Pupal Colour Dimorphism Research Articles

A Novel Genetic Sexing Strain of Anastrepha ludens for Cost-Effective Sterile Insect Technique Applications: Improved Genetic Stability and Rearing Efficiency.

Simple SummaryTephritid flies, including the Mexican fruit fly Anastrepha ludens, are key agricultural pests responsible for billions of dollars of damage each year due to the female flies which lay eggs and develop maggots in the fruits of hundreds of species of economically-important plants. Integrated pest management practices such as the sterile insect technique were developed which rely on the mass rearing and release of millions of sterile males of the same pest species in order to suppress the pest reproductive capacity. The presence of females in early bisexual strains often caused high rearing and release costs plus damage to crops by oviposition. Therefore, using classical genetic tools, genetic sexing strains were developed for some fruit flies in order to produce male-only colonies which enhanced the technique efficacy, cost-efficiency and reduced undesirable side-effects such as fruit damage by the mass reared females. In this paper the process for the development and characterization of a new genetic sexing strain (GSS) for A. ludens is documented, using the low-dose irradiation and line selection techniques. The new GUA10 GSS, when compared with its predecessor Tapachula-7, promises to further increase the sterile insect technique performance given its higher quality, yield and genetic stability.Anastrepha ludens (Loew) is one of the most destructive insect pests damaging several fruits of economic importance. The sterile insect technique (SIT) is used under an area-wide integrated pest management approach, to suppress these pest populations. Mass rearing facilities were initially established to produce sterile males of bi-sexual strains in support of SIT. The first genetic sexing strain (GSS) for A. ludens, Tapachula-7, based on pupal color dimorphism, was a key development since the release of males-only significantly increases the SIT efficiency. In this study, we document the development of a novel pupal color-based GSS. Twelve radiation-induced translocation lines were assessed as potential GSS in terms of recombination rates and rearing efficiency at a small scale. The best one, GUA10, was cytogenetically characterized: it was shown to carry a single translocation between the Y chromosome and chromosome 2, which is known to carry the black pupae marker. This GSS was further evaluated at medium and large scales regarding its genetic stability, productivity and quality versus Tapachula-7. GUA10 presented better genetic stability, fecundity, fertility, production efficiency, flying ability, and male mating, clear indicators that GUA10 GSS can significantly improve the efficacy and cost-effectiveness of SIT applications against this pest species.

Pupal colour dimorphism in a desert swallowtail (Lepidoptera: Papilionidae) is driven by changes in food availability, not photoperiod

1. The swallowtail butterfly Battus polydamas archidamas Boisduval, 1936, exhibits polyphenism for pupal coloration (green and brown). It is distributed across arid regions with winter rains and is monophagous on Aristolochia plants, which emerge after the winter rains and dry out the during summer. Thus, day length does not covary positively with host plant productivity. It was hypothesised that pupal colour was driven by food availability, not photoperiod. The benefits of pupal coloration matching the colour of pupation sites in terms of field survival were also investigated to evaluate the adaptive value of pupa colour.2. Larvae were reared under a factorial array of two photoperiods (LD 10:14 h and LD 14:10 h) and two food availability regimes (leaves ad libitum and available every other day) to assess the frequency of green and brown pupae. Field survival of green and brown pupae was quantified in three commonly used habitats that differ in background coloration (cacti, rocks and shrubs).3. Food availability determined pupal colour. Larvae in the ad libitum regime resulted mostly in green pupae, while those with restricted food were mostly brown. In contrast, photoperiod did not influence pupal colour. Survival probability of pupae placed on cacti was higher than those placed on rocks and shrubs, and the lowest predation risk across habitats was for green pupae on cacti.4. Food availability plays a major role in the seasonal polyphenism for pupal colour of specialist butterflies inhabiting arid environments with winter rains.

Development, genetic and cytogenetic analyses of genetic sexing strains of the Mexican fruit fly, Anastrepha ludens Loew (Diptera: Tephritidae).

BackgroundAnastrepha ludens is among the pests that have a major impact on México's economy because it attacks fruits as citrus and mangoes. The Mexican Federal government uses integrated pest management to control A. ludens through the Programa Nacional Moscas de la Fruta [National Fruit Fly Program, SAGARPA-SENASICA]. One of the main components of this program is the sterile insect technique (SIT), which is used to control field populations of the pest by releasing sterile flies.ResultsTo increase the efficiency of this technique, we have developed a genetic sexing strain (GSS) in which the sexing mechanism is based on a pupal colour dimorphism (brown-black) and is the result of a reciprocal translocation between the Y chromosome and the autosome bearing the black pupae (bp) locus. Ten strains producing wild-type (brown pupae) males and mutant (black pupae) females were isolated. Subsequent evaluations for several generations were performed in most of these strains. The translocation strain named Tapachula-7 showed minimal effect on survival and the best genetic stability of all ten strains. Genetic and cytogenetic analyses were performed using mitotic and polytene chromosomes and we succeeded to characterize the chromosomal structure of this reciprocal translocation and map the autosome breakpoint, despite the fact that the Y chromosome is not visible in polytene nuclei following standard staining.ConclusionsWe show that mitotic and polytene chromosomes can be used in cytogenetic analyses towards the development of genetic control methods in this pest species. The present work is the first report of the construction of GSS of Anastrepha ludens, with potential use in a future Moscafrut operational program.

Genetic and Cytogenetic Characterization of Genetic Sexing Strains of <I>Bactrocera dorsalis</I> and <I>Bactrocera cucurbitae</I> (Diptera: Tephritidae)

In the current study, we performed genetic and cytogenetic analyses of two genetic sexing strains (GSSs), one for Bactrocera dorsalis s.s. and one for melon fly, Bactrocera cucurbitae Coquillett, the first such strains ever constructed in these species. In both strains, the genetic sexing mechanism is based on a pupal color dimorphism (white or brown) and is the result of a reciprocal translocation between the Y chromosome and the autosome bearing the white pupae (wp) locus. Based on genetic analysis and cytological data on mitotic metaphases and larval salivary gland polytene chromosomes, we succeeded in mapping the autosome breakpoints in the two Y-autosome translocations even though the Y chromosome is not visible in polytene nuclei. We show that polytene chromosomes can be used in cytogenetic analyses toward the development of genetic control methods in these pest species. The results of the genetic analysis are in full agreement with the cytological description of the strains.

Characterization and evaluation of microsatellite markers in a strain of the oriental fruit fly, Bactrocera dorsalis (Diptera: Tephritidae), with a genetic sexing character used in sterile insect population control

The oriental fruit fly, Bactrocera dorsalis, is a key economic insect pest reducing fruit yield and generating constraints in the international market. The application of the sterile insect technique (SIT) continues to reveal areas where new technologies can improve the effectiveness of fruit fly control. One such advancement concerns insect strains. In the present study, a mass-reared strain of the fly with a translocation-based genetic sexing character (Salaya1) based on a brown-white pupal colour dimorphism was genetically characterized using 11 microsatellite DNA markers. Subsequently, these markers were used to evaluate the maintenance of genetic variability in the strain under mass-rearing conditions. Mating competitiveness of this strain was also tested in field cages. Two of the newly characterized Y-pseudo-linked microsatellite markers were used for strain identification in field monitoring traps. The strain was also validated in a pilot integrated pest management (IPM) programme using male-only SIT in a fruit orchard. The programme resulted in the suppression of the fruit fly population.

Diapause dynamics, seasonal phenology, and pupal color dimorphism of Papilio polyxenes in southern Florida, USA

AbstractThe seasonal phenology, pupal diapause, and pupal color dimorphism of a Papilio polyxenes Fabr. (Lepidoptera: Papilionidae: Papilionini) population from subtropical southern Florida, USA, were studied. Adult eclosion from field‐collected individuals indicated that this population is primarily active from the late dry season through the wet season (March–September). Most pupae entering diapause in April eclosed the same year but one pupa eclosed the following February. In laboratory tests, larval rearing under short days (L10:D14) induced 88.6% pupal diapause. Diapause responses to relatively longer (L12:D12–L16:D8) photoperiods ranged from 35.1–51.5%, and were statistically equivalent. These results indicate greater variability in the photoresponse of subtropical P. polyxenes compared to temperate populations that generally show little diapause under long‐day conditions and complete diapause under short days. The proportions of diapause pupae and brown pupal color, among broods reared at photoperiods ≥L12:D12, were both normally distributed. Diapause pupae were sensitive to photoperiods from L10:D14 to L16:D8. Diapause duration was inversely related to the photophase length to which the pupae were continuously exposed. Four generations of selection, at L10:D14, for non‐diapause reduced pupal diapause from 88.6 to 20.6%, indicating the existence of considerable additive genetic variance for this trait. Selection for non‐diapause increased the percentage of green pupae from 21.8 to 58.8% and decreased the incidence of diapause in both green and brown pupae. Brown pupal color and liability to diapause are linked, but this linkage is weaker than that documented in temperate populations. The overriding effect of short days (L10:D14) inducing only brown diapause pupae did not occur in southern Florida P. polyxenes.

Interspecific Comparison of Pupation Site Preference in Swallowtail Butterflies (Lepidoptera: Papilionidae): Implications for Evolution of Plasticity in Pupal Color

Abstract Variation in pupation site preference is hypothesized to drive the evolution of environmentally cued pupal color dimorphism in swallowtail butterflies. Support for this hypothesis comes from comparisons of natural pupation sites of species monomorphic and dimorphic for pupal color. Here, we show that interspecific differences in pupation site preferences in nature are to a large extent mimicked in a controlled common garden experiment, suggesting that these differences are genetic. We gave larvae of three swallowtail species a choice of yellow and blue surfaces for pupation. Given the absorption spectra of green vegetation and the spectral sensitivities of the larval eyes, yellow and blue surfaces should be strong indicators of green and brown pupation sites, respectively. Papilio glaucus L., which produces only brown pupae and pupates near the ground in nature, chose to pupate near the bottom of the blue surfaces. In contrast, Battus philenor (L.) and Eurytides marcellus (Cramer), which produce ...

Pupation site preference and environmentally cued pupal colour dimorphism in the swallowtail butterfly Papilio polyxenes Fabr. (Lepidoptera: Papilionidae)

Environmentally cued polymorphisms are hypothesized to evolve when the environment is coarse-grained and different genotypes are unable to choose the habitats in which they are most fit. InPapilio polyxenes, which has an environmentally cued pupal colour dimorphism, there is genetic variation in both tendency to produce brown or green pupae and preference for green- or brown-inducing pupation sites, but the two traits are not correlated.

Pupation site preference and environmentally cued pupal colour dimorphism in the swallowtail butterflyPapilio polyxenesFabr. (Lepidoptera: Papilionidae)

Environmentally cued polymorphisms are hypothesized to evolve when the environment is coarse-grained and different genotypes are unable to choose the habitats in which they are most fit. InPapilio polyxenes, which has an environmentally cued pupal colour dimorphism, there is genetic variation in both tendency to produce brown or green pupae and preference for green- or brown-inducing pupation sites, but the two traits are not correlated.

Cytogenetic analysis of three genetic sexing strains of Ceratitits capitata

Polytene chromosomes of three genetic sexing strains of Ceratitis capitata were analyzed. The genetic sexing mechanism is based on a pupal color dimorphism (white-brown) and is the result of a reciprocal translocation between the Y chromosome and the autosome bearing the w locus (white pupal case). The analyzed polytene chromosomes were derived from two different pupal tissues, the orbital bristle and fat body cells. The Y chromosome is visible in both tissues, while the autosomes present a different banding pattern. Based on these features, the autosome breakpoints in the three Y; autosome translocations were mapped, and the homology of the translocated autosome in both tissues was established. In addition, the location of the break-points was compared to the stability of these three strains.

Pupal colour dimorphism in swallowtail butterflies: timing of the sensitive period and environmental control

ABSTRACT. Two North American swallowtail butterflies with pupal colour dimorphism, Eurytides marcellus (Cramer) and Papilio troilus L., use chiefly the colour of the pupation substrate to determine pupal colour, and are affected hardly (P.troilus) or not at all (E.marcellus) by substrate texture. The use of colour cues in these species is in contrast to the greater importance of texture in two other sympatric swallowtails (Hazel & West, 1979). E.marcellus larvae evacuate the gut and start prepupal wandering around mid‐day. If they have not reached the sensitive period for pupal colour determination by nightfall they will delay the sensitive period until the next day. Among other North American swallowtails with pupal colour dimorphism there is no tendency for those species that use textural cues for pupal colour determination to evacuate the gut later in the day than those using pupation site colour.

The genetic and environmental basis of pupal colour dimorphism in Papilio zelicaon (Lepidoptera: papilionidae)

The genetic and environmental basis of brown and green pupal colour dimorphism in the butterfly Papilio zelicaon was studied using univoltine, multivoltine, and selected low-diapause populations. The propensity for formation of brown pupae and the positive correlation between brown pupae and diapause show both inter- and intrapopulation variability. Reciprocal hybrids had colour frequencies and magnitude of the pupal colour-diapause correlation intermediate between parental population values with evidence for maternal effects in the latter. Colour frequencies among individual broods were normally distributed. One generation of selection increased incidence of green pupae and was most effective at a high selection differential. Selection results plus a heritability determination indicated that pupal colour dimorphism in P. zelicaon is a threshold trait with quantitative genetic variation. Short days and cool temperatures induced mostly diapause brown pupae irrespective of pupation substrate whereas long days and warm temperatures facilitated continuous development and cryptic colour matching of pupae to their substrate.

Pupal colour dimorphism in California Battus philenor: pupation sites, environmental control, and diapause linkage

ABSTRACT. Natural pupation sites and corresponding pupal colour (green or brown) were determined for samples of Battus philenor (L.) from two Californian populations. Larvae pupate off the ground on trees, shrubs and man‐made objects. The vertical distribution of pupation sites and relative frequencies of pupae formed on narrow twigs and broad substrates show interpopulation variability, and seem to be determined by habitat‐specific and possibly behavioural differences among populations. The percentage of‘mismatched’pupae in green leafy environments (brown) is greater than that on wide substrates (green). Heterogeneity in samples of the latter suggest strong but sporadic predation pressure on non‐cryptic pupae in exposed areas. Green and brown substrates generally promoted formation of cryptic green and brown pupae although rearing conditions modified pupal colour response to substrate colour and larval pupation site choice. Warm temperatures and long days increased the production of brown pupae. Short photoperiods increased the tendency of larvae to pupate on narrow twig‐like substrates and to form green pupae. Green pupae show less tendency to diapause than brown pupae. The difference between percentage diapause in the two colour forms increases under conditions favouring progressively more continuous development.

Pupal colour dimorphism in swallowtail butterflies as a threshold trait: Selection in Eurytides marcellus (Cramer)

Pupal colour dimorphism in swallowtail butterflies as a threshold trait: Selection in Eurytides marcellus (Cramer)

Neuroendocrine mechanism involved in pupal colour dimorphism in swallowtail Papilio xuthus L.

Neuroendocrine mechanism involved in pupa) colour dimorphism in Papilio xuthus L. has been studied using ultrastructural techniques. The browning hormone in the form of neurosecretory material is secreted in the brain during the larval stage and transported to the axonal endings in the prothoracic ganglion, irrespective of the colour of the future pupa. If larvae select for pupation environmental conditions that are conducive for the formation of a brown pupa, release of the browning hormone occurs in the middle of the prepupal stage. No release occurs in larvae that have selected environmental conditions that favour the formation of green pupae. It is suggested that the brain, having integrated and interpreted the environmental conditions selected by the larva for pupation, gives the order to release the browning hormone. Such an order is conveyed via neural path from the brain to either the prothoracic ganglion, or some still unknown neurohaemal organ associated with it, from which release then takes place.

Automated sexing ofCeratitis capitata [Dip.: Tephritidae]: The development of strains with inherited, sex-limited pupal color dimorphism

The wild-type allele of a “dark pupae” mutant of the Mediterranean fruitfly,Ceratitis capitata Wied. was translocated to the male's Y-chromosome. Through a series of crosses and backcrosses, 2 lines of the Mediterranean fruitfly with the male linked translocation were produced. These lines produced continuously wild-type (brown pupae) males and mutant “dark pupae” females. The lines are true-breeding. Automated sex-sorting of such lines may be feasible using the pupal color dimorphism.

The genetic basis of pupal colour dimorphism and its maintenance by natural selection in Papilio polyxenes (Papilionidae: lepidoptera)

The genetic basis of pupal colour dimorphism in the swallowtail Papilio polyxenes was studied by surveying the frequencies of brown and green pupae in broods from 23 wild caught females, and by selecting for production of brown and green pupae. It was concluded that the genetic basis of the dimoprhism is a threshold trait with quantitative genetic variation underlying the two phenotypes. It was further concluded that the dimorphism is maintained in nature by weak stabilising selection, thus explaining the occurrence of mismatches between pupal and background colour.