Displaying all 9 publications

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  1. Lee HL, Vasan S, Ahmad NW, Idris I, Hanum N, Selvi S, et al.
    Transgenic Res., 2013 Feb;22(1):47-57.
    PMID: 22700207 DOI: 10.1007/s11248-012-9625-z
    We conducted the world's first experiments under semi-field conditions (ACL-2 field house) to assess the mating competitiveness of genetically sterile RIDL male mosquitoes (513A strain). The field house is a state-of-the-art, fully-contained trial facility, simulating the living space for a household of 2-4 people in Peninsular Malaysia. Ten genetically sterile RIDL male A. aegypti mosquitoes competed with ten wild type males inside this field house to mate with ten wild type females. Hatched larvae from mated females were screened under a fluorescent microscope for genetic markers to determine if they were fathered by RIDL male or wild type male, and all results were cross-checked by PCR. Two such experiments were conducted, each repeated sufficient number of times. All strains were on a Malaysian lab strain background for the first experiment, while the RIDL males alone were on a recently-colonised Mexican strain background for the second experiment. A total of 52 % of the matings were with RIDL males in the first experiment, while 45 % of the matings were with RIDL (Mexican) males in the second experiment. Statistically, this is not significantly different from 50 % of the matings expected to take place with RIDL males if the latter were as competitive as that of the wild type males. This shows that A. aegypti RIDL-513A has excellent mating competitiveness under semi-field conditions, verifying earlier trends obtained in small lab cages. We also observed high mating compatibility between recently-colonised Mexican RIDL males and lab-reared Malaysian wild type females.
    Matched MeSH terms: Sexual Behavior, Animal/physiology
  2. Nazni WA, Lee HL, Dayang HA, Azahari AH
    PMID: 19323032
    Reciprocal and homologous mating experiments between Malaysian Aedes aegypti and Aedes albopictus mosquitoes were conducted in the laboratory. Two methods were employed, namely an artificial mating technique and a natural cage mating technique. The study demonstrated there exists a strong reproductive isolation between Ae. aegypti and Ae. albopictus. Insemination occurred in cross-mating experiments between Ae. aegypti females and Ae. albopictus males and also between Ae. albopictus females and Ae. aegypti males. Cross mating between Ae. aegypti females and Ae. albopictus males produced more eggs than that between Ae. albopictus females and Ae. aegypti males with both artificial mating and natural cage mating techniques. The matings did not result in the production of viable eggs by the females. No embryonation of these eggs was observed when the eggs were bleached. With homologous mating Aedes aegypti produced significantly greater numbers of eggs compared to Aedes albopictus mosquitoes, and all the eggs hatched successfully.
    Matched MeSH terms: Sexual Behavior, Animal/physiology*
  3. Schilthuizen M
    BMC Evol. Biol., 2003 Jun 05;3:13.
    PMID: 12791170
    BACKGROUND: Many groups of land snails show great interspecific diversity in shell ornamentation, which may include spines on the shell and flanges on the aperture. Such structures have been explained as camouflage or defence, but the possibility that they might be under sexual selection has not previously been explored.

    PRESENTATION OF THE HYPOTHESIS: The hypothesis that is presented consists of two parts. First, that shell ornamentation is the result of sexual selection. Second, that such sexual selection has caused the divergence in shell shape in different species.

    TESTING THE HYPOTHESIS: The first part of the hypothesis may be tested by searching for sexual dimorphism in shell ornamentation in gonochoristic snails, by searching for increased variance in shell ornamentation relative to other shell traits, and by mate choice experiments using individuals with experimentally enhanced ornamentation. The second part of the hypothesis may be tested by comparing sister groups and correlating shell diversity with degree of polygamy.

    IMPLICATIONS OF THE HYPOTHESIS: If the hypothesis were true, it would provide an explanation for the many cases of allopatric evolutionary radiation in snails, where shell diversity cannot be related to any niche differentiation or environmental differences.

    Matched MeSH terms: Sexual Behavior, Animal/physiology*
  4. Aziz HA, Peh KK, Tan YT
    J Sex Med, 2009 Mar;6(3):682-95.
    PMID: 19143913 DOI: 10.1111/j.1743-6109.2008.01157.x
    Khat (Catha edulis) is an evergreen tree/shrub that is thought to affect sexual motivation or libido. Its positive effect on sexual desire is more frequently observed in females than in males and occurs when khat is chewed. Thus, khat's effects on sexual behavior may depend on the release mode of its active constituent.
    Matched MeSH terms: Sexual Behavior, Animal/physiology*
  5. Rogers DW, Baker RH, Chapman T, Denniff M, Pomiankowski A, Fowler K
    J Evol Biol, 2005 May;18(3):642-50.
    PMID: 15842493
    Traditionally it was thought that fitness-related traits such as male mating frequency, with a history of strong directional selection, should have little additive genetic variance and thus respond asymmetrically to bidirectional artificial selection. However, recent findings and theory suggest that a balance between selection for increased male mating frequency and opposing selection pressures on physiologically linked traits will cause male mating frequency to have high additive genetic variation and hence respond symmetrically to selection. We tested these hypotheses in the stalk-eyed fly, Cyrtodiopsis dalmanni, in which males hold harems comprising many females and so have the opportunity to mate at extremely high frequencies. We subjected male stalk-eyed flies to artificial selection for increased ('high') and decreased ('low') mating frequency in the presence of ecologically realistic, high numbers of females. High line males mated significantly more often than control or low line males. The direct response to selection was approximately symmetric in the high and low lines, revealing high additive genetic variation for, and no significant genetic constraints on, increased male mating frequency in C. dalmanni. In order to investigate trade-offs that might constrain male mating frequency under natural conditions we examined correlated responses to artificial selection. We measured accessory gland length, testis length and eyespan after 7 and 14 generations of selection. High line males had significantly larger accessory glands than low line males. No consistent correlated responses to selection were found in testis length or eyespan. Our results suggest that costs associated with the production and maintenance of large accessory glands, although yet to be identified, are likely to be a major constraint on mating frequency in natural populations of C. dalmanni.
    Matched MeSH terms: Sexual Behavior, Animal/physiology*
  6. Matsumura Y, Kamimura Y, Lee CY, Gorb SN, Rajabi H
    Sci Rep, 2021 04 12;11(1):7920.
    PMID: 33846369 DOI: 10.1038/s41598-021-86864-1
    We unveiled the penile penetration mechanics of two earwig species, Echinosoma horridum, whose intromittent organ, termed virga, is extraordinarily long, and E. denticulatum, whose virga is conversely short. We characterised configuration, geometry, material and bending stiffness for both virga and spermatheca. The short virga of E. denticulatum has a material gradient with the stiffer base, whereas the long virga of E. horridum and the spermathecae of both species are homogeneously sclerotised. The long virga of E. horridum has a lower bending stiffness than the spermatheca. The virga of E. denticulatum is overall less flexible than the spermatheca. We compared our results to a previous study on the penetration mechanics of elongated beetle genitalia. Based on the comparison, we hypothesised that the lower stiffness of the male intromittent organ comparing to the corresponding female structure is a universal prerequisite for the penetration mechanics of the elongated intromittent organ in insects.
    Matched MeSH terms: Sexual Behavior, Animal/physiology*
  7. Ang HH, Lee KL, Kiyoshi M
    J Basic Clin Physiol Pharmacol, 2004;15(3-4):303-9.
    PMID: 15803965 DOI: 10.1515/jbcpp.2004.15.3-4.303
    Eurycoma longifolia Jack commonly known as Tongkat Ali in Malaysia, has been used in Malaysia to increase male virility and sexual prowess. The objective of this study is to evaluate sexual arousal in sexually sluggish old male rats, 24 months old and retired breeders, receiving 200, 400, or 800 mg/kg of various fractions of E. longifolia Jack, twice daily, for 10 days. Control rats received 3 ml/kg of normal saline. The aphrodisiac effect was monitored by the act of yawning and stretching because yawning, either alone or associated with stretching, is considered an ancestral vestige surviving throughout evolution that promotes sexual arousal. The results showed that 800 mg/kg of E. longifolia Jack increased yawning by 50% and stretching by 16.7% in sexually sluggish old male rats, by 676-719% and 31-336%, respectively, in sexually active male rats, and by 22-44% and 75-100%, respectively, in middle aged, 9 months old and retired breeders. We conclude that the results of this study support the folk use of this plant as an aphrodisiac.
    Matched MeSH terms: Sexual Behavior, Animal/physiology
  8. Wee SL, Tan KH
    J Chem Ecol, 2005 Apr;31(4):845-58.
    PMID: 16124255 DOI: 10.1007/s10886-005-3548-6
    Bactrocera carambolae and B. papayae are major fruit fly pests and sympatric sibling species of the B. dorsalis complex. They possess distinct differences in male pheromonal components. In the 1990's, wild Bactrocera fruit flies with morphological traits intermediate between those of B. carambolae and B. papayae were often captured in traps baited with methyl eugenol (ME). Chemical analyses of rectal glands of ME-fed males revealed that the laboratory Fl, F2, and backcross hybrids possessed ME-derived sex pheromonal components ranging from that typical of B. papayae to that of B. carambolae without any specific trend, which included a combination of pheromonal components from both parental species within an individual hybrid. ME-fed hybrids without any ME-derived pheromonal components were also detected. Further chemical analysis of rectal glands from wild Bactrocera males, after ME feeding in the laboratory, showed a combination of pheromonal components similar to that found in the ME-fed, laboratory-bred hybrids. These findings present circumstantial evidence for the occurrence of a natural hybrid of the two Bactrocera species.
    Matched MeSH terms: Sexual Behavior, Animal/physiology*
  9. Hee AK, Tan KH
    J Chem Ecol, 2004 Nov;30(11):2127-38.
    PMID: 15672660 DOI: 10.1023/B:JOEC.0000048778.02561.70
    Pharmacophagy of methyl eugenol (ME)--a highly potent male attractant, by Bactrocera papayae results in the hydroxylation of ME to sex pheromonal components, 2-ally-4,5-dimethoxyphenol (DMP) and (E)-coniferyl alcohol (CF). These compounds, which are also male attractants, are then sequestered and stored in the rectal gland prior to their release during courtship at dusk. Chemical analyses of the digestive tract (excluding the crop and rectal gland) showed the absence of the sex pheromonal components and their precursor, ME. However, B. papayae males were attracted to and fed on the ME-fed male hemolymph extracts but not on hemolymph extracts of ME-deprived males. After thin layer chromatography in a hexane:ethyl acetate solvent system, flies were attracted to and fed on the original point on the TLC plate where the hemolymph extract had been spotted, suggesting that the pheromone components were bound in polar complexes. Chemical analyses of the ME-fed male hemolymph and crop extracts revealed the presence of the sex pheromonal components. The presence of the ME-derived pheromonal components and the absence of ME in the hemolymph suggest that the hemolymph is involved in the transportation of sex pheromonal components from the crop to the rectal gland.
    Matched MeSH terms: Sexual Behavior, Animal/physiology
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