Functional morphology and structural characteristics of the hind wings of the bamboo weevil Cyrtotrachelus buqueti (Coleoptera,Curculionidae)

Research data of the microstructure and surface morphology of insect wings have been used to help design micro air vehicles (MAV) and coating materials. The present study aimed to examine the microstructure and morphology of the hind wings of Cyrtotrachelus buqueti using inverted fluorescence microscopy (IFM), scanning electron microscopy (SEM), and a mechanical testing system. IFM was used to investigate the distribution of resilin in the hind wing, and SEM was performed to assess the functional characteristics and cross-sectional microstructure of the wings. Moreover, mechanical properties regarding the intersecting location of folding lines and the bending zone (BZ) were examined. Resilin, a rubber-like protein, was found in several mobile joints and in veins walls that are connected to the wing membranes. Taken together, structural data, unfolding motions, and results of tensile testing suggest two conclusions on resilin in the hind wing of C. buqueti: firstly, the resilin distribution is likely associated with specific folding mechanisms of the hind wings, and secondly, resilin occurs at positions where additional elasticity is needed, such as in the bending zone, in order to prevent structural damage during repeated folding and unfolding of the hind wings. The functional significance of resilin joints may shed light on the evolutionary relationship between morphological and structural hind wing properties.     

Extraction and identification of cuticular semiochemical components of Cyrtotrachelus buqueti Guerin-Meneville ( Coleoptera: Curculionidae)

为了确定我国南方竹林主要害虫长足大竹象Cyrtotrachelus buqueti Guerin-Meneville雌虫是否存在诱引雄虫的化学信息素以及所释放的相关化学信息素的成分,本研究利用风洞和“Y”型嗅觉仪测试到长足大竹象雄虫对雌虫及雌虫体表提取化合物具有正趋向行为反应,随后用GC-EAD和GC-MS对雌虫体表提取化合物进行了分析.在GC-EAD分析时发现雄虫触角对雌虫体表粗提液和体表物质标准品化合物的触角电位反应时有5个GC峰有电生理活性;通过质谱法确定这5个电生理活性GC峰的化学成分分别为苯酚、已酸乙酯、2-壬酮、壬醛和十五酸甲酯.风洞和GCEAD分析表明,这5种成分的标准品化合物对长足大竹象雄虫具有诱引生物活性和触角电生理活性.结果说明长足大竹象雌虫体表粗提液中存在的苯酚、已酸乙酯、2-壬酮、壬醛和十五酸甲酯是长足大竹象成虫的化学信息素物质.     

Microstructure of the prothoracic mycangia in the ambrosia beetle Platypus koryoensis (Coleoptera: Curculionidae: Platypodinae)

Platypus koryoensis (Murayama) (Coleoptera: Curculionidae: Platypodinae) is a minute ambrosia beetle that can cause significant damage to live oak trees (Quercus mongolica) along with its symbiotic pathogenic fungus (Raffaelea sp.). Although both sexes of the beetle have a number of cuticular depressions for carrying microorganisms, only the females have mycangia that are typical in size on the pronotum. The mycangial cavities are filled with a mass of amorphous substances including yeast-like spores. In addition, mycangial cavities are equipped with cuticular pores which release substances to support symbiotic microorganisms during storage. Small depressions of both sexes can be subdivided into two clusters according to their relative sizes and locations. Although they have a typical cuticular peg (basiconic sensillum), they also share a common morphological characteristic with the typical mycangium of female: a round outlet and an invaginated reservoir containing a mass of secretory substances. Accordingly, our fine structural data suggest that both the female mycangia and the clusters of small cuticular depressions in both sexes also have a mycangial function in common regardless of their relative size and location.     

Sex-related variability of rostrum morphometry of Aristeus antennatus (Decapoda: Aristeidae) from the Ionian Sea (Eastern Mediterranean, Greece)

Sex-related rostral variability was studied in the aristeid shrimp Aristeus antennatusfrom the Eastern Ionian Sea (Mediterranean). Shrimps were collected on a monthly basis from December 1996 to November 1997 using a commercial bottom trawl in a depth range of 446–728 m. Female relative growth of rostrum proved to be negative allometric both seasonally and in the pooled annual data set. Males on the other hand, showed no or negative correlation of rostrum length with size. Mature males with short rostra dominated in the male population all year around. The appearance of males with long and intermediate rostra during winter, which disappear thereafter in favour of those with short rostra, indicates that rostrum shortening takes place during the end of winter. The increase of mated females during spring supports the hypothesis already addressed by other authors on the function of the male short rostrum in this species mating behaviour. Nevertheless, the paucity, in comparison to other Mediterranean populations, of males with long or intermediate rostra could indicate that for the bulk of the male population, the process of rostrum shortening in the Eastern Ionian Sea occurs outside the geographical locality or depth range sampled.     

Grandlure dosage and attraction of boll weevils (Coleoptera: Curculionidae)

The effects of grandlure dosage on of boll weevil, Anthonomus grandis grandis Boheman (Coleoptera: Curculionidae), attraction were assessed. Traps collected more boll weevils under field and laboratory conditions as the amount of grandlure in laminated plastic strips was increased from 0 to 10, 30, and 60 mg. Spreading the point source of the lure by cutting the strip into quarters and positioning each quarter on separate corners of the large capacity trap to create an expanded source for the pheromone plume, however, resulted in fewer trap captures than traps with quartered lures all positioned on a single corner. The large capacity trap with the quartered lure on one corner also caught more weevils than the traps with an intact lure fastened to one corner. Although aging lure strips for three weeks reduced emissions of the four pheromone components and their attractiveness to boll weevils, cutting the aged lure into quarters resulted in greater emissions and attraction than lures that were aged intact or as quarters. Some pheromone components volatilized faster than others, resulting in time-related changes in blend ratios, but the underlying factor in boll weevil attraction to grandlure strips was dosage, the amount of volatilized pheromone available for interacting with an adult boll weevil.     

Size-dependent feeding and reproduction by boll weevil (Coleoptera: Curculionidae)

The considerable variation in adult size of the boll weevil, Anthonomus grandis grandis Boheman, has been well documented, but the influences of adult size on reproductive rate are not known. We examined the relationship between the size of boll weevils and their feeding and oviposition. Weevils weighed to the nearest milligram were grouped into five categories based on pupal weight: < or =5, 6-10, 11-15, 16-20, and >20 mg. Numbers of lifetime punctures produced in flower buds (squares) of cotton, Gossypium hirsutum L., by both sexes of adults tended to increase with pupal weight. Boll weevil females with pupal weights >10 mg produced progeny with significantly higher survival to adulthood and also produced a higher percentage of female progeny than those with pupal weights < or =10 mg. The population growth indices for females having pupal weights >10 mg averaged 1.8-fold higher than those of females weighing < or =10 mg. Survivorship of adults of both sexes also tended to increase with pupal weight. The percentage of females laying eggs on any given day averaged 2.1 times higher when their pupal weights were >10 mg than when their pupal weights were < or =10 mg. Although small size negatively affected female reproductive potential, even extremely small females produced some viable offspring. However, the penalties of small adult size, in terms of longevity and reproductive potential, suggest that cultural practices that result in the production of small adults may be used to impact weevil populations.     

Mating tactics and courtship behavior inCleogonus rubetra (Fabricius) (Coleoptera: Curculionidae)

Females of the tropical weevilCleogonus rubetra oviposit into fruits of the leguminous treeAndira inermis, and larvae develop in the pulp and seed of these fruits. We hypothesized three alternative tactics by which males might secure matings. By using focal observations of males and by evaluating predictions specific to each hypothesis, we demonstrate that males search within aggregations of conspecifics for receptive females, and upon finding a suitable partner, males mount and perform courtship behavior consisting of stroking the eyes and sides of the female's abdomen. Males also stridulate and emit a sequence of short buzzing sounds. While mounted, males actively prevent rival males from mating with their partner. Males defend their mates for a mean duration of 3.7 h (including copulation). As predicted, paired males were larger than solitary individuals, although the difference was marginally nonsignificant. The overabundance of fruits relative to males, the prolonged period during which females are active, and the probability of last male sperm precedence are factors that may have contributed to the evolution of this female-defense tactic by males. Paired females were significantly larger than solitary females. We observed no competition among females for mates, and the correlation between elytron length of paired males and females was not significant.     

萧氏松茎象的早期寄主研究

本文以调查的事实材料为基础,对萧氏松茎象的早期寄主进行了研究,说明该虫最先在马尾松树种上发生,而后逐渐蔓延到从国外引进的湿地松、火炬松和国外松上猖獗危害。 萧氏松茎象（ＨｙｌｏｂｉｔｅｌｕｓｘｉａｏｉＺｈａｎｇ）是江西省吉安地区 １９８８年发现的国外松新害虫。十多年来,该虫蔓延十分迅速,危害国外松特别严重。据１９９９年调查,江西省４０余县（市）有分布．发生面积１万公顷以上,成为国外松的主要害虫。究竟此虫最初寄主是何树种,它为什么发展那么快呢？弄清这一问题十分重要,不仅对制订正确的防范措施,而且对研…     

Speciation in the sub-Antarctic weevil genus Dusmoecetes Jeannel (Coleoptera: Curculionidae)

Relatively few instances of sympatric speciation have been reported in the literature, and both theoretical and empirical studies of this mode of speciation remain controversial. Recently, a model of sympatric speciation less restrictive than earlier ones has been proposed. This study presents a hypothetical speciation scenario, based on current observations, which seems to be consistent with the new model. Two morphologically similar, though ecologically separated, species are identified in the Dusmoecetes similis (C. O. Waterhouse) species complex on Marion Island (46° 54'S, 37° 45'E), based on a study of the morphology, biology and ecology of the group. Differences between the demands placed on angiosperm- and bryophyte-feeding members of the complex, and the differing demands of bryophyte and angiosperm-dominated communities, coupled with low vagility and a high degree of assortative mating, suggest that a sympatric model can be used to explain speciation in this genus, which probably occurred within the last 10,000 years. Differences between Dusmoecetes marioni Jeannel and D. Similis (Waterhouse) are discussed, and a lectotype designated for the latter species.     

Hypersensitive response of beans to Apion godmani (Coleoptera: Curculionidae)

High levels of resistance to Apion godinani Wagner have been reported in bean, Phaseolus vulgaris L., landraces from Mexico. We report on the role of hypersensitivity to A. godmani in five resistant and three susceptible bean genotypes. In susceptible genotypes (cultivars 'Canario 107','Jamapa', and 'Zacatecas 45'), the eggs and first instars of A. godmani were embedded in the pod mesocarp and usually were surrounded by healthy tissue. In contrast, in resistant landraces ('Amarillo 154', 'Amarillo 155', 'J-117', 'Puebla 36', and 'Pinto 168'), necrotic tissues developed concentrically around the oviposition site, encapsulating eggs and dead larvae. An inverse relationship between percentage egg and larval encapsulation at the early immature pod stages and percentage of damaged seeds at harvest was found. Results indicate that hypersensitivity in developing pods plays an important role in antibiosis to A. godmani in beans. This information will facilitate future genetic and biochemical research and provide much needed information concerning the phenotypic basis of resistance to A. godmani in bean.     

Pollination of Anthurium (Araceae) by derelomine flower weevils (Coleoptera: Curculionidae)

Cyclanthura flower weevils (Coleoptera: Curculionidae: Derelomini) are identified for the first time as pollinators of multiple species of Anthurium (Araceae) in Costa Rica. The weevils are present on the inflorescences in small numbers during the pistillate and staminate phase of anthesis, and consume plant tissues and pollen. The individuals of one species of Cyclanthura can visit several Anthurium species within the same locality. They also engage in reproductive activities and are likely to oviposit into the flowers. The mating strategies suggest that sperm precedence selects males that are able to secure their position as the last partner prior to oviposition.     

Mango seed weevil (Coleoptera: Curculionidae) and premature fruit drop in mangoes

The effect of infestations of mango seed weevil, Sternochetus mangiferae (F.), on premature fruit drop of mangoes was investigated. Mango fruits ('Haden') of equal size were collected both off the ground and from the tree at four times during the season (June-August). If weevil-infested fruit were more prone to dropping than uninfested fruit, the prediction was that a higher infestation rate would be found in fruit on the ground compared with fruit on the tree. Average fruit weight was used as an indicator of fruit maturity. The seed infestation rate was significantly higher in fruit collected off the ground compared with fruit collected from the tree in 38 g and 79 g (early-season) fruit but not significantly different in 207 g (midseason) and 281 g (late season) fruit. The age distribution of weevils and the number of insects in infested fruits were similar for ground and tree fruits on all dates. Results suggest that mango seed weevil infestation can increase fruit drop during early fruit development.     

Boll weevil (Coleoptera: Curculionidae) bait sticks: toxicity and malathion content

Assays of malathion content and toxicity to boll weevil, Anthonomus grandis grandis Bohemian, were conducted on boll weevil bait sticks, now marketed as Boll Weevil Attract and Control Tubes (BWACTs; Plato Industries, Houston, TX). In general, the longer BWACTs were in the field, the lower the mortality of weevils that were exposed to them. Bioassays of weevil mortality correlated with hexane washes of BWACT surfaces showed highly variable mortality when surface malathion fell below approximately 20 ng per 1 microl of hexane, but consistently high mortality (> or = 90%) when surface malathion was above 30 ng per 1 microl of hexane. A linear equation was calculated to predict mortality as a function of malathion on a BWACT surface. Although mortality was related to surface amounts of malathion, it was unrelated to the total amount of malathion present in BWACTs. Similarly, surface malathion was unrelated to the total amount present in BWACTs. As with mortality, amount of surface malathion declined with time, but total malathion did not decline with time. Boll weevils placed on fresh BWACTs tended to accumulate more malathion and died in greater numbers as time spent on fresh tubes increased, but not as time spent on tubes aged in the field (for 5 mo total) increased. Weevils that landed on tubes after a short flight died in approximately the same numbers as those that were placed on tubes using proper methodology. The amount of malathion expected to cause 90% mortality of boll weevils subjected to proper methodology was 47% higher than for a less stringent methodology (34.3 versus 23.4 ng), which demonstrates the importance of strictly adhering to proper methodology; nevertheless, chemical assay of malathion on the BWACT surface proved to be a more consistent measure of BWACT toxicity than bioassay, and it should replace the bioassay.     

A study of polyploidy in races of Japanese weevils (Coleoptera: Curculionidae)

The chromosomes of two Japanese weevils, Blosyrus japonicus Sharp and Callirhopalus (= Pseudocneorhinus) obesus Roelofs, were studied. The former consists of four races: one 2n and bisexual (= Blosyrus falcatus Faust) and three parthenogenetic-4n, 5n, and 6n. In general the races are allopatric. The latter species has two races: 4n and 6n, again with distinct geographical distributions.     

First Record of Teratopactus nodicollis (Coleoptera: Curculionidae) in Dry Bean (Phaseolus vulgaris)

Observations on the bioecology and damage of Teratopactus nodicollis Boheman on Phaseolus vulgaris were carried out on field samples by assessing the number of larvae and root damage in 40?ha of a dry bean field from the Federal District, Brazil (16°4??28.41???W; 47°30??21.13???S). Larvae caused the greatest damage at the stage of germination, emergence, and primary leaves, producing 50?% stand reduction. Most larvae pupated in August and September, and adult emergence occurred in middle October. Some larvae were infected with the fungus Metarhizium spp., a biological agent that would be naturally controlling this insect.     

Strain distribution of alfalfa weevil (Coleoptera: Curculionidae) in an intergrade zone

Strain distribution for the alfalfa weevil, Hypera postica (Gyllenhal), was determined for the five major alfalfa-growing regions of New Mexico. Mitochondrial DNA from field-collected weevils at each location was digested and sequenced to differentiate among strains. Eastern, Egyptian, and western strains were recovered, along with a population not matching any known strain. The majority of sites examined had populations of two strains intermingled within a field. This is the first confirmation of the presence of all three strains within the same geographic region. Possible implications for alfalfa weevil management are discussed.