Immune Responses and Their Potential Role in Insect Outbreaks

Abstract

Species References Density-dependent prophylaxis-hosts living at high densities suffer a greater risk of disease and therefore invest more in immunity. M − Larval mortality from NPV declined as density increased. Mythimna separata* Kunimi and Yamada 1990 M + Resistance to granulosis virus increased as density increased. Mythimna separata* Kunimi and Yamada 1990 M − Larvae were most susceptible to infection at high densities. Mamestra brassicae Goulson and Cory 1995 M + Larval transmission of viruses declined as density increased. Lymantria dispar* D'Amico et al. 1996 M + Larger egg masses had higher resistance to NPV. Malacosoma californicum p.* Rothman and Myers 1996 HM, M, PO + Higher densities were more resistant to fungus. Tenebrio moliator Barnes and Siva-Jothy 2000 EN, PO + Immunity measures increased with increasing gregariousness. Spodoptera exempta* Wilson et al. 2001 AB, EN, HM, PO + Increased pathogen resistance under crowded conditions.

Covert Infection of Insects by Baculoviruses

“…Studies on host immune response to viruses often use hemocyte counts and phenyloxidase activity in the hemolymph as indicators of immune function ( Klemola et al, 2007 ; Shikano et al, 2010 ; Silva et al, 2013 ). In some cases not all aspects of the immune functions respond equally to immune stimuli, so that trade-offs may be observed between different aspects of immune function depending on the nature of each potential threat ( Shlichta and Smilanich, 2012 ; Wilson and Cotter, 2013 ).…”

Temperature and host plant species affect the performance and immunocompetence of an outbreak defoliator in northwestern Patagonia

“…For example, the response of the immune system to natural enemies, such as parasitoids, depends on several factors, among which atmospheric temperature can have a significant effect (Thomas & Blanford, 2003). In turn, host plant quality appears to be critical (Myers & Cory, 2013; Shlichta & Smilanich, 2012), but the link between increased temperature and host plant quality on herbivore's immune response in the context of insect outbreaks has remained largely untested. In contrast to the immune response, research efforts have found a clear link between changes in performance and insect outbreaks in the face of environmental temperature increase and host plant diet (Posledovich et al, 2015).…”

“…On the one hand, metabolising a large diversity and/or amounts of plant chemical defences can be energetically expensive for both generalist and specialist herbivores, diverting resources otherwise invested in immune responses (Carper et al, 2019;Smilanich et al, 2009). On the other hand, some secondary compounds may aid the insect immune system (Kapari et al, 2006;Laurentz et al, 2012;Ojala et al, 2005;Shlichta & Smilanich, 2012;Smilanich et al, 2009Smilanich et al, , 2011, as they can act as free radical neutralisers, decreasing the cost of encapsulation (e.g., plant-derived antioxidants) (Ojala et al, 2005).…”

“…In contrast to the immune response, research efforts have found a clear link between changes in performance and insect outbreaks in the face of environmental temperature increase and host plant diet (Posledovich et al, 2015). However, the relationship between immune response and insect herbivore performance is variable (Diamond & Kingsolver, 2011; Ojala et al, 2005; Shlichta & Smilanich, 2012) as temperature and host plant quality may impact both performance and immune response in similar or opposite directions.…”

Toxin or medication? Immunotherapeutic effects of nicotine on a specialist caterpillar

“…For example, D. melanogaster fed diet supplemented with l ‐Arginine displayed increased resistance to parasitoids (Kraaijeveld et al., 2011). Although there is no global analysis for determining nutritional quality, it has been suggested that plant nutritional content can be gauged broadly by quantifying percent nitrogen and secondary metabolite profile (Shlichta & Smilanich, 2012).…”