Density‐dependent prophylaxis: evidence from Lepidoptera–baculovirus interactions?

Wilson, Kenneth; Reeson, Andrew

doi:10.1046/j.1365-2311.1998.00107.x

Cited by 165 publications

(162 citation statements)

References 8 publications

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“…Similar patterns have been found with other phase polyphenic insects that exhibit highdensity forms (Barnes and Siva-Jothy, 2000;Cotter et al, 2004). These patterns are predicted by the density-dependent prophylaxis hypothesis, which states that crowding increases disease transmission risk, which induces increased investment in immune function (Wilson and Reeson, 1998). Importantly, this hypothesis predicts direct selection on immune function and not necessarily n.s.…”

Section: Discussionsupporting

confidence: 74%

Seasonality influences cuticle melanization and immune defense in a cricket: support for a temperature-dependent immune investment hypothesis in insects

Fedorka

Copeland

Winterhalter

2013

Journal of Experimental Biology

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SUMMARYTo improve thermoregulation in colder environments, insects are expected to darken their cuticles with melanin via the phenoloxidase cascade, a phenomenon predicted by the thermal melanin hypothesis. However, the phenoloxidase cascade also plays a significant role in insect immunity, leading to the additional hypothesis that the thermal environment indirectly shapes immune function via direct selection on cuticle color. Support for the latter hypothesis comes from the cricket Allonemobius socius, where cuticle darkness and immune-related phenoloxidase activity increase with latitude. However, thermal environments vary seasonally as well as geographically, suggesting that seasonal plasticity in immunity may also exist. Although seasonal fluctuations in vertebrate immune function are common (because of flux in breeding or resource abundance), seasonality in invertebrate immunity has not been widely explored. We addressed this possibility by rearing crickets in simulated summer and fall environments and assayed their cuticle color and immune function. Prior to estimating immunity, crickets were placed in a common environment to minimize metabolic rate differences. Individuals reared under fall-like conditions exhibited darker cuticles, greater phenoloxidase activity and greater resistance to the bacteria Serratia marcescens. These data support the hypothesis that changes in the thermal environment modify cuticle color, which indirectly shapes immune investment through pleiotropy. This hypothesis may represent a widespread mechanism governing immunity in numerous systems, considering that most insects operate in seasonally and geographically variable thermal environments.

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Section: Discussionsupporting

confidence: 74%

Seasonality influences cuticle melanization and immune defense in a cricket: support for a temperature-dependent immune investment hypothesis in insects

Fedorka

Copeland

Winterhalter

2013

Journal of Experimental Biology

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“…However, the immune system of larvae from high-density populations might be compromised under conditions of increased physical stress. We agree with Wilson and Reeson (1998) that an adaptive investment in immune function in response to population densities may be a widespread phenomenon in some taxa, especially those that exhibit density-dependent phase polyphenism. Our results were obtained in a laboratory settings, but larval prophylaxis to 178 H. Kong et al biocontrol agents with increasing population density will be further investigated by us using field populations.…”

Section: Discussionsupporting

confidence: 88%

Density-dependent prophylaxis in crowded Beet Webworm,Loxostege sticticalis(Lepidoptera: Pyralidae) larvae to a parasitoid and a fungal pathogen

Kong

Cheng

LiZhi

et al. 2013

International Journal of Pest Management

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“…This often occurs in crowded insect populations as a form of density-dependent prophylaxis when the risk of infection is high [6,[10][11][12]. To date, however, most melanism studies have been limited to investigations of the degree of melanization, as well as certain aspects of the insect immune response such as lysozyme, PO and haemocyte activity, and their tradeoff with fecundity, lifespan and size.…”

Section: Introductionmentioning

confidence: 99%

More than a colour change: insect melanism, disease resistance and fecundity

et al. 2013

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A 'dark morph' melanic strain of the greater wax moth, Galleria mellonella, was studied for its atypical, heightened resistance to infection with the entomopathogenic fungus, Beauveria bassiana. We show that these insects exhibit multiple intraspecific immunity and physiological traits that distinguish them from a non-melanic, fungus-susceptible morph. The melanic and non-melanic morphs were geographical variants that had evolved different, independent defence strategies. Melanic morphs exhibit a thickened cuticle, higher basal expression of immunity-and stress-management-related genes, higher numbers of circulating haemocytes, upregulated cuticle phenoloxidase (PO) activity concomitant with conidial invasion, and an enhanced capacity to encapsulate fungal particles. These insects prioritize specific augmentations to those frontline defences that are most likely to encounter invading pathogens or to sustain damage. Other immune responses that target late-stage infection, such as haemolymph lysozyme and PO activities, do not contribute to fungal tolerance. The net effect is increased larval survival times, retarded cuticular fungal penetration and a lower propensity to develop haemolymph infections when challenged naturally (topically) and by injection. In the absence of fungal infection, however, the heavy defence investments made by melanic insects result in a lower biomass, decreased longevity and lower fecundity in comparison with their non-melanic counterparts. Although melanism is clearly correlated with increased fungal resistance, the costly mechanisms enabling this protective trait constitute more than just a colour change.

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Density‐dependent prophylaxis: evidence from Lepidoptera–baculovirus interactions?

Cited by 165 publications

References 8 publications

Seasonality influences cuticle melanization and immune defense in a cricket: support for a temperature-dependent immune investment hypothesis in insects

Seasonality influences cuticle melanization and immune defense in a cricket: support for a temperature-dependent immune investment hypothesis in insects

Density-dependent prophylaxis in crowded Beet Webworm,Loxostege sticticalis(Lepidoptera: Pyralidae) larvae to a parasitoid and a fungal pathogen

More than a colour change: insect melanism, disease resistance and fecundity

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