Vector preference and host defense against infection interact to determine disease dynamics

Abstract

Vector preference based on host infection status has long been recognized for its importance in disease dynamics. Prior theoretical work has assumed that all hosts are uniformly susceptible to the pathogen. Here we investigated disease dynamics when this assumption is relaxed using a series of vector–host epidemiological compartment models with variable levels of host resistance or tolerance to infection – collectively termed defense. In our models, vectors cannot acquire the infection from resistant hosts but can acquire from tolerant hosts. Specifically, we investigated the interacting effects of vector preference and host defense in a series of single‐ and two‐patch models. Results indicate that resistant host types generally reduce disease prevalence and pathogen spillover, independent of vector preference. The epidemiological consequences of host tolerance, however, depended on vector preference. When vectors preferred diseased hosts, tolerance reduced incidence compared to susceptible hosts; when vectors avoided diseased hosts, tolerance enhanced disease prevalence. Finally, a variation of the model that included preference‐based vector patch leaving rates suggests that both resistance and tolerance can promote pathogen spillover if vectors prefer diseased hosts, because of increased vector dispersal into susceptible patches. Collectively, we found complex, context‐dependent effects of vector preference and host defense on disease dynamics. In the context of management programs for vector‐borne diseases, managers should consider both the precise form of host defense present in a population, breed, or cultivar, as well as vector feeding behavior.

How Do Plant Diseases Caused byXylella fastidiosaEmerge?

“…Increased tension in a water column leads to a food source that is energetically expensive for insects, resulting in the ingestion of less xylem sap (Andersen et al 1992;Miranda et al 2013) and promoting the movement of vectors to another host (Krugner et al 2012). Since symptomatic plants are heavily colonized by X. fastidiosa (Newman et al 2003), avoidance of infected plants by vectors may act to reduce transmission rates when disease incidence is low (Sisterson 2008;Zeilinger and Daugherty 2014) and select for decreased bacterial virulence. This effect could be important when transmission rates are low; however, if vectors are common and transmission rates high, rapid bacterial growth leading to increased virulence may be favored, a pattern often observed in diseases that are vector-transmitted between hosts (e.g., malaria; de Roode et al 2005).…”

Transmission ofXylella fastidiosato Grapevine by the Meadow Spittlebug

“…Transmission can also be affected by within plant feeding preferences by insect vectors (Daugherty et al 2010) or vector discrimination against disease symptomatic plant tissue (Zeilinger and Daugherty 2014). There are no data on spittlebug-X.…”

Bayesian vector transmission model detects conflicting interactions from transgenic disease‐resistant grapevines

“…Given the combination of reduced Pierce's disease symptoms (Lindow et al. ) and greater vector colonization efficiency, DSF plants could represent significant pathogen reservoirs and could, under some conditions, enhance the spread of X. fastidiosa to more susceptible hosts (Zeilinger and Daugherty ).…”

“…In particular, sharpshooter vectors of X. fastidiosa, including G. atropunctata, prefer to feed on asymptomatic grapevines rather than Pierce's disease symptomatic vines (Daugherty et al 2011(Daugherty et al , 2017. Given the combination of reduced Pierce's disease symptoms (Lindow et al 2014) and greater vector colonization efficiency, DSF plants could represent significant pathogen reservoirs and could, under some conditions, enhance the spread of X. fastidiosa to more susceptible hosts (Zeilinger and Daugherty 2014).…”