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Philippe Vernon - One of the best experts on this subject based on the ideXlab platform.

  • changes in free amino acids in Alphitobius diaperinus coleoptera tenebrionidae during thermal and food stress
    Comparative Biochemistry and Physiology A-molecular & Integrative Physiology, 2006
    Co-Authors: David Renault, Alain Bouchereau, Yannick R Delettre, Frederic Hervant, Philippe Vernon
    Abstract:

    Temporal changes in free amino acid pools are examined in starved and cold-exposed (10 °C) beetles (Alphitobius diaperinus) (control beetles; 4, 7, 14, 28 and 56 days of cold-exposure). The range of individual responses and the effect of gender on survival and free amino acid levels are evaluated. Females survived significantly longer (Lt50 and Lt90) than males under stressing conditions. Pro, Gln, Ala, Arg and Thr are the major components of the free amino acid pool in the whole body of adult beetles. Multivariate analysis indicates that the duration of exposure explains most of the observed variation in amino acid levels, while sex effect is not significant. Moreover, amino acid levels fluctuate strongly within each sampled date, revealing a high inter-individual heterogeneity. However, this heterogeneity decreases after four weeks of cold-exposure and starvation. The increase in Ala level and the concomitant decrease of Pro after four weeks suggest that Pro might be an important fuel for metabolism when fat reserves are reduced. We conclude that changes in free amino acid pools are due to a combination of reduced individual heterogeneity, cold-acclimation and amino acid degradation for energetic purposes.

  • the importance of fluctuating thermal regimes for repairing chill injuries in the tropical beetle Alphitobius diaperinus coleoptera tenebrionidae during exposure to low temperature
    Physiological Entomology, 2004
    Co-Authors: David Renault, Frederic Hervant, O Nedved, Philippe Vernon
    Abstract:

    .  In this study, the impact of acclimation (1 month at 15 °C vs. breeding at 30 °C) and fluctuating thermal regimes (daily transfers from low temperatures to various higher temperatures for 2 h) on the cold tolerance of the tropical beetle, Alphitobius diaperinus Panzer (Coleoptera: Tenebrionidae) was examined. Acclimation increased significantly the duration of survival (Lt50) at a constant 5 °C (7.7 ± 0.3 days to 9.7 ± 0.5 days). Survival of acclimated and nonacclimated beetles increased slightly at alternating temperatures of 5 °C/10 °C or 5 °C/15 °C. When daily transfer to 20 °C was applied, survival (Lt50) was improved markedly (nonacclimated: 15.5 ± 0.7 days, acclimated: 19.6 ± 0.6 days). The higher temperatures may allow progressive repair of injuries, and the effects of chilling may be repaired completely at 25 and 30 °C, a phenomenon recorded here for the first time. It is estimated that the theoretical upper threshold of chill injury (Th) of nonacclimated beetles is 15.1 °C whereas it is shifted down to 11.2 °C in acclimated beetles, which might enable this temperature to allow effective repair of injury.

  • is body size an influential parameter in determining the duration of survival at low temperatures in Alphitobius diaperinus panzer coleoptera tenebrionidae
    Journal of Zoology, 2003
    Co-Authors: David Renault, G Vannier, Thierry Hance, Philippe Vernon
    Abstract:

    Physiological and morphological parameters that affect survival were measured at the individual level in adults of the lesser mealworm Alphitobius diaperinus kept at 6degreesC and 10'C. Survival differed significantly among individuals and sexes and at different temperatures. At 6degreesC, pervasive effects of cold, i.e. chill injuries, were too strong to allow survival, whereas the duration of survival was significantly influenced by the adult body size at 10degreesC; initial fresh mass was positively correlated with survival in both sexes. The management of energy reserves was also significantly different among individuals. Weight loss was significantly slower in both males and females that had the longest longevity and kept at 10degreesC when compared to males and females that had shortest longevity (3.05+/-0.47 mug/mg fresh weight/day and 2.71+/-0.60 mug/mg fresh weight/day, respectively, vs 5.68+/-3.77 and 9.01+/-9.39 mug/mg fresh weight/day). The largest insects lost weight at a constant but slower rate than the smallest ones. Prolonged exposures at 10degreesC enforced inactivity and led to depletion of the energy reserves in both males and females through low food availability. The water ratio was significantly decreased over time: both males and females that had the longest longevity had significantly lower water ratio than males and females that had the shortest longevity.

  • controlling the mealworm Alphitobius diaperinus coleoptera tenebrionidae in broiler and turkey houses field trials with a combined insecticide treatment insect growth regulator and pyrethroid
    Journal of Economic Entomology, 2003
    Co-Authors: C Salin, Yannick R Delettre, Philippe Vernon
    Abstract:

    Trials were conducted during one year under field conditions to control the lesser mealworm, Alphitobius diaperinus (Panzer), in broiler and turkey houses. The tested combined treatment included an adulticidal compound (pyrethroid: cyfluthrin) and a larvicidal compound (insect growth regulator [IGR]: triflumuron). The combined insecticide treatment greatly reduced the adult and larval stocks throughout the different broiler growing periods, and control of A. diaperinus populations was achieved by the end of the second treatment. Control of the insect population in a turkey house was not similar. A reestablishment of the insect population was observed during the second turkey growing period in summer. Building characteristics and management practices of the breeding system (duration of the breeding period, management of the litter) interact with the the combined insecticide treatment and lead to a different efficiency.

  • a sexually dimorphic response in supercooling temperature enhanced by starvation in the lesser mealworm Alphitobius diaperinus coleoptera tenebrionidae
    Journal of Thermal Biology, 2000
    Co-Authors: C Salin, David Renault, G Vannier, Philippe Vernon
    Abstract:

    The effect of starvation on supercooling temperature (SCP) distribution was investigated in adults and larvae of Alphitobius diaperinus (Coleoptera: Tenebrionidae). The mean values for SCPs of adults fed at 20°C were −14.5±2.4°C (31 males) and −10.3±1.3°C (29 females). The distribution of the SCPs of these control adults was unimodal. No significant differences were observed in either mean wet weight or mean dry weight between males and females. The mean values for SCPs of adults starved for 1 month at 20°C were found to be bimodal due to sexual dimorphism. The mean SCPs for males was lower (−17±2.6°C; 28) than that for females (−11.2±1.8°C; 26). No significant differences were observed in either mean dry weight or wet weight between males and females. The SCPs of both fed and starved larvae, kept for 1 month at 20°C were −12.3±2.4°C (fed) and −18.0±2.6°C (starved).

Pedro Manuel Oliveira Janeiro Neves - One of the best experts on this subject based on the ideXlab platform.

  • Susceptibly of Alphitobius diaperinus to Beauveria bassiana extracts
    2018
    Co-Authors: Juliana Feijó De Souza Daniel, Adriano Vinícius Scalco, Roberto Molina De Souza, Fernanda Maria Marins Ocampos, Andersson Barison, Luis Francisco Angeli Alves, Pedro Manuel Oliveira Janeiro Neves
    Abstract:

    Alphitobius diaperinus is an important pathogen with worldwide distribution that causes severe economic loss of efficiency in broilers. This study evaluates the potential of organic extracts of two strains entomopathogenic fungus Beauveria bassiana (CG71 and UNI40) as a biocontrol agent on A. diaperinus and promotes the phytochemical investigation. The effective percentages of mortalities were 95.97% (UNI40 methanolic extract), 69.23, 64.64, and 50.39% (CG 71 methanolic, ethyl acetate and butanol extracts). However, there was a decrease in the lesser mealworms susceptibility in relation to the use of insecticides and extracts. The metabolites 5-hydroxymethyl-2-furanoic acid, dipicolinic acid and monomethyl dipicolinate were isolated from ethyl acetate extract, and β-adenosine of butanolic extract of B. bassiana CG 71. In addition, the cyclodepsipeptides were identified in methanolic extracts of the two strains. The insecticide activity results indicated that the B. bassiana extracts are an alternative to A. diaperinus control.

  • growth regulator insecticides for the control of the lesser mealworm beetle Alphitobius diaperinus coleoptera tenebrionidae
    Revista Colombiana De Entomologia, 2015
    Co-Authors: Janaina Zorzetti, Kelly Christiane Constanski, Patricia Helena Santoro, Ines Cristina De Batista Fonseca, Pedro Manuel Oliveira Janeiro Neves
    Abstract:

    The purpose of this study was to evaluate the efficiency of the insecticides methoxyphenozide, teflubenzuron, pyriproxyfen, chlorantraniliprole and also Azadirachta indica in the control of Alphitobius diaperinus (Coleoptera: Tenebrionidae). The study was carried out in the Microbial Control laboratory of Universidade Estadual Londrina (Brazil) and consisted of two bioassays. In the first, A. diaperinus larvae were fed with corn feed treated with the insecticides in seven dosages. In the second bioassay, the different treatments were sprayed on the larvae only at the three highest dosages. Evaluations were performed daily, quantifying larval mortality, and on the 30th day, the number of pupae and adults were evaluated. Teflubenzuron, chlorantraniliprole and A. indica were responsible for the greatest percentage of mortalities in larvae fed with treated feed. The treatments with methoxyphenozide and pyriproxyfen caused the lowest mortalities; however, with pyriproxyfen the larvae were not transformed into pupae and adults up to the 30th day of assessment. The treatment with teflubenzuron showed the greatest toxicity, with the lowest survival time (ST50) When the products were applied directly on to the larvae, the most efficient treatments were teflubenzuron, chlorantraniliprole and A. indica; however, there was a reduction in the mortality percentages with teflubenzuron and chlorantraniliprole in relation to the feed bioassay. For A. indica, the application method did not affect the mortality levels. Pyriproxyfen, which had not led to mortality through feed ingestion, obtained an increase of up to 30% after being applied directly on to the larvae.

  • associacao de pos inertes com fungo entomopatogenico para o controle do cascudinho Alphitobius diaperinus
    Ciencia Rural, 2010
    Co-Authors: Patricia Helena Santoro, Pedro Manuel Oliveira Janeiro Neves, Junio Tavares Amaro, Kelly Christiane Constanski, Ernesto Antonio Lema Lopez, Luis Alves
    Abstract:

    The objective of this study was to evaluate the efficacy of Beauveria bassiana (Bb) of diatomaceous earth (TD) and the dust of rock Protesyl and Rocksil, alone or in combinations, for Alphitobius diaperinus to control. The control agents were applied in dried by mixing with the poultry liter. The concentration of Bb conidia was 0.08% on the weight of the substrate, and for the dust inert were 0.5, 1.0 and 1.5%. Twenty treatments with five repetitions of 200 insects were tested for 10 days. The treatments with highest efficiency were TD 1.5% and Bb 0.08% + TD 1.5%, with 60.2 and 57.8%, respectively. Protesyl and Rocksil in the three concentrations and TD 0.5% did not differ from control. For the interaction between control agents no advantage was observed for the association. Additive effect occurred for Bb + TD and Bb + Rocksil at the three concentrations and for Bb + Protesyl at 1.5%. The action of the fungus was reduced in association with Protesyl with antagonistic non-additive effect in 0.5 and 1.0%. Diatomaceous earth, isolated our in association with B. bassiana its a good alternative for A. diaperinus control. Just rock dust Protesyl and Rochsil were not efficient for insect control.

  • factors affecting diatomaceous earth effectiveness in the control of Alphitobius diaperinus panzer coleoptera tenebrionidae adults
    Neotropical Entomology, 2008
    Co-Authors: Luis Alves, Daian Guilherme Pinto De Oliveira, Pedro Manuel Oliveira Janeiro Neves
    Abstract:

    Diatomaceous earth (DE) is a potential alternative to control the lesser mealworm of poultry farms Alphitobius diaperinus (Panzer). Our study aimed to understand the role of some of the environmental and insect behavioral factors play on DE effectiveness, such as the substrate (chicken food and poultry house litter), temperature and DE repellent activity on lesser mealworm adults. Mortality was higher at the highest temperature (32oC), and it increased with DE concentration (53 and 84% respectively, for concentrations of 86 and 172 g/m2) (P < 0.05). The substrate also influenced DE effectiveness: 95% mortality was observed in the feed, against 4% in the poultry litter. Part of these results can be attributed to the removal of DE particles by the poultry bedding, as supported by scanning electron microscopy (SEM) observations and rhodamine concentration on the surface of the insects. As to insect behavior, DE had a repellent effect, since trap capture decreased nearly 50% in traps containing DE as opposed to those containing only food. Therefore, environmental factors do affect the DE effectiveness, and they must be taken into consideration when looking into developing control strategies in the field.

  • selection of beauveria bassiana isolates to control Alphitobius diaperinus
    Journal of Invertebrate Pathology, 2008
    Co-Authors: Patricia Helena Santoro, Pedro Manuel Oliveira Janeiro Neves, Talita Moretto Alexandre, Daniele Sartori, Luis Alves, Maria Helena Pelegrinelli Fungaro
    Abstract:

    Abstract This paper presents results on isolates of the entomopathogenic fungus Beauveria bassiana for Alphitobius diaperinus (Coleoptera: Tenebrionidae) control. Of the 30 isolates tested, four (CG 71, CG 152, UNIOESTE 4, and UNIOESTE 40) resulted in mortality rates ⩾40% within 10 days. These mortality rates could be considered high because of the resistance of these species to B. bassiana . Tests were conducted using these isolates to estimate LC 50 , mortality rate over time, vegetative growth, and conidial production on artificial medium and on insects. Isolates CG 71, CG 152, and UNIOESTE 4 showed the best performance and great potential to be used in an integrated management program in poultry farms to control A. diaperinus. Also, the molecular profiles of 12 isolates were analyzed using the RAPD technique. The high-virulence isolates presented a more homogeneous RAPD pattern than the others. Genetic sequencing of the ITS region was performed for one of the virulent isolates (UNIOESTE 4) and compared with sequences deposited at the NCBI database, confirming its taxonomical position as belonging to B. bassiana Clade A.

Tawni L Crippen - One of the best experts on this subject based on the ideXlab platform.

  • susceptibility of Alphitobius diaperinus in texas to permethrin and β cyfluthrin treated surfaces
    Pest Management Science, 2017
    Co-Authors: Brandon N Lyons, Tawni L Crippen, Le Zheng, Pete D Teel, Sonja L Swiger, Jeffery K Tomberlin
    Abstract:

    BACKGROUND Effective control of the lesser mealworm beetle, Alphitobius diaperinus, relies heavily on insecticides. The susceptibility level of beetles to these insecticides can be dependent on active ingredient, population treated, formulation, surface treated and timing of observation. The susceptibility of adult beetles from six populations to β-cyfluthrin was determined up to 48 h after exposure. The susceptibility of adult beetles to the label rate of β-cyfluthrin and permethrin formulations on concrete, wood-chip-type particle board and pressure-treated wood was determined up to 48 h post-exposure. RESULTS Variation in LC50 values at 2 and 24 h was found within and between beetle populations from two regions of Texas. The permethrin formulation had lower mean mortality than the β-cyfluthrin formulation on all surfaces tested. The permethrin formulation had high levels of recovery on all surfaces tested after 2 h. Surface affected the efficacy of the insecticides tested on killing adult beetles. CONCLUSION Permethrin-based insecticide had lower knockdown and persistence on various surfaces over time than β-cyfluthrin-based insecticide. Beetle recovery in less susceptible populations may necessitate longer observation periods for efficacy evaluations. Our study also shows that surfaces chosen can affect the efficacy of the compound on killing adult beetles. © 2016 Society of Chemical Industry

  • transient gut retention and persistence of salmonella through metamorphosis in the lesser mealworm Alphitobius diaperinus coleoptera tenebrionidae
    Journal of Applied Microbiology, 2012
    Co-Authors: Tawni L Crippen, Longyu Zheng, Cynthia L Sheffield, Jeffrey K Tomberlin, Ross C Beier, Ziniu Yu
    Abstract:

    Aims:  This study was undertaken to determine the retention of Salmonella through Alphitobius diaperinus metamorphosis and its contribution, through defecation, to external contamination. Methods and Results:  Insects were exposed to a tagged Salmonella enterica and evaluated for external elimination. (i) Each day for 3 weeks, a filter collected frass from a restrained insect for analysis. (ii) Exposed larvae in a closed container were followed through pupation, and newly emerged adults were examined for their retention of marker bacteria. Conclusions:  Exposed adults and larvae produced Salmonella-positive frass for an average of 8 days, ranging from 6 to 11 days and 6 to 12 days, respectively. Nineteen per cent of the larvae carried Salmonella through metamorphosis and eclosion, with 5% of the pupal exuviae being positive as well. Significance and Impact of the Study:  Many sources of foodborne pathogens within the poultry production facilities, including reservoir populations, currently go unrecognized. This diminishes the ability of producers to mitigate the transfer of pathogens between animals, humans and the environment. Poultry management standards accept the reutilization of litter. Alphitobius diaperinus survive between flock rotations on the reutilized litter, and it was demonstrated in this study that the Salmonella they carry can survive with them.

  • evaluation of salmonella movement through the gut of the lesser mealworm Alphitobius diaperinus coleoptera tenebrionidae
    Vector-borne and Zoonotic Diseases, 2012
    Co-Authors: Longyu Zheng, Tawni L Crippen, Cynthia L Sheffield, T L Poole, Jeffrey K Tomberlin
    Abstract:

    Abstract Aims: The lesser mealworm, Alphitobius diaperinus is an important poultry pest prevalent during production that is capable of vectoring pathogens. This study was undertaken to determine th...

  • evaluation of salmonella movement through the gut of the lesser mealworm Alphitobius diaperinus coleoptera tenebrionidae
    Vector-borne and Zoonotic Diseases, 2012
    Co-Authors: Longyu Zheng, Tawni L Crippen, Cynthia L Sheffield, T L Poole, Ziniu Yu, Jeffrey K Tomberlin
    Abstract:

    Abstract Aims: The lesser mealworm, Alphitobius diaperinus is an important poultry pest prevalent during production that is capable of vectoring pathogens. This study was undertaken to determine the gut transit time of Salmonella for biosecurity risk analysis of pathogen dispersal into the environment. Methods: Adult and larval A. diaperinus were exposed to two concentrations of a fluorescently labeled Salmonella enterica for 15, 30, and 60 min time periods then externally disinfected to evaluate internal transfer of Salmonella. The insects were monitored every 30 min over 4 h and evacuated frass (feces) processed for the marker Salmonella. The minimum time monitored was 45 min (15 exposure+30 min time point), and the maximum was 5 h (60 exposure+4 h time point). Results: Adults treated with 106 or 108 colony-forming units (cfu)/mL, which produced Salmonella positive frass within the 5 h experimental time, displayed a mean gut transit time of 144.4 min (range 90–270 min) and 186.3 min (range 120–300 min),...

  • improved visualization of Alphitobius diaperinus panzer coleoptera tenebrionidae part i morphological features for sex determination of multiple stadia
    Psyche: A Journal of Entomology, 2012
    Co-Authors: Jesus F Esquivel, Tawni L Crippen, L A Ward
    Abstract:

    The lesser mealworm, Alphitobius diaperinus (Panzer), is a perennial pest of poultry facilities and known to transmit pathogens of poultry and humans. Ongoing research examining reservoir potential of A. diaperinus revealed the need for a comprehensive, user-friendly guide for determining sex of A. diaperinus at different stadia. This paper is unique in providing a comprehensive illustrated guide of characters used for differentiation of sexes in A. diaperinus.

M J Hassemer - One of the best experts on this subject based on the ideXlab platform.

  • revisiting the male produced aggregation pheromone of the lesser mealworm Alphitobius diaperinus coleoptera tenebrionidae identification of a six component pheromone from a brazilian population
    Journal of Agricultural and Food Chemistry, 2016
    Co-Authors: M J Hassemer, Josue Santana, Miguel Borges, David M Withall, J A Pickett, Marcio Wandre Morais De Oliveira, R A Laumann, Michael A Birkett, Maria Carolina Blassiolimoraes
    Abstract:

    The lesser mealworm, Alphitobius diaperinus Panzer 1797 (Coleoptera: Tenebrionidae), is a cosmopolitan insect pest affecting poultry production. Due to its cryptic behavior, insecticide control is usually not efficient. Thus, sustainable and effective methods would have an enormous and positive impact in poultry production. The aim of this study was to confirm the identity of the male-produced aggregation pheromone for a Brazilian population of A. diaperinus and to evaluate its biological activity in behavioral assays. Six male-specific compounds were identified: (R)-limonene (1), (E)-ocimene (2), 2-nonanone (3), (S)-linalool (4), (R)-daucene (5), all described before in an American population, and a sixth component, (E,E)-α-farnesene (6), which is apparently exclusive to a Brazilian population. Y-Tube bioassays confirmed the presence of a male-produced aggregation pheromone and showed that all components need to be present in a similar ratio and concentration as emitted by male A. diaperinus to produce a...

  • revisiting the male produced aggregation pheromone of the lesser mealworm Alphitobius diaperinus coleoptera tenebrionidae identification of a six component pheromone from a brazilian population
    Journal of Agricultural and Food Chemistry, 2016
    Co-Authors: M J Hassemer, Josue Santana, Miguel Borges, David M Withall, J A Pickett, Marcio Wandre Morais De Oliveira, R A Laumann, Michael A Birkett
    Abstract:

    The lesser mealworm, Alphitobius diaperinus Panzer 1797 (Coleoptera: Tenebrionidae), is a cosmopolitan insect pest affecting poultry production. Due to its cryptic behavior, insecticide control is usually not efficient. Thus, sustainable and effective methods would have an enormous and positive impact in poultry production. The aim of this study was to confirm the identity of the male-produced aggregation pheromone for a Brazilian population of A. diaperinus and to evaluate its biological activity in behavioral assays. Six male-specific compounds were identified: (R)-limonene (1), (E)-ocimene (2), 2-nonanone (3), (S)-linalool (4), (R)-daucene (5), all described before in an American population, and a sixth component, (E,E)-α-farnesene (6), which is apparently exclusive to a Brazilian population. Y-Tube bioassays confirmed the presence of a male-produced aggregation pheromone and showed that all components need to be present in a similar ratio and concentration as emitted by male A. diaperinus to produce a positive chemotactic response.

  • chemical composition of Alphitobius diaperinus coleoptera tenebrionidae abdominal glands and the influence of 1 4 benzoquinones on its behavior
    Journal of Economic Entomology, 2015
    Co-Authors: M J Hassemer, Miguel Borges, R A Laumann, J Santana, M W M De Oliveira, M Caumo, Maria Carolina Blassiolimoraes
    Abstract:

    This study aimed to identify and quantify the compounds present in the abdominal glands of Alphitobius diaperinus Panzer, 1797 (Coleoptera: Tenebrionidae) and to evaluate the influence of these compounds on its behavior. The extraction of volatiles present in the abdominal glands was made by dissection (10 individuals per sex) and by air entrainment (200 insects per sex), and they were analyzed by gas chromatography-flame ionization detector, gas chromatograph-mass spectrometer, and gas chromatograph-electroantennography detector (GC-EAD). The influence of these volatiles on the behavior of conspecifics was evaluated in a four-arm olfactometer. Twenty-three compounds were identified from male and female abdominal gland extracts, of which six were quinones: the 2-methyl-1,4-benzoquinone and the 2-ethyl-1,4-benzoquinone were the major components, and 1,4 benzoquinone and three hydroquinones were registered for the first time for this species. The GC-EAD analysis using the crude extracts from abdominal glands showed that male and female antennae responded to the three major benzoquinones. For the olfactometer bioassays, both genders were repelled either by the abdominal gland extracts or by synthetic solutions containing the three benzoquinones. The results suggest that the 1,4-benzoquinones play a role as a repellent to A. diaperinus.

David Renault - One of the best experts on this subject based on the ideXlab platform.

  • differences in the susceptibility to commercial insecticides among populations of the lesser mealworm Alphitobius diaperinus collected from poultry houses in france
    Insects, 2021
    Co-Authors: David Renault, Hervé Colinet
    Abstract:

    The control of insect pests often relies on the recurrent application of insecticides. This is the case for the lesser mealworm, Alphitobius diaperinus, an invasive beetle infesting poultry farms. There is evidence that A. diaperinus can develop resistance to several insecticides. Evaluation of such resistance has never been conducted in France, despite the beetle’s presence since the 1970s. We assess insecticide susceptibility in 10 populations from French poultry farms and compare patterns with two susceptible populations. Adults are subjected to short-term exposures (4 h) to four commercial insecticides and their recovery is assessed. Temporal survival also is scored during constant exposures for seven days. Clear-cut differences among the farm populations are found. Except for three populations that have patterns similar to those of the two susceptible populations, all the other farm populations have a much greater capacity to recover and survive insecticide exposures, especially to pyrethroid-based formulations. Three populations in particular even exhibit clear signs of resistance to pyrethroids, with median lethal times more than 10-fold superior to values of the susceptible population. No insect in any population recovers from the pirimiphos-methyl exposure, and all beetles are apparently dead after 15 h. Our results demonstrate the existence of resistant populations to pyrethroids in Brittany France.

  • A model for the time-temperature-mortality relationship in the chill-susceptible beetle, Alphitobius diaperinus, exposed to fluctuating thermal regimes
    Journal of Thermal Biology, 2011
    Co-Authors: Hervé Colinet, Lisa Lalouette, David Renault
    Abstract:

    Exposing insects to a fluctuating thermal regime (FTR) compared with constant low temperature (CLT) significantly reduces cold-induced mortality. The beneficial effects of FTR result from physiological repair during warming intervals. The duration and the temperature experienced during the recovery period are supposed to strongly impact the resulting cold survival; however, disentangling the effects of both recovery variables had not been broadly investigated. In this study, we investigate cold tolerance (lethal time, Lt50) of the polyphagous beetle Alphitobius diaperinus. We examined adult survival under various CLTs (0, 5, 10 and 15 1C), and under 20 different FTR conditions, where the 0 1C exposure alternated with various recovery temperatures (Rt) (5, 10, 15 and 20 1C) combined with various recovery durations (Rds) (0.5, 1, 2, 3 and 4 h). Under CLTs, Lt50 increased with temperature until no mortality occurred above the upper limit of cold injury zone (ULCIZ). Under FTRs, Lt50 increased with both Rt and Rd. The magnitude of the survival gain was clearly boosted when Rt was above the ULCIZ (at 20 1C). Based on a data matrix of lethal times with multiple Rt Rd combinations, a predictive model showed that cold survival increased exponentially with Rt and Rd. This model was subsequently validated with additional survival tests. We suggest that increasing recovery durations associated with optimal recovery temperatures eventually leads to a progressive chilling compensation.

  • changes in free amino acids in Alphitobius diaperinus coleoptera tenebrionidae during thermal and food stress
    Comparative Biochemistry and Physiology A-molecular & Integrative Physiology, 2006
    Co-Authors: David Renault, Alain Bouchereau, Yannick R Delettre, Frederic Hervant, Philippe Vernon
    Abstract:

    Temporal changes in free amino acid pools are examined in starved and cold-exposed (10 °C) beetles (Alphitobius diaperinus) (control beetles; 4, 7, 14, 28 and 56 days of cold-exposure). The range of individual responses and the effect of gender on survival and free amino acid levels are evaluated. Females survived significantly longer (Lt50 and Lt90) than males under stressing conditions. Pro, Gln, Ala, Arg and Thr are the major components of the free amino acid pool in the whole body of adult beetles. Multivariate analysis indicates that the duration of exposure explains most of the observed variation in amino acid levels, while sex effect is not significant. Moreover, amino acid levels fluctuate strongly within each sampled date, revealing a high inter-individual heterogeneity. However, this heterogeneity decreases after four weeks of cold-exposure and starvation. The increase in Ala level and the concomitant decrease of Pro after four weeks suggest that Pro might be an important fuel for metabolism when fat reserves are reduced. We conclude that changes in free amino acid pools are due to a combination of reduced individual heterogeneity, cold-acclimation and amino acid degradation for energetic purposes.

  • water loss of male and female Alphitobius diaperinus coleoptera tenebrionidae maintained under dry conditions
    European Journal of Entomology, 2004
    Co-Authors: David Renault, Yann Coray
    Abstract:

    Survival under dry conditions was examined in males and females of Alphitobius diaperinus Panzer (Coleoptera: Tenebri- onidae), a beetle of tropical origin. The range of individual responses and the effect of gender on water loss were also evaluated. Females exhibit significantly longer survival (Lt50 and Lt90) than males under desiccating conditions. Larger females beetles have a greater initial water mass and hence can tolerate greater water losses. Such beetles have longer survival under dry conditions. Males and females loose an average of 54.8 and 58.9% of their body water prior to death. The insects were inactive most of the time, when kept under dry conditions; the rate of decrease in body water was thus reduced. Beetles of both gender display a negative correlation between the rates of water loss under desiccating conditions and the duration of survival. We conclude that the difference in survival period between males and females is due to a combination of greater female tolerance to desiccation and larger body size.

  • the importance of fluctuating thermal regimes for repairing chill injuries in the tropical beetle Alphitobius diaperinus coleoptera tenebrionidae during exposure to low temperature
    Physiological Entomology, 2004
    Co-Authors: David Renault, Frederic Hervant, O Nedved, Philippe Vernon
    Abstract:

    .  In this study, the impact of acclimation (1 month at 15 °C vs. breeding at 30 °C) and fluctuating thermal regimes (daily transfers from low temperatures to various higher temperatures for 2 h) on the cold tolerance of the tropical beetle, Alphitobius diaperinus Panzer (Coleoptera: Tenebrionidae) was examined. Acclimation increased significantly the duration of survival (Lt50) at a constant 5 °C (7.7 ± 0.3 days to 9.7 ± 0.5 days). Survival of acclimated and nonacclimated beetles increased slightly at alternating temperatures of 5 °C/10 °C or 5 °C/15 °C. When daily transfer to 20 °C was applied, survival (Lt50) was improved markedly (nonacclimated: 15.5 ± 0.7 days, acclimated: 19.6 ± 0.6 days). The higher temperatures may allow progressive repair of injuries, and the effects of chilling may be repaired completely at 25 and 30 °C, a phenomenon recorded here for the first time. It is estimated that the theoretical upper threshold of chill injury (Th) of nonacclimated beetles is 15.1 °C whereas it is shifted down to 11.2 °C in acclimated beetles, which might enable this temperature to allow effective repair of injury.