Breeding structure of an isolated cactophilic Drosophila population on a sandstone table hill

The effect of host cacti on the breeding structure of an isolated population of cactophilic Drosophila gouveai was studied. A comparison was made, using F statistics, of the allozyme frequencies at 11 loci among temporal samples of the adult population and six samples of progeny obtained from individual rotting cactus cladodes. The population appears to be structured by the cacti, forming breeding groups, and approximately four individuals contribute gametes to the progeny of each cladode. This D. gouveai population had a low degree of heterozygosity, compared with mean values for most Drosophila species, however it was within the range of values reported for other cactophilic Drosophila.     

Resource availability and population size in cactophilic Drosophila

1. Four species of Drosophila, Drosophila nigrospiracula ( Patterson & Wheeler 1942 ) , Drosophila mettleri ( Heed 1977 ) , Drosophila pachea ( Patterson & Wheeler 1942 ) , and Drosophila mojavensis ( Patterson & Crow 1940 ) , are endemic to the Sonoran Desert of North America and breed in different species of necrotic columnar cacti. Differences in resource availability have been suggested to explain the interspecific variability in fly population biology, but resource availability for these species has not been quantitatively assessed thoroughly in either spatial or temporal terms. The resource availability was quantified quarterly at three sites for 3 years and population sizes for each Drosophila species were estimated.
2. Spatial and temporal availability of resources differed significantly among species of host cacti, with organpipe cactus ( Stenocereus thurberi ) being the least abundant and senita ( Lophocereus schottii ) the most abundant spatially.
3. Drosophila species differed significantly in population size. The largest population sizes were found for D. nigrospiracula and D. mojavensis and smallest for D. pachea . Populations of D. mettleri were intermediate to these.
4. Population size was greatest for fly species utilizing host species having the largest and longest lasting necroses.
5. Resource availability does not explain the reduction of fly populations in the summer. Necroses were most abundant when flies were absent.     

The Drosophila flavopilosa species group (Diptera,Drosophilidae)

The D. flavopilosa group encompasses an ecologically restricted set of species strictly adapted to hosting flowers of Cestrum (Solanaceae). This group presents potential to be used as a model to the study of different questions regarding ecologically restricted species macro and microevolutionary responses, geographical vs. ecological speciation and intra and interspecific competition. This review aims to revisit and reanalyze the patterns and processes that are subjacent to the interesting ecological and evolutionary properties of these species. Biotic and abiotic niche properties of some species were reanalyzed in face of ecological niche modeling approaches in order to get some insights into their ecological evolution. A test of the potential of DNA-Barcoding provided evidences that this technology may be a way of overcoming difficulties related to cryptic species differentiation. The new focus replenishes the scenario with new questions, presenting a case where neither geographical nor ecological speciation may be as yet suggested.     

Incipient reproductive isolation between two morphs of Drosophila elegans (Diptera: Drosophilidae)

Drosophila elegans is a flower-breeding species occurring in tropical and subtropical regions of Asia. Two morphs, brown and black, are known in this species. The brown morph is recorded from southern China, Philippines, Indonesia and New Guinea, while the black morph is from the Okinawa islands and Taiwan. The present crossing experiment suggests that the difference of body colour between them was due to alleles on a single locus or closely linked loci on an autosome; F₁ hybrids exhibited intermediate body colour. Female choice tests revealed asymmetrical premating isolation between the brown and black morphs; isolation indices ranged from 0.55 to 0.83 in the tests using females of the black morph (deviation from random mating was significant), but from — 0.03 to 0.50 in the tests using females of the brown morph (deviation from random mating was insignificant). However, body colour was not used as a criterion of mate choice by females. A weak and asymmetrical postmating isolation was also observed between the brown and black morphs; viability was lowered in F₂ progenies of crosses between females of the brown morph and males of the black morph. No premating or postmating isolation was observed between geographic strains of each morph. Under irradiation, body temperature was higher in the black morph than in the brown morph. On the other hand, no significant difference was observed in tolerance to cold, heat and desiccation between the brown and black morphs.     

Negative correlations between resistance to three organophosphate insecticides and productivity within a natural population of Drosophila melanogaster (Diptera: Drosophilidae)

To investigate the relationship between resistance to organophosphate insecticides and fitness components, we first measured resistance to three organophosphates, malathion, prothiophos, and fenitrothion, and productivity, a measure of fitness components, for each of the isofemale lines from the same natural population of Drosophila melanogaster (Meigen). Pearson correlation coefficients indicated that positive correlations among resistance to the organophosphates and negative correlations between resistance to each of the organophosphates and the productivity existed within the natural population. We further investigated the genetic basis of the correlations among resistance to the organophosphates and the productivity, by using chromosome-substituted lines between a resistant and a susceptible inbred line established from the same natural population. Chromosomal analyses indicated that the third chromosome from the resistant line exhibited not only significant, positive effects on resistance to all of the organophosphates tested but also a significant negative effect on the productivity, suggesting positive genetic correlations between resistance to each organophosphate and negative genetic correlations between resistance to each organophosphate and the productivity. In addition, a significant negative effect on the productivity was also detected from the second chromosome, which did not exhibit significant major effects on resistance to the organophosphates. This suggests that fitness components of resistant lines could be also affected by factors independent of insecticide resistance. The dynamics of genetic variation in resistance to the organophosphates within the natural population of D. melanogaster are discussed from the standpoint of negative genetic correlations between resistance to the organophosphates and the productivity.     

New synonym of Drosophila yakuba Burla, 1954 (Diptera: Drosophilidae)

New biological and bibliographic information confirms that the widely accepted name Drosophila yakuba Burla, 1954 and the unused name Drosophila opisthomelaina are synonymous. The latter was coined by Nolte & Stoch in a 1950 work containing a disclaimer and is unavailable by strict application of Article 8b of the International Code of Zoological Nomenclature (3rd edn, 1985). In a previously overlooked publication, Nolte (1958) cites D.opisthomelaina as a senior synonym; the work also contains diagnostic information. Synonymy is not disputed but before 1958 the name was unavailable. Thus D. opisthomelaina Nolte, 1958 is treated as a junior rather than a senior synonym of D.yakuba. These nomenclatural corrections remove confusion concerning records of this species in southern Africa and will probably be met with general approval. The distribution in southern Africa and Madagascar of D.yakuba and closely related species: D.melanogaster Meigen, 1830, D.simulans Sturtevant, 1919 and D.teissieri Tsacas, 1971, are summarized.     

Utilization of a Photosystem by Drosophila melanogaster Larvae (Diptera: Drosophilidae)

Foraging-stage third-instar larvae from most wild-type (normal) Drosophila melanogaster stocks are generally repelled by light. To identify factors that affect the larval photoresponse, we elucidated the effects of age, temperature, and time on the photoresponse of larvae from a wild-type Canton-S stock. In addition, we analyzed the larvae from the LI2 isofemale line, which are unresponsive to light in a photoassay. To determine whether LI2 larvae behave abnormally on other behavioral paradigms, in comparison to Canton-S controls, we tested larvae in taste and olfactory assays and observed them to determine whether they dispersed in a food source. Like Canton-S larvae, LI2 larvae and other isofemale lines whose progenitors were collected from the same natural population are responsive to taste and olfactory stimuli. Moreover, LI2 larvae disperse in the food source, as do Canton-S larvae tested in the dark. Larvae expressing para^sbl mutations, which respond normally to light but not to chemical stimuli, do not disperse normally in the food source, suggesting that dispersal may be mediated by perception of chemical cues.     

An ecological interaction between citrus fruit, Penicillium moulds and Drosophila immigrans Sturtevant (Diptera: Drosophilidae)

Abstract. 1. Potential Drosophila breeding sites were collected from a fruit market, and the adults allowed to emerge from them.
2. D.immigrans and D.melanogaster were the species with the highest frequency of emergences from citrus fruit.
3. D.immigrans was especially associated with citrus fruits infected with Penicillium italicum or P.digitatum , two specialist moulds of citrus. D.melanogaster was more often found in uninfected fruit.
4. In the laboratory D.immigrans larvae survived better than D.melanogaster larvae on Penicillium-infected citrus fruit.
5. These adaptations suggest that D.immigrans may have originally evolved as a citrus specialist, becoming a domestic species as these fruits were exploited commercially.     

Structure of cephalic abnormalities in Drosophila melanogaster (Diptera: Drosophilidae)

Scanning and transmission electron microscopy were utilized in studying the cephalic abnormalities of the tu-h strain of Drosophila melanogaster. Abnormalities, appearing as protuberances (growths) of different shapes and sizes, were observed only on or in close proximity to receptor cites. Compound eyes of some flies, besides having such protuberances, either had modified corneal lenses or were absent altogether. Cuticles of the growths were thinner than that of the normal surrounding layer. The epidermal cells associated with setae on the growths or underlying modified corneal lenses remained undifferntiated. Both setae and growths lacked innervation. The receptor portions (retinular sensory cells and secondary pigment cells) of the abnormal compound eye, where the dioptric portions were replaced by protuberances or remained undifferentiated, were unaffected by the mutation. Nuclei of several cells, including oenocytes and fat bodies, close to or underlying epidermal cells of abnormalities, were large and contained compact nucleoli without nucleonemas. Viruslike particles were observed in several nuclei of growth cells. It was concluded from the present study that the alterations induced by the mutation can be only a localized phenomenon restricted to at least several cephalic epidermal cells and/or their derivatives.     

Hierarchical structure in the Drosophila mojavensis cluster (Diptera: Drosophilidae)

Sequences from three gene regions from the nuclear and mitochondrial genomes were used to examine the extent and nature of hierarchical structure in the Drosophilamojavensis cluster (Drosophila arizonae, D. mojavensis and D. navojoa) of the D. repleta species group. To determine the genetic divergence of these three species, sequence data were analyzed using maximum parsimony and population aggregation analysis. Individual and combined gene genealogies indicate that D. arizonae and D. mojavensis are neither diagnosable nor monophyletic with respect to one another. Although D. navojoa has differentiated from D. arizonae and D. mojavensis, as diagnosed by nuclear gene sequences, it may have undergone a reticulation event with D. arizonae. Our results suggest that either these taxa are still undergoing differentiation at the molecular level or have experienced gene flow in the recent past.     

The Drosophila obscura species-group (Diptera,Drosophilidae) from Yunnan Province,Southern China

Three new and two known species of the Drosophila (Sophophora) obscura species-group are reported from Yunnan Province, southern China. The sinobscura species-subgroup is newly established by D. sinobscura, D. hubeiensis and D. luguensis sp. nov. Geographic distribution of the obscura group in and around China is discussed, and a key to 10 Chinese species of the obscura group is provided.     

Increasing the data size to accurately reconstruct the phylogenetic relationships between nine subgroups of the Drosophila melanogaster species group (Drosophilidae, Diptera)

Previous phylogenetic analyses of the melanogaster species group have led to conflicting hypotheses concerning their relationship; therefore the addition of new sequence data is necessary to discover the phylogeny of this species group. Here we present new data derived from 17 genes and representing 48 species to reconstruct the phylogeny of the melanogaster group. A variety of statistical tests, as well as maximum likelihood mapping analysis, were performed to estimate data quality, suggesting that all genes had a high degree of contribution to resolve the phylogeny.Individual locus was analyzed using maximum likelihood (ML), and the concatenated dataset (12,988 bp) were analyzed using partitioned maximum likelihood (ML) and Bayesian analyses. Separated analysis produced various phylogenetic relationships, however, phylogenetic topologies from ML and Bayesian analysis based on concatenated dataset, at the subgroup level, were completely identical to each other with high levels of support. Our results recovered three major clades: the ananassae subgroup, followed by the montium subgroup, the melanogaster subgroup and the oriental subgroups form the third monophyletic clade, in which melanogaster (takahashii, suzukii) forms one subclade and ficusphila [eugracilis (elegans, rhopaloa)] forms another. However, more data are necessary to determine the phylogenetic position of Drosophila lucipennis which proved difficult to place.     

Male Sexual Signals and Female Choice in Drosophila grimshawi (Diptera: Drosophilidae)

Sexual selection and sexual signaling have been prominent topics in recent behavioral studies, but limited data have led to controversy regarding these topics. For example, the Hawaiian Drosophila are often cited as examples in which female choice has resulted in the evolution of elaborate male courtship signals, but relatively few data exist to test these claims adequately. We studied D. grimshawi, a lek-forming Hawaiian Drosophila, to determine whether there was evidence for female choice without male competition and to elucidate the possible cues females use to discriminate. Male mating success was found to be nonrandom and males that courted females intensely and deposited many pheromone-containing streaks on the substrate were the most successful. Hence, multiple cues seem to be involved in male mating success in this species. Some males performed only one display, however, and may represent an alternate male mating tactic. The protein content of the adult male diet significantly influenced the level of pheromone streak deposition, and thus, foraging environment may affect the outcome of sexual selection.     

Predator-mediated coexistence in laboratory communities of mycophagous Drosophila (Diptera: Drosophilidae)

Abstract. 1. This laboratory experiment examined the effects of interspecific competition and predation by Ontholestes cingulatus Gravenhorst (Coleoptera: Staphylinidae) on three species of mycophagous Drosophila (Diptera: Drosophilidae): D.tripunctata Loew, D.falleni Wheeler and D.putrida Sturtevant.
2. Single-species and three-species assemblages were exposed to single commercial mushrooms on wet pine shavings in 200 ml culture bottles. A predacious rove beetle (Ontholestes cingulatus) was present in half of the three-species replicates. The stocked adult flies and beetles were removed after 4 days, and the number, biomass and mean mass of emerging progeny was recorded.
3. For all three species the abundance and biomass of the progeny emerging in the 'no predator' communities' was significantly less than for the progeny emerging in single-species replicates, suggesting an interspecific competitive effect. D.tripunctata was the competitive dominant; it emerged in abundance from all seven three-species 'no predator' communities while D.putrida and D.falleni were often excluded.
4. The decrease in production was attributed to strong interspecific competition among larva and not interference among ovipositing adults.
5. Predation on ovipositing adults significantly reduced the number and biomass of D.tripunctata progeny emerging, and indirectly facilitated the number and biomass of emerging D.falleni and D.putrida.Predation on adults reduced larval recruitment, relaxed larval competition, and released the inferior competitors.     

A new trap and lure for Drosophila melanogaster (Diptera: Drosophilidae)

We conducted a series of nine laboratory experiments testing the response of "vinegar flies," Drosophila melanogaster Meigen (Diptera: Drosophilidae), released in bioassay chambers to experimental traps and lures. These experiments showed that an effective trap could be constructed from a clear 225-ml screw-cap jar fitted with a hollow 8-mm-diameter cylindrical cross bridge. Flies could enter the trap from either end of the cylindrical "gate" and in turn could enter the interior chamber of the trap through a cut out portion at mid-span of the cylinder. The experiments also showed that a natural-component lure could be made using a teabag containing freeze-dried banana powder, yeast, and carrageenan gum powder as a humectant. When dipped in water for 10-15 s and then placed in the bottom of a trap, the teabag provided effective attraction for at least 7 d. Captured flies were immobilized on a sticky card placed in the trap, allowing them to be easily seen. Unlike other traps that cannot be opened and have liquid lures, the cylindrical-gate trap can be reused repeatedly if the teabag and sticky card are replaced. A final two experiments showed that the prototype operational cylindrical-gate trap with a teabag lure captured 3.3 and 2.3 times more released flies, respectively, than the next best of three commercially available traps.     

Chromosome variability in Brazilian populations of Drosophila buzzatii (Diptera, Drosophilidae).

Analysis of 28 strains of Drosophila buzzatii from six different localities revealed that populations from southern Brazil apparently differ from northeastern populations in chromosome structure. Of the 16 polymorphic chromosome inversions detected in this species, only two (2j and 5c2) were present in southern populations. The Northeastern populations were the first of this species found not to have the 2j inversion. This suggests that the populations of Drosophila buzzatii may have lost chromosome polymorphism during dispersion, supporting the idea that the current geographic distribution of this species in South America is due to active dispersion.     

The Effect of Resource pH on Pupation Height in Drosophila (Diptera: Drosophilidae)

This paper describes the effects of the pH of the larval resource on the pupation height of two cosmopolitan species of Drosophila: D. melanogaster and D. hydei. The pH levels of artificial media were modified using solutions of acids (hydrochloric, acetic, and citric) and a positive relationship was found between pupation height and resource pH; i. e., the more acidic the resource, the closer the larvae pupated to the resource surface. The clearest trends were between pupation height and the final pH of the resource, the larvae apparently responding to the pH they encountered just before pupation commenced. When using natural resources a difference in pupation height was found between the types of fruits used but there was no obvious trend linking pupation height with pH. This suggests that some other environmental factor(s) was (were) overriding the effects of pH, and consequently resource pH may play only a minor role in determining pupation behavior in nature.     

Drosophila subpulchrella, a new species of the Drosophila suzukii species subgroup from Japan and China (Diptera: Drosophilidae)

Drosophila (Sophophora) subpulchrella Takamori and Watabe, sp. nov., of the D. suzukii subgroup in the D. melanogaster species group, is described from Japan and southern China, and compared with its sibling species, D. pulchrella Tan et al. distributed in the Yun‐Gui Highland, south‐western China. The results of cross‐experiments show a complete pre‐mating isolation between D. subpulchrella and D. pulchrella.     

Seasonal monitoring of Drosophila suzukii (Diptera: Drosophilidae) in a mixed fruit production system

Drosophila suzukii Matsumura (Diptera: Drosophilidae), an invasive pest native to Southeast Asia, is now reported throughout North America and Europe. We used traps baited with apple cider vinegar to monitor D. suzukii adult presence in multiple crops and associated fruiting plants at the Wolfskill USDA Germplasm Repository in Winters, CA, USA from 2011 to 2013. Traps were placed in small (~ 160 m × 40 m on average) almond, apricot, cherry, fig, grape, mulberry, peach, persimmon, plum, and pomegranate deciduous fruit orchard blocks as well as a citrus block and evergreen trees located near a house at the repository. D. suzukii was present in all blocks with the greatest monthly deciduous fruit captures in the cherry and fig blocks. Few D. suzukii were captured in almond, apricot, pomegranate and grape blocks. Deciduous fruit blocks had two distinct periods of trap capture: spring through midsummer and again in fall. Most deciduous fruit blocks had low trap captures during the hottest summer months (August to September) and the coldest winter months (December to April). However, from late December through mid-January, high trap captures were associated with the citrus and house sites. This study provides seasonal trapping data of D. suzukii adults in an unsprayed multi-crop mosaic, and may serve as a model of adult capture patterns across smaller mixed-crop commercial orchards and associated urban landscapes.