Performance of the tsetse, Glossina morsitans morsitans reared under various feeding regimens in Zambia

Groups of Glossina morsitans morsitans Westwood fed at emergence and thereafter daily, every second or third day respectively, up to the end of their first pregnancy cycle, survived well (73–79%) and produced virtually the same number of puparia/ (0.83–0.85) in the same puparial weight class (23–24 mg). However, adult survival (29%), number of puparia/ (0.30) and puparial weight (19 mg) were much lower in the group consistently fed every 4th day after the initial meal at emergence. It is proposed that tsetse colonies could be fed on Mondays, Wednesdays and Fridays without jeopardising adult survival, puparial production/ and the size (weight) of puparia produced.

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Performances en Zambie de la mouche Tsé-Tsé (Glossina morsitans morsitans) élevée en utilisant différents régimes alimentaires

Résumé Afin d'estimer si une alimentation quotidienne de G. morsitans morsitans présente un avantage sur une alimentation moins fréquente, nous avons enrigestré la survie des adultes, la production et le poids des pupes chez des individus nourris à l'émergence et, ensuite, tous les jours ou tous les 2, 3 ou 4 jours. Les femelles alimentées quotidiennement, ou tous les 2 ou 3 jours, ont produit le même nombre de pupes (0,83–0,85), avec des poids de même ordre (23–24 mg), et avec une aussi bonne survie (73 à 79%). Alimentées tous les 4 jours, elles ont produit 0,30 pupe/femelle, pesant 19 mg/pupe et avec une plus faible survie (29%). Ces résultats montrent qu'il est inutile de nourrir les mouches chaque jour au lieu de tous les 2 ou 3 jours. Cependant une alimentation à des intervalles supérieurs à 3 jours, a eu des conséquences clairement défavorables. Ainsi, peuvent être considérablement réduits et le travail et le coût des élevages, sans porter préjudice à la production, en alimentant les mouches 3 fois par semaine, par ex. les lundis, mercredis et vendredis.

     

Tsetse mating behaviour: effects of age and hunger in Glossina morsitans morsitans and G.pallidipes

ABSTRACT. The effects of age and hunger on the responses of male Glossina morsitans morsitans Westwood and G.pallidipes Austen to freeze-killed female decoys, were examined in the laboratory. In both species, activity, estimated as the total number of interactions between males and decoys, increased with both age and hunger. Interactions were divided into short-stay (<60 s) and long-stay, full copulatory responses. In both species, young, unfed males were significantly less likely to attempt to copulate with a decoy after encounter than were fed males. Among fed males the proportion of interactions that proceeded to full copulatory attempts did not change with increasing age, but decreased consistently with increasing hunger. At all ages and hunger levels, G.pallidipes were more active than G.m.morsitans. However, after encountering a decoy, G.pallidipes were less likely to attempt to copulate than G.m.morsitans. In both species the duration of copulatory attempts did not change with age, but declined with increasing hunger. Copulatory attempts by G.pallidipes were significantly shorter than those of G.m.morsitans. The results are discussed in relation to the behaviour of tsetse in response to control devices such as traps and targets.     

Horizontal transmission of mycotic infection in adult tsetse,Glossina morsitans morsitans

AdultGlossina morsitans morsitans exposed to wet conidia ofBeauveria bassiana andMetarhizium anisopliae suffered high mortalities ranging from 90 to 100% by 2 weeks post-exposure. Infected ♂ ♂ maintained in the same cages with non-infected ♀♀ throughout the experimental period transmitted the fungal infection to the ♀♀ resulting in mortalities of 65% withB. bassiana and 55% withM. anisopliae. Likewise, infected ♀♀ maintained together with non-infected ♂♂ transmitted the infection to the ♂♂ resulting in mortalities of 75% withB. bassiana and 45% withM. anisopliae. Female tsetse flies infected withB. bassiana andM. anisopliae and maintained in the same cages with non-infected ♀♀ also transmitted infection to the non-infected tsetse resulting in mortalities of 62% and 48% withB. bassiana andM. anisopliae respectively. Infected tsetse exposed to non-infected tsetse of the opposite sex for only 30 min were also able to transmit the fungal infection. Pupae produced by female tsetse infected withB. bassiana andM. anisopliae exhibited higher pupal mortality than those produced by non-infected ♀♀. However, pupae exposed directly to dry spores ofB. bassiana andM. anisopliae had no increase in pupal mortality but adults emerging from theB. bassiana-exposed pupae had markedly reduced longevity.      

Pheromone perception in the tsetse fly Glossina morsitans morsitans

The perception of cuticular female sex pheromone (15, 19, 23-trimethylheptatriacontane=morsilure) in Glossina m. morsitans was studied electrophysiologically and behaviourally. Electrophysiological studies indicated no sensitivity of the tibial sensilla or the contact chemoreceptive hairs on the legs of males to the pheromone. However, electroantennograms were recorded during stimulation of antennae from male flies with the odour of morsilure, which indicated that the pheromone is detected by the insect via olfactory receptors on the antennae. This was further confirmed by behavioural experiments in which the antennal movements of intact males stimulated with the odour of both synthetic pheromone and female decoys were studied. Behavioural responsiveness to morsilure increased with increasing starvation and was not due to a general sensitivity to paraffins. These studies indicate that tsetse flies may be able to recognize conspecifics at close range using their sense of olfaction.

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Résumé La perception de la phéromone sexuelle des femelles de Glossina m.morsitans, la morsilure (15, 19, 23-triméthylheptatriacontane) a été examinée par électrophysiologie et par le comportement. L'électrophysiologie n'a pas révélé de sensibilité des sensilles tibiales, ni des poils chimioréceptives de contact sur les pattes des mâles à la phéromone. Cependant, les électroantennogrammes recueillis pendant la stimulation des antennes des mâles par l'odeur de morsilure, ont montré que la phéromone est décelée par l'insecte grâce aux récepteurs olfactifs des antennes. Ceci a été confirmé ultérieurement par des expériences de comportement au cours desquelles ont été examinés les mouvements antennaires de mâles intacts stimulés par l'odeur de phéromone synthétique et de femelles.La réponse comportementale à la morsilure a augmenté avec le jeûne, elle n'était pas due à une sensibilité générale aux paraffines.Ces études montrent que les mouches tsé-tsé peuvent être capables de reconnaître leurs congénères à faible distance grâce à l'olfaction.

     

The effect of host odour on the landing responses of tsetse flies (Glossina morsitans morsitans) in a wind tunnel with and without visual targets

Abstract The effect of artificial host odour on the landing responses of males of Glossina m.morsitans West, and on their reaction to visual targets has been investigated in a wind tunnel. Landing was induced in flies that traversed steep odour gradients as they flew upwind and downwind across the edge of an odour plume, irrespective of whether visual targets were present or not; the landing response could be elicited over a wide range of odourconcentrations. When targets were present such odour gradients also tended to increase the proportion of landing flies which alighted on or near the targets; and the bigger the target, or the hungrier the flies, the greater was the propensity for target landing. In air which was more uniformly permeated with odour, the propensity to land on targets was increased only at high odour concentration.     

Polytene chromosome maps in four species of tsetse flies Glossina austeni, G. pallidipes, G. morsitans morsitans and G. m. submorsitans (Diptera: Glossinidae): a comparative analysis

Photographic polytene chromosome maps from pupal trichogen cells of four tsetse species, Glossina austeni, G. pallidipes, G. morsitans morsitans and G. m. submorsitans were constructed and compared. The homology of chromosomal elements between the species was achieved by comparing banding patterns. The telomeric and subtelomeric chromosome regions were found to be identical in all species. The pericentromeric regions were found to be similar in the X chromosome and the left arm of L1 chromosome (L1L) but different in L2 chromosome and the right arm of L1 chromosome (L1R). The L2 chromosome differs by a pericentric inversion that is fixed in the three species, G. pallidipes, G. morsitans morsitans and G. m. submorsitans. Moreover, the two morsitans subspecies appeared to be homosequential and differ only by two paracentric inversions on XL and L2L arm. Although a degree of similarity was observed across the homologous chromosomes in the four species, the relative position of specific chromosome regions was different due to chromosome inversions established during their phylogeny. However, there are regions that show no apparent homology between the species, an observation that may be attributed to the considerable intra—chromosomal rearrangements that have occurred following the species divergence. The results of this comparative analysis support the current phylogenetic relationships of the genus Glossina.     

Patterns of genetic diversity and differentiation in the tsetse fly <Emphasis Type="Italic">Glossina morsitans morsitans</Emphasis> Westwood populations in East and southern Africa

Genetic diversity and differentiation within and among nine G. morsitans morsitans populations from East and southern Africa was assessed by examining variation at seven microsatellite loci and a mitochondrial locus, cytochrome oxidase (COI). Mean COI diversity within populations was 0.63 ± 0.33 and 0.81 taken over all populations. Diversities averaged over microsatellite loci were high (mean number of alleles/locus ≥7.4; mean H _E ≥ 65%) in all populations. Diversities averaged across populations were greater in East Africa (mean number of alleles = 22 ± 2.6; mean h _e = 0.773 ± 0.033) than in southern Africa (mean number of alleles = 18.7 ± 4.0; mean h _e = 0.713 ± 0.072). Differentiation among all populations was highly significant (R _ST = 0.25, F _ST = 0.132). Nei’s G _ij statistics were 0.09 and 0.19 within regions for microsatellites and mitochondria, respectively; between regions, G _ij was 0.14 for microsatellites and 0.23 for mitochondria. G _ST among populations was 0.23 for microsatellite loci and 0.40 for mitochondria. The F, G and R statistics indicate highly restricted gene flow among G. m. morsitans populations separated over geographic scales of 12–917 km.     

The flight and landing of tsetse (Glossina) in response to components of host odour in the field

ABSTRACT. Studies were conducted in Zimbabwe of the responses of Glossina morsitans morsitans Westwood and Glossina pallidipes Austen to various host odours using either arrangements of electrocuting nets or visual observations. Tsetse flying upwind in a plume of carbon dioxide, acetone and octenol turned downwind upon flying into a plume of acetone or octenol, but did not turn upon flying into a plume of carbon dioxide. They also turned in response to a transient decline in odour concentration. Tsetse landed on the ground in the vicinity of a source of natural odour or artificial odour containing carbon dioxide but not at sources of acetone or octenol only. The proportion of female G.pallidipes caught at a source of natural odour (37%) was significantly different from that caught at a source of synthetic odour (17%). Resting tsetse stimulated by natural odour took off sooner than non-stimulated flies and had a strong upwind bias in the direction of take off. Tsetse stimulated with artificial odour did not take off sooner than non-stimulated flies. It is suggested that there is an unidentified components) of ox odour that activates resting tsetse.     

Genetic architecture of a feeding adaptation: garter snake (Thamnophis) resistance to tetrodotoxin bearing prey

Detailing the genetic basis of adaptive variation in natural populations is a first step towards understanding the process of adaptive evolution, yet few ecologically relevant traits have been characterized at the genetic level in wild populations. Traits that mediate coevolutionary interactions between species are ideal for studying adaptation because of the intensity of selection and the well-characterized ecological context. We have previously described the ecological context, evolutionary history and partial genetic basis of tetrodotoxin (TTX) resistance in garter snakes (Thamnophis). Derived mutations in a voltage-gated sodium channel gene (Na_v1.4) in three garter snake species are associated with resistance to TTX, the lethal neurotoxin found in their newt prey (Taricha). Here we evaluate the contribution of Na_v1.4 alleles to TTX resistance in two of those species from central coastal California. We measured the phenotypes (TTX resistance) and genotypes (Na_v1.4 and microsatellites) in a local sample of Thamnophis atratus and Thamnophis sirtalis. Allelic variation in Na_v1.4 explains 23 per cent of the variation in TTX resistance in T. atratus while variation in a haphazard sample of the genome (neutral microsatellite markers) shows no association with the phenotype. Similarly, allelic variation in Na_v1.4 correlates almost perfectly with TTX resistance in T. sirtalis, but neutral variation does not. These strong correlations suggest that Na_v1.4 is a major effect locus. The simple genetic architecture of TTX resistance in garter snakes may significantly impact the dynamics of phenotypic coevolution. Fixation of a few alleles of major effect in some garter snake populations may have led to the evolution of extreme phenotypes and an ‘escape’ from the arms race with newts.     

Temperature-dependence of metabolic rate in Glossina morsitans morsitans (Diptera, Glossinidae) does not vary with gender, age, feeding, pregnancy or acclimation

While variation in metabolic rate at a single temperature can occur for a variety of reasons and the effect of temperature is well established in insects, within-generation variation of metabolic rate-temperature relationships has been relatively poorly explored. In this study, we investigate the effects of gender, age, feeding and pregnancy, as well as three acclimation temperatures (19, 24, 29 degrees C), on standard metabolic rate and its temperature-dependence within post-developmental (i.e. non-teneral) adult G. morsitans morsitans. Although most of the independent variables influenced metabolic rate at a single test temperature (P<0.001 in most cases), and cold-acclimation resulted in significant up-regulation of metabolic rate at all test temperatures relative to 24 and 29 degrees C acclimation (P<0.0001), mass-independent metabolic rate-temperature relationships were surprisingly invariant over all experimental groups (P>0.05 in all cases). Slopes of log10 metabolic rate (ml CO2h(-1)) against temperature ( degrees C) ranged from a minimum of 0.03035 (+/-S.E.=0.003) in young fasted females to a maximum of 0.03834 (+/-0.004) in mature fasted males. These findings have implications for predicting the metabolic responses of tsetse flies to short-term temperature variation and may also have applications for modelling tsetse population dynamics as a function of temperature.     

Cloning, characterization and promoter analysis of S-RNase gene promoter from Chinese pear (Pyrus pyrifolia)

The 5'-flanking region of the S(12)-, S(13)-, S(21)-RNase with a length of 854 bp, 1448 bp and 1137 bp were successfully isolated by TAIL-PCR from genomic DNA from 'Jinhua', 'Maogong' (Pyrus pyrifolia) and 'Yali' (Pyrus bretschneideri) genomic DNA. Sequence alignment and analysis of S(13)-, S(12)-, S(21)-RNase gene promoter sequences with S(2)-, S(3)-, S(4)-, S(5)-RNase 5'-flanking sequences indicated that a homology region of about 240 bp exists in the regions just upstream of the putative TATA boxes of the seven Chinese/Japanese pear S-RNase genes. Phylogenetic tree suggests that the homology region between the Chinese/Japanese pear and apple S-RNase gene promoter regions reflects the divergence of S-RNase gene was formed before the differentiation of subfamilies. Full length and a series of 5'-deletion fragments-GUS fusions were constructed and introduced into Arabidopsis thaliana plants. GUS activity were detected in S(12)-pro-(1 to 5)-GUS-pBll01.2 transgenic pistils and progressively decreased from S(12)-pro-1-GUS-pBI l01.2 to S(12)-pro-5-GUS-pBll01.2. No GUS activity was detected in S(12)-pro-6-GUS-pBll01.2 transgenic pistil and other tissues of non-transformants and all transgenic plants. The result suggested S(12)-RNase promoter is pistil specific expression promoter.     

Extreme male leg polymorphic asymmetry in a new empidine dance fly (Diptera: Empididae)

A new dance fly (Empididae: Empidinae) with hugely modified male fore tarsus, either on the right, left, both or neither sides, is described from Japan. Such massive polymorphic asymmetry occurring with so high an incidence in a population is previously unreported. In view of the courtship behaviour of other Empidinae, we hypothesize that the oversized tarsus is a secondary sexual character employed by males for attracting females. Alternative hypotheses are also discussed. We suggest that this extraordinary new species is a potential model for the study of mating biology in Empidinae and the evolution of mating systems in general.     

Introgressive hybridization as a promoter of genome reshuffling in natural homoploid fish hybrids (Cyprinidae,Leuciscinae)

Understanding the mechanisms underlying diversification and speciation by introgressivehybridization is currently one of the major challenges in evolutionary biology. Here, theanalysis of hybridization between two pairs of Iberian Leuciscinae provided new data onindependent hybrid zones involving Achondrostoma oligolepis (AOL) andPseudochondrostoma duriense (PDU), and confirmed the occurrence of hybridsbetween AOL and Pseudochondrostoma polylepis (PPO). A multilevel survey combiningmorphological, genetic and cytogenomic markers on a vast population screening successfullysorted the selected fishes as admixed. Results were similar in both AOL × PDU andAOL × PPO systems. Overall, hybrid morphotypes, cytogenomic data and geneticprofiling indicated preferential backcrossing and suggested AOL as a major genomiccontributor. Moreover, results implied AOL as more permissive to introgression than PDU orPPO. Although PDU- and PPO-like individuals appeared more resilient to genomemodifications, AOL appeared to be more involved and affected by the ongoing hybridizationevents, as chromosomal translocations were only found in AOL-like individuals. All hybridsanalysed evidenced extensive ribosomal DNA (rDNA) polymorphism that was not found inparental species, but usually seen falling within the range of possible parentalcombinations. Yet, transgressive phenotypes that cannot be explained by normalrecombination, including more rDNA clusters than expected or the occurrence of syntenicrDNAs, were also detected. Present results proved rapid genomic evolution providing thegenetic novelty for species to persist. In addition, although the ultimate consequences ofsuch apparently extensive and recurrent events remain unknown, modern genome-widemethodologies are of great promise towards answering questions concerning the causes,dynamics and impacts of hybridization.     

Phylogeographic inferences concerning evolution of Brazilian Passiflora actinia and P. elegans (Passifloraceae) based on ITS (nrDNA) variation

BACKGROUND AND AIMS: Passiflora actinia and P. elegans, two markedly parapatric species, have their southern and northern distribution limits, respectively, in the most southern part of the Brazilian Atlantic Rain Forest. Despite the fact that they are classified in different taxonomic series, previous phylogenetic studies of this genus revealed a high genetic similarity between them. The aim of the present work was to analyse in more detail their geographical range in this region of overlap, to investigate intraspecific genetic variability and phylogeographic structure, and to search for possible hybrids. METHODS: Eighty-two localities were searched for these species, and nuclear internal transcribed spacer (ITS) sequences were investigated for 32 individuals of P. actinia, 20 of P. elegans and one putative interspecific hybrid. Plastid trnL-trnF and psbA-trnH were examined for 12 plants of each species and the putative hybrid. KEY RESULTS: Both species showed a high level of intraspecific and intra-individual ITS variability. Network analysis revealed a north-south geographic gradient in their intra and interspecific relationships. Mismatch analyses suggested a recent population expansion of P. elegans. The plastid markers showed restricted variability but, together with the nuclear data, they contributed to the identification of an interspecific hybrid of intermediate morphology at the border of the distribution of these two species. Both genetic and morphological data indicate the absence of an extensive hybridization zone between these species. CONCLUSIONS: Gene flow between lineages is the possible cause for the presence of different ITS sequences within a given plant, the absence of homogenization being due to the high degree of vegetative reproduction in the two species. Differentiation of P. actinia into geographic groups and the origin of P. elegans may have been influenced by the Atlantic Forest migration towards southern Brazil. The genetic pattern of the interspecific hybrid indicates that plastid inheritance in these species is at least sometimes paternal.     

Sarcophaga (Liosarcophaga) dux (Diptera: Sarcophagidae): A flesh fly species of medical importance

Background

Although tropical climate of Thailand is suitably endowed with biodiversity of insects, flies of medical importance is not well investigated. Using information from literature search, fly survey approach and specialist’s experience, we review database of Sarcophaga (Liosarcophaga) dux Thomson (Diptera: Sarcophagidae), one of the priorities flesh fly species of medical importance in Thailand.

Results

This review deals with morphology, bionomics and medical involvement. Important morphological characteristics of egg, larva, puparia and adult were highlighted with illustration and/or micrographs. Search pertaining to molecular analysis used for fly identification and developmental rate of larvae were included. Medical involvement of larvae was not only myiasis-producing agent in humans and animals, but associated with human death investigations.

Conclusions

This information will enable us to accurate identify this species and to emphasis the increase medically important scene in Thailand.