Effect of low levels of Bacillus thuringiensis exposure on the growth, food consumption and digestion efficiencies of Trichoplusia ni resistant and susceptible to Bt

Janmaat, Alida F.; Bergmann, Luke; Ericsson, Jerry D.

doi:10.1016/j.jip.2014.04.001

Cited by 23 publications

(14 citation statements)

References 45 publications

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“…However, while unchallenged parents on diluted diet exhibited compensatory feeding by gaining similar weight (92% relative to good diet) over 48 h, those feeding on Bt‐ treated poor diet only gained 50% compared to those on Bt‐ treated good diet (see Table S5, Supporting information). This, coupled with the fact that the rate of ingestion of Bt‐ treated diet is a function of Bt concentration (Janmaat, Bergmann & Ericsson ), would suggest that the quantity of Bt spores ingested was similar between our two treatment diets. Transgenerational priming from Bt‐ challenge has been reported previously in the red flour beetle, Tribolium castaneum , but the priming was induced by pricking the parents with a needle dipped in heat‐killed bacteria (Roth et al .…”

Section: Discussionmentioning

confidence: 82%

Trade‐offs between transgenerational transfer of nutritional stress tolerance and immune priming

et al. 2015

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Summary1. Transgenerational effects are often assumed to have adaptive value as a driver of variation in offspring and parental fitness. Studies of transgenerational effects often focus on single environmental variables. However, in nature, it is unlikely for one factor to vary independently from others and there are likely to be trade-offs between different stressors. 2. We altered the nutritional environment of both parents and offspring to examine how nutritional stress influences transgenerational immune priming (TGIP) with a sublethal challenge by the bacterial pathogen Bacillus thuringiensis, in the cabbage looper, Trichoplusia ni. 3. Transgenerational immune priming was adaptive when offspring encountered the same pathogen experienced by their parents, such that offspring resistance to B. thuringiensis increased 1Á5-fold and antibacterial activity in the haemolymph increased by as much as 4-fold. However, this was not a general increase in pathogen resistance as susceptibility to a second pathogen, the baculovirus, TnSNPV remained the same. Interestingly, nutritional stress in the parents both enhanced nutritional stress tolerance of offspring and heightened resistance to both B. thuringiensis and TnSNPV. Elevated pathogen resistance was linked to increased egg size. 4. There was a significant trade-off between TGIP and the transfer of nutritional stress tolerance when parents encountered both stressors simultaneously, such that parents transferred resistance to pathogens but not nutritional stress tolerance. 5. These results highlight the trade-offs that can modulate the occurrence and magnitude of transgenerational effects and illustrate the importance of assessing interactions between multiple environmental variables. At high population densities, disease risk increases and resources become depleted. Thus, our findings could have significant implications for population dynamics.

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Section: Discussionmentioning

confidence: 82%

Trade‐offs between transgenerational transfer of nutritional stress tolerance and immune priming

et al. 2015

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“…Second, at high infection rates, resource allocation tradeoffs (as discussed above) divert resources from growth to survival, producing smaller female pupal weights. Although compensatory growth mechanisms in response to environmental challenges have been observed across many organisms (Janmaat et al, 2014; Dmitriew, 2011; Korves & Bergelson, 2004; Tammaru et al, 2004; Ali et al, 2003; Agrawal, 2000; Monteiro & Falconer, 1966), further research is required to test whether this is the correct mechanism. In general, however, these results agree with previous studies showing that female size is especially sensitive to environmental variation (Teder & Tammaru, 2005).…”

Section: Discussionmentioning

confidence: 99%

Effects of pathogen exposure on life‐history variation in the gypsy moth (Lymantria dispar)

Páez

Fleming-Davies

Dwyer

2015

J of Evolutionary Biology

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Investment in host defenses against pathogens may lead to tradeoffs with host fecundity. When such tradeoffs arise from genetic correlations, rates of phenotypic change by natural selection may be affected. However, genetic correlations between host survival and fecundity are rarely quantified. To understand tradeoffs between immune responses to baculovirus exposure and fecundity in the gypsy moth (Lymantria dispar), we estimated genetic correlations between survival probability and traits related to fecundity, such as pupal weight. In addition, we tested whether different virus isolates have different effects on male and female pupal weight. To estimate genetic correlations, we exposed individuals of known relatedness to a single baculovirus isolate. To then evaluate the effect of virus isolate on pupal weight, we exposed a single gypsy moth strain to 16 baculovirus isolates. We found a negative genetic correlation between survival and pupal weight. In addition, virus exposure caused late-pupating females to be identical in weight to males, whereas unexposed females were 2–3 times as large as unexposed males. Finally, we found that female pupal weight is a quadratic function of host mortality across virus isolates, which is likely due to tradeoffs and compensatory growth processes acting at high and low mortality levels, respectively. Overall, our results suggest that fecundity costs may strongly affect the response to selection for disease resistance. In nature, baculoviruses contribute to the regulation of gypsy moth outbreaks, as pathogens often do in forest-defoliating insects. We therefore argue that tradeoffs between host life-history traits may help explain outbreak dynamics.

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“…However, it is important to keep in mind that nutrient intake is a dynamic process that will be influenced by environmental stressors. For example, our Bt -resistant T. ni were recently shown to increase food consumption and weight gain when fed artificial diet treated with low doses of Bt compared to a control [65].…”

Section: Discussionmentioning

confidence: 99%

Dietary Mechanism behind the Costs Associated with Resistance to Bacillus thuringiensis in the Cabbage Looper, Trichoplusia ni

Shikano

Cory

2014

PLoS ONE

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Beneficial alleles that spread rapidly as an adaptation to a new environment are often associated with costs that reduce the fitness of the population in the original environment. Several species of insect pests have evolved resistance to Bacillus thuringiensis (Bt) toxins in the field, jeopardizing its future use. This has most commonly occurred through the alteration of insect midgut binding sites specific for Bt toxins. While fitness costs related to Bt resistance alleles have often been recorded, the mechanisms behind them have remained obscure. We asked whether evolved resistance to Bt alters dietary nutrient intake, and if reduced efficiency of converting ingested nutrients to body growth are associated with fitness costs and variation in susceptibility to Bt. We fed the cabbage looper Trichoplusia ni artificial diets differing in levels of dietary imbalance in two major macronutrients, protein and digestible carbohydrate. By comparing a Bt-resistant T. ni strain with a susceptible strain we found that the mechanism behind reduced pupal weights and growth rates associated with Bt-resistance in T. ni was reduced consumption rather than impaired conversion of ingested nutrients to growth. In fact, Bt-resistant T. ni showed more efficient conversion of nutrients than the susceptible strain under certain dietary conditions. Although increasing levels of dietary protein prior to Bt challenge had a positive effect on larval survival, the LC50 of the resistant strain decreased when fed high levels of excess protein, whereas the LC50 of the susceptible strain continued to rise. Our study demonstrates that examining the nutritional basis of fitness costs may help elucidate the mechanisms underpinning them.

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Effect of low levels of Bacillus thuringiensis exposure on the growth, food consumption and digestion efficiencies of Trichoplusia ni resistant and susceptible to Bt

Cited by 23 publications

References 45 publications

Trade‐offs between transgenerational transfer of nutritional stress tolerance and immune priming

Trade‐offs between transgenerational transfer of nutritional stress tolerance and immune priming

Effects of pathogen exposure on life‐history variation in the gypsy moth (Lymantria dispar)

Dietary Mechanism behind the Costs Associated with Resistance to Bacillus thuringiensis in the Cabbage Looper, Trichoplusia ni

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