Laboratory Mating Research Articles

Identification of a laboratory mating form of the Simulium damnosum Theobald complex in West Africa

Larvae and pupae of Simulium damnosum s.l. were collected from the Begba rapids on the Mono river. Emerging adults were induced to mate, blood feed and oviposit. Six out of 13 discrete egg batches counted were fertile. The F1 females did not blood feed and thus no F2 eggs were obtained. Larvae from the breeding site and the F1 generation were identified as being the Beffa form of the S. sanctipauli/S. soubrense group. This form appears to be the only member of the S. damnosum complex in West Africa which mates in the laboratory and is almost certainly the same form as that colonized by Simmons and Edman (1982). The mating behaviour of West African S. damnosum s.l. described by several authors is similar to that observed in the Beffa form, and the possibility that earlier reports referred to the Beffa form is discussed.

R-plasmid transfer in a wastewater treatment plant.

Enteric bacteria have been examined for their ability to transfer antibiotic resistance in a wastewater treatment plant. Resistant Salmonella enteritidis, Proteus mirabilis, and Escherichia coli were isolated from clinical specimens and primary sewage effluent. Resistance to ampicillin, chloramphenicol, streptomycin, sulfadiazine, and tetracycline was demonstrated by spread plate and tube dilution techniques. Plasmid mediation of resistance was shown by ethidium bromide curing, agarose gel electrophoresis, and direct cell transfer. Each donor was mated with susceptible E. coli and Shigella sonnei. Mating pairs (and recipient controls) were suspended in unchlorinated primary effluent that had been filtered and autoclaved. Suspensions were added to membrane diffusion chambers which were then placed in the primary and secondary setting tanks of the wastewater treatment plant. Resistant recombinants were detected by replica plating nutrient agar master plates onto xylose lysine desoxycholate agar plates that contained per milliliter of medium 10 micrograms of ampicillin, 30 micrograms of chloramphenicol, 10 micrograms of streptomycin, 100 micrograms of sulfadiazine, or 30 micrograms of tetracycline. Mean transfer frequencies for laboratory matings were 2.1 X 10(-3). In situ matings for primary and secondary settling resulted in frequencies of 4.9 X 10(-5) and 7.5 X 10(-5), respectively. These values suggest that a significant level of resistance transfer occurs in wastewater treatment plants in the absence of antibiotics as selective agents.

Linkage relationships among five enzyme-coding gene loci in the copepod Tigriopus californicus: a genetic confirmation of achiasmiatic meiosis.

Linkage relationships among five polymorphic enzyme-coding gene loci in the marine copepod Tigriopus californicus have been determined using electrophoretic analysis of progeny from laboratory matings. Phosphoglucose isomerase (PGI; EC 5.3.1.9) was found to be tightly linked to glutamate-pyruvate transaminase (GPT; EC 2.6..1.2), with only one recombinant observed in 364 progeny; glutamate-oxaloacetate transaminase (GOT; EC 2.6.1.1) is linked to the PGI-GPT pair, with a recombination fraction of approximately 0.20 in male double heterozygotes. Phosphoglucomutase (PGM; EC 2.7.5.1) and an esterase (EST; EC 3.1.1.1) are not linked to the PGI, GPT, GOT grouping, which has been designated linkage group I. Reciprocal crosses have revealed that no recombination occurs in female T. californicus; this observation confirms a previous report that meiosis in female Tigriopus is achiasmatic.

Hormonal and behavioral changes at puberty in the squirrel monkey

Developmental changes in the reproductive behavior and physiology of 9 male and 15 female juvenile squirrel monkeys were evaluated in a 20-month study. Plasma levels of gonadal steroids remained relatively low for this species until most animals reached puberty between 2.5 and 3 years of age. Longitudinal assessment of plasma progesterone levels indicated that the onset of ovarian cycles tended to be synchronized between females although the 5 heaviest females began to cycle earlier than the rest. The heavier females reached puberty at a time which was appropriate to their birth in the wild, whereas most of the remaining females conceived 6 months later during a second period of reproductive activity that coincided with the laboratory mating season. Pubescent males underwent their first seasonal elevation in plasma testosterone levels during the second period and its onset was synchronized across all males. Thus, even in the absence of adults, pubertal processes in the squirrel monkey were strongly influenced by the seasonal breeding pattern. In addition, behavioral observations revealed that social maturation closely parallels reproductive ability in females, whereas males enter a protracted subadult stage after puberty.

The genetic basis of a dorsal color polymorphism in Rana pipiens.

Leopard frogs (Rana pipiens Schreber) from Colorado were used in laboratory matings to investigate the mode of inheritance of green-brown, dorsal background color polymorphism. A total of 624 F1 progeny were produced in 18 successful matings. The results support the hypothesis that the control of dorsal color in Rana pipens is a two-allele, one-locus system with the allele for green color dominant to the allele for brown color.

Hybridization and mating behavior in Aedes aegypti (Diptera: Culicidae).

In the Rabai District of Kenya 2 distinct forms of the mosquito Aedes aegypti are found: a domestic form, which breeds in the houses of villages, and a sylvan form, which breeds primarily in tree holes in forested regions. The dimorphism is maintained in spite of the sympatric distribution of the forms, which appears to provide ample opportunity for gene flow. The possibility that hybrid breakdown serves to isolate the forms was tested by setting up hybrid crosses and backcrosses to parental types. The hatchabilities of the eggs from these crosses were determined, and the offspring were examined for morphological defects. The possibility of assortative mating was tested in a laboratory mating preference experiment. Each form was bred to be homozygous for a different allele at the ldh-2 locus, which was assayed by gel electrophoresis. Virgin males and females of the 2 forms were placed together in a cage, and their mating preferences were determined by assaying 1 offspring of each female by electrophoresis. No hybrid breakdown or any deviation from random mating was detected. These data are consistent with the contention that Aedes aegypti is a single polytypic species.

Hybridization and the Detection of Hybrids in the Fairy Shrimp Genus Streptocephalus

Viable adult hybrids were obtained in laboratory mating tests involving five species pairs of Streptocephalus fairy shrimps. Three hybrid types were distinguished from parental types using prominent diagnostic features of parental species: two hybrid types resembled only one parental species in diagnostic features. Laboratory hybrids provided a search image for detecting natural hybrids in collections of mixed-species populations. These studies suggest, but do not prove, that S. mackini hybridizes to.a limited extent with both S. dorothae and S. texanus where they co-occur. Introduction Hybrid animals are not often found in nature (Mayr, 1963), and it is generally assumed that matings between species are correspondingly rare. For many animal groups this is undoubtedly true. However, our ability to recognize hybrids is directly related to the extent of our knowledge about the morphological variation within and between species, and all too often we know species only by their diagnostic characters. Since hybrids sometimes reflect the diagnostic features of only one parental species, natural hybrids may go undetected. Laboratory mating studies provide information which aids in the detection of hybrids in natural mixed-species populations. These laboratory tests indicate which species pairs are likely to hybridize and provide a search image for natural hybrids based on the morphology of laboratory hybrids. This approach is particularly useful for evaluating material, such as museum collections, which cannot be altered for more detailed morphometric or biochemical studies. Laboratory mating studies have demonstrated a high degree of reproductive compatibility between species of Streptocephalus fairy shrimps (Wiman, in press). Crosses were attempted between eight species pairs, and five of these mating combinations resulted in adult hybrid offspring. All five successful crosses involved S. mackini as one parental species. The present study documents some of the morphological features of laboratory hybrids which may be of use in distinguishing hybrids from parental species in natural populations. Natural hybrids are most likely to be found where closely related allopatric species come into secondary contact (Remington, I960). Belk (1977) recently presented evidence suggesting that the ranges of Streptocephalus fairy shrimp species may be expanding due to the creation of many new man-made temporary pond habitats. Even though species ranges overlap to various degrees and two species sometimes occur in the same pond, species are largely allopatric (Wiman, 1978). Thus some of the Streptocephalus species may be characterized as allopatric species which have recently come into secondary contact. Given the geographic and reproductive relationships of these fairy shrimp species, one would expect hybridization to occur in natural populations. This study presents evidence for natural hybridization in the few available collections of mixed-species populations of Streptocephalus. Materials and Methods Laboratory hybrids were obtained from no-choice mating tests involving six species of Streptocephalus: S. mackini, S. dorothae, S. texanus, S. seali, S. linden and S. bou vie ri. When fertilized eggs were obtained from interspecific crosses, they were allowed to dry in 25-ml vials for at least 2 weeks at 19-22 C. The vials were then

Dynamics of a lactate dehydrogenase polymorphism in the wood louse Porcellio scaber latr.: evidence for partial assortative mating and heterosis in natural populations.

Electrophoretic separation of lactate dehydrogenase (LDH) of Porcellio scaber from 14 natural populations in California, and one each in Oregon, Delaware and Massachusetts, indicates a biallelic polymorphism. Phenotypes are recovered from laboratory matings of virgin females in frequencies agreeing with simple Mendelian inheritance, and the frequency distributions of phenotypes in natural populations are typically in agreement with the appropriate Hardy-Weinberg distributions for these same populations. The same allele predominates in all natural populations examined. Temporal stability within populations suggests that the polymorphism is at, or near, equilibrium. The spatial distribution of allele frequencies, however, is apparently mosaic. Abrupt discontinuities in gene frequency over short distances (50 m to 1 km) suggest that interpopulation migration is insufficient to swamp local differences in gene frequency. Analysis of the transmission dynamics of the polymorphism in natural populations using mother-offspring genotype comparisons suggests that the allelic frequencies of transmitted male gametes are not independent of female genotype. Specifically, the observed mating scheme in natural populations appears to be partially assortative. Comparisons of progeny genotype distributions with yearling (or adult) genotype distributions from the same populations indicate a superior post-partum viability of heterozygous individuals relative to homozygotes. The distortion of progeny genotypic distributions created by assortment is thus apparently counteracted by subsequent heterosis.

Some genetic analysis of supernumerary chromosomes in the black rat in laboratory matings.

Segregation phenomena of 66 offspring from matings of the black rat (Rattus rattus) having 1, 2 and 3 supernumeraries are analysed cytogenetically. The occurrence of a large number of the supernumeraries in the offspring is informative of nondisjunction in meiosis of the parents.

Cultivation of the warble-fly Oestromyia leporina pall. (Diptera, Hypodermatidae) and its biological prerequisites (author's transl)

The warble-fly Oestromyia leporina was cultivated for four generations in the laboratory. In the present paper the technic of laboratory mating and the modus of experimental infection of the host are described. The fertility of females is tested by experiments and by dissections. It is shown how the diapause of the puparia can be shortened and how it can be omitted. The successful infection of several species of small mammals demonstrates that O. leporina can be colonized not only on the natural host but also on some common laboratory animals like mice and rats.

Studies on the laboratory mating habits of the mosquito Culex pipiens

SYNOPSISThe variation in copulatory activity in three strains of Culex pipiens is investigated and the results are discussed in relation to genetic control of mosquito populations.

Preferential Mating and the Maintenance of the Sex-Limited Dimorphism in Papilio glaucus: Evidence From Laboratory Matings

Preferential Mating and the Maintenance of the Sex-Limited Dimorphism in Papilio glaucus: Evidence From Laboratory Matings

Postembryonic development of the spider Enoplognatha ovata (Clerck) (Araneae: Theridiidae)

The postembryonic development of the three colour varieties of Enoplognatha ovata (CI.) was studied in the field and in the laboratory for two generations. Native and European spiders of this species were compared. Estimates of the number and duration of each stage were obtained from laboratory mating studies and verified by field studies. Males and females matured after five instars. Males matured faster than females but did not live as long. Each instar was characterized by several measurable parameters. All varieties over-winter in the second instar. Sexes could be easily separated at the fourth instar by comparing the ratio of the tarsal to patellar width of the pedipalps. Sexual dimorphism occurs at maturation ecdysis. Filial and mating studies indicate that the three colour varieties belong to a single species.

Rapid incorporation of wild genotypes of Culex nigripalpus (Diptera: Culicidae) into laboratory-adapted strains.

Laboratory mating activities were analyzed in wild and colonized forms of Culex nigripalpus Theobald. Mating experiments utilizing colony females produced insemination levels of about 75% whereas in those experiments involving wild females the insemination rates were less than 2%. Mating success was independent of the type of male used in each cross. Wild genetic material was rapidly incorporated into colony strains via wild males crossed to colony females. This method was used to establish a laboratory marker strain which contains the mutant form, orange fat color.

Successful laboratory mating of two species of jackrabbit bot flies.

Various authors (Catts 1964, J. Med. Ent . 1: 195–96; Scholten 1964, J. Parasit . 50: 444) have recorded induced matings of rodent bot flies of the genus Cuterebra . To our knowledge there is no record of induced matings of Cuterebra jellisoni or C. ruficrus in the literature. Both species commonly occur as subcutaneous parasites of jackrabbits and other lagomorphs in the western United States. Ignoffo (1961, Ann. Ent. Soc. Amer . 54: 509–12) mentions fertile C. jellisoni eggs, but does not state how the fertility was achieved.

Progeny from Experimental Mating Tests with Mice of the Peromyscus leucopus Group

Sixty-six progeny from 79 laboratory mating tests between Pero-myscus leucopus and P. gossypinus were critically examined for hybrids. From the 39 cross-matings between gossypinus and leucopus in which a choice of mates was offered, there were 23 leucopus-reared progeny and two gossypinus-reared prog¬eny. The control tests using two pair of gossypinus produced three progeny and the 20 control tests for leucopus produced 38 progeny. Of the 25 progeny from crossmating tests, none showed the morphological intermediacy of hybrids and all could be assigned to one species or the other. Sexual isolation between the two species, and a preference for mates of their own kind, was operative under laboratory conditions in the absence of ecological isolation between the sympatric stocks and spatial isolation between the allopatric stocks. Stocks of leucopus from populations allopatric with gossypinus produced 19 litters while sympatric leucopus contributed only two litters. Although the ethological patterns within the species group are imperfectly understood, these tests support the hypothesis that differ-erences exist between the species and they agree with findings suggesting that ethological isolation reinforces other isolating mechanisms.

Controlled Mating, Karyology, Morphology, and Sex-Ratio in the Dendroctonus ponderosae Complex12

Laboratory mating experiments and observations on developmental rate, karyology, and morphology confirm the recent synonymy of Dendroctonus monticolae Hopkins with D. ponderosae Hopkins, but establish the species integrity of D. jeffreyi Hopkins, also previously considered a synonym of ponderosae. D. monticolae from British Columbia and 8 California localities were interfertile and morphologically similar. D. ponderosae from Colorado were interfertile with monticolae from California, but their mean pronotal widths, 2.44 mm and 2.10 mm, respectively, and indices of pronotal punctation, 5.43 and 6.12, respectively, were very significantly different. D. monticolae and its hybrid with ponderosae showed the karyotypic formula 11AA + Neo-XY. D. jeffreyi is larger (pronotal width = 2.63 mm) and its pronotum less densely punctured (index = 4.19) than monticolae and ponderosae. The karyotype of jeffreyi is also 11AA + Neo-XY, but the Neo-X is usually constricted and 1.4 times longer than the Neo-Y while the Neo-X of monticolae is rarely constricted and only slightly larger than the Neo-Y. In addition, a tiny supernumerary chromosome was present in some jeffreyi. In reciprocal pairings of monticolae and jeffreyi, none of the 846 eggs laid by 21 monticolae females hatched, but 8 larvae and 1 sterile female resulted from 362 eggs laid by 10 jeffreyi females. Five pairings of jeffreyi and pondcrosae produced no brood. Several jeffreyi (control) pairings showed a marked reduction in egg hatchability and only female progeny were produced. A male-lethal factor attacking the embryos is suggested, but pedigree data are insufficient to determine whether chromosomal or cytoplasmic factors are involved.

Laboratory Mating Studies of the Corn Earworm, Heliothis zea (Lepidoptera: Noctuidae)12

In laboratory mating studies of the corn earworm, Heliothis zea (Boddie), conducted through 5 generations, stocking the cage with plant material and special cage linings significantly improved the percentage of mating. The plant effect probably resulted from either its physical presence or a “triggering effect” related to infrared radiation and/or scent molecules. The effect of lining the cages with low emissivity aluminum foil probably resulted from the amplification of organic scent molecules by stimulated emission of radiation (maser action). No increase in the percentage of mating resulted when pairs of moths were associated more than 2 days; mating after 2 days was confined to second and third matings by females which had already mated.

THE POPULATION BIOLOGY OF THE BUTTERFLY, EUPHYDRYAS EDITHA. IV. SPERM PRECEDENCE-A PRELIMINARY REPORT.

The reproductive biology of the checkerspot butterfly, Euphydryas editha, is being investigated in order to integrate the details of the mating system of this nymphalid with other aspects of its population biology which have been elucidated (Ehrlich, 1961; Ehrlich and Mason, 1966; Labine, 1964). In the course of these investigations it was found that some females of E. editha in natural populations mate more than once during their reproductive life. For example, spermatophore counts showed that about a third of the females collected late in the 1964 season from the Silver Creek population, San Jose, California, had mated twice. Females have considerable capacity for storage. In laboratory matings a single insemination is usually sufficient to fertilize all of a female's eggs, which can occasionally number 1200 or more. Clearly, most females mating for the second time in the field have, at the time of mating, from their first mate stored in the spermatheca. Thus, they will subsequently lay eggs which theoretically could have been fertilized by either of the two males. The apportioning of paternity after second matings is obviously of great selective importance to individual males, and its specification seemed critical to an understanding of the mating system of E. editha. Two possible alternatives have been considered: either the two males mating with the same female contribute offspring to the the next generation in numbers directly proportional to the relative amounts of their in the spermatheca, or one of the males fertilizes a disproportionate number of the eggs. In Tribolium (Schlager, 1960) and Drosophila (LeFevre and Jonsson, 1962) the latter alternative has been found. Females mating with several males lay eggs which have been predominantly fertilized by of the last male to mate. This phenomenon has been described as sperm or sperm displacement. The following experiments were undertaken to determine if precedence occurred with multiple matings of E. editha. It should be emphasized at the start that Euphydryas editha is a difficult animal with which to work in the laboratory. Although much effort has been expended, techniques of continuous culture have yet to be devised. Until such efforts are successful, animals can be obtained only once a year, and then only for a short period. The work reported in this paper extended over two years. Techniques were refined during the spring of the first year, and during the spring of the second year, the experiments described below were performed. The results obtained are in some ways unsatisfactory. The number of animals involved was of necessity small, and the definitiveness of the results clearly could be improved by additional experimentation. On the other hand, the results do provide persuasive evidence of the operation of precedence in Euphydryas editha. Since this information directs attention to a ph'enomenon which is probably of considerable importance in shaping reproductive strategies in Lepidoptera, and which also provides an explanation for some of the peculiarities of the reproductive biology of Euphydryas editha, presentation of these preliminary results seems justified. 1 This work was supported in part by Grant GB-1430 from the National Science Foundation and Grant 5T1-GM-365 from the Public Health Service.

Inducing Mating and Oviposition of the Warble Flies Hypoderma bovis (L.) and H. lineatum (De Vill.) (Diptera: Oestridae) in Captivity

Certain investigations of the cattle grubs Hypoderma bovis (L.) and H. lineatum (De Vill.) have been hampered by difficulties in inducing the flies to mate and oviposit in captivity. For example, Parish (1955, 1957) suggested that infesting cattle with standard numbers of grubs would facilitate properly controlled experiments with therapeutic agents, and hc attempted artificial insemination of the female flies toward this objective. In addition, procedures that would induce mating and oviposition in thc laboratory could be used to analyse the reproductive behavior of the flies and the characteiistics of the resulting cattle grub populations.