Fossil history of Mesozoic weevils (Coleoptera: Curculionoidea)

Abstract The first synopsis of Mesozoic weevils (Curculionoidea: Coleoptera) is presented. Changes of family, genera and species abundance during the Mesozoic revealed three distributional patterns. The Jurassic (Karatau) fauna was dominated by the Nemonychidae. During the Early Cretaceous (beginning at the Jurassic/Cretaceous border), the Ithyceridae was the prevalent group with a significant role played by the Nemonychidae. In the Late Cretaceous (Cenomanian and Turonian), the major groups were the Curculionidae and Brentidae. Obviously, the change of weevil fauna during this period was due to the expansion of the angiosperms, which provided multiple niches in their vegetative and reproductive organs for weevil development.     

On Udvardy's Insulantarctica province: a test from the weevils (Coleoptera: Curculionoidea)

'The scattered islands of the southern, cold ocean have clear affinities with one another . . . They are the basis for my Insulantarctica province.'
Udvardy, 1987, p. 190
Analyses of the distributional patterns of weevils (Coleoptera: Curculionoidea) from several Subantarctic islands, namely, Campbell, Auckland, Snares, Antipodes, Chatham, Falklands, Tierra del Fuego, Tristan da Cunha, Inaccessible, Nightingale, Gough, Marion, Prince Edward, Crozet, Kerguelen, and Heard, as well as South America and New Zealand, were carried out in order to determine their historical relationships, and to test the validity of Udvardy's (1987 ) Insulantarctica province. Three parsimony analyses of endemicity (PAE) considering (a) only species, (b) only supraspecific taxa, and (c) species and supraspecific taxa together, were undertaken. The following four groups emerged from the analyses: (1) New Zealand with the Snares, Auckland, Campbell, and Chatham Is., where New Zealand is the sister area to the Chatham Is., and the Auckland Is. are the sister area to Campbell I.; (2) South America with the Falkland Is. and Tierra del Fuego, where South America and Tierra del Fuego together are the sister area to the Falkland Is.; (3) Tristan da Cunha-Gough group, with the islands following the sequence Gough, Tristan da Cunha, Inaccessible, and Nightingale Is.; and (4) Kerguelen, Heard, Crozet, Marion, and Prince Edward Is., with Kerguelen and Heard Is. being sister areas, and Marion and Prince Edward Is. together being the sister area to the Crozet Is. It is concluded that the weevil fauna does not support the existence of an Insulantarctica province; the similarities among the different Subantarctic islands are due more to similar environmental conditions rather than to a common history.     

Influence of maternal age on the fitness of progeny in the rice weevil, Sitophilus oryzae (Coleoptera: Curculionidae)

We studied the effects of maternal age on fitness of progeny in the rice weevil, Sitophilus oryzae L. (Coleoptera: Curculionidae). Five-, 20-, and 50-d-old female rice weevils were used to study the effects of maternal age on the lifetime fecundity and longevity of their daughters. In addition, we determined the effects of maternal age on the weight and survivorship of daughters' progeny. Daughters of 5- and 20-d-old weevils lived longer, and the numbers and weights of the progeny of these daughters were higher than for daughters of 50-d-old weevils. Survivorship of immature grand-offspring of 5-, 20-, and 50-d-old female weevils was similar. None of the fitness characteristics of the daughters and grand-offspring of 5- and 20-d-old weevils that were measured differed significantly. We believe maternal age effects on rice weevil progeny fitness may at least partly be acting through maternal age effect on egg size. Individuals that developed from younger 5- and 20-d-old weevils had a greater fitness than those produced by older 50-d-old females. Our study shows maternal age is impacting life history parameters that influence population dynamics across generations. Therefore, maternal age could significantly affect population development and have far reaching implications for pest management and simulation modeling of rice weevil populations.     

Lethal and sublethal effects of rice polishing process on Sitophilus oryzae (Coleoptera: Curculionidae)

The mechanical impact of rice polishingon the rice weevil, Sitophilus oryzae (L.), and the subsequent postpolishing effects associated with rice quality were studied. "Brown" rice (not polished), "White (infest then polish)" rice, and "White (polish then infest)" rice were used with different polishing process intensities and different initial weevil densities. Weevil progeny were more numerous in Brown than in White (infest then polish) or White (polish then infest) rice. Polishing corresponding to a weight loss of 11% in rice generated an immediate mortality of approximately 40%; the subsequent mortality caused by rice quality was also 40% (total >80%). A polishing process corresponding to 14 and 16% of rice weight loss generated a drastic mortality in the weevil population (>95%). The progeny per adult weevil was similar with high and low initial weevil densities. The development of weevil progeny was also delayed by about 1 wk in White (infest then polish) rice compared with Brown rice. Furthermore, weevil adults of the progeny were significantly heavier in Brown than in White (infest then polish) or White (polish then infest) rice.     

Contribution to the weevil fauna (Coleoptera,Curculionoidea) of Turkey

37 species of the weevil families Brentidae, Apionidae, Nanophyidae, Dryophthoridae, Erirhinidae, and Curculionidae are recorded for Turkey or for the Asian part of the country, most of them, for the first time. Some of the species are also newly recorded for other countries.     

Towards the phylogeny of the Curculionoidea (Coleoptera): Reconstructions from mitochondrial and nuclear ribosomal DNA sequences

With about 60,000 described species, Curculionoidea represent the most species-rich superfamily in the animal kingdom. The immense diversity apparently creates difficulties in the reconstruction of the phylogenetic relationships. Independent morphological studies have led to very different classifications. This study is based on molecular data from two independent molecular sources, the 16S and 18S rDNA. Sensitivity analyses were conducted for the sequence alignment (gap costs were varied) as well as the phylogenetic reconstruction algorithms and some of their parameters. The higher-level relationships reconstructed within Curculionoidea are sensitive to alignment and reconstruction method. Nemonychidae or Oxycorynidae+Belidae were found to be sister to all remaining Curculionoidea in many analyses. The 16S rDNA sequence data (obtained from 157 species) corroborate many tribes and genera as monophyletic. It is observed that the phylogenetic reconstruction of genera with specific genetic features such as polyploidy and parthenogenetic reproduction is difficult in weevils. The curculionid subfamily Lixinae appears monophyletic. A new monophylum consisting of Entiminae, Hyperinae, Cyclominae, Myllorhinus plus possibly the Cossoninae is distinguished and we call it Entiminae s.l. For most other subfamilies and families homoplasy concealed the phylogenetic signal (due to saturation of the 16S sequences), or the species sampling was insufficient, although our sampling scheme was rather broad. We observed that although data from one source can easily be misleading (16S) or hardly informative (18S), the combination of the two independent data sets can result in useful information for such a speciose group of organisms. Our study represents the most thorough analysis of molecular sequence data of the Curculionoidea to date and although the phylogenetic results appear less stable than expected, they reflect the information content of these sequence data realistically and thus contribute to the total knowledge about the phylogeny of the Curculionoidea.     

Influence of growing location and cultivar on Rhyzopertha dominica （Coleoptera： Bostrichidae） and Sitophilus oryzae （Coleoptera： Curculionidae） infestation of rough rice

Long-grain rice cultivars Cocodrie, Wells, and XP 723 grown in three locations （Hazen, MO; Essex and Newport, AR, USA）, and medium-grain rice cultivars Bengal and XP 713 grown in two locations （Jonesboro and Lodge Corner, AR, USA）, were harvested and assayed for susceptibility to Rhyzopertha dominica （F.） （Coleoptera： Bostrichidae）, the lesser grain borer, and Sitophilus oryzae （L.） （Coleoptera： Curculionidae）, the rice weevil, on rice held at 27℃, 57% and 75% relative humidity （RH）. Separate samples from the same harvest lots were also analyzed for the physical characteristics of brown rice yield, percentage whole kernels and kernel thickness. Progeny production and feeding damage of R. dominica were significantly different among long-grain cultivars within two of the three locations （P 〈 0.05）, but not for location or RH （P ≥ 0.05）, while progeny production of S. oryzae was different among cultivars, location, and RH （P 〈 0.05）. On medium-grain rice, both cultivar and location were significant for progeny production of R. dominica, but not RH, while cultivar and RH were significant for progeny production of S. oryzae, but not location. On both rice types, feeding damage of R. dominica followed the same trends and was always strongly positively correlated with progeny production （P 〈 0.05）, but for S. oryzae there were several instances in which progeny production was not correlated with feeding damage （P ≥ 0.05）. Physical characteristics of both rice types were statistically significant （P 〈 0.01） but actual numerical differences were extremely small, and were generally not correlated with progeny production of either species. Results indicate that the location in which a particular rice cultivar is grown, along with its characteristics, could affect susceptibility of the rice to R. dominica and S. oryzae.     

The elytra-to-body binding mechanism of the flightless rainforest species Tabarus montanus Kaszab (Coleoptera: Tenebrionidea)

The elytra-to-body binding mechanism of the flightless rainforest species Tabarus montanus Kaszab (Coleoptera: Tenebrionidea) is described. Previously, studies on this complex character system in tenebrionids have focused mostly on either fully-winged or flightless, desert-dwelling species with a hermetically sealed subelytral cavity. Data presented here show that the rainforest species Ta. montanus has permanently joined interlocking macrostructures between the two elytra along the midline and between the elytral epipleuron and the sides of the body. These are very similar adaptations to ones found in flightless desert tenebrionids. Frictional patches of microtrichia, previously reported in all wing-folding beetle suborders including flightless taxa, are completely absent in Ta. montanus. This constitutes the first report of the complete loss of frictional microtrichia patches in a beetle with fully-developed elytra. Sensory organs (hair sensilla), usually involved in the correct positioning of the elytra over the beetles’ body at rest are also absent in Ta. montanus. The significance of these results relating to the evolution of the tenebrionid subelytral cavity is discussed.     

A new genus of nemonychid weevil from Burmese amber (Coleoptera,Curculionoidea)

The first fossil nemonychid (Nemonychidae) in Burmese amber, belonging to the subfamily Rhinorhynchinae, is described and figured as Burmonyx zigrasi Davis & Engel, gen. n. and sp. n. While this specimen also comprises the first definitive record of the subfamily in the Asian continent, other compression fossils exist at least from the Yixian Formation of China and the Karatau site of Kazakhstan which may also deserve placement within this group. Although several important areas of the body are obscured by the shape and fragmented condition of the amber piece, a sufficient number of features are visible to consider adequate placement within Rhinorhynchinae, including the fairly strongly punctate elytral striae and appendiculate, nearly bifid pretarsal claws.     

Host gene response to endosymbiont and pathogen in the cereal weevil Sitophilus oryzae

Background

Maternally inherited bacterial symbionts infecting arthropods have major implications on host ecology and evolution. Among them, the genus Arsenophonus is particularly characterized by a large host spectrum and a wide range of symbiotic relationships (from mutualism to parasitism), making it a good model to study the evolution of host-symbiont associations. However, few data are available on the diversity and distribution of Arsenophonus within host lineages. Here, we propose a survey on Arsenophonus diversity in whitefly species (Hemiptera), in particular the Bemisia tabaci species complex. This polyphagous insect pest is composed of genetic groups that differ in many ecological aspects. They harbor specific bacterial communities, among them several lineages of Arsenophonus, enabling a study of the evolutionary history of these bacteria at a fine host taxonomic level, in association to host geographical range and ecology.

Results

Among 152 individuals, our analysis identified 19 allelic profiles and 6 phylogenetic groups, demonstrating this bacterium's high diversity. These groups, based on Arsenophonus phylogeny, correlated with B. tabaci genetic groups with two exceptions reflecting horizontal transfers. None of three genes analyzed provided evidence of intragenic recombination, but intergenic recombination events were detected. A mutation inducing a STOP codon on one gene in a strain infecting one B. tabaci genetic group was also found. Phylogenetic analyses of the three concatenated loci revealed the existence of two clades of Arsenophonus. One, composed of strains found in other Hemiptera, could be the ancestral clade in whiteflies. The other, which regroups strains found in Hymenoptera and Diptera, may have been acquired more recently by whiteflies through lateral transfers.

Conclusions

This analysis of the genus Arsenophonus revealed a diversity within the B. tabaci species complex which resembles that reported on the larger scale of insect taxonomy. We also provide evidence for recombination events within the Arsenophonus genome and horizontal transmission of strains among insect taxa. This work provides further insight into the evolution of the Arsenophonus genome, the infection dynamics of this bacterium and its influence on its insect host's ecology.

     

Effectiveness of monoterpenes and phenylpropenes on Sitophilus oryzae L. (Coleoptera: Curculionidae) in stored wheat

Six monoterpenes, ((?)-citronellal, p-cymene, (?)-menthone, α-pinene, α-terpinene and (?)-terpinen-4-ol) and two phenylpropenes, (trans-cinnamaldehyde and eugenol) were tested for their insecticidal activity against the rice weevil, Sitophilus oryzae under laboratory conditions. The bioassays were carried out on wheat at the concentrations of 0.5, 1.0 and 5.0?g/kg. Adult mortality was assessed after 14?days of exposure. After this interval, the treated wheat was retained for an additional period of 90?days, in order to evaluate progeny production and wheat loss. At the concentrations of 0.5 and 1.0?g/kg, trans-cinnamaldehyde and eugenol achieved highest adult mortality. At 5.0?g/kg, all compounds except for p-cymene and α-pinene caused complete (100%) adult mortality. Generally, trans-cinnamaldehyde was the most potent compound causing complete inhibition of progeny at the three concentrations. Similarly, no progeny were observed in the wheat treated with (?)-citronellal, eugenol, p-cymene, (?)-menthone, and (?)-terpinen-4-ol at 5.0?g/kg after 45 and 90?days. Similar trends were noted for wheat weight loss and damage as the treatment with monoterpenes and phenylpropenes at the highest rate preserved the wheat intact and free from damage by S. oryzae for 90?days. Our findings suggest the tested compounds except p-cymene and α-pinene could be recommended for use as part of an integrated pest management program for S. oryzae control in stored wheat.     

Immediate and delayed mortality of Rhyzopertha dominica (Coleoptera: Bostrichidae) and Sitophilus oryzae (Coleoptera: Curculionidae) adults exposed to spinosad-treated commodities

A series of tests was conducted to characterize differences in the mortality of the lesser grain borer, Rhyzopertha dominica (F.) (Coleoptera: Bostrichidae), and rice weevil, Sitophilus oryzae (L.) (Coleoptera: Curculionidae), exposed to three commodities treated with a liquid and dry spinosad formulation. In laboratory bioassays, adults of the two insect species were exposed to untreated wheat, Triticum aestivum L., corn, Zea mays L., and sorghum, Sorghum bicolor (L.) Moench., and to commodities treated with 1 mg (AI)/kg of liquid and dry spinosad formulations. Mortality was assessed from independent samples examined at specific time intervals to determine immediate mortality and after 24 h of recovery on untreated grain at 28 degrees C and 65% RH to determine delayed mortality. Comparison of the time required for 50% (LT50) and 95% (LT95) mortality indicated that R. dominica adults were consistently and significantly more susceptible (died quickly) than S. oryzae adults when exposed to spinosad-treated commodities. In general, the toxicity of liquid and dry spinosad formulations was similar against R. dominica or S. oryzae. The toxicity of spinosad to each species varied slightly among the three commodities, and there were no consistent trends to suggest that spinosad was more effective on one commodity versus another. LT50 values based on immediate mortality for R. dominica on all commodities ranged from 0.45 to 0.74 d; corresponding values based on delayed mortality ranged from 0.04 to 0.23 d, suggesting delayed toxic action of spinosad in R. dominica. LT50 values based on immediate and delayed mortality for S. oryzae on all three commodities treated with the two spinosad formulations were essentially similar and ranged from 2.75 to 4.56 d. LT95 values for R. dominica based on immediate mortality on spinosad-treated commodities ranged from 1.75 to 3.36 d, and those based on delayed mortality ranged from 0.49 to 1.88 d. There were no significant differences in LT95 values based on immediate and delayed mortality for S. oryzae on spinosad-treated commodities, and the LT95 values ranged from 7.62 to 18.87 d. The toxicity of spinosad was enhanced during a 24-h holding period after removal from spinosad-treated commodities only against R. dominica adults, and possible reasons for increased postexposure mortality of R. dominica adults after brief exposures to spinosad warrant further study.     

Efficacy of cashew kernel extracts in the control of the maize weevil,Sitophilus zeamais (Coleoptera: Curculionidae)

Six different solvents namely: methanol, ethanol, water, acetone, pet-ether or n-hexane was used to extract the essential oils from cashew kernel. The extracted oils were evaluated on Sitophilus zeamais (Motschulsky 1855) for mortality, oviposition and adult emergence effects. The long-term storage and water absorption capacity of the treated maize grains was also investigated. Results showed that the steam distillate was most lethal on S. zeamais. The least potent extracts on S. zeamais were those extracted with methanol and ethanol. The extracts drastically reduced oviposition in S. zeamais. Maize grains treated with steam distillate extract had the lowest water absorption capacity, while the highest water absorption capacity was obtained in grains treated with ethanol and methanol. Extracts of steam distillate, n-hexane, petroleum ether and acetone completely prevented infestation and subsequence damage of the treated maize grains for a period of three months. In the grains treated with the methanol and ethanol extracts, damage of 28.61% and 6.24%, respectively were obtained. The results obtained reveal that extracts of cashew kernel are effective in controlling S. zeamais and could serve as an alternative to synthetic insecticides.     

Imaging and automated detection of Sitophilus oryzae (Coleoptera: Curculionidae) pupae in hard red winter wheat

Computed tomography, an imaging technique commonly used for diagnosing internal human health ailments, uses multiple x-rays and sophisticated software to recreate a cross-sectional representation of a subject. The use of this technique to image hard red winter wheat, Triticum aestivm L., samples infested with pupae of Sitophilus oryzae (L.) was investigated. A software program was developed to rapidly recognize and quantify the infested kernels. Samples were imaged in a 7.6-cm (o.d.) plastic tube containing 0, 50, or 100 infested kernels per kg of wheat. Interkernel spaces were filled with corn oil so as to increase the contrast between voids inside kernels and voids among kernels. Automated image processing, using a custom C language software program, was conducted separately on each 100 g portion of the prepared samples. The average detection accuracy in the five infested kernels per 100-g samples was 94.4 +/- 7.3% (mean +/- SD, n = 10), whereas the average detection accuracy in the 10 infested kernels per 100-g sample was 87.3 +/- 7.9% (n = 10). Detection accuracy in the 10 infested kernels per 100-g samples was slightly less than the five infested kernels per 100-g samples because of some infested kernels overlapping with each other or air bubbles in the oil. A mean of 1.2 +/- 0.9 (n = 10) bubbles (per tube) was incorrectly classed as infested kernels in replicates containing no infested kernels. In light of these positive results, future studies should be conducted using additional grains, insect species, and life stages.     

Distribution of the related weevil species Sitophilus oryzae and S. zeamais in Brazil

The genus Sitophilus （Coleoptera： Curculionidae） encompasses species of great economic importance as stored grain pests worldwide. Among these species, the maize and the rice weevils （Sitophilus zeamais and Sitophilus oryzae, respectively） are partic- ularly important in warmer climates. These two weevils exhibit closely morphological and ecological resemblance making difficult their proper identification and recognition of their distribution in grain-producing regions. Both species are recorded in South America and particularly in Brazil, but their respective distribution and prevalence were not yet assessed in the region. Therefore, several insect samples throughout Brazil were collected and subjected to morphological identification using male genitalia and also using molec- ular identification with species-specific primers designed for clear recognition of both the species. The primers were designed for the specific amplification of a gene fragment of the cytochrome oxidase subunit I, which exhibited high specificity during our prelimi- nary experiments with insects from six populations of known species （either S. zeamais or S. oryzae）. Both identification strategies provided the same results indicating preva- lence of the maize weevil S. zeamais throughout the country. Two hypotheses may explain such prevalence： （i） the likely host preference ofS. zeamais for maize because this is the most cultivated cereal in Brazil, and （ii） the prevalence ofS. zeamais in tropical regions as compared with S. oryzae, which is more disseminated in subtropical and temperate regions.     

Massive presence of insertion sequences in the genome of SOPE, the primary endosymbiont of the rice weevil Sitophilus oryzae

Bacteria that establish an obligate intracellular relationship with eukaryotic hosts undergo an evolutionary genomic reductive process. Recent studies have shown an increase in the number of mobile elements in the first stage of the adaptive process towards intracellular life, although these elements are absent in ancient endosymbionts. Here, the genome of SOPE, the obligate mutualistic endosymbiont of rice weevils, was used as a model to analyze the initial events that occur after symbiotic integration. During the first phases of the SOPE genome project, four different types of insertion sequence (IS) elements, belonging to well-characterized IS families from gamma-proteobacteria, were identified. In the present study, these elements, which may represent more than 20% of the complete genome, were completely characterized; their relevance as a source of gene inactivation, chromosomal rearrangements, and as participants in the genome reductive process are discussed herein.     

Cytochrome c oxidase inhibition in the rice weevil Sitophilus oryzae (L.) by formate, the toxic metabolite of volatile alkyl formates

Volatile alkyl formates are potential replacements for the ozone-depleting fumigant, methyl bromide, as postharvest insecticides and here we have investigated their mode of insecticidal action. Firstly, a range of alkyl esters, ethanol and formic acid were tested in mortality bioassays with adults of the rice weevil, Sitophilus oryzae (L.) and the grain borer, Rhyzopertha dominica (F.) to determine whether the intact ester or one of its components was the toxic moiety. Volatile alkyl formates and formic acid caused similar levels of mortality (LC(50) 131-165 micromol l(-1)) to S. oryzae and were more potent than non-formate containing alkyl esters and ethanol (LC(50)>275 micromol l(-1)). The order of potency was the same in R. dominica. Ethyl formate was rapidly metabolised in vitro to formic acid when incubated with insect homogenates, presumably through the action of esterases. S. oryzae and R. dominica fumigated with a lethal dose of ethyl formate had eight and 17-fold higher concentrations of formic acid, respectively, in their bodies than untreated controls. When tested against isolated mitochondria from S. oryzae, alkyl esters, alcohols, acetate and propionate salts were not inhibitory towards cytochrome c oxidase (EC 1.9.3.1), but sodium cyanide and sodium formate were inhibitory with IC(50) values of 0.0015 mM and 59 mM, respectively. Volatile formate esters were more toxic than other alkyl esters, and this was found to be due, at least in part, to their hydrolysis to formic acid and its inhibition of cytochrome c oxidase.     

Efficacy of diatomaceous earth to control internal infestations of rice weevil and maize weevil (Coleoptera: Curculionidae)

Densities of 10, 20, and 30 hard red winter wheat kernels, Triticum aestivum L., were infested with different life stages of the rice weevil, Sitophilus oryzae (L.), mixed with 35 g of wheat treated with 300 ppm of the Protect-It (Mississauga, Ontario, Canada) formulation of diatomaceous earth (DE), and held at 22, 27, and 32 degrees C. A similar test was conducted by exposing densities of 6, 12, and 18 corn kernels infested with different life stages of the maize weevil, Sitophilus zeamais Motschulsky, mixed with 30 g of corn, Zea mays L., treated with 300 ppm of DE. Mortality of adults emerging from kernels in wheat treated with DE was always greater than controls, and ranged from 56 to 90% at 22 degrees C and was >90% at 27 and 32 degrees C. In most treatment combinations, exposure to DE suppressed F1 progeny by 60-90% relative to untreated controls. Mortality of adult maize weevils on treated corn held at 22 and 27 degrees C was lower than mortality of rice weevils on wheat, and ranged from 4 to 84%. F1 production was low in corn held at 22 degrees C, and no F1s were produced in either the controls or the treatments at 32 degrees C. In treated corn held at 27 degrees C, exposure to the DE suppressed F1 progeny by approximately 70-80% relative to the untreated controls. Results of this study show that rice weevils and maize weevils emerging from infested kernels as adults are susceptible to DE, and these results are comparable to other studies in which adult weevils were exposed directly on wheat or corn treated with DE. Although adult weevils will be killed by exposure to DE, some oviposition could still occur and progeny suppression may not be complete; however, application of DE to commodities already infested with internal feeders, such as the rice weevil and the maize weevil, could help eliminate or suppress the infestation.