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Table 1 The qualitatively different behavioural responses (parameterisation and associated vector behaviours) described by the new formula

From: How do biting disease vectors behaviourally respond to host availability?

Response type

Ecological equivalent

Parametric conditions

Vector behaviour

Type I

Analogous to Holling’s Type I

α = 1

β = 1

Indiscriminate; or vector biting that is consistent (proportionate) across relative availabilities of alternative hosts.

Type II

Analogous to Holling’s Type II

α < 1

β ≥ 1

The HBI of an anthropophilic vector saturates whereby even when humans and non-humans have similar availability, almost all blood meals are secured from humans.

Type III

Analogous to Holling’s Type III

α ≥ 1

β > 1

Similar to a Type II response, the HBI saturates, but at low levels of human availability vectors are uninclined to bite them. Corresponding with the analogous Holling’s Type, this could be associated with a learned behaviour with an increased rate of human encounters.

Type IV

Inversion of Holling’s Type II

α > 1

β ≤ 1

A zoophilic vector is uninclined to bite humans until they constitute all but the only available blood source.

Type V

Inversion of Holling’s Type III

α ≤ 1

β < 1

HBI saturates and becomes relatively invariant when humans and non-human hosts are at similar availability. This is analogous to ‘negative prey switching’ whereby the ‘predator’ consumes disproportionately less of the more available ‘prey’ [41]. Eventually, when non-humans become vanishingly rare, the HBI is forced to increase sharply to unity.