The impact of diseases and pathogens on insect population dynamics

The compatibility of a nucleopolyhedrosis virus control with resistance management for Bacillus thuringiensis: Co-infection and cross-resistance studies with the diamondback moth, Plutella xylostella

“…NPV products are commercially available for heliothine pests in the US and Australia and have been successfully used globally in various agricultural and horticultural settings (Hunter-Fujita et al, 1998) and in the development of IPM in cotton (Mensah, 2002). While NPVs have limitations as insecticides, especially in their cost of production, they can, through the build-up of infectious particles and secondary cycles of infection in pest populations, be an eVective means of long-term population control (Reed and Springett, 1971;Entwistle et al, 1983;Dwyer and Elkinton, 1993;Fuxa and Richter, 1994;Young, 1998;Bonsall, 2004). This, in turn can lead to increased spray intervals and reduced costs for growers (Moscardi, 1999).…”

The impact of non-lethal synergists on the population and evolutionary dynamics of host–pathogen interactions

“…The combination of high levels of parasite-induced mortality, large pathogen yields, long-lived resting 28 stages and relative low rates of host population growth can give rise to population instabilities (Anderson and May 1981;Myers 1988). These effects can be mitigated or enhanced by addi-30 tional ecological factors such as the effects of refuges (Hochberg 1989), the role of intraspecific competition (Bowers, et al 1993;Bonsall et al 1999) or competitive interactions between 32 strains (Hochberg and Holt 1990;Bonsall 2004). Studies have also highlighted how pathogens may exist as covert or latent infections (Burden et al 2003), that multiple pathogen genotypes 34 can coexist within a single host (Hodgson et al 2003) and that multiple strain infections can affect the virulence, transmission and competitive interaction amongst pathogens (Raymond et 36 al.…”

Modelling contact spread of infection in host–parasitoid systems: Vertical transmission of pathogens can cause chaos

“…The study of host-pathogen interactions has received a good deal of recent attention Godfray, 1995, 1996;Grenfell and Dobson, 1995;Hudson et al, 2002;Bonsall, 2004;Elderd et al, 2008), but the theoretical investigation of disease dynamics in host-parasitoid systems has not kept pace with associated empirical research (Grenfell and Dobson, 1995;Gulland, 1995;Sait et al, 2000). It has been demonstrated that the inclusion of competitive disease dynamics into a model system can not only promote biodiversity of the system, but also can have sometimes unexpected effects on its dynamics (Holt and Roy, 2007).…”

“…Preedy et al (2006), for example, examined the consequences of introducing contact spread host infection into a simple model of a one-host-two-parasitoid system, and found that the presence of the infection not only promoted coexistence of the two parasitoid species, but also that it induced complex population dynamics in the system as a whole, including chaos, and when an explicitly spatial element was introduced into the model, complex spatiotemporal heterogeneity was observed. Clearly, however, infections may be transmitted not only through direct contact between susceptible and infected individuals, but also indirectly through a vector (Bonsall, 2004). In human systems, much has been done on the spread of malaria and yellow fever via mosquitoes (Aron and May, 1982;Anderson, 1982;Brauer and Castillo-Chavez, 2001), and host-parasitoid models have often been used as metaphors for the dynamics of such infections (see for example Barlow, 2000).…”