Mycangia of the ambrosia beetle, Austroplatypus incompertus (Schedl) (Coleoptera: Curculionidae: Platypodinae)

Abstract  Ambrosia beetles have an obligate relationship with the ambrosia fungi that they feed on. This requires that the beetles have means to transport those fungi when they colonise new hosts. Some ambrosia beetles have special structures called mycangia to transport fungi in. This paper describes the mycangia of the ambrosia beetle Austroplatypus incompertus and illustrates how the mycangical hairs are probably used by the beetle to acquire fungal spores for transport. The mycangia and probable method of fungal acquisition of this species are compared with those of other ambrosia beetles.     

Ploidy of the eusocial beetle Austroplatypus incompertus (Schedl) (Coleoptera, Curculionidae) and implications for the evolution of eusociality

In the hymenopterans, haplodiploidy, leading to high-genetic relatedness amongst full sisters has been regarded as critical to kin selection and inclusive fitness hypotheses that explain the evolution of eusociality and altruistic behaviours. Recent evidence for independent origins of eusociality in phylogenetically diverse taxa has led to the controversy regarding the general importance of relatedness to eusociality and its evolution. Here, we developed a highly polymorphic microsatellite marker to test whether the eusocial ambrosia beetle Austroplatypus incompertus (Schedl) is haplodiploid or diplodiploid. We found that both males and females of A. incompertus are diploid, signifying that altruistic behaviour resulting from relatedness asymmetries did not play a role in the evolution of eusocialty in this species. This provides additional evidence against the haplodiploidy hypothesis and implicates alternative hypotheses for the evolution of eusociality.     

Successful development of microsatellite markers in a challenging species: the horizontal borer Austroplatypus incompertus (Coleoptera: Curculionidae)

The analysis of microsatellite loci has allowed significant advances in evolutionary biology and pest management. However, until very recently, the potential benefits have been compromised by the high costs of developing these neutral markers. High-throughput sequencing provides a solution to this problem. We describe the development of 13 microsatellite markers for the eusocial ambrosia beetle, Austroplatypus incompertus, a significant pest of forests in southeast Australia. The frequency of microsatellite repeats in the genome of A. incompertus was determined to be low, and previous attempts at microsatellite isolation using a traditional genomic library were problematic. Here, we utilised two protocols, microsatellite-enriched genomic library construction and high-throughput 454 sequencing and characterised 13 loci which were polymorphic among 32 individuals. Numbers of alleles per locus ranged from 2 to 17, and observed and expected heterozygosities from 0.344 to 0.767 and from 0.507 to 0.860, respectively. These microsatellites have the resolution required to analyse fine-scale colony and population genetic structure. Our work demonstrates the utility of next-generation 454 sequencing as a method for rapid and cost-effective acquisition of microsatellites where other techniques have failed, or for taxa where marker development has historically been both complicated and expensive.     

New data on the cytology of parthenogenetic weevils (Coleoptera,Curculionidae)

Parthenogenesis and, in particular, polyploidy are rare in animals. A number of cases, known among weevils, represent apomictic parthenogenesis-a reproductive mode in which eggs undergo one maturation division, the chromosomes divide equationally, and no reduction takes place. Among parthenogenetic weevils there are two diploids, 48 triploids, 18 tetraploids, six pentaploids, three hexaploids and one decaploid. Eight examined parthenogenetic species are triploids with 33 chromosomes of different morphology, confirming that triploidy is the most common level of ploidy in weevils. The karyotypes are heterogeneous with the presence of meta-, submeta-, subtelo- and acrocentric chromosomes. The C-banding method showed that only two species possess a large amount of heterochromatin visible as a band around the centromere during mitotic metaphase. This agrees with observations that weevils are characterized by a small amount of heterochromatin, undetectable in metaphase plates after C-banding. In three species an atypical course of apomictic oogenesis occurs with stages similar to meiosis, in which chromosomes form bivalents and multivalent clusters. This association of chromosomes probably represents the remnants of meiosis, although these events have nothing to do with recombination. The results support the hypothesis that the evolution of apomictic parthenogenesis in weevils has proceeded through a stage of automixis.     

The spermatogenesis of crustaceans: The external morphology of the spermatozoa of heterocypris incongruens,ramdohr (Ostracoda)

In various papers on the original spermatozoon of the Ostracoda, its helicoidal disposition has been indicated as the principle characteristic of this gamete, at cell structure level as well as in its external morphology. Through a combined study with scanning electron microscope (SEM) and transmission electron microscope (TEM), we have been able to establish the corresponding relationship between the cell architecture and the spermatozoon's external morphology. In the case of Heterocypris incongruens, the helicoidal relief of the gamete's external surface along the greatest part of its length, is the result of the twisting and undulating of a structure derived from the nucleus' external membrane, endoplasmic reticulum, and Golgi apparatus, called “feather-like organelle.” In keeping with the shape of this surface relief, the spermatozoon can be divided into three regions: An anterior one with a corkscrew form, a middle one showing a relief in the form of a screw with four threads, and a posterior or tail one without helicoidal relief. Finally, we discuss the different criteria existing on the possible orientation of this spermatozoon when it moves, as well as the functional advantages that the possession of a filiform, helicoidal, and mobile gamete represents.     

Characterization of microsatellite loci in Amphitmetus transversus (Kolbe, 1897) (Coleoptera,Curculionidae)

We developed six microsatellite markers for Amphitmetus transversus (Kolbe, 1897) (Coleoptera, Curculionidae), a beetle widely distributed in the guineo‐congolian rainforests of east Africa. The numbers of alleles per locus range from three to eight, with a mean number of 4.6. They will be used for population genetic analysis. The ongoing study concentrates on the genetic differentiation and variability of isolated populations in the Kakamega Forest, a highly degraded and fragmented rainforest remnant in western Kenya.     

A latitudinal cline and response to vernalization in leaf angle and morphology in Arabidopsis thaliana (Brassicaceae)

Adaptation to latitudinal patterns of environmental variation is predicted to result in clinal variation in leaf traits. Therefore, this study tested for geographic differentiation and plastic responses to vernalization in leaf angle and leaf morphology in Arabidopsis thaliana. Twenty-one European ecotypes were grown in a common growth chamber environment. Replicates of each ecotype were exposed to one of four treatments: 0, 10, 20 or 30 d of vernalization. Ecotypes from lower latitudes had more erect leaves, as predicted from functional arguments about selection to maximize photosynthesis. Lower-latitude ecotypes also had more elongated petioles as predicted by a biomechanical constraint hypothesis. In addition, extended vernalization resulted in shorter and more erect leaves. As predicted by functional and adaptive hypotheses, our results show genetically based clinal variation as well as environmentally induced variation in leaf traits.     

External microstructure of the ambrosia beetle Platypus koryoensis (Coleoptera: Curculionidae: Platypodinae)

Platypus koryoensis is a minute ambrosia beetle found in forests. It can cause significant economic damage to oak trees. Recently in Korea, it has been reported as a major pest of oak trees, because it causes sooty mold of oak by introducing the pathogenic fungus Raffaelea sp. In this paper, we demonstrate the fine structural aspects of the external body of the ambrosia beetle using field emission scanning electron microscopy, as a part of basic research into this pest so that strategies for its control might be developed. This beetle has a sensory system well developed to respond to both visual and chemical stimuli. Both sexes have a pair of faceted compound eyes and a pair of knobbed antennae, but simple eyes are absent. The mouthparts on its distinct snouts are effective devices for penetration and for boring holes. The mouthparts consist of the labrum, a pair of mandibles, a pair of maxillae and the labium. Both the maxillary and the labial palpi have the function of directing the food to the mouth and holding it while the mandibles chew the food. The distal ends of these palpi are flattened and have shovel‐like setae. The thorax has a particularly hard exoskeleton and hard elytra, including powerful muscles that operate both the wings and the legs. The legs are multi‐segmented and have a strong femur and tibia, including one pair of claws on the end of each tarsal segment. Characteristically, both male and female beetles have mycangial cavities for storing spores and other microorganisms, but only females have three pairs of large depressions on their dorsal thorax.     

The spermatogenesis of crustaceans. VI. The external morphology of the mature spermatozoa of mytilicola intestinalis,steuer (copepoda)

The external structure of the male gamete of Mytilicola intestinalis is studied under a scanning electron microscope and compared with transmission electron micrographs of thin sections corresponding to the different parts of same. The cell in question is long and filiform, showing, along a significant part of its length, two ridges or expansions helicoidally arranged and diametrically opposed. Four different parts or segments can be identified in this spermatozoon: segment A, characterized by its screw-like aspect; segment B, the longest, provided with well-developed helicoidal expansions; segment C, showing an uneven surface and lacking expansions; and segment D, with a smooth surface and decreasing diameter. The significance of this original structure in a spermatozoon, considered immobile until now, is discussed, stating different hypotheses with regard to the possible mobility of the cell just before fertilization takes place.     

Sexual dimorphism and allometry of external morphology in Oreochromis mossambicus

Sexual dimorphism in growth of conventional morphometric characters was investigated in juveniles and young adults (size range: 31 to 91 mm) of Oreochromis mossambicus . A closely associated set of traits was identified that shows sexually dimorphic growth, which was positively allometric in the males. These traits correspond to two different morphological complexes: jaw structure and anal/dorsal fins. The best sex discriminators among this set of traits were premaxilla width, anal fin height and snout length. These findings may be explained in terms of intra– and inter–sexual selection acting together and favouring males with strong and large mouths and high dorsal and anal fins, traits that are important in agonistic displays (jaw and fins), fighting and nest digging (jaw).     

Fossil weevils (Coleoptera: Curculionidae) from latitude 85°S Antarctica

Two species of fossil listroderine weevils (Coleoptera: Curculionidae: Rhytirhinini: Listroderina) are reported from the Meyer Desert Formation at a locality on the Beardmore Glacier in the Transantarctic Mountains about 500 km from the South Pole. Associated fossils include wood, leaves and pollen of Nothofagus, stems and leaves of several species of mosses, achenes of Ranunculus, shells of freshwater molluscs and a fish tooth. The age of the fossiliferous strata is contentious but probably within the range of Pliocene to mid-Miocene. The fossils represent organisms that colonised the margins of a glacier at the head of a fjord during an interglaciation. The autecology of the listroderine species indicates that temperatures during summer months averaged 5°C. The mean annual temperature, with winter temperatures constrained by 6 months of darkness, is estimated to have been about −8°C compared to the −26°C estimated for sea level at latitude 85°S today. The closest evolutionary link of the fossil listroderines is with South American rather than Australian or New Zealand taxa. Divergence of the taxa, at least at the level of tribe, had most probably occurred on Gondwana before the continent broke apart. The fossil species are considered to be the descendants of Antarctic lineages which evolved on the continent in the Late Cretaceous or Palaeogene and survived until the Neogene. Extinction of the listroderines and most other Antarctic terrestrial biota occurred with the growth of the polar ice sheets and the change to the polar desert climate.     

Deep phylogenetic divergence between Scolytoplatypus and Remansus,a new genus of Scolytoplatypodini from Madagascar (Coleoptera,Curculionidae, Scolytinae)

Scolytoplatypodini Blandford is a monotypic tribe of ambrosia beetles found in Asia, Madagascar and Africa. Only three species are currently known from Madagascar and four additional species are here described as new to science. Phylogenetic analyses of morphological and molecular data revealed that four of the seven endemic species are deeply separated from all other species by genetic and distinct morphological characters and therefore placed in a new genus Remansus Jordal. The split between this ancient lineage and Scolytoplatypus Schaufuss was estimated to approximate Palaeocene age (63 Ma), extending the minimum age of ambrosia feeding for this tribe to the beginning of the Palaeocene‒Eocene thermal maximum (PETM). In addition to the ancient origin of Remansus in Madagascar during the Palaeocene, a second origin occurred in Scolytoplatypus no more than 13 Ma. A geographical origin of the latter in South-Eastern Africa was unequivocally inferred from the phylogenies.     

The Seed-Head Weevil,Larinus Latus Herbst (Coleoptera: Curculionidae) as a New Record in Egypt on the Milk Thistle,Silybum Marianum (L.) (Asteraceae: Compositaea)

The seed-head weevil, Larinus latus Herbst (Coleoptera: Curculionidae) was recorded for the first time in Egypt on the milk thistle, Silybum marianum (L.) (Asteraceae: Compositaea), which is considered as a weed in certain winter field crops and as a herb with medical importance. The general morphology and biology of this insect pest as well as the host plant were described.     

Survival of boll weevil （Coleoptera： Curculionidae） adults after feeding on pollens from various sources

The survival of overwintering boll weevil, Anthonomus grandis grandis （Boheman）, adults on non-cotton hosts in the Lower Rio Grande Valley （LRGV） of Texas was examined from 2001 to 2006. The success of the Boll Weevil Eradication Program, which was reintroduced into the LRGV in 2005, depends on controlling overwintering boll weevil populations. Laboratory studies were conducted using boll weevil adults that were captured in pheromone traps from September through March. The number of adults captured per trap declined significantly in the field from fall to the beginning of spring （3.5-7.0-fold）. The proportion of trapped males and females did not differ significantly. The mean weight of boll weevil adults captured in September was 13.3 mg, while those of captured adults from November to February were significantly lower and ranged from 6.7 to 7.8 mg. Our results show that boll weevil adults can feed on different plant pollens. The highest longevity occurred when adults were fed almond pollen or mixed pollens （72.6 days and 69.2 days, respectively） and the lowest when they fed on citrus pollen or a non-food source （9.7 days or 7.4 days, respectively）. The highest adult survival occurred on almond and mixed pollens [88.0%-97. 6% after 1st feeding period （10 days）, 78.0%-90.8% after 3rd feeding period （10 days）, 55. 0%-83.6% after 5th feeding period （10 days）, and 15.2%-32.4% after lOth feeding period （10 days）]. The lowest adult survival occurred on citrus pollen [52.0%-56.0% after 1st feeding period （10 days）, 13.3% after 3rd and 5th feeding periods （10 days）, and 0 after 6th feeding period （10 days）]. Pollen feeding is not a behavior restricted to adult boll weevils of a specific sex or physiological state. Understanding how boll weevil adults survive in the absence of cotton is important to ensure ultimate success of eradicating this pest in the subtropics.     

Larinus berti sp. n. (Coleoptera,Curculionidae, Lixinae) from North Africa

A new species, Larinus berti sp. n. is described from Morocco and assigned to subgenus Cryphopus Petri, 1907 (Curculionidae: Lixinae; Lixini). Diagnostic characters of the new species are large size, elongate-ovate body, bisulcate sub-quadrangular rostrum, triangularly raised dorsum of rostrum, flat subgena and submentum, Y-shaped apodeme of sternite VIII of female and thin nodulus of spermatheca.     

Comparative nutritional ecology of bryophyte and angiosperm feeders in a sub-Antarctic weevil species complex (Coleoptera: Curculionidae)

Abstract.

• 1 Highly productive and st,ructurally diverse angiosperm communities occur on sub-Antarctic Marion Island, yet cryptogams are the main source of energy and nutrients for five of the six native weevil species (Curculionidae: Ectemnorhinini) that occur there.
• 2 Previously it has been hypothesized that low-temperature regimes, during the Pleistocene, precluded angiosperm herbivory. This hypothesis was based, inter alia, on the assumption that at low temperatures feeding on bryophytes is more nutritionally advantageous than feeding on vascular plants.
• 3 This assumption was tested by comparing the consumption rate (CR) and approximate digestibility (AD) (mass and energy) of bryophytes and angiosperms in two Dusmoecetes species indigenous to Marion Island.
• 4 The approximate digestibility of Blepharidophyllum densifolium (Scapaniaceae) energy and dry mass were similar for D.marioni Jeannel adults at 5°C and at 10°C. D.similis (C. O. Waterhouse) adults fed Azorella selago Hook (Apiaceae) leaves also had similar AD for food dry mass and energy at 5°C and at 10°C. However, the performance of D.similis on A.selago leaves and flowers at 5°C was better than that of D.marioni on bryophytes at both temperatures.
• 5 Bryophyte feeding does not appear to be nutritionally more advantageous at low temperatures in the sub-Antarctic, nor does angiosperm herbivory appear to be comparatively disadvantageous at low temperatures, although D.similis does not feed on Acaena magellanica (Lam.) (Rosaceae) at 5°C. It seems likely that moss-feeding evolved in response to an absence of angiosperms during glacial periods, rather than because of a nutritional advantage associated with bryophagy at low temperatures.

     

The ultrastructure and function of follicle cells in Foucartia squamulata (Herbst) (Curculionidae)

Summary The follicle cells of Foucartia squamulata are involved in the formation of both vitelline membrane and chorion. Precursors for these egg coverings are synthesized by the rough endoplasmic reticulum and condensed within dictyosomes. The vitelline membrane and the chorion appear on the oocyte surface simultaneously, which is an unusual phenomenon for insects. The follicular epithelium has not been found to contribute to vitellogenesis in the species under study.