbivores from consuming plants of ecological,economic and aesthetic importance.Understanding how these repellents function on a behavioural mechanistic l...Background:Browsing repellents are widely used to deter large herbivores from consuming plants of ecological,economic and aesthetic importance.Understanding how these repellents function on a behavioural mechanistic level is critical to predicting effectiveness.Here,we illustrate how these mechanisms can be tested,by exposing a model mammalian herbivore,the fallow deer,to different concentrations of a commercial chemical repellent(HaTe2)in two-choice feeding trials.Results:The repellent acted as a defensive chemical for the food by both reducing visitation and the amount consumed.Deer favoured the less defended feeders before ingesting any food,suggesting that the repellent altered olfactory and/or visual cues.Deer also consumed less of the more defended food when choosing between low and high repellent feeders than no and low repellent feeders,indicating that the repellent modified flavour and/or sensation.Repellent effectiveness declined with increased exposure,suggesting that consumption had no negative post-ingestive effects,and thus,deterrence was not caused by a conditioned aversion or irritation.Instead,this pattern suggests that deer learned,through repeated sampling of repellent-treated food,that there was no adverse physiological effect of ingesting it.Conclusions:These results imply that HaTe2 repellent will not be effective over prolonged periods or in the absence of alternative untreated food.Understanding the mechanisms driving repellent function using two-choice trials could help practitioners decide whether a particular repellent is likely to be effective against mammalian herbivory in their management scenario.展开更多
文摘Background:Browsing repellents are widely used to deter large herbivores from consuming plants of ecological,economic and aesthetic importance.Understanding how these repellents function on a behavioural mechanistic level is critical to predicting effectiveness.Here,we illustrate how these mechanisms can be tested,by exposing a model mammalian herbivore,the fallow deer,to different concentrations of a commercial chemical repellent(HaTe2)in two-choice feeding trials.Results:The repellent acted as a defensive chemical for the food by both reducing visitation and the amount consumed.Deer favoured the less defended feeders before ingesting any food,suggesting that the repellent altered olfactory and/or visual cues.Deer also consumed less of the more defended food when choosing between low and high repellent feeders than no and low repellent feeders,indicating that the repellent modified flavour and/or sensation.Repellent effectiveness declined with increased exposure,suggesting that consumption had no negative post-ingestive effects,and thus,deterrence was not caused by a conditioned aversion or irritation.Instead,this pattern suggests that deer learned,through repeated sampling of repellent-treated food,that there was no adverse physiological effect of ingesting it.Conclusions:These results imply that HaTe2 repellent will not be effective over prolonged periods or in the absence of alternative untreated food.Understanding the mechanisms driving repellent function using two-choice trials could help practitioners decide whether a particular repellent is likely to be effective against mammalian herbivory in their management scenario.
