Is decreased generalized immunity a cost of Bt resistance in cabbage loopers Trichoplusia ni?

Ericsson, Jerry D.; Janmaat, Alida F.; Lowenberger, Carl; Myers, Judith H.

doi:10.1016/j.jip.2008.10.007

Cited by 47 publications

(39 citation statements)

References 45 publications

(54 reference statements)

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“…In our dataset, two prophenoloxydases (PPO, involved in melanization) and four genes coding for anti-microbial peptides were significantly under-transcribed in the LiTOX strain (table 2), and none were over-transcribed. In line with this, the basal immunity of a Bt-resistant cabbage looper line was shown to be lower than its susceptible counterpart [14], and we also observed a lower basal immunity in strains selected with Bti-toxins as compared with the susceptible strain (data not shown). This suggests that the depressed immunity observed in Bt-resistant insects is explained by the high cost of expression of immune genes.…”

Section: Resultssupporting

confidence: 81%

Chemical and biological insecticides select distinct gene expression patterns in Aedes aegypti mosquito

et al. 2014

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Worldwide evolution of mosquito resistance to chemical insecticides represents a major challenge for public health, and the future of vector control largely relies on the development of biological insecticides that can be used in combination with chemicals (integrated management), with the expectation that populations already resistant to chemicals will not become readily resistant to biological insecticides. However, little is known about the metabolic pathways affected by selection with chemical or biological insecticides. Here we show that Aedes aegypti, a laboratory mosquito strain selected with a biological insecticide (Bacillus thuringiensis israelensis, Bti) evolved increased transcription of many genes coding for endopeptidases while most genes coding for detoxification enzymes were under-expressed. By contrast, in strains selected with chemicals, genes encoding detoxification enzymes were mostly over-expressed. In all the resistant strains, genes involved in immune response were under-transcribed, suggesting that basal immunity might be a general adjustment variable to compensate metabolic costs caused by insecticide selection. Bioassays generally showed no evidence for an increased susceptibility of selected strains towards the other insecticide type, and all chemical-resistant strains were as susceptible to Bti as the unselected parent strain, which is a good premise for sustainable integrated management of mosquito populations resistant to chemicals.

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Section: Resultssupporting

confidence: 81%

Chemical and biological insecticides select distinct gene expression patterns in Aedes aegypti mosquito

et al. 2014

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“…Although the molecular bases of the Bt toxin-mediated induction are not known, possible causes may involve signaling functions of Bt toxin (23) or toxin-mediated damage to gut lining, and contact of gut-derived elicitors with hemolymph, including enterobacteria (3), which enhance the induction and toxicity but are not obligatory to toxicity (13). Whatever the mechanism, gut-derived toxin has multiple effects in hemolymph, such as the reduction of hemolymph proteins and an increase in PPO and the number of circulating hemocytes (6), as well as a reduction in hemocyte phagocytosis (5) and an increase in PO-inhibiting proteins (7). These data suggest that induction of the immune defense by gut-derived elicitors generates a wide range of metabolic responses that includes defense reactions against an intruding toxin or pathogen and also downregulation of the insect's own defense responses, such as coagulation and melanization, that are potentially damaging if allowed to spread within the hemocoel.…”

Section: Discussionmentioning

confidence: 99%

Developmental Penalties Associated with Inducible Tolerance in Helicoverpa armigera to Insecticidal Toxins from Bacillus thuringiensis

Rahman

Glatz

Roush

et al. 2011

Appl Environ Microbiol

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Exposure of insect larvae to sublethal concentrations of crystal toxins from the soil bacterium Bacillus thuringiensis (Bt toxins) causes the induction of immune and metabolic responses that can be transmitted to offspring by epigenetic inheritance mechanisms. Given that the elevated immune status carries significant developmental penalties, we wanted to establish the relationships between immune induction, tolerance to the toxin and developmental penalties. A laboratory culture of Helicoverpa armigera was induced by a sublethal bacterial suspension containing crystal toxin Cry1Ac in one generation and maintained in the presence of toxin, acquiring significant levels of tolerance to the toxin within 12 generations of continuous exposure. Comparing tolerant and susceptible insects, we show that the induction of larval immune response and the coincident alteration of development-related metabolic activities by elicitors in the larval gut (larval induction) differs from the elevated immune status transmitted by epigenetic mechanisms (embryonic induction). Because the damaging effects of larval induction processes are higher compared to embryonic induction, it is likely that overall developmental penalties depend on the relative contribution of the two induction processes. When insects are kept with the same amount of toxin in the diet for subsequent generations, the embryonic induction process increases its contribution compared to the larval induction, resulting in reduced overall developmental penalty, while tolerance to the toxin is maintained.

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“…Inoculation thus rendered the internal larval environment conducive to massive multiplication of enteric bacteria. B. thuringiensis is known to alter the host's innate immune response by affecting both humoral and cellular factors (Dubovskiy et al, 2008a,b;Ericsson et al, 2009), possibly giving rise to a concomitant increase in enteric bacterial populations in certain hosts. The pattern of increase relative to progression of larval mortality, including a possible leveling off after completion of mortality (96 h p.i.…”

Section: Discussionmentioning

confidence: 99%

Interactions between Bacillus thuringiensis subsp. kurstaki HD-1 and midgut bacteria in larvae of gypsy moth and spruce budworm

Frankenhuyzen

Liu

Tonon

2010

Journal of Invertebrate Pathology

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Is decreased generalized immunity a cost of Bt resistance in cabbage loopers Trichoplusia ni?

Cited by 47 publications

References 45 publications

Chemical and biological insecticides select distinct gene expression patterns in Aedes aegypti mosquito

Chemical and biological insecticides select distinct gene expression patterns in Aedes aegypti mosquito

Developmental Penalties Associated with Inducible Tolerance in Helicoverpa armigera to Insecticidal Toxins from Bacillus thuringiensis

Interactions between Bacillus thuringiensis subsp. kurstaki HD-1 and midgut bacteria in larvae of gypsy moth and spruce budworm

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