杂拟谷盗的热适应特性

为了解杂拟谷盗Tribolium confusum Jacquelin du Val的热适应特性,将杂拟谷盗分别于15,25和35℃下驯化2周后,用温度梯度仪测量在不同温度驯化下杂拟谷盗的最适温度、临界低温和临界高温。结果表明,驯化温度对杂拟谷盗最适温度、临界低温和临界高温的影响极显著(P<0.01),最适温度、临界低温、临界高温均随着驯化温度的升高而升高。最适温区的范围随着驯化温度的升高而扩大。驯化温度对杂拟谷盗最适温度的影响最大(0.317),对临界低温的影响(0.310)大于临界高温(0.255)。     

Effects of terpinen-4-ol fumigation on protein levels of detoxification enzymes in Tribolium confusum

Terpinen-4-ol has high fumigating activity to stored-grain pests including Tribolium confusum. To understand the detoxification of terpinen-4-ol in insects, proteomic analysis was performed to identify related proteins and pathways in response to terpinen-4-ol fumigation in T. confusum. By using isobaric tags for relative and absolute quantitation (iTRAQ)-based strategy, 4,618 proteins were obtained from T. confusum adults in the present study. Comparative proteomic analysis showed that 148 proteins were upregulated and 137 proteins were downregulated in beetles under the LC₅₀ of terpinen-4-ol treatment for 24 hr. According to functional classifications, differentially expressed proteins (DEPs) were enriched in xenobiotic metabolism pathways. In the detoxification pathway, the levels of 25 cytochrome P450s, 5 glutathione S-transferases, and 2 uridine diphosphate (UDP)-glucuronosyltransferases were changed, most of which were upregulated in T. confusum exposed to terpinen-4-ol. The results indicated that terpinen-4-ol was potentially metabolized and detoxified by enzymes like P450s in T. confusum.     

Pyrimidines and the X-ray response of Tribolium confusum Duval

Radiosensitizing effects of incorporation into DNA of the halogenated pyrimidines 5-bromouracil or 5-iodouracil, or their nucleosides (BUdR and IUdR), have been demonstrated in a variety of cell types. The results indicate that these antimetabolites influence lethality in x-irradiated adult Tribolium. At relatively low concentrations in the medium, BUdR and IUdR exhibit toxicity 3 to 5 weeks after transfer of beetles to analog-containing medium. Toxicity of IUdR on nonirradiated adults is less pronounced than that of BUdR and is slower to develop. Analog-treated Tribolium exposed to 7 kR, which is sublethal for adults in normal medium, die much earlier than those treated with analog alone or with lethal doses of x-rays alone. Transfer of beetles to normal medium after 3 weeks or less in the presence of analog virtually eliminates lethality attributable to the analog. X-irradiation at the time of transfer, however, leads to high mortality, and the amount of mortality appears to be a function of the duration of analog treatment. Insects grown in medium containing uracil or thymine exhibit the same survival as those reared in unsupplemented medium. Two weeks after 7 kR of irradiation a sharp decline in survival is seen in both uracil- and thymine-treated groups.     

Phenotypic diversity of Tribolium confusum pupae in heterogeneous environments

During the developmental period from egg to pupae Tribolium confusum (Coleoptera: Tenebrionidae; DuVal 1886) beetles were exposed to homogeneous and heterogeneous environments at two initial egg densities as well as undiluted and diluted media. The medium consisted of flour, flour and yeasts or flour and yeasts diluted with sawdust. Initial egg density had a strong influence on the variability of pupal weight: the weight was more variable in high density, where the coefficients of variation ranged between 0.121–0.189, compared to the coefficients of variation in low density ranging between 0.058–0.183. The dilution of the medium did not influence the pupal weight variability. Heterogeneity influenced pupation site choice. In the majority of cases larvae chose the apparently less crowded, poorer compartment, to pupate. Survival and developmental time were influenced by egg density. Environmental heterogeneity acted only as reinforcer, not as a factor itself causing variability.

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Résumé Pendant le développement de l'uf à la chrysalide, des ufs de Tribolium confusum (Coleoptera: Tenebrionidae; DuVal 1886) ont été soumis à differents traitements de façon à établir un lieu entre la variabilité phénotypique chez les chrysalides de cet espèce et la composition de l'habitat. L'hypothèse voulait que la variabilité phénotypique soit releé au degré de complexité de l'habitat a été testé en modifiant la qualité du substrat nutritif et la concentration initiale des ufs dans le milieu.Un milieu hétérogène a été obtenu en separant un bocal par une cloison contenant d'une côté un substrat nutritif de haute qualité et de l'autre un substrat nutritif de pauvre qualité. Le milieu de haute qualité était composé de 95% de farine et 5% de levain alors que le pauvre milieu se composait de farine et levain dilués dans 3 portions de sciure pour 1 potion de farine et levain. Deux témoins ont été préparés: l'un deux comprenait deux bocaux contenant un substrat nutritif de même valeur et l'autre comprenant le même milieu mais sans cloison. Les différentes expériences ont été repétées avec des ufs concentration initiale élevée (100 ufs/1 g de substrat) ou faible (25 ufs/1 g de substrat).La proportion moyenne d'insects qui ont survécu jusqu'à la nymphose était de 0.705±0.161 (SE) à faible densité et de 0.312±0.163 (SE) à densité élevé. La phase larvaire s'étola sur 27 jours (durée médiane) à faible densité sur 42 à densité élevée.L'hétérogéneité du milieu a aussi influencé le choix du lieu de nymphose: la majorité des larves se sont metamorphosées du côté du substrat de faible valeur nutritive. La densité initiale de ufs dans le milieu influença le poids de chrysalides: à densité élevée la variabilité phénotypique (CV) du poids de ces chrysalides était de 0.121–0.189 et de 0.058–0.183 à faible densité. Les differences des associations statistiques du poids de chrysalides entre densité et hétérogéneité, densité et dilution, hétérogéneité et dilution étaient toutes significatives.

     

Density-related mortality of the flour beetle,Tribolium confusum duval

Life tables were constructed to assess the relative importance of some factors causing mortality of Tribolium confusum and to gauge their response to increasing population density. Observations focussed on three population densities (100, 400 and 800 individual/8 g medium) from the egg to the adult stage. The medium was not renewed in order to maximize predatory interactions. Generation mortality at densities 100, 400 and 800 was 42%, 50% and 74% respectively, i. e. density-dependent. Mortality in the first 10 days was also density-dependent reaching a maximum of 27% at density 800: predation by small larvae on eggs seemed the principal causative factor. The overall pattern of larval mortality was density-independent. Data on the mortality of pupae and callows were ultimately consistent with an inversely density-dependent pattern. Apparently, only mortality occurring within the first 10 days was capable of population regulation.     

Extra-large Tribolium confusum: a new autosomal recessive mutant.

A new mutant of Tribolium confusum Jacquelin duVal (Coleoptera: Tenebrionidae), extra-large (designated xl), was isolated in mating competition tests with red-eye (re) and wild-type (+). Crosses showed that it was autosomal recessive gene with subvital effects. The pupal weights averaged 6.1 and 7.3 mg for males and females, respectively, about twice the weights of the ancestral wild-type. The generation time (egg to adult) was approximately 8 to 9 weeks compared with about 4 weeks for the wild-type. This increase resulted from a lengthening of the larval stage since the durations of the egg and pupal stages were within the ranges of the wild-type. Mean longivity of xl males and females was reduced to 8.5 and 6.0 weeks, respectively at 26.7 +/- 1 degree C and 60% RH.     

Circadian oxygen consumption rhythm of the flour beetle, Tribolium confusum

Oxygen consumption is circadian (about 24 hr) rhythmic in sterilized Tribolium confusum adults kept on a 12 hr light-12 hr dark regimen. High values for oxygen consumption occur shortly after ‘light-on’ and low ones at the beginning of the dark span. When the light-dark cycle is advanced by 6 hr, the oxygen consumption rhythm is phase-shifted within about 6 days; with a delay of the light-dark schedule (a return to the initial regimen) the oxygen consumption rhythm re-adjusts in 3 days. This directedness or polarity of the phase-shift adjustment constitutes a quantitative circadian system characteristic shared by organisms studied thus far.     

Tribolium confusum responses to blends of cereal kernels and plant volatiles

In this study, we report on the behavioural responses of the Tribolium confusum to 6 blends of cereal volatiles. There were tested four doses (1 ng/min, 10 ng/min, 100 ng/min and 1000 ng/min in 50 μl of hexane applied on filter paper). A Y‐tube experiment revealed that T. confusum females and males were attracted to the blend 1, 4 and 5 at the concentrations between 1 and 10 ng/min. Confused T. confusum females and males were not attracted to any concentration of blend 2 and 3. Yet the beetle females and males were repelled by the highest concentrations (1000 ng/min) for all the blends tested and also by the concentration 100 ng/min of all the blends tested, except for blend 1 and 4. Females and males were also repelled by the three blend 6 concentrations tested (10, 100 and 1000 ng/min).     

Relative susceptibility of Tribolium confusum life stages exposed to elevated temperatures

Methyl bromide, a space fumigant used in food-processing facilities, may be phased out in the United States by 2005. The use of elevated temperatures or heat treatment is gaining popularity as a methyl bromide alternative. During heat treatment, the temperature of the whole food-processing facility, or a portion of it, is raised and held between 50 and 60 degrees C for 24-36 h to kill stored-product insects. We determined time-mortality responses of the confused flour beetle, Tribolium confusum (Jacquelin du Val), eggs, young larvae, old larvae, pupae, and adults exposed to six constant temperatures between 46 and 60 degrees C. Responses of all five insect stages also were measured using exposure times of 160, 40, and 12 min at 46, 50, and 60 degrees C, respectively. Time-mortality responses of all T. confusum life stages increased with an increase in exposure time and temperature. Both time-mortality and fixed time responses showed eggs and young larvae to be most susceptible at elevated temperatures and old larvae to be least susceptible. Our results suggest that old larvae should be used as test insects to gauge heat treatment effectiveness, because heat treatment aimed at controlling old larvae should be able to control all other T. confusum life stages. Besides providing baseline data for successful use of heat treatments, time-mortality data collected at the six temperatures can be used for developing thermal death kinetic models for this species to predict mortality during actual facility heat treatments.