Morphological and developmental analysis of peripheral antennal chemosensory sensilla and central olfactory glomeruli in worker castes of Camponotus compressus (Fabricius, 1787)

The antennal lobes of different castes of the ant species Camponotus compressus show a marked diversity in the organization of their olfactory glomeruli. Notably, there is a significant difference in the number and size of glomeruli between the reproductives and the workers and among the different worker castes. In this report, we investigate the notion that these caste-specific differences in glomerular number might be accounted for, at least in part, by the differences in numbers of olfactory sensilla that target the antennal lobe. For this, we examine the number of sensilla on the antennal flagella of all the individual castes of C. compressus. This analysis reveals a striking correlation between sensillar number and the number of antennal glomeruli in a given caste. As a first step in investigating the causal mechanisms that might give raise to this correlation, we carry out an initial characterization of olfactory system development in the minor workers of C. compressus. We analyze the temporal pattern of innervations of the developing antennal lobe by olfactory sensory neuron axons. We document the development of the olfactory glomeruli in the antennal lobe during this process, which occurs during early pupal stages. Our findings provide the basis for future manipulative developmental studies on the role of sensory afferent number in glomerular development of different castes within the same species.     

Characterization of 8 polymorphic microsatellite loci in the neotropical ant-garden ant, Camponotus femoratus (Fabricius)

Camponotus femoratus is an abundant and behaviorally dominant ant in lowland Amazonian rainforests, where this species participates in a complex and obligate seed-dispersal mutualism. C. femoratus typically cohabits with another ant species Crematogaster levior in an apparently amiable but poorly understood interaction. Despite these outstanding characteristics, the population genetics and dispersal patterns of C. femoratus are unknown. We isolated eight polymorphic microsatellite loci for C. femoratus from a genomic library enriched for di-, tri-, and tetra-nucleotide repeats. We detected 2 to 17 alleles per locus, with levels of observed heterozygosity ranging from 0.286 to 0.714.     

Comparative dynamics of gestalt odour formation in two ant species Camponotus fellah and Aphaenogaster senilis (Hymenoptera: Formicidae)

Abstract. Ant colonies experience continuous shifts in worker populations, which may affect odour composition in the nest. A major question regarding the dynamics of gestalt formation is that of the speed at which the scent of a new individual will be incorporated into the gestalt. It is predicted from the gestalt model of colony odour that workers have to exchange recognition cues continuously to maintain themselves within the gestalt and become well integrated within their colony. Using radioactive tracers the rates of transfer were measured between a labelled donor ant and one or 10 recipient ants, as a close approximation to the within-nest situation. The labelled hydrocarbons were first transferred to a small number of individuals and progressively to all the individuals of the group so that the distribution of hydrocarbon transfer rate approached a normal distribution. Furthermore, in Camponotus fellah Dalla Torre, which performs trophallaxis, homogeneity was reached more rapidly than in Aphaenogaster senilis Mayr, which does not show this behaviour. In the latter species, the gestalt seems to be maintained mainly by allogrooming. These experiments were accompanied by behavioural observations to ascertain the respective importance of trophallaxis and allogrooming in the behavioural time-budget of the ants. In A. senilis , allogrooming was more frequent than in ants that trophallax, which corroborates the role of allogrooming in the establishment of the gestalt in this species.     

A peculiar case of parasitisation with two new species of wasps parasitizing the rice leaf-roller Pelopidas mathias (Fabricius, 1798) (Lepidoptera: Hesperiidae) from southern India

Systematic Parasitology - Paddy, Oryza sativa L. (Poales: Poaecea) is infested by a series of lepidopteran, coleopteran, hemipteran, and acarine pests in India. Of the long list, the species Rice...     

Social organisation and interspecific interactions in two sympatric species of Ranidella (Anura)

Summary The socio-spatial organisation of two sympatric species of anurans was investigated by analyses of the spatial and temporal structure of breeding assemblages. Ranidella signifera breeds earlier in the year than its congener, R. parinsignifera, though there is an overlap of 6 to 8 weeks. Males of both species show high affinities for discrete spatial locations (preferred calling stations). These stations are regularly-spaced, and temporally-stable. Satellite behaviour occurs, though most satellites are past or future residential males. There appears to be a spatial-energetic limit to the number of calling residents of both species that a pond can support. There is no differentiation of calling sites between the two species, and the males of R. parinsignifera appear to displace their congeners from the preferred stations located on the land/water interface of ponds. The breeding season of R. signifera in sympatry is abbreviated relative to nearby (20 km) allopatric localities. The breeding seasons of conspecific males and females are well-synchronised, though the ratio of males to females is high early in the breeding season.     

Foraging patterns in three sympatric forest ant species, Prenolepis imparis, Paratrechina melanderi and Aphaenogaster rudis (Hymenoptera: Formicidae)

Abstract.

• 1 Ecological segregation was studied in Aphaenogaster rudis Emery, Paratrechina melanderi (Wheeler) and Prenolepis imparis (Say), the three commonest surface-foraging ants in a Maryland (U.S.A.) hardwood forest community.
• 2 P.imparis retreats from the surface during mid-summer, but shows more cool-season activity than do the other two species. P.melanderi is most active during the warmest months of the years. A.rudis is the most generalized of the three species in its seasonal activity pattern.
• 3 P.imparis is a highly aggressive species which forms large mobilizations at rich food sources. P.melanderi is a timid species which forms small mobilizations. A.rudis is intermediate in both respects.
• 4 Based on the results of baiting trials, P.imparis shows an apparent preference for protein-fat food, P.melanderi prefers carbohydrate food, and A.rudis exhibits no significant preference for either fclod type.
• 5 As a result of its extended seasonal activity, weak circadian periodicity, and lack of food specialization, A.rudis has the broadest annual niche of the three species studied.
• 6 The unusual seasonal activity pattern of P.imparis results in a relatively low degree of annual niche overlap between this species and either of the other two. Overlap between A.rudis and P.melanderi is substantially higher.
• 7 Experimental manipulations confirm that rates of resource removal by a behaviourally subordinate species (Amdis) are reduced in the presence of a dominant species (P.imparis).
• 8 Persistence of these three widespread, abundant, relatively generalized ant species in local sympatry may in part reflect their differential success in: (a) finding food, (b) defending food, and (c) handling food items of different sizes.

     

The use of the anaesthetic, enflurane, for determination of metabolic rates and respiratory parameters in insects, using the ant, Camponotus maculatus (Fabricius) as the model

This study investigated the effects of the anaesthetic, enflurane, on metabolic rates and ventilation patterns in the spotted sugar ant, Camponotus maculatus, using flow-through respirometry. The standard metabolic rate was not affected by the anaesthetic. While the ants were anaesthetised they exhibited a similar discontinuous gas exchange cycle to that observed when they were voluntarily motionless, but their spiracles remained open for a longer time during the open or burst phase even though the amount of CO(2) emitted during this phase remained constant. We discuss this finding in the context of the central nervous system control of the spiracle muscle. For both the determination of standard metabolic rate and ventilation patterns the individual ant has to be motionless. From this study we recommend the use of enflurane to ensure immobility in ants, and other small active insects, during the determination of standard metabolic rates, but the anaesthetic cannot be used to quantify the respiration pattern.     

Ovary organization and oogenesis in two species of Lumbriculida (Annelida,Clitellata)

The aim of the present study is to describe the organization of the ovary and mode of oogenesis at the ultrastructural level in two representatives of Lumbriculida – Lumbriculus variegatus and Stylodrilus heringianus. In both species studied, the ovaries are small and conically shaped structures that are attached to the intersegmental septum via a thin ligament. The ovaries are composed of germline cysts formed by germ cells interconnected by stable cytoplasmic bridges. As a rule, the cyst center is occupied by a poorly developed anuclear cytoplasmic mass, termed a cytophore, whereas the germ cells are located at the periphery of the cyst. Germline cysts are enveloped by somatic cells. The ovaries of the species studied are polarized, i.e., along the long axis of the ovary there is an evident gradient of germ cell development. The data obtained suggest ovary meroism, i.e., two categories of germ cells were found: oocytes, which continue meiosis, gather nutrients, grow and protrude into the body cavity, and nurse cells, which do not grow and are supposed to supply oocytes with cell organelles and macromolecules via the cytophore. The ovary structure and mode of oogenesis in the species studied were compared with those of other clitellate annelids. As a rule, in all clitellates studied to date, the ovaries are composed of germline cysts equipped with a cytophore and associated with somatic cells; however, the ovary morphology differs between taxa regarding several quantitative and qualitative features. The ovary organization and mode of oogenesis in L. variegatus and S. heringianus strongly resemble those found in Tubificinae and Branchiobdellida studied to date. Our results also support a sister-group relationship between Lumbriculida and a clade comprising ectoparasitic clitellates (i.e., Branchiobdellida, Acanthobdellida and Hirudinida) with Branchiobdellida as a plesiomorphic sister group to Acanthobdellida and Hirudinida.     

Demonstration of interspecific competition between two sympatric egg parasitoids of Riptortus pedestris (Fabricius) in laboratory condition

Ooencyrtus nezarae Ishii (Hymenoptera: Encyrtidae) acts as a facultative hyperparasitoid of Gryon japonicum (Ashmead) (Hymenoptera: Platygastridae) sympatric parasitoid of Riptortus pedestris (Fabricius) (Hemiptera: Alydidae). A longer period of host egg exploitation by both parasitoid species would be beneficial for O. nezarae, while G. japonicum tends to be successful when the parasitoids have only a short exploitation period. We demonstrated the interspecific competition by measuring parasitism in nine combinations of host densities (10, 20, and 40 eggs) and exploitation times (1, 3, and 5 days). To reflect the gregarious-solitary dichotomy of the two species, three O. nezarae and one G. japonicum mated females were compared in addition to a one-to-one competition design. We found that O. nezarae was the better competitor when exploitation time was longer than 1 day, irrespective of host density. Total parasitism rate and progeny emergence of O. nezarae were 1.6–2.8 and 4.7–7.3 times higher than for G. japonicum in three-to-one competition design, respectively. Although G. japonicum females were more effective in host finding (as shown by their higher per capita rate of parasitism when exploitation time was short), their progeny suffered high mortality from the larval interspecific competition inside multiparasitized host eggs. These results suggest that gregarious O. nezarae is the superior competitor when host eggs are available for longer period of time while solitary G. japonicum is superior when host resources are available for only a limited time.     

Quaternary refugia in southwestern Iran: insights from two sympatric moth species (Insecta, Lepidoptera)

Alternating glacial and interglacial periods led to range shifts (contractions and expansions), persistence in distinct glacial refugia and extinction events in various temperate organisms. Today, the integrative analysis of molecular markers and spatial distribution models conducted for multiple taxa allows the detection of phylogeographical patterns, thus reconstructing major biogeographical events in their shared evolutionary history. In this study, the effects of past climate change on the evolutionary history of two sympatric moth species (Gnopharmia colchidaria s.l. and G. kasrunensis) and their host plants (Prunus scoparia and P. fenzliana) were inferred for the largely neglected biodiversity hot spot Iran. We complementarily analyzed the population structure of both moth species (187 specimens, based on COI) in congruence with batched species distribution models (SDMs) for all four taxa and for the times of the Last Glacial Maximum (21 ky BP), 6 ky BP and today. Coincidence of SDMs and the distribution of haplotype lineages indicated a shared refugium for the southwestern Zagros Mountains and potential species-specific refugial areas in the southern Caucasus and the Kope-Dagh Mountains. Both moth species experienced past population expansion.     

Parallel occurrence of asynaptic sex chromosomes in gray voles (Microtus Schrank, 1798)

In many eutherian species, pairing and recombination of X and Y chromosomes are indispensable for normal meiotic progression and correct segregation of sex chromosomes. The rodent subfamily Arvicolinae provides an interesting exception. The majority of arvicoline species with asynaptic sex chromosomes belong to the genus Microtus sensu lato. However, some vole species of the genus Microtus and other genera display normal X-Y pairing in meiosis. These observations indicate that synaptic condition was typical for the common ancestor of all voles, but the gaps in taxonomic sampling makes impossible to identify a lineage or lineages, in which the asynapsis occurred. The methods of electron and fluorescent microscopy were used to study the synapsis of sex chromosomes in males of some additional species of the subfamily Arvicolinae. This extended taxonomic list allowed us to identify asynaptic species in every large lineage of the tribe Microtini. Apparently, the ability of sex chromosomes to pair and recombine in male meiosis was lost in arvicoline evolution for at least three times independently. Our results indirectly suggest the unnecessity of sex chromosome pairing in male meiosis of arvicoline rodents, and presence of alternate molecular mechanism of sex chromosome segregation in this large mammalian tribe.     

Flexibility of first brood production in a claustral ant, Camponotus japonicus (Hymenoptera: Formicidae)

The numbers of first-batch eggs and workers (minims) in a carpenter ant Camponotus japonicus are not fixed but are regulated in response to various internal and external factors of founding queens. The initial body weight of founding queens was positively correlated with the number of minims. The amount of queen weight loss during the founding period was highly correlated with the number of minims. The numbers of first-batch eggs and minims for artificially fed queens were significantly greater than those for control group queens and for unfed queens, respectively. The number of eggs laid by a queen increased when eggs deposited in the early stage of founding were removed. In contrast, artificial addition of alien eggs reduced the number of eggs laid by a queen. The adaptive implications of this flexibility in the production of the first-batch brood in C. japonicus are discussed. Received: December 18, 2000 / Accepted: March 19, 2001     

The anatomy and histology of the midgut and hindgut of Charybdis (Goniohellenus) truncata (Fabricius, 1798) (Decapoda: Brachyura)

The midgut of C. (G.) truncata accounts for half of the postgastric intestinal tract. The paired anterior midgut caeca arise just behind the pyloric stomach, on either side of the midgut. The unpaired posterior midgut caecum arises dorsally at the rear end of the midgut, where this joins the hindgut. The midgut and its caeca help in the digestive absorption of food. The hindgut is of ectodermal origin and is lined with chitin of a collagenous nature. The connective tissue of the anterior part of the hindgut is packed with tegumental glands whose secretion contains both sulphated and weakly acidic mucosubstances, which facilitate the passage of faecal matter and help to bind food particles. The digestive gland - the hepatopancreas - opens into the anterior part of the midgut, below the anterior midgut caeca. Histologically, its tubules contain three different types of cells - "F", "R" and "B" cells.     

Natural hybridization and introgression in sympatric Ligularia species (Asteraceae, Senecioneae)

The difficulty in clarifying species of genus Ligularia Cass.has been attributed to rapid and continuous allopatric speciation in small and isolated populations,combined with interspecific diploid hybridization in the Qinghai-Tibetan Plateau and adjacent areas.However,no concrete example has been reported to prove this hypothesis.We studied a natural mixed population of six species of Ligularia in which some individuals were morphologically intermediate between L.subspicata and L.nelumbifolia.Based on DNA sequences (trnC-E trnL-rpL32,trnQ5'rpsl6,trnK-rpsl6,and internal transcribed spacer) and inter-simple sequence repeat data,we concluded that putative hybrids are primarily products of hybridization between L.nelumbifolia and L.subspicata.The other four species or additional,unknown species may also be involved in hybridization.This hybridization is bidirectional but asymmetrical.Hybrid individuals were mostly the first generation,but F2 and later-generation hybrids were also present.Moreover,the backcrossed individuals detected indicate that natural gene flow occurs among at least three Ligularia species.Hybrids may become stabilized to form new species or may function as intermediates in evolutionary diversification.     

Quantitative studies of the mating system in two sympatric species of Ipomoea (Convolvulaceae)

The rates of outcrossing in sympatric populations of Ipomoea purpurea and I, hederacea were estimated (using electrophoretic markers) to be 70% and 7% respectively. The difference in outcrossing rate is not apparently due to differences in pollinator service received by the species, but is associated with differences in anther-stigma distance. In I. purpurea stigmas are generally exserted and there is much genetic variation for anther-stigma distance. Variation in this character has a significant effect on the ease with which selfpollination occurs. In contrast there is no variation for the character in the I. hederacea population, the anthers being invariably held at the same level as the stigma, an arrangement promoting self-pollination.     

Crossfostered drones ofApis cerana (Fabricius, 1793) andApis koschevnikovi (Buttel-Reepen, 1906) fly at their species specific mating times

Summary Reciprocal transfer of sealed drone brood between colonies ofApis cerana andApis koschevnikovi was successful and resulted in four colonies (two of each species) with a mixed drone population. Flights ofApis cerana drones occurred between 14.00 and 16.15 regardless whether they were in a conspecific or alien colony.Apis koschevnikovi drones also flew at their species specific time from 16.45 to 18.30. A variance estimation revealed that 99.4% of the total variance depended on the species of the drone. In contrast to theApis drone's general biological dependence upon the colony, crossfostered drones ofApis cerana andApis koschevnikovi showed an unexpected autonomy in chosing their mating flight time.     

Diapause termination in two species of tropical butterfly, Euploea core (Cramer) and Euploea sylvester (Fabricius) (Lepidoptera: Nymphalidae)

Abstract This study examined the factors used as cues for diapause termination by two Euploea species. Euploea core and E. sylvester were collected from two overwintering sites at Chillagoe, Queensland. Under tropical wet-season conditions, more butterflies terminated diapause (approximately 60%) than those kept under dry-season conditions (approximately 40%). However, 100% diapause termination occurred only when butterflies were kept under wet-season conditions and were fed with honey. For reproductive success, Euploea species need to terminate diapause rapidly to synchronise oviposition with fresh, rapid growth of their larval host plants, which often occurs after rain. The presence of rainfall, increased temperature and long days alone is not a fail-safe set of cues for this event. Our results suggest that food (as nectar), in conjunction with these combined environmental factors, provide Euploea species with a reliable signal that larval host resources are available for oviposition.     

Relative importance of ballistic and ant dispersal in two diplochorous Viola species (Violaceae)

Viola is one of the diplochorous plant genera that disperse their seeds in two ways, ballistic and ant dispersal. We compared the seed dispersal of two major Viola species of northern Japan, V. selkirkii and V. verecunda. The mean weight of seed was less in V. verecunda (0.42 ± SD 0.03 mg) than in V. selkirkii (0.61 ± 0.12 mg). The elaiosome of V. selkirkii (0.02 ± 0.004 mg) was larger than in of V. verecunda (0.006 ± 0.0004 mg), whereas the lipid component of elaiosome was not remarkably different between the two species. In ballistic dispersal, the mean dispersal distance was 56.0 ± 17.5 cm in V. verecunda but only 38.3 ± 5.1 cm in V. selkirkii. In ant dispersal, the mean dispersal distance was 28.1 ± 24.9 cm in V. selkirkii and 36.1 ± 33.7 cm in V. verecunda; however, the seed removal frequency of V. selkirkii (15.5%) was much higher than that of V. verecunda (3.0%). These results suggest that V. selkirkii is more dependent on ant dispersal while V. verecunda is more dependent on ballistic dispersal. The effect of seed predation was very serious in both species. In the quadrat census, 99.0% of V. selkirkii seeds and 99.1% of V. verecunda seeds were damaged by ground beetles, spiders, ticks, and others which frequently devoured diaspores. An experiment with V. verecunda seeds demonstrated that the overdispersion of seeds on the forest floor enhanced the frequency of removal by ants and reduced seed damage by predators.