Molecular evidence of host-associated genetic divergence in the holly leafminer Phytomyza glabricola (Diptera: Agromyzidae): apparent discordance among marker systems

Host races play a central part in understanding the role of host plant mediated divergence and speciation of phytophagous insects. Of greatest interest are host-associated populations that have recently diverged; however, finding genetic evidence for very recent divergences is difficult because initially only a few loci are expected to evolve diagnostic differences. The holly leafminer Phytomyza glabricola feeds on two hollies, Ilex glabra and I. coriacea, that are broadly sympatric throughout most of their ranges. The leafminer is often present on both host plants and exhibits a dramatic life history difference on the two hosts, suggesting that host races may be present. We collected 1393 bp of mitochondrial cytochrome oxidase I (COI) sequence and amplified fragment length polymorphism (AFLP) data (45 polymorphic bands) from sympatric populations of flies reared from the two hosts. Phylogenetic and frequency analysis of mitochondrial COI sequence data uncovered considerable variation but no structuring by the host plant, and only limited differentiation among geographical locations. In contrast, analysis of AFLP frequency data found a significant effect with host plant, and a much smaller effect with geographical location. Likewise, neighbour-joining analysis of AFLP data resulted in clustering by host plant. The AFLP data indicate that P. glabricola is most likely comprised of two host races. Because there were no fixed differences in mitochondrial or AFLP data, this host-associated divergence is likely to have occurred very recently. P. glabricola therefore provides a new sympatric system for exploring the role of geography and ecological specialization in the speciation of phytophagous insects.     

Recent Mediterranean fruit fly (Diptera: Tephritidae) infestations in Florida--a genetic perspective

Microsatellite and mitochondrial DNA (mtDNA) variability data were used to study infestations of the Mediterranean fruit fly, Ceratitis capitata (Wiedemann) in Florida in 1997 and 1998. A total of 132 flies collected in monitoring traps or as larvae removed from fruit were examined at three polymorphic mtDNA restriction sites and two microsatellite loci. All of the flies sampled in Florida in 1997 displayed the mitochondrial AAB haplotype and represent a novel introduction of Mediterranean fruit flies into the state. All flies collected in central Florida in 1998 also displayed the AAB haplotype. Microsatellite analysis of these specimens from 1998 detected only alleles that were present in 1997. These results strongly indicate that the 1998 Florida outbreaks were derived from the Florida populations from the previous year. According to our analyses, the Mediterranean region is the most likely source for the 1997 Florida infestation. Flies from a small outbreak in Miami Springs, Dade County, FL, early in 1998 had a different mtDNA haplotype, characterized by the AAC restriction pattern. Microsatellites of these specimens showed significant differences in their allelic distribution from AAB flies, indicating an origin from a separate source population. South America is the most likely source for the Miami Springs flies.     

THE EFFECTS OF WINTER LENGTH ON THE GENETICS OF APPLE AND HAWTHORN RACES OF RHAGOLETIS POMONELLA (DIPTERA: TEPHRITIDAE)

Host plant-associated fitness trade-offs are central to models of sympatric speciation proposed for certain phytophagous insects. But empirical evidence for such trade-offs is scant, which has called into question the likelihood of nonallopatric speciation. Here, we report on the second in a series of studies testing for host-related selection on pupal life-history characteristics of apple- (Malus pumila L.) and hawthorn- (Crataegus mollis L. spp.) infesting races of the Tephritid fruit fly, Rhagoletis pomonella (Walsh). In particular, we examine the effects of winter length on the genetics of these flies. We have previously found that the earlier fruiting phenology of apple trees exposes apple-fly pupae to longer periods of warm weather preceding winter than hawthorn-fly pupae. Because R. pomonella has a facultative diapause, we hypothesized that this selects for pupae with more recalcitrant pupal diapauses (or slower metabolic/development rates) in the apple-fly race. A study in which we experimentally manipulated the length of the prewintering period for hawthorn-origin pupae supported this prediction. If the period preceding winter is important for apple- and hawthorn-fly pupae, then so too should be the length (duration) of winter; the rationale for this prediction is that “fast developing” pupae that break diapause too early will deplete their energy reserves and disproportionately die during long winters. To test this possibility, we chilled apple- and hawthorn-origin pupae collected from a field site near Grant, Michigan, in a refrigerator at 4°C for time periods ranging from one week to two years. Our a priori expectation was that longer periods of cold storage would select against allozyme markers that were associated with faster rates of development in our earlier study. Since these electromorphs are typically found at higher frequencies in hawthorn flies, extending the overwintering period should favor “apple-fly alleles” in both races. The results from this “overwinter” experiment supported the diapause hypothesis. The anticipated genetic response was observed in both apple and hawthorn races, as allele frequencies became significantly more “apple-fly-like” in eclosing adults surviving longer chilling periods. This indicates that it is the combination of environmental conditions before and during winter that selects on the host races. Many tests for trade-offs fail to adequately consider the interplay between insect development, host plant phenology, and local climatic conditions. Our findings suggest that such oversight may help to explain the paucity of reported fitness trade-offs.     

Morphological adaptation in host races of Tephritis conura

The present study investigates morphological differentiation among host races of the fruit fly Tephritis conura Loew (Diptera: Tephritidae) for two fitness‐related traits and whether these traits are host induced or genetically determined. Flies were analyzed from independent sympatric regions, and from one syntopic site where parental host plants [Cirsium heterophyllum (L.) Hill. and Cirsium oleraceum (L.) Scop. (Cardueae)] and hybrid plants (C. heterophyllum×C. oleraceum) co‐occur. As both host races may oviposit on hybrid plants and hybrid plants provide an identical environment for larvae of both host races, flies emerging from C. heterophyllum×C. oleraceum hybrids were used to assess whether host‐race morphological differences are genetically determined or due to phenotypic plasticity. No significant size (wing length) differences were found among host races, whereas flies emerging from C. heterophyllum had on average 8.4% longer ovipositors than flies emerging from C. oleraceum. The mean size‐corrected ovipositor length (i.e., the ratio ovipositor/wing length) was 10.3% longer. These proportions were repeated among host races emerging from hybrid plants. Although flies of the C. heterophyllum host race from hybrid plants were smaller than on parental host plants, the ratio ovipositor/wing length was constant. Hybrid flies (which emerged only on hybrid plants) were intermediate in relative and absolute ovipositor length. Thus, ovipositor‐length differences among T. conura host races most likely have a genetic basis. This suggests that host‐related differences in ovipositor length reflect adaptations to the respective host‐plant species, most likely to the host's flower‐head size, whereas both host races experience similar selection regimes on body size.     

Beta-alanine and adaptation in Drosophila

Populations of Drosophila melanogaster show melanistic polymorphism. Adult melanization is inversely related to the rate of incorporation of beta-alanine into tanning cuticles. Light tan pigmentation is directly related to this incorporation. Beta-alanine induced tanning serves to protect pupae from ultraviolet light damage. Flies which do not fail to incorporate injected beta-alanine into developing cuticles, but which exhibit inhibited beta-alanine synthesis (flies homozygous for the gene ‘b’) are not only protected, as pupae, from ultraviolet damage by beta-alanine injection but also show enhanced mating success when injected as newly emerged adults. The metabolic block in this mutant appears in the pathway from orotic acid through uracil to beta-alanine.     

Incomplete barriers to mitochondrial gene flow between pheromone races of the North American pine engraver,Ips pini (Say) (Coleoptera,Scolytidae)

The pine engraver Ips pini (Say) is known to include three pheromone races, but gene flow between these races has not been investigated. We used maternally inherited mitochondrial DNA (mtDNA) variation to infer gene flow between 22 widely distributed North American populations of I. pini for a total of 217 individuals, based on 354 bp of the cytochrome oxidase I gene. Gene flow was estimated cladistically as migrants per generation (Nm) and as haplotype variation between populations (N_st). Three distinct mtDNA haplotype lineages, generally corresponding to eastern (I), Rocky Mountain (II) and western (III) regions of North America, were resolved with a total of 34 distinct I. pini haplotypes. The distributions of these lineages were largely congruent with the geographical ranges of the ''New York'', ''California'' and ''Idaho–Montana'' pheromone races. Only individuals with lineage I mtDNA were observed among eastern populations, whereas individuals with lineage II or III mtDNA predominated among western populations. Gene flow (Nm and N_st) was generally moderate between all populations. However, the presence of lineage I mtDNA on the eastern side of western North America and the absence of lineage II and III mtDNA in eastern North America suggest directional gene flow from east to west. These results indicate that female-controlled assortative mating among pheromone races may disrupt gene flow between conspecifics, reflecting incomplete pre-mating barriers.     

Description of a Foliar Nematode,Aphelenchoides fragariae (Nematoda: Aphelenchida) with Additional Characteristics from Korea

The foliar nematode, Aphelenchoides fragariae (Ritzema Bos) Christie, was extracted from infected leaves of Helianthus tuberosus and Weigela subsessilis. The morphology and morphometry was studied and details provided additional morphological characteristics. The present population is characterized by having 4–5 annuli on lip region, visible with scanning electron microscopy. The two hosts, H. tuberosus and W. subsessilis, are newly recorded for the nematode in Korea.     

Barcoding Queensland Fruit Flies (Bactrocera tryoni): impediments and improvements

Identification of adult fruit flies primarily involves microscopic examination of diagnostic morphological characters, while immature stages, such as larvae, can be more problematic. One of the Australia’s most serious horticultural pests, the Queensland Fruit Fly (Bactrocera tryoni: Tephritidae), is of particular biosecurity/quarantine concern as the immature life stages occur within food produce and can be difficult to identify using morphological characteristics. DNA barcoding of the mitochondrial Cytochrome Oxidase I (COI) gene could be employed to increase the accuracy of fruit fly species identifications. In our study, we tested the utility of standard DNA barcoding techniques and found them to be problematic for Queensland Fruit Flies, which (i) possess a nuclear copy (a numt pseudogene) of the barcoding region of COI that can be co‐amplified; and (ii) as in previous COI phylogenetic analyses closely related B. tryoni complex species appear polyphyletic. We found that the presence of a large deletion in the numt copy of COI allowed an alternative primer to be designed to only amplify the mitochondrial COI locus in tephritid fruit flies. Comparisons of alternative commonly utilized mitochondrial genes, Cytochrome Oxidase II and Cytochrome b, revealed a similar level of variation to COI; however, COI is the most informative for DNA barcoding, given the large number of sequences from other tephritid fruit fly species available for comparison. Adopting DNA barcoding for the identification of problematic fly specimens provides a powerful tool to distinguish serious quarantine fruit fly pests (Tephritidae) from endemic fly species of lesser concern.     

The Mediterranean fruit fly in California: evidence for multiple introductions and persistent populations based on microsatellite and mitochondrial DNA variability

Microsatellite and mitochondrial DNA (mtDNA) variability data were used to study outbreaks of Mediterranean fruit fly in California in the years 1992-94 and 1997-99. A total of 359 flies caught in monitoring traps during these years were examined at three polymorphic mtDNA restriction sites and two microsatellite loci. Composite genotypes obtained through analysis of these markers indicate at least five independent introductions of medflies into California between 1992 and 1998. Whereas the majority of specimens displayed a single mtDNA haplotype (AAA), variation of microsatellite alleles among these flies suggests at least one additional introduction in 1993 into southern California. Flies displaying the AAB haplotype sampled in 1992 both in northern and southern California shared microsatellite alleles absent in AAA flies although lacking others commonly found in AAA specimens, thus supporting the hypothesis of an independent introduction of these flies from a different source. In contrast to earlier infestations, a few specimens caught in southern California in 1993 and again in 1998 showed both mtDNA and microsatellite patterns consistent with a Hawaiian origin. Single flies collected in Santa Clara County in 1997 and in El Monte, Los Angeles County & in 1999 most likely represent a sixth and seventh distinct introduction, respectively.     

Dynamics of mitochondrial polymorphism in a natural population of <Emphasis Type="Italic">Drosophila littoralis</Emphasis>

During seven years, we observed stable mtDNA polymorphism in a local population of Drosophila littoralis. Using RFLP, a number of mitochondrial haplotypes were revealed, two of which were the core and in condition of stable equilibrium. To explain the absence of fixation of one haplotype, we checked a hypothesis that the D. littoralis population had a complex structure, being subdivided into several partially isolated races existing on the same territory. Analysis of highly hypervariable nuclear sequence of retrotransposons Tv1 showed positive correlation of the mitochondrial haplotype with a particular allelic form of Tv1. This supports the proposal that the D. littoralis natural population forms the population system consisting of genetically differentiated races.     

Fluid physico-chemical properties influence capture and diet in Nepenthes pitcher plants

Background and Aims Nepenthes pitcher plants have evolved modified leaves with slippery surfaces and enzymatic fluids that trap and digest prey, faeces and/or plant detritus. Although the fluid’s contribution to insect capture is recognized, the physico-chemical properties involved remain underexplored and may vary among species, influencing their diet type. This study investigates the contributions of acidity and viscoelasticity in the fluid’s capture efficiency of two ant and two fly species in four Nepenthes species with different nutrition strategies.Methods Four Nepenthes species were studied, namely N. rafflesiana, N. gracilis, N. hemsleyana and N. ampullaria. Fluid was collected from pitchers of varying ages from plants growing in the field and immediately transferred to glass vials, and individual ants (tribe Campotini, Fomicinae) and flies (Calliphora vomitoria and Drosophila melanogaster) were dropped in and observed for 5 min. Water-filled vials were used as controls. Survival and lifetime data were analysed using models applied to right-censored observations. Additional laboratory experiments were carried out in which C. vomitoria flies were immersed in pH-controlled aqueous solutions and observed for 5 min.Key Results Pitcher fluid differed among Nepenthes species as regards insect retention capacity and time-to-kill, with differences observed between prey types. Only the fluids of the reputedly insectivorous species were very acidic and/or viscoelastic and retained significantly more insects than the water controls. Viscoelastic fluids were fatal to flies and were able to trap the broadest diversity of insects. Younger viscoelastic fluids showed a better retention ability than older fluids, although with less rapid killing ability, suggesting that a chemical action follows a mechanical one. Insect retention increased exponentially with fluid viscoelasticity, and this happened more abruptly and at a lower threshold for flies compared with ants. Flies were more often retained if they fell into the traps on their backs, thus wetting their wings. Insect retention and death rate increased with fluid acidity, with a lower threshold for ants than for flies, and the time-to-kill decreased with increasing acidity. The laboratory experiments showed that fewer flies escaped from acidic solutions compared with water.Conclusions In addition to viscoelasticity, the pitcher’s fluid acidity and wetting ability influence the fate of insects and hence the diet of Nepenthes. The plants might select the prey that they retain by manipulating the secretion of H⁺ ions and polysaccharides in their pitcher fluid. This in turn might participate in possible adaptive radiation of this genus with regard to nutrient sequestration strategy. These plants might even structurally influence insect fall-orientation and capture-probability, inspiring biomimetic designs for pest control.     

Two mitochondrial haplotypes in Pterochloroides persicae (Hemiptera: Aphididae: Lachninae) associated with different feeding sites

Pterochloroides persicae (Cholodkovsky) is an aphid species belonging to the subfamily Lachninae that uses different members of Rosaceae (specially Prunus spp.) as hosts. Partial sequences from the mitochondrial cytochrome c oxidase 1 (COI) and the nuclear long‐wave opsin genes were obtained for approximately 100 P. persicae aphid individuals sampled from 34 colonies collected mainly in Tunisia and other Mediterranean locations. The variability found at the mitochondrial locus revealed the presence of two maternal haplotypes in the studied area that differed in a single nucleotide. The nuclear gene analyzed, however, failed to reveal any variability in this species. The variability found at the COI locus was related to the season of aphid sampling and with the site of feeding, with haplotype I mostly detected in samples collected in spring and summer on trunks and branches and haplotype II only detected in aphids collected in autumn on roots. The observed pattern of molecular variation suggests the presence of two clonal races of P. persicae coexisting in the studied area differentially adapted to conditions prevalent in the alternative seasons and/or to different feeding sites.     

Divergence before the host shift? Prezygotic reproductive isolation among three varieties of a specialist fly on a single host plant

1. Although divergence via host‐plant shifting is a common theme in the speciation of some phytophagous insects, it is not clear whether host shifts are typically initiators of speciation or if they instead contribute to divergence events already in progress. While host shifts appear to be generally associated with speciation events for flies in the genus Strauzia, three sympatric varieties of the sunflower fly [Strauzia longipennis (Wiedemann)] co‐occur on the same host plant in the Midwestern United States and may have evolved reproductive barriers without a host shift. 2. The strength of two prezygotic reproductive barriers was compared among the three S. longipennis varieties: one barrier that is often associated with divergent ecological selection (allochronic isolation), and another that is more likely to be independent of ecological selection (pre‐copulatory sexual isolation). The presence and relative strength of each barrier between fly varieties were evaluated using microsatellites, no choice mating experiments, studies of allochronic isolation, and field collection data. 3. Evidence for both allochronic isolation and pre‐copulatory sexual isolation was detected between the three varieties of S. longipennis. The measure of isolation calculated for each barrier between the three varieties was lower than measures calculated between different species of Strauzia found on different hosts, suggesting that subsequent host shifts may increase the degree of reproductive isolation. For Strauzia and other specialist insects, some reproductive isolation may evolve prior to, and indeed may facilitate, host shifts.     

Detection of Foodborne Bacterial Pathogens from Individual Filth Flies

There is unanimous consensus that insects are important vectors of foodborne pathogens. However, linking insects as vectors of the pathogen causing a particular foodborne illness outbreak has been challenging. This is because insects are not being aseptically collected as part of an environmental sampling program during foodborne outbreak investigations and because there is not a standardized method to detect foodborne bacteria from individual insects. To take a step towards solving this problem, we adapted a protocol from a commercially available PCR-based system that detects foodborne pathogens from food and environmental samples, to detect foodborne pathogens from individual flies.Using this standardized protocol, we surveyed 100 wild-caught flies for the presence of Cronobacter spp., Salmonella enterica, and Listeria monocytogenes and demonstrated that it was possible to detect and further isolate these pathogens from the body surface and the alimentary canal of a single fly. Twenty-two percent of the alimentary canals and 8% of the body surfaces from collected wild flies were positive for at least one of the three foodborne pathogens. The prevalence of Cronobacter spp. on either body part of the flies was statistically higher (19%) than the prevalence of S. enterica (7%) and L.monocytogenes (4%). No false positives were observed when detecting S. enterica and L. monocytogenes using this PCR-based system because pure bacterial cultures were obtained from all PCR-positive results. However, pure Cronobacter colonies were not obtained from about 50% of PCR-positive samples, suggesting that the PCR-based detection system for this pathogen cross-reacts with other Enterobacteriaceae present among the highly complex microbiota carried by wild flies. The standardized protocol presented here will allow laboratories to detect bacterial foodborne pathogens from aseptically collected insects, thereby giving public health officials another line of evidence to find out how the food was contaminated when performing foodborne outbreak investigations.     

Dispersal of the cabbage root fly

The dispersal rates of wild and culture cabbage root flies Erioischia brassicae were determined in release-recapture experiments at Wellesbourne in 1971–3. The experiments were concerned mainly with the first 7 days of adult life. The flies, released from nine locations in the area, were recaptured in yellow water-traps. Dispersal was affected by wind, rain and the terrain the flies were crossing. The flies least often recaptured were those released into the host crop when 6–12 days old. The results indicated the following pattern of behaviour. Flies moved little during the first 2 days of adult life but by the third day both sexes had dispersed to c. 100 m from the release point. Flies are known to mate about the fourth day and after this the males continued to disperse at c. 100 m per day for the three subsequent days. ‘Wild’ females from field-collected pupae carried out a ‘migratory’ flight, however, and dispersed at c. 1000 m per day during the fifth and sixth days, the days preceding the start of oviposition. Similar rates of dispersal were recorded from flies released across host crop and non-host crop areas. Some females did not stop at the first crop they encountered. The culture females from the laboratory-reared pupae dispersed only c. one-third of the distance of the wild females. There was considerable intermingling of local populations. The percentage recapture of young culture and wild flies released during the pre-oviposition period of this species was 38 ± 4 and 19 ±4 for males, and 15 + 2 and 8+1 for females, respectively. The dispersal range of the cabbage root fly is probably within a 2000–3000 m radius of the site of infestation.     

Phytophthora infestans isolates from Northern China show high virulence diversity but low genotypic diversity

Phenotypic and genotypic characteristics of 48 Phytophthora infestans isolates , collected in five provinces in Northern China between 1997 and 2003, were determined and compared with reference isolates. Characterisation included mating type, virulence, mitochondrial DNA (mtDNA) haplotype and DNA fingerprinting patterns based on simple sequence repeats (SSR) and amplified fragment length polymorphisms (AFLP). All isolates had the A1 mating type, mtDNA haplotype IIa and an identical SSR genotype (designated as SG-01-01) that differed from SSR genotypes found in the reference isolates, including those representing the 'old' US-1 lineage that dominated the P. infestans population worldwide prior to 1980. In contrast, the virulence spectra were highly variable and virulence to all resistance genes present in the standard differential set ( R1 to R11 ) was found. AFLP analysis revealed some diversity; eight different AFLP genotypes were found that could be grouped into two major clusters. This study shows that there is very little genotypic diversity in the P. infestans population in Northern China. The occurrence of many different races within this rather uniform population is discussed in the framework of recent insights into the molecular determinants of avirulence in potato– P. infestans 'gene-for-gene' interactions.     

Efficacy of methuselah gene mutation toward tolerance of dichlorvos exposure in Drosophila melanogaster

Adverse reports on the exposure of organisms to dichlorvos (DDVP; an organophosphate insecticide) necessitate studies of organismal resistance/tolerance by way of pharmacological or genetic means. In the context of genetic modulation, a mutation in methuselah (mth; encodes a class II G-protein-coupled receptor (GPCR)) is reported to extend (~35%) the life span of Drosophila melanogaster and enhance their resistance to oxidative stress induced by paraquat exposure (short term, high level). A lack of studies on organismal tolerance of DDVP by genetic modulation prompted us to examine the protective efficacy of mth mutation in exposed Drosophila. Flies were exposed to 1.5 and 15.0 ng/ml DDVP for 12–48 h to examine oxidative stress endpoints and chemical resistance. After prolonged exposure of flies to DDVP, antioxidant enzyme activities, oxidative stress, glutathione content, and locomotor performance were assayed at various days (0, 10, 20, 30, 40, 50) of age. Flies with the mth mutation (mth¹) showed improved chemical resistance and rescued redox impairment after acute DDVP exposure. Exposed mth¹ flies exhibited improved life span along with enhanced antioxidant enzyme activities and rescued oxidative perturbations and locomotor insufficiency up to middle age (~20 days) over similarly exposed w¹¹¹⁸ flies. However, at late (≥30 days) age, these benefits were undermined. Further, similarly exposed mth-knockdown flies showed effects similar to those observed in mth¹ flies. This study provides evidence of tolerance in organisms carrying a mth mutation against prolonged DDVP exposure and further warrants examination of similar class II GPCR signaling facets toward better organismal health.     

Genetic variability of Fusarium wilt pathogen isolates of chickpea (Cicer arietinum L.) assessed by molecular markers

Genetic variability among 43 isolates of Fusarium oxysporum f.sp. ciceri, the chickpea wilt pathogen, collected from nine states of India including the four well-characterized races of the pathogen were assessed using the molecular markers, RAPDs and AFLP. Principal coordinate analysis of the similarity index data generated from the molecular marker studies mostly gave three different clusters: Of these two clusters represented race-1 and race-2, and the third cluster consisted of race-3 and race-4 pathogen isolates. In RAPDs a fourth cluster was seen which did not go with any of the four races of the pathogen. The molecular markers established the distinctness of race-1 and race-2 pathogen isolates and the close similarity of pathogen isolates of race-3 with that of race-4. AFLP was found to be more informative as it differentiated more number of the pathogen isolates with the known races with minimum of outliers. The high levels of DNA polymorphism observed with the molecular markers suggest the rapid evolution of new recombinants of the pathogen in the chickpea growing fields. This revised version was published online in June 2006 with corrections to the Cover Date.     

Cold temperature improves mobility and survival in Drosophila models of autosomal-dominant hereditary spastic paraplegia (AD-HSP)

Autosomal-dominant hereditary spastic paraplegia (AD-HSP) is a crippling neurodegenerative disease for which effective treatment or cure remains unknown. Victims experience progressive mobility loss due to degeneration of the longest axons in the spinal cord. Over half of AD-HSP cases arise from loss-of-function mutations in spastin, which encodes a microtubule-severing AAA ATPase. In Drosophila models of AD-HSP, larvae lacking Spastin exhibit abnormal motor neuron morphology and function, and most die as pupae. Adult survivors display impaired mobility, reminiscent of the human disease. Here, we show that rearing pupae or adults at reduced temperature (18°C), compared with the standard temperature of 24°C, improves the survival and mobility of adult spastin mutants but leaves wild-type flies unaffected. Flies expressing human spastin with pathogenic mutations are similarly rescued. Additionally, larval cooling partially rescues the larval synaptic phenotype. Cooling thus alleviates known spastin phenotypes for each developmental stage at which it is administered and, notably, is effective even in mature adults. We find further that cold treatment rescues larval synaptic defects in flies with mutations in Flower (a protein with no known relation to Spastin) and mobility defects in flies lacking Kat60-L1, another microtubule-severing protein enriched in the CNS. Together, these data support the hypothesis that the beneficial effects of cold extend beyond specific alleviation of Spastin dysfunction, to at least a subset of cellular and behavioral neuronal defects. Mild hypothermia, a common neuroprotective technique in clinical treatment of acute anoxia, might thus hold additional promise as a therapeutic approach for AD-HSP and, potentially, for other neurodegenerative diseases.KEY WORDS: Spastin, Hereditary spastic paraplegia, AD-HSP, Microtubule severing, Cold treatment, Therapeutic hypothermia, Drosophila disease model