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At least 235 records · Page 13Linked to original sources
PubMed2005

Limiting cheaters in mutualism: evidence from hybridization between mutualist and cheater yucca moths.

Mutualisms are balanced antagonistic interactions where both species gain a net benefit. Because mutualisms generate resources, they can be exploited by individuals that reap the benefits of the interaction without paying any cost. The presence of such 'cheaters' may have important consequences, yet we are only beginning to understand how cheaters evolve from mutualists and how their evolution may be curtailed within mutualistic lineages. The yucca-yucca moth pollination mutualism is an excellent model in this context as there have been two origins of cheating from within the yucca moth lineage. We used nuclear and mitochondrial DNA markers to examine genetic structure in a moth population where a cheater species is parapatric with a resident pollinator. The results revealed extensive hybridization between pollinators and cheaters. Hybrids were genetically intermediate to parental populations, even though all individuals in this population had a pollinator phenotype. The results suggest that mutualisms can be stable in the face of introgression of cheater genes and that the ability of cheaters to invade a given mutualism may be more limited than previously appreciated.

Adaptation, Biological↗
PubMed2003

Genetic isolation between two sympatric host-plant races of the European corn borer, Ostrinia nubilalis Hübner. I. Sex pheromone, moth emergence timing, and parasitism.

Adaptation to different environments may be a powerful source of genetic differentiation between populations. The biological traits selected in each environment can pleiotropically induce assortative mating between individuals of these genetically differentiated populations. This situation may facilitate sympatric speciation. Successful host shifts in phytophagous insects provide some of the best evidence for the ecological speciation that occurs, or has occurred, in sympatry. The European corn borer, Ostrinia nubilalis (Lepidoptera: Crambidae), colonized maize after its introduction into Europe by humans about 500 years ago. In northern France, two sympatric host races feed on maize (Zea mays) and mugwort (Artemisia vulgaris), respectively. We investigated the factors involved in the genetic isolation of these two races at a field site near Paris, France. We identified two biological differences that might make a significant contribution to the genetic divergence between sympatric populations feeding on the two host plants. First, assortative mating may be due to differences in the moth emergence pattern between the two races: mugwort-race moths emerged on average 10 days earlier than maize-race moths. In addition, the males emerged earlier than females in both races. Hence, the likelihood of mating between maize-race males and mugwort-race females was higher than that of mating between mugwort-race males and maize-race females. Second, the females feeding on mugwort and maize produced sex pheromones with different E/Z isomeric ratios of delta-11-tetradecenyl acetate. This difference in mate recognition systems reinforces the potential for assortative mating in the two races. During the experiment, overwintering mortality was much lower on maize than on mugwort. This difference was due to a braconid parasitoid wasp, Macrocentrus cingulum, that killed more than 50% of the larvae overwintering on mugwort but did not infest larvae diapausing on maize. Hence, by colonizing maize, European corn borer populations probably escaped from numerous predators, competitors, and parasitoids, such as M. cingulum. This decrease in host-associated selection may have favored the colonization of this new host. Finally, throughout this experiment we observed selection at two allozyme loci (or at linked loci): Tpi and Mpi. The Tpi locus is tightly linked with the genes involved in the response of the male to the sex pheromone and in developmental timing. The location of these traits on the Z chromosome may play a role in shortening the time required for the evolution of premating barriers.

Alleles↗
PubMed2004

Parasites and sexual reproduction in psychid moths.

Persistence of sexual reproduction among coexisting asexual competitors has been a major paradox in evolutionary biology. The number of empirical studies is still very limited, as few systems with coexisting sexual and strictly asexual lineages have been found. We studied the ecological mechanisms behind the simultaneous coexistence of a sexually and an asexually reproducing closely related species of psychid moth in Central Finland between 1999 and 2001. The two species compete for the same resources and are often infected by the same hymenopteran parasitoids. They are extremely morphologically and behaviorally similar and can be separated only by their reproductive strategy (sexual vs. asexual) or by genetic markers. We compared the life-history traits of these species in two locations where they coexist to test predictions of the cost-of-sex hypothesis. We did not find any difference in female size, number of larvae, or offspring survival between the sexuals and asexuals, indicating that sexuals are subject to cost of sex. We also used genetic markers to check and exclude the possibility of Wolbachia bacteria infection inducing parthenogenesis. None of the samples was infected by Wolbachia and, thus, it is unlikely that these bacteria could affect our results. We sampled 38 locations to study the prevalence of parasitoids and the moths' reproductive strategy. We found a strong positive correlation between prevalence of sexual reproduction and prevalence of parasitoids. In locations where parasitoids are rare asexuals exist in high densities, whereas in locations with a high parasitoid load the sexual species was dominant. Spatial distribution alone does not explain the results. We suggest that the parasite hypothesis for sex may offer an explanation for the persistence of sexual moths in this system.

Analysis of Variance↗
PubMed1994

Complete base sequence for the mitochondrial large subunit ribosomal RNA of the gypsy moth Lymantria dispar (L.).

A 1355 bp sequence (accession number L32141) isolated from a gypsy moth (Lymantria dispar) cDNA library showed 68-74% sequence identity to mitochondrial large subunit ribosomal RNA (mt IrRNA) sequences of Locusta migratoria, Apis mellifera, Aedes albopictus, Anopheles gambiae and two Drosophila species. A comparison of the primary sequences of the mt IrRNAs from the above insects in four orders and from Esherichia coli demonstrated regions of conservation which presumably correspond to regions of functional and/or structural homology. A secondary structure for the gypsy moth mt IrRNA sequence was derived based on the proposed secondary structures of Drosophila yakuba and Aedes albopictus mt IrRNAs (Gutell & Fox, Nucleic Acid Res 16 (Suppl.), r175-r269, 1988). This sequence was found to hybridize to about 10-15% of the clones in several (eleven) gypsy moth cDNA libraries.

Animals↗
PubMed1996

Identification and characterization of a RAPD-PCR marker for distinguishing Asian and North American gypsy moths.

The recent introduction of the Asian gypsy moth (Lymantria dispar L.) into North America has necessitated the development of genetic markers to distinguish Asian moths from the established North American population, which originated in Europe. We used RAPD-PCR to identify a DNA length polymorphism that is diagnostic for the two moth strains. The polymorphism maps to an autosomal locus with codominant Mendelian inheritance. DNA sequence analyses of the Asian and North American forms enabled development of locus-specific primers so that this marker, designated FS-1, will be useful for strain identification under varying conditions in different laboratories.

Animals↗
PubMed2006

Pheromone component patterns of moth evolution revealed by computer analysis of the Pherolist.

1. The Pherolist internet site listing moth sex pheromone components reported in the literature was downloaded and processed by a basic program into a database with 2931 combinations of 377 unique chemical names of sex pheromone attractants used by 1572 moth species in 619 genera and 49 families. Names of pheromone compounds were analysed for aliphatic chain length, unsaturation position, geometric configuration, functional group (aldehyde, alcohol, acetate, epoxide, methyl-branched and hydrocarbon) and number of instances such combinations are used by species and families. 2. The analyses revealed pheromone blends of species ranged from one to eight components (45% species with one component, 36% two, 12% three, 5% four, 1% five, < or = 0.5% for > or = six). The numbers of different components of various chain lengths and functional groups, the numbers of instances such compounds are used by species and the numbers of species using such compounds are presented. 3. The average number of pheromone components per species increased as the number of species in a family increased based on linear regression of components in the 10 largest families, with species numbers ranging from 19 to 461. Pooling the four largest families gave a mean of 1.96 components per species that was significantly greater than the mean of the next 14 smaller families (1.63). Because related species in a large family would need more communication channels, this suggests that these species on average evolved to produce and detect more components in their pheromone blends to achieve a unique communication channel than was needed by species in smaller families. 4. Speciation in moths would entail evolutionary changes in both pheromone biosynthetic and sensory systems that avoided competition for communication channels of existing species. Regression analysis indicated that the more species in a family the more unique pheromone components, but the increase diminishes progressively. This suggests that, as the number of components increases with species number in a family, new species are more likely to evolve a unique blend comprising a communication channel from among existing components of the family.

Animal Communication↗
PubMed2006

Assessment of the diversity and species specificity of the mutualistic association between Epicephala moths and Glochidion trees.

The obligate mutualisms between flowering plants and their seed-parasitic pollinators constitute fascinating examples of interspecific mutualisms, which are often characterized by high levels of species diversity and reciprocal species specificity. The diversification in these mutualisms has been thought to occur through simultaneous speciation of the partners, mediated by tight reciprocal adaptation; however, recent studies cast doubt over this general view. In this study, we examine the diversity and species specificity of Epicephala moths (Gracillariidae) that pollinate Glochidion trees (Phyllanthaceae), using analysis of mitochondrial and nuclear gene sequences. Phylogenetic analysis of Epicephala moths associated with five Glochidion species in Japan and Taiwan reveal six genetically isolated species that are also distinguishable by male genital morphology: (i) two species specific to single host species (G. acuminatum and G. zeylanicum, respectively); (ii) two species that coexist on G. lanceolatum; and (iii) two species that share two, closely-related parapatric hosts (G. obovatum and G. rubrum). Statistical analysis shows that the two species associated with G. lanceolatum are not sister species, indicating the colonization of novel Glochidion host in at least one lineage. Behavioural observations suggest that all six species possess the actively-pollinating habit, thus none of the studied species has become a nonmutualistic 'cheater' that exploits the benefit resulting from pollination by other species. Our results parallel recent findings in ecologically similar associations, namely the fig-fig wasp and yucca-yucca moth mutualisms, and contribute to a more general understanding of the factors that determine ecological and evolutionary outcomes in these mutualisms.

Adaptation, Physiological↗
PubMed1991

Tussockosis: an outbreak of dermatitis caused by tussock moths in Singapore.

An outbreak of acute pruritic rash occurred in March 1990 among 141 residents of a high-rise public housing estate in Bukit Panjang, Singapore. The typical rash consisted of urticarial lesions distributed over the limbs and trunk. The outbreak was associated with a transient increase in tussock moths in the residential estate following an unusual, short dry spell. The aetiology was established when patch tests with crude moth material produced similar eruptions in 5 out of 7 adult volunteers between 40 min and 12 h. Pharmacological experiments with an aqueous extract of moth hairs in isolated guinea pig ileum elicited a response similar to that induced by histamine.

Adolescent↗
PubMed2004

Clinical effects of exposure to the White-stemmed gum moth (Chelepteryx collesi).

BACKGROUND: The White-stemmed gum moth (Chelepteryx collesi) can be found in eastern Australia. The clinical effects of injuries caused by its many spine-like hairs are poorly defined and concern about the numerous hairs that remain embedded following contact with the cocoon have led to heroic means of removal. OBJECTIVE: To examine the clinical effects of injuries by the caterpillar or cocoon of the White-stemmed gum moth. METHODS: Prospective observational study of caterpillar injuries from calls to the New South Wales Poisons Information Centre. Cases resulting from C. collesi exposure were included for analysis. Caterpillars and cocoons were expertly identified where available and a follow-up consultation of all patients was conducted. Information was collected on the circumstances of exposure, local and systemic effects and treatment. RESULTS: From the 26 included cases, seven had confirmed caterpillar contact (all children aged 1-11), six had confirmed cocoon contact and 13 had exposures consistent with C. collesi, but no caterpillar was caught. All cases occurred in summer. Of 13 confirmed exposures there was no difference between caterpillars and cocoons, and these were considered together. Affected areas were hands, feet, or both, following C. collesi being handled or trodden on. Pain was reported in all 13 cases, one with severe pain. In 10 cases pain duration was < 60 min. Six subjects had more than 100 hairs embedded (small black dots). In three cases, the hairs were surrounded by swelling and yellow discolouration. Despite the attempted removal of multiple hairs, they remained embedded for prolonged periods but caused no sequelae. CONCLUSION: The clinical effects of the White-stemmed gum moth were minor with local pain. Although hairs remained in all cases, they caused no problems. Complete removal of hairs is neither possible nor necessary, and painful and invasive methods should be avoided.

Adolescent↗
PubMed1963

Motor responses of moths to low-intensity x-ray exposure.

A brief burst of x-rays elicited flight activity in moths placed in a darkened x-ray exposure room. Wing-beat activity was recorded as an index of this behavior. Wing-beat activity could be initiated in resting moths or amplitude augmented in active moths by x-ray dose rates of 0.01 to 1.5 roentgens per second, with a latency of less than 1 second after onset of exposure.

Animals↗
PubMed1976

Commercial formulations of Bacillus thuringiensis for control of Indian meal moth.

Doses of four commercial formulations and one experimental formulation of Bacillus thuringiensis Berliner were mixed with the diet used to rear colonies of the Indian meal moth Plodia interpunctella (Hübner). Indian meal moth eggs were introduced to the treated diet, and the resultant adult emergence was tabulated. The experimental formulations ranked as follows in efficacy in controlling the Indian meal moth: Dipel (50% lethal concentration [LC50], 25 mg/kg) greater than Bactospeine WP (LC50, 100 mg/kg) greater than Thuricide (LC50, 150 mg/kg) greater than IMC 90007 (LC30, 180 mg/kg) greater than Bactospeine Flowable (LC50, 440 mg/kg).

Animals↗
PubMed1999

Integrative model for binding of Bacillus thuringiensis toxins in susceptible and resistant larvae of the diamondback moth (Plutella xylostella).

Insecticidal crystal proteins from Bacillus thuringiensis in sprays and transgenic crops are extremely useful for environmentally sound pest management, but their long-term efficacy is threatened by evolution of resistance by target pests. The diamondback moth (Plutella xylostella) is the first insect to evolve resistance to B. thuringiensis in open-field populations. The only known mechanism of resistance to B. thuringiensis in the diamondback moth is reduced binding of toxin to midgut binding sites. In the present work we analyzed competitive binding of B. thuringiensis toxins Cry1Aa, Cry1Ab, Cry1Ac, and Cry1F to brush border membrane vesicles from larval midguts in a susceptible strain and in resistant strains from the Philippines, Hawaii, and Pennsylvania. Based on the results, we propose a model for binding of B. thuringiensis crystal proteins in susceptible larvae with two binding sites for Cry1Aa, one of which is shared with Cry1Ab, Cry1Ac, and Cry1F. Our results show that the common binding site is altered in each of the three resistant strains. In the strain from the Philippines, the alteration reduced binding of Cry1Ab but did not affect binding of the other crystal proteins. In the resistant strains from Hawaii and Pennsylvania, the alteration affected binding of Cry1Aa, Cry1Ab, Cry1Ac, and Cry1F. Previously reported evidence that a single mutation can confer resistance to Cry1Ab, Cry1Ac, and Cry1F corresponds to expectations based on the binding model. However, the following two other observations do not: the mutation in the Philippines strain affected binding of only Cry1Ab, and one mutation was sufficient for resistance to Cry1Aa. The imperfect correspondence between the model and observations suggests that reduced binding is not the only mechanism of resistance in the diamondback moth and that some, but not all, patterns of resistance and cross-resistance can be predicted correctly from the results of competitive binding analyses of susceptible strains.

Animals↗
PubMed1999

Central processing of pulsed pheromone signals by antennal lobe neurons in the male moth Agrotis segetum.

Male moths use female-produced pheromones as orientation cues during the mate-finding process. In addition to the needs of evaluating the quality and quantity of the pheromone signal, the male moth also needs to resolve the filamentous structure of the pheromone plume to proceed toward the releasing point successfully. To understand how a discontinuous olfactory signal is processed at the central level, we used intracellular recording methods to characterize the response patterns of antennal lobe (AL) neurons to pulsatile stimulation with the full female-produced pheromone blend and its single components in male turnip moths, Agrotis segetum. Air puffs delivered at frequencies of 1, 3, 5, 7, or 10 Hz were used to carry the stimulus. Two types of AL neurons were characterized according to their capabilities to resolve stimulus pulses. The most common type could resolve at least 1-Hz pulses, thus termed fast neurons; another type could not resolve any pulses, thus termed slow neurons. When fast neurons were excited by stimuli, they always displayed biphasic response patterns, a depolarization phase followed by a hyperpolarization phase. This pattern could be evoked by stimulation with both the single pheromone components and the blend. The pulse-resolving capability of the fast neurons correlated significantly with the size of the hyperpolarization phase. When the amplitude was higher and the fall time of the hyperpolarization faster, the neuron could follow more pulses per second. Moreover, interactions between different pheromone components eliciting different response patterns did not improve the pulse-resolving capability of fast neurons.

Animals↗
PubMed2006

Inheritance of olfactory preferences I. Pheromone-mediated behavioral responses of Heliothis subflexa x Heliothis virescens hybrid male moths.

Shifts in male preference for qualitatively different pheromone blends appear to have played a fundamental role in the divergence of olfactory communication and evolution of moth species. As an initial step in documenting the genetic complexity underlying such shifts, we characterized the behavioral responses of hybrid male moths created by mating two heliothine moth species, Heliothis subflexa and Heliothis virescens. Between 67 and 96% of hybrid males flew upwind and contacted the pheromone source when presented with a blend consisting of (Z)-11-hexadecenal (Z11-16:Ald), (Z)-9-hexadecenal (Z9-16:Ald), and (Z)-11-hexadecenol (Z11-16:OH) in a 1:0.5:0.1 ratio that has previously been shown to be attractive to H. subflexa males. In addition, an H. virescens blend of Z11-16:Ald and (Z)-9-tetradecenal (Z9-14:Ald) enhanced by the addition of Z11-16:OH (in a 1:0.05:0.1 mixture) was attractive to hybrid males (26-64% source contact), but significantly fewer males reached the odor source compared to the blend containing Z9-16:Ald. A blend in which the dosage of Z9-14:Ald was doubled, however, was equally attractive (75-77% source contact) as the Z9-16:Ald-containing blend. Consecutive presentation of two blends revealed that individual hybrid males responded equally well to blends containing either Z9-14:Ald or Z9-16:Ald. Together these results suggest that in addition to Z11-16:Ald, hybrid males: (1) required either Z9-16:Ald (likeH. subflexamales) or Z9-14:Ald (like H. virescens males); (2) required the presence of Z11-16:OH (H. subflexa dominant); (3) were not adversely affected by the presence of Z11-16:Ac (H. subflexa dominant). The behavioral response phenotype of hybrid males was therefore influenced by genetic factors inherited from both parental species.

Animal Communication↗
PubMed1988

Measured behavioural latency in response to sex-pheromone loss in the large silk moth Antheraea polyphemus.

Males of the giant silk moth Antheraea polyphemus Cramer (Lepidoptera: Saturniidae) were video-recorded in a sustained-flight wind tunnel in a constant plume of sex pheromone. The plume was experimentally truncated, and the moths, on losing pheromone stimulus, rapidly changed their behaviour from up-tunnel zig-zag flight to lateral casting flight. The latency of this change was in the range 300-500 ms. Video and computer analysis of flight tracks indicates that these moths effect this switch by increasing their course angle to the wind while decreasing their air speed. Combined with previous physiological and biochemical data concerning pheromone processing within this species, this behavioural study supports the argument that the temporal limit for this behavioural response latency is determined at the level of genetically coded kinetic processes located within the peripheral sensory hairs.

Animals↗
PubMedDate not supplied

Flight and molecular modeling study on the response of codling moth, Cydia pomonella (Lepidoptera: Tortricidae) to (E,E)-8,10-dodecadien-1-ol and its geometrical isomers.

In a previous study we have reported that both (E,Z)-8,10-dodecadienol (E,Z) and (Z,Z)-8,10-dodecadienol (Z,Z) isomers inhibit the attraction of male codling moth, Cydia pomonella L. when added to (E,E)-8,10-dodecadienol (E,E) while the (Z,E)-8,10-dodecadienol (Z,E) isomer induces slight increase in the number of males attracted to the pheromone source. In the present study, we have tested the behavioral activity of the individual geometrical isomers E,Z; Z,E and Z,Z. A few number of codling moth males flew to the Z,E-isomer while the other two isomers (i.e. E,Z and Z,Z) did not elicit any upwind orientation. Analysis of the flight behavior to the E,E- and Z,E-isomer showed significant differences in most of the flight parameters evaluated. Based on the biological observations and molecular modeling, we suggest that the behavioral activity of the Z,E-isomer is due to presence of specific receptors for this isomer on male antennae and not to its structural resemblance to the E,E-isomer. These results underline the importance of the Z,E-isomer in sex attraction of male codling moth.

Animals↗
PubMed2000

Binding and toxicity of Bacillus thuringiensis protein Cry1C to susceptible and resistant diamondback moth (Lepidoptera: Plutellidae).

We studied mechanisms of resistance to Bacillus thuringiensis insecticidal crystal protein Cry1C in the diamondback moth, Plutella xylostella (L.). Binding assays with midgut brush border membrane vesicles prepared from whole larvae showed no significant difference between resistant and susceptible strains in binding of radioactively-labeled Cry1C. These results indicate that reduced binding of Cry1C to midgut membrane target sites did not cause resistance to Cry1C. Thus, the mechanism of resistance to Cry1C differs from that observed in several previously reported cases of resistance to Cry1A toxins in diamondback moth. We tested Cry1C toxin and Cry1C crystalline protoxin against resistant and susceptible larvae using leaf disk bioassays. After adjusting for the size difference between Cry1C toxin and protoxin, we found that with resistant larvae, toxin was significantly more toxic than protoxin. In contrast, with susceptible larvae, no significant difference in toxicity occurred between Cry1C toxin and protoxin. The resistance ratios for Cry1C were 19 for toxin and 48 for protoxin. These results suggest that reduced conversion of Cry1C protoxin to toxin is a minor mechanism of resistance to Cry1C. Because neither reduced binding nor reduced conversion of protoxin to toxin appear to be major mechanisms, one or more other mechanisms are important in diamondback moth resistance to Cry1C.

Animals↗
PubMed2001

The effects of cations on the activity of the gypsy moth (Lepidoptera: Lymantriidae) nuclear polyhedrosis virus.

Fourteen cations were tested at a 1% concentration (wt:wt), as chlorides, for their effects on the biological activity of the gypsy moth, Lymantria dispar (L.), nuclear polyhedrosis virus (LdMNPV). Cupric chloride was toxic to gypsy moth larvae. Ferrous and ferric chloride were inhibitory to larval growth and development as well as to virus activity. Strontium chloride was inhibitory to virus activity but had no apparent effects on gypsy moth larvae. Six cations had little or no effect on virus activity (i.e., calcium, lanthanum, magnesium, nickel, potassium, sodium), whereas four cations (i.e., cobalt, manganese, ruthenium, zinc) acted as viral enhancers, as indicated by reductions in LC50s.

Animals↗