Influence of age, mating status, sex, quantity of food, and long-term food deprivation on red flour beetle (Coleoptera: Tenebrionidae) flight initiation

Effects of age, sex, presence or absence of food, mating status, quantity of food, and food deprivation on rate of and time of flight initiation of the red flour beetle, Tribolium castaneum (Herbst), were determined. Flight initiation declined with increasing age in both presence and absence of food. However, flight initiation was lower when food was present in the flight chambers than in the absence of food. In the presence of food, both mated and virgin beetles were equally likely to disperse by flight. However, in the absence of food, mated beetles initiated flight more readily that virgin individuals. Flight initiation was greatest when little or no food was present. The presence of varying quantities of food inside the flight chambers impacted the number of progeny produced by females before flight, but not the timing of flight. Rate of flight initiation was higher for beetles deprived of food for short periods of time compared with flight initiation of beetles with food in the flight chamber. Flight initiation decreased with increasing time without food. There were no differences in flight tendencies between males and females in the experiments reported here. Our results suggest that T. castaneum uses flight as a mechanism to disperse to new environments during almost any part of their life span and that this type of dispersion does not fit with the model of the so-called true migratory species that involves an "oogenesis-flight syndrome.     

Thermal death kinetics of red flour beetle (Coleoptera: Tenebrionidae)

While developing radio frequency heat treatments for dried fruits and nuts, we used a heating block system developed by Washington State University to identify the most heat-tolerant life stage of red flour beetle, Tribolium castaneum (Herbst), and to determine its thermal death kinetics. Using a heating rate of 15 degrees C/min to approximate the rapid heating of radio frequency treatments, the relative heat tolerance of red flour beetle stages was found to be older larvae > pupae and adults > eggs and younger larvae. Lethal exposure times for temperatures of 48, 50, and 52 degrees C for the most heat-tolerant larval stage were estimated using a 0.5th order kinetic model. Exposures needed for 95% mortality at 48 degrees C were too long to be practical (67 min), but increasing treatment temperatures to 50 and 52 degrees C resulted in more useful exposure times of 8 and 1.3 min, respectively. Red flour beetle was more sensitive to changes in treatment temperature than previously studied moth species, resulting in red flour beetle being the most heat-tolerant species at 48 degrees C, but navel orangeworm, Amyelois transitella (Walker), being most heat tolerant at 50 and 52 degrees C. Consequently, efficacious treatments for navel orangeworm at 50-52 degrees C also would control red flour beetle.     

Effects of proteinase inhibitors on digestive proteinases and growth of the red flour beetle,Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae)

The physiology of the gut lumen of the red flour beetle, T. castaneum, was studied to determine the conditions for optimal protein hydrolysis. Although the pH of gut lumen extracts from T. castaneum was 6.5, maximum hydrolysis of casein by gut proteinases occurred at pH 4.2. The synthetic substrate N-alpha-benzoyl-DL-arginine-rho-nitroanilide was hydrolyzed by T. castaneum gut proteinases in both acidic and alkaline buffers, whereas hydrolysis of N-succinyl-ala-ala-pro-phe rho-nitroanilide occurred in alkaline buffer. Inhibitors of T. castaneum digestive proteinases were examined to identify potential biopesticides for incorporation in transgenic seed. Cysteine proteinase inhibitors from potato, Job's tears, and sea anemone (equistatin) were effective inhibitors of in vitro casein hydrolysis by T. castaneum proteinases. Other inhibitors of T. castaneum proteinases included leupeptin, L-trans-epoxysuccinylleucylamido [4-guanidino] butane (E-64), tosyl-L-lysine chloromethyl ketone, and antipain. Casein hydrolysis was inhibited weakly by chymostatin, N-tosyl-L-phenylalanine chloromethyl ketone, and soybean trypsin inhibitor (Kunitz). The soybean trypsin inhibitor had no significant effect on growth when it was bioassayed alone, but it was effective when used in combination with potato cysteine proteinase inhibitor. In other bioassays with single inhibitors, larval growth was suppressed by the cysteine proteinase inhibitors from potato, Job's tears, or sea anemone. Levels of inhibition were similar to that observed with E-64, although the moles of proteinaceous inhibitor tested were approximately 1000-fold less. These proteinaceous inhibitors are promising candidates for transgenic seed technology to reduce seed damage by T. castaneum.     

Compensatory proteolytic responses to dietary proteinase inhibitors in the red flour beetle, Tribolium castaneum (Coleoptera: Tenebrionidae)

Increasing levels of inhibitors that target cysteine and/or serine proteinases were fed to Tribolium castaneum larvae, and the properties of digestive proteinases were compared in vitro. Cysteine proteinases were the major digestive proteinase class in control larvae, and serine proteinase activity was minor. Dietary serine proteinase inhibitors had minimal effects on either the developmental time or proteolytic activity of T. castaneum larvae. However, when larvae ingested cysteine proteinase inhibitors, there was a dramatic shift from primarily cysteine proteinases to serine proteinases in the proteinase profile of the midgut. Moreover, a combination of cysteine and serine proteinase inhibitors in the diet prevented this shift from cysteine proteinase-based digestion to serine proteinase-based digestion, and there was a corresponding substantial retardation in growth. These data suggest that the synergistic inhibitory effect of a combination of cysteine and serine proteinase inhibitors in the diet of T. castaneum larvae on midgut proteolytic activity and beetle developmental time is achieved through the prevention of the adaptive proteolytic response to overcome the activity of either type of inhibitor.     

Digestive proteinases of the larger black flour beetle, Cynaeus angustus (Coleoptera: Tenebrionidae)

Digestion in the larger black flour beetle, Cynaeus angustus (LeConte), was studied to identify new control methods for this pest of stored grains and grain products. The physiological pH of the larval gut, as measured with extracts in water, was approximately 6.1, and the pH for optimal hydrolysis of casein by gut extracts was 6.2 when buffers were reducing. However, under non-reducing conditions, hydrolysis of casein and synthetic serine proteinase substrates was optimal in alkaline buffer. Three major proteinase activities were observed in zymograms using casein or gelatin. Caseinolytic activity of C. angustus gut extracts was inhibited by inhibitors that target aspartic and serine proteinase classes, with minor inhibition by a cysteine proteinase inhibitor. In particular, soybean trypsin and trypsin/chymotrypsin inhibitors were most effective in reducing the in vitro caseinolytic activity of gut extracts. Based on these data, further studies are suggested on the effects of dietary soybean inhibitors of serine proteinases, singly and in combination with aspartic and cysteine proteinase inhibitors, on C. angustus larvae. Results from these studies can be used to develop new control strategies to prevent damage to grains and stored products by C. angustus and similar coleopteran pests.     

Insecticidal potential of natural zeolite and diatomaceous earth formulations against rice weevil (Coleoptera: Curculionidae) and red flour beetle (Coleoptera: Tenebrionidae)

Insecticidal potential of natural zeolites and diatomaceous earths originating from Serbia against Sitophilus oryzae (L.) and Tribolium castaneum (Herbst) was evaluated. Two natural zeolite formulations (NZ and NZ Modified) were applied to wheat at rates of 0.50, 0.75, and 1.0 g/kg, while two diatomaceous earth (DE) formulations (DE S-1 and DE S-2) were applied at rates of 0.25, 0.50, 0.75, and 1.0 g/kg. A bioassay was conducted under laboratory conditions: temperature of 24 +/- 1 degrees C, relative humidity in the range 50-55%, in tests with natural zeolites, and 60-65%, in tests with DEs, and in all combinations for progeny production. Mortality was assessed after 7, 14, and 21 d of insect contact with treated wheat, and the total mortality after an additional 7-d recovery on untreated broken wheat. Progeny production was also assessed after 8 wk for S. oryzae and 12 wk for T. castaneum. The highest mortality for S. oryzae and T. castaneum was found after the longest exposure period and 7 d of recovery, on wheat treated with NZ at the highest rate and DEs at rates of 0.50 -1.0 g/kg. Progeny reduction higher than 90% was achieved after 14 and 21 d of contact of both beetle pests with wheat treated with DE S-1 at 0.50-1.0 g/kg and DE S-2 at 0.75-1.0 g/kg, while the same level of reduction was achieved only for T. castaneum after its contact with the highest rate of NZ formulation. NZ Modified, applied even at the highest rate, revealed much lower insecticidal potential.     

Phosphine resistance in the rust red flour beetle, Tribolium castaneum (Coleoptera: Tenebrionidae): inheritance, gene interactions and fitness costs

The recent emergence of heritable high level resistance to phosphine in stored grain pests is a serious concern among major grain growing countries around the world. Here we describe the genetics of phosphine resistance in the rust red flour beetle Tribolium castaneum (Herbst), a pest of stored grain as well as a genetic model organism. We investigated three field collected strains of T. castaneum viz., susceptible (QTC4), weakly resistant (QTC1012) and strongly resistant (QTC931) to phosphine. The dose-mortality responses of their test- and inter-cross progeny revealed that most resistance was conferred by a single major resistance gene in the weakly (3.2×) resistant strain. This gene was also found in the strongly resistant (431×) strain, together with a second major resistance gene and additional minor factors. The second major gene by itself confers only 12-20× resistance, suggesting that a strong synergistic epistatic interaction between the genes is responsible for the high level of resistance (431×) observed in the strongly resistant strain. Phosphine resistance is not sex linked and is inherited as an incompletely recessive, autosomal trait. The analysis of the phenotypic fitness response of a population derived from a single pair inter-strain cross between the susceptible and strongly resistant strains indicated the changes in the level of response in the strong resistance phenotype; however this effect was not consistent and apparently masked by the genetic background of the weakly resistant strain. The results from this work will inform phosphine resistance management strategies and provide a basis for the identification of the resistance genes.     

A method for rearing the desert beetle Anatolica polita (Coleoptera : Tenebrionidae: Tentyriini)

为了解决深入研究荒漠甲虫环境适应机制时所遇到的各发育阶段试虫材料短缺的问题,本文介绍了饲养拟步甲科鳖甲族昆虫光滑鳖甲Anatolica polita Kaszab的有效方法.将早春季节在野外采集的成虫饲养在2L的塑料烧杯中,收集卵.用玻璃培养皿孵育卵;用改装的盛有沙土的矿泉水瓶单只饲养3龄以上幼虫,以防止幼虫自相残杀.为保持幼虫饲养瓶内的适当湿度,在瓶子底部加入72mL的水,再装入800g沙子,借助毛细现象,形成渐变式含水基质,在最上层的干沙表面加麦麸以饲养幼虫.如需观察计数,可将预蛹、蛹和初孵成虫置于玻璃培养皿中培养.采用此方法饲养的光滑鳖甲可顺利完成生活史,其卵的孵化率为68.67％±2.45％,1～2龄幼虫的存活率为82.95％±7.72％,3～9龄幼虫的存活率为73.80％±4.95％;预蛹、蛹和幼嫩成虫的存活率分别为84.68％±2.35％、88.45％±2.75％和90.56％±4.20％.该方法可以有效实现光滑鳖甲的室内饲养,并可用于其他一些沙栖拟步甲科昆虫的人工饲养.     

Novel molecular identification methods for the larger black flour beetle,Cynaeus angustus (Coleoptera: Tenebrionidae)

Two new methods were developed for identifying Cynaeus angustus (LeConte) (Coleoptera: Tenebrionidae) by DNA amplification using simplex and real-time PCR targeting the cytochrome c oxidase subunit I (COI) sequence reported previously. The specificities of the PCR primers and probe were also confirmed by the two PCR methods using the 22 main stored-product insect species, including DNA samples from nine tenebrionid beetle species. The results showed that the newly developed simplex and real-time PCR-based methods have sufficient specificity for analysis. The limits of detection for C. angustus total DNA by the simplex and multiplex PCR were 320 fg and 20 pg, respectively.

     

Fitness consequences of malathion-specific resistance in red flour beetle (Coleoptera: Tenebrionidae) and selection for resistance in the absence of malathion

Malathion resistance in the red flour beetle, Tribolium castaneum (Herbst), is a worldwide problem and is very stable once it becomes widespread in natural populations. In the absence of insecticide the proportion of resistant phenotypes may rapidly decline but the development of resistance does not always involve reduced fitness. Malathion-specific resistance in T. castaneum seems not to involve any loss of fitness in laboratory or field conditions. Susceptible beetles were in competition with resistant beetles at different initial frequencies and modifications of susceptible gene frequency were estimated in these laboratory populations over 10 generations. A significant decrease in susceptible gene frequency was observed in Tribolium populations over time. The selection coefficient of the susceptible allele was estimated and the fitness of susceptible alleles in all tests was observed to range from 0.89 to 0.93 compared with the fitness of resistant genotypes, which was assumed to be 1. Data provided evidence that the resistant strains exhibited fitness advantages in the absence of malathion. We also compared the biotic potential (fecundity and developmental time) of the susceptible strain, the homozygous malathion-specific resistant strain, and their hybrids. Malathion-specific resistant strains showed an 8 -23% increase in biotic potential relative to the susceptible strain. These findings are consistent with those of malathion-specific resistance in T. castaneum; the fitness of the insects seems independent of the genetic background and the fitness of the resistant insects is not affected by this resistance mechanism.     

Susceptibility of last instar red flour beetles and confused flour beetles (Coleoptera: Tenebrionidae) to hydroprene.

Last instar larvae of the red flour beetle, Tribolium castaneum (Herbst), and the confused flour beetle, Tribolium confusum Jacquelin du Val, were either exposed for 8-144 h on concrete treated with 1.9 x 10(-3) mg(AI)/per cm2 hydroprene, or continually exposed on concrete treated with 9.8 x 10(-4) to 1.9 x 10(-3) mg[AI]/per cm2 hydroprene. In both tests, larvae were exposed and held at 27 or 32 degrees C and 40, 57, or 75% RH. When larvae were exposed with no food to hydroprene for different time intervals, then transferred to untreated concrete containing flour, consistent effects were produced only at 144 h. At this exposure interval, the percentage of beetles arrested in the larval stage after 3-4 wk was generally greater at 75% RH compared with 40 and 57% RH, but there were no differences between species or temperature. The percentages of dead adult red flour beetles and live adults with morphological deformities were also greatest at 75% RH, and defects were more prevalent in red flour beetles than in confused flour beetles. When larvae were continually exposed to different concentrations of hydroprene on concrete that contained flour, the percentage of arrested larvae, dead adults, and live adults of both species generally increased with concentration. There were more deleterious effects at 75% RH compared with either 40 or 57% RH, and effects were more pronounced in the red flour beetle compared with the confused flour beetle. In both experiments, temperature effects were variable and inconclusive. Results indicate that continual exposure of last instar red flour beetle and confused flour beetle to hydroprene can limit population development, but exposure intervals of >6 d may be required for maximum effectiveness.     

The early stages of ommatidial development in the flour beetle Tribolium castaneum (Coleoptera; Tenebrionidae)

 Using electron microscopy, the first stages of ommatidial development in the flour beetle Tribolium castaneum were analysed in relation to the cellular architecture of the adult compound eye and were compared to the corresponding patterning process in the fruit fly Drosophila melanogaster. The ommatidia of the slightly horse-shoe shaped beetle compound eye contain six peripheral and two central retinula cells. The rhabdomere of the posteriorly located central photoreceptor cell is restricted to the distal half of the rhabdom whilst that of the anterior one is restricted to its proximal half. The development of the compound eye takes place in an external eye imaginal disc. Most stages of ommatidial development, as known from Drosophila, i.e. arc-like cell groups, five-cell clusters, immature eight-cell clusters and symmetrical eight-cell clusters, are very precisely conserved between the two species. Two major differences exist: 1. In Tribolium, the cone cell precursor cells synchronously join to the immature eight-cell cluster. As a consequence, the symmetrical eight-cell cluster immediately transforms into a four-cone-cell cluster. 2. The maturing ommatidia do not undergo rotation in Tribolium. Overall, no morphological indiation for an equator in the adult Tribolium compound eye could be found. Considering the strong evolutionary conservation of early ommatidial development, homology of photoreceptor cells of distantly related insects is proposed to be inferred from their ontogenetic origin. Received: 6 November 1995 / Accepted: 9 April 1996     

Dormancy-inducing factors of rubber litter beetle, Luprops tristis (Coleoptera: Tenebrionidae)

Abstract  The effect of photoperiod, temperature, humidity, rainfall and moisture were examined on the annual migration of Luprops tristis (Fabricius, 1801) (Coleoptera: Tenebrionidae) from rubber plantations to shelters, and the induction of 9 months dormancy thereafter. Results confirm the role of rainfall-mediated wetness from summer showers as the cue that induces dormancy in Luprops tristis and provide further proof to the function and significance of moisture in diapause induction in tropical insects. Other factors did not have any significant independent effect on migration and dormancy induction. Reserve food accumulation by teneral adults well ahead of the onset of adverse conditions and the non-return of beetles to the field in short-term favorable conditions strongly indicate that Luprops tristis has evolved the ability to predict and avoid adverse conditions and the inheritance of dormancy-regulating factors from the parent generation.     

Toxicity of diatomaceous earth to red flour beetles and confused flour beetles (Coleoptera: Tenebrionidae): effects of temperature and relative humidity

Red flour beetles, Tribolium castaneum (Herbst), and confused flour beetles, Tribolium confusum (DuVal), were exposed for 8-72 h to diatomaceous earth (Protect-It) at 22, 27, and 32 degrees C and 40, 57, and 75% RH (9 combinations). Insects were exposed to the diatomaceous earth at 0.5 mg/cm2 on filter paper inside plastic petri dishes. After exposure, beetles were held for 1 wk without food at the same conditions at which they were exposed. Mortality of both species after initial exposure was lowest at 22 degrees C but increased as temperature and exposure interval increased, and within each temperature decreased as humidity increased. With 2 exceptions, all confused flour beetles were still alive after they were exposed at 22 degrees C, 57 and 75% RH. Mortality of both species after they were held for 1 wk was greater than initial mortality for nearly all exposure intervals at each temperature-humidity combination, indicating delayed toxic effects from exposure to diatomaceous earth. For both species, the relationship between mortality and exposure interval for initial and 1-wk mortality was described by linear, nonlinear, quadratic, and sigmoidal regression. Mortality of confused flour beetles was lower than mortality of red flour beetles exposed for the same time intervals for 46.7% of the total comparisons at the various temperature-relative humidity combinations.     

Field trial of diatomaceous earth in cotton gin trash against the larger black flour beetle, Cynaeus angustus (Coleoptera: Tenebrionidae)

The larger black flour beetle, Cynaeus angustus (LeConte) (Coleoptera: Tenebrionidae), is an agricultural and home nuisance pest in North America. In the Southern High Plains of Texas, the larger black flour beetle is associated with cotton gin trash, by-products of cotton ginning that are field stored in large piles for economic reasons. Larger black flour beetle overwinter in gin trash piles but may disperse by the millions in summer and autumn, entering houses as far as 2 km away where they cause distress to homeowners. Because > 1.2 billion kg of gin trash is produced annually in Texas alone, the potential consequences of the larger black flour beetle are enormous. We conducted a field experiment that evaluated the efficacy of diatomaceous earth (DE) on the abundance of the larger black flour beetle in gin trash. There were no significant differences in numbers of larger black flour beetle among treatments and controls (mean number of adults summed over time: controls = 115.41, layered treatment = 87.60, top and bottom treatment = 96.50, bottom treatment = 115.16). There were sufficient numbers of beetles in treated piles to still pose a potential home nuisance problem, likely because the moisture content of field-stored gin trash is too high for DE to work effectively. Therefore, treating cotton gin trash with diatomaceous earth will probably be unable to prevent home infestations of larger black flour beetle. Location within a gin trash pile and season influenced pest numbers, which has implications for long-term field storage of cotton gin trash.     

Karyological notes on six beetle species from Armenia (Coleoptera: Tenebrionidae,Cerambycidae, Curculionidae)

Karyotypic details were studied in males of six beetle species from three families, viz. Tenebrionidae: Dailognatha pumila Bdy. (2n = 20, n(male) = 9 + Xy(p)), Pachyscelis musiva Ménétr. (2n = 18, n(male) = 8 + Xy(p)), Pimelia capito Kryn. (2n = 18, n(male) = 8 + Xy(p)); Cerambycidae: Agapanthia walteri Reitt. (2n = 20, n(male) = 9+Xy(p)), Agapanthia korostelevi Danilevsky (2n = 20, n(male) = 9 + Xy(p)); Curculionidae: Phyllobius caucasicus Stierl. (2n = 22, n(male) = 10 + Xy(p)). The chromosome number and sex determining system of all beetle species are described for the first time. Evolutionary trends in karyotypes of the studied beetle groups are briefly discussed.     

Impairment of reproduction in the red flour beetle, Tribolium castaneum (Herbst) (Col., Tenebrionidae) due to larval feeding on triflumuron-treated diet

The larvae of Tribolium castaneum (Herbst) of different ages were exposed to various concentrations viz., 0.0001, 0.001 and 0.01 ppm of triflumuron up to pupation. The adults were allowed to feed on untreated diet. The preoviposition period, fecundity, egg viability and incubation period of the eggs laid were studied. Triflumuron significantly lengthened the preoviposition and incubation periods (P < 0.001). Fecundity and egg viability were also reduced (P < 0.001) due to the treatment. Both the strains were affected by the treatment.     

Effects of food deprivation on the development of Coleomegilla maculata (De Geer) (Coleoptera: Coccinellidae)

The lady beetle Coleomegilla maculata (De Geer) is a natural enemy of several insect pests and feeds on pollen and nectar to survive periods when prey is scarce. The effect of the feeding interval on the development, survival, fecundity, and longevity of C. maculata was determined. Newly hatched larvae of C. maculata were reared individually and fed with eggs of the Mediterranean flour moth Anagasta kuehniella (Zeller) at intervals of one, two, and three days under controlled conditions (23 ± 1oC; 60 ± 10% RH; 12 h phtophase). The duration of larval instars and the total larval stage was prolonged as the feeding interval increased. The larval period lasted on average 9.2 ± 0.19 days when the larvae were fed daily with prey, and 14.6 ± 0.48 days when food was offered at three-day intervals. There was an inverse relationship between food intervals, survival, and weight of larvae and adults of the coccinellid. Survival rate of larvae fed daily was 76.8%, while the rate was 50.0% and 23.4% for larvae fed every two and three days, respectively. Coleomegilla maculata showed fecundity of 781.1 ± 149.02, 563.4 ± 80.81 and 109.0 ± 103.0 eggs when fed daily and at intervals of two and three days, respectively.