Interspecific Mating Research Articles

Does hunger lead to hybridization in a genus of sexually cannibalistic insects (Orthoptera: Prophalangopsidae)?

Abstract Allochronic isolation can be a strong mechanism for reproductive isolation and speciation. However, imperfect allochrony and the expression of phenological plasticity can erode temporal barriers to gene flow and result in hybridization between divergent lineages. Here, we combine behavioural ecology and genomics to investigate this scenario in two closely related species of grigs in the genus Cyphoderris. These species exhibit a unique mating system whereby females feed on the fleshy hind wings of the male during copulation, and copulation with conspecific males is more likely in food-restricted females than in well-fed females. In western Canada, Cyphoderris buckelli and Cyphoderris monstrosa are sympatric but largely allochronically separated, with C. buckelli breeding earlier. However, their breeding seasons can overlap, leading to potential for older C. buckelli females to mate with young C. monstrosa males to obtain resources via sexual cannibalism. We used behavioural assays to test whether female feeding status affects the propensity for interspecific mating between C. buckelli females and C. monstrosa males. We then tested for hybridization and gene exchange in wild populations of both species, using morphology, mitochondrial DNA and genome-wide nuclear markers. We found that interspecific courtship and mating can occur, but the relationship between food restriction and increased propensity for hybridization was not significant. Although we observed intraspecific population genetic structure in both species, we found no signatures of hybridization in the morphological or genetic datasets, which suggests that postmating reproductive barriers might be preventing successful hybridization in the wild.

Mixed-species associations and attempted mating suggest hybridization between purple-faced and tufted gray langurs of Sri Lanka.

Hybridization is increasingly recognized as an important mechanism of evolutionary change in the order Primates. Here, we present the first observational data supporting natural hybridization between the critically endangered purple-faced langur (Semnopithecus vetulus philbricki) and the threatened tufted gray langur (Semnopithecus priam thersites) in Kaludiyapokuna Forest Reserve in Sri Lanka. In one case study, we observed a long-term (> 1 year) mixed-species group consisting of one adult tufted gray langur male coexisting with seven adult purple-faced females. Although copulations were not observed, two infants were conceived during the male’s tenure, and the coat color of one of these infants transitioned into that intermediate between those of the two langur species. The tufted gray langur male was also aggressive toward extra-group males of both species, as well as towards purple-faced juveniles within his group. However, we never witnessed the male exhibiting aggression towards the infants conceived during his tenure. In a second case study, a female purple-faced langur visited and sexually solicited a tufted gray langur male in a known study group of this species over the course of 2 days, in what resembled a sexual consortship. Taken together, the observed mixed-species association and attempted interspecific mating suggest that hybridization is very likely in these sympatric species. Genetic data are needed to confirm and determine the extent of hybridization in the dry zone of Sri Lanka where purple-faced langurs live in sympatry with tufted gray langurs.

Breeding and fruiting evaluation of new strains by the interspecific mating of the high commercial potential mushroom Pleurotus tuoliensis with its closely related P. eryngii

Pleurotus tuoliensis (Bailinggu) is a precious mushroom species cultivated industrially in eastern Asia. The long cropping cycle, high deformity rate, and low yield are the major bottlenecks for its widespread cultivation. There is thus a need for improved P. tuoliensis cultivars. In the present study, interspecific crossing of monokaryons between P. tuoliensis and P. eryngii was carried out. Six out of nine pairings were observed to result in clamp connections. Dikaryotized regions within a mating Petri dish varied considerably with the compatible pairings. A total of nine hybrids were isolated within the junction zone and on the periphery at either sides of the paired colonies from three selected crosses. The internal transcribed spacer (ITS) restriction fragment length polymorphism (ITS-RFLP) profiles, together with ITS sequencing revealed significant genetic differences between the nine selected hybrids with parental strains. The polymerase chain reaction (PCR) amplification revealed that the inheritance of mitochondrial DNA was uniparental between these two species. Of nine crossbred strains, six were selected for fruiting test. Compared with their parental P. tuoliensis strains, all the six tested hybrids fruited faster, and three hybrids showed improved biological efficiency compared to their parents, either P. tuoliensis or P. eryngii. Two hybrids (Ht-26 and He-26) formed a white-colored fruit body, with improved biological efficiency (62.5 %–64.2 %) compared to parents P. tuoliensis (41.8 %) and P. eryngii (52.1 %), and thus hold great potential as new cultivars for the commercial production of P. tuoliensis.

Morphology, distribution, ultrastructure, and possible function of the external sensilla on antennae and mouthparts of Echinothrips americanus Morgan (Thysanoptera: Thripidae)

Abstract To better understand the semiochemical detection and reception mechanisms that involved in intra- and interspecific communication, host selection and mating behavior of Echinothrips americanus (Thysanoptera: Thripidae), scanning electron microscopy was used to examine the external morphology, distribution and ultrastructure of the sensilla on antennae and mouthparts. According to serial SEM images, seven types of antennal sensilla in total were observed in both sexes. Sensilla on mouthparts were observed concentrating on the maxillary palps, labial palps, and paraglossa, which is consistent with the previous conclusions. Possible function of the external sensilla is also discussed.

Patterns of hybridization and cryptic introgression among one- and four-needled pinyon pines.

Background and AimsPinyon pine hybridization is widely acknowledged, but the frequency of and contributors to such interspecific mating remain largely unstudied. Pinus quadrifolia has three to four needles per fascicle, suggesting that it is a result of hybridization between the five-needled P. juarezensis and the single-needled P. monophylla. In this study we address the taxonomic validity of P. juarezensis, the hybrid origin of P. quadrifolia and the presence of hybridization and intermediate morphology as a result of interspecific hybridization in this complex.MethodsWe address these questions by combining a genomic and morphological approach. We generated 1868 single nucleotide polymorphisms (SNPs) to detect genetic clusters using principal co-ordinates analyis, discriminant analysis of principal components, fastSTRUCTURE and ADMIXTURE analyses, and performed a morphological analysis of the leaves.Key ResultsWe found that the five-needled pinyons did not differ genetically from the four-needled P. quadrifolia, reducing the status of P. juarezensis to P. quadrifolia. We also found no evidence that P. quadrifolia is of hybrid origin from P. juarezensis × P. monophylla but is instead a genetically distinct species with natural needle number variation that has yet to be explained. Hybridization does occur in this complex, but mostly between P. quadrifolia and P. californiarum, and less commonly between P. quadrifolia and P. monophylla. Interestingly, some hybrid derivatives were detected between both single-needled taxa, P. monophylla and P. californiarum, a hybrid combination that has not yet been proposed. Hybrids have intermediate morphology when they have similar genetic contributions from both parental species; however, when one parent contributes more, hybrid derivatives resemble the parent with higher genetic contribution, resulting in cryptic introgression.ConclusionsOur detailed sampling across the distribution of this complex allows us to describe the patterns of hybridization among these taxa, resolves an ancient taxonomic conflict and provides insights into the challenges of exclusively using morphological traits when identifying these taxa with cryptic hybridization and variable morphology.

Interspecific Mating Behavior Between Introduced Zacco platypus and Native Opsariichthys evolans in Taiwan.

Introduced freshwater fishes considerably influence the ecology and populations of native species. Previous research has revealed that introduced Zacco platypus may hybridize with chubs that are sister but distinct genera. However, we have little knowledge of Z. platypus' mate choice or its impact on Taiwanese chubs. Therefore, this study identified the interspecific mating behavior between introduced Z. platypus and native Opsariichthys evolans and evaluated the former's invasive impact on cohabitants. Our observations showed that interspecific mating pairs do occur between Z. platypus male(s) and O. evolans female(s). Fifty-three percent of spawning events were interspecific mating and only 43% were between native O. evolans mating pairs. This study showed that Z. platypus male satellites might prefer to engage with Z. platypus, while O. evolans might engage by chance. However, introduced males of Z. platypus may be unable to recognize conspecific females. Meanwhile, introduced females of Z. platypus also have a mate choice preference for males of Z. platypus. Therefore, Z. platypus male hybridization might significantly reduce the successful mating ratio of O. evolans, leading to a dramatic reduction in native O. evolans offspring in the future.

Interspecific Hybridization between the Two Sympatric Termite Reticulitermes Species under Laboratory Conditions.

Closely related species have similar reproductive behaviors and recognition systems, which contribute to interspecific interactions. However, few studies have explored interspecific reproduction choice and mating in termites. We investigated whether hybridization between two sympatric termites, Reticulitermes flaviceps and R. chinensis, occurs under laboratory conditions. We found that frequencies of acceptance were significantly higher than those of agonism between interspecific partners. There were no significant differences in frequencies of tandem and mating behaviors between intraspecific and interspecific partners. However, the allogrooming frequencies of interspecific partners were significantly higher than intraspecific partners. There were no significant differences in the duration of tandem, allogrooming, or mating behavior at each time between conspecific partners and heterospecfic partners. Genotyping analyses further showed that both intraspecific and interspecific mating were able to produce offspring. We conclude that interspecific hybridization does occur between two termite Reticulitermes species under laboratory conditions.

Inferring responses to climate warming from latitudinal pattern of clonal hybridization.

Climate warming may affect reproductive isolation between sympatric sister species by modifying reproductive phenology or mate choice. This is expected to result in a latitudinal progression of hybridization in response to the shifting of environmental conditions. The fish species northern redbelly dace (Chrosomus eos) and finescale dace (C. neogaeus) display a wide sympatric distribution in North America. The asexual reproduction of their hybrids allows determining where and when hybridization occurred. The aim of this study was twofold: first, to assess whether temperature affected reproductive isolation, and second, whether the effects of climate warming resulted in a latitudinal progression of hybridization. We performed a 500 km latitudinal survey (51 sites) in southeastern Quebec (Canada) and determined the distribution of clonal hybrid lineages. Results revealed a total of 78 hybrid lineages, including 70 which originated locally. We detected a significant difference between the southern and northern range of the survey in terms of the proportion of sites harboring local hybrids (20/23 vs. 8/28 sites, respectively) and hybrid diversity (57 vs. 13 lineages, respectively). This confirmed that there was more frequent interspecific mating in the warmest sites. In the southern range, diversity of lineages and simulations suggest that hybridization first took place (>7,000 years) in sites characterized by a longer growing season, followed by northerly adjacent sites (ca. 3,500–5,000 years). Moreover, evidence of hybridization occurring in present‐day time was detected. This suggests that the current warming episode is going beyond the limits of the previous warmest period of the Holocene.

Reproductive interference by alien hornet Vespa velutina threatens the native populations of Vespa simillima in Japan.

The yellow-legged hornet Vespa velutina has become one of the major alien species in European and East Asian countries. As in its homeland, the invading V. velutina is reported as the major predator of honeybees and is becoming a threat to beekeeping in Europe. However, it remains unknown how V. velutina might affect native hornets when it invades Asia, where a large number of Vespa species are distributed. Thus, by analyzing the mitochondrial cytochrome c oxidase subunit I gene, we investigated whether interspecific mating occurs between V. velutina and Japanese native Vespa spp. Our results showed that the alien V. velutina causes reproductive interference in Japanese native hornet Vespa simillima. Forty-three percent of native V. simillima queens had the sperm of V. velutina males, and among the all V. simillima queens analyzed, 28% only had V. velutina sperm. We did not find evidence of V. velutina queens having the sperm of V. simillima males. These findings suggest that reproductive interference by V. velutina males poses a threat to the native V. simillima populations. A decline of V. simillima may also negatively affect other insects that interact with V. simillima.

Friend-or-foe? Behavioural evidence suggests interspecific discrimination leading to low probability of hybridization in two coexisting rock lizard species (Lacertidae, Darevskia)

The parthenogenetic rock lizard Darevskia rostombekowi is considered to be the product of hybridization between female Darevskia raddei and male Darevskia portschinskii. These two species coexist within several secondary contact areas; however, no trace of their hybridization has been previously reported. We conducted focal observations of individually marked lizards in 2017 and 2018 to establish if there is behavioural isolation between these species. We demonstrate that individuals distinguish between lizards of the same and different species. Individuals of both studied species interacted regularly, but we found no evidence of males of either species using interspecific interference competition for resources or for females. Neutral reactions prevailed in the reactions of males to the individuals of the different species; aggressive or submissive behaviour was more common towards males of the same species. The differences in reactions of males to females of the same and different species were less clear and interspecific social interactions were almost as common as intraspecific interactions. Interspecific male mating behaviour was rare and unsuccessful; only a single female with heterospecific copulation marks on the body was found. The mating period in both species overlapped broadly in late May and early June; body size (SVL) in females of both species was equal. Hence, we suggest that the selection of the sexual partner and preference of the conspecific partner for the social and sexual contacts is the most plausible explanation of the revealed behavioural asymmetry in intra- and interspecific relationship. Here, we present the first description of the social and sexual behaviour of two bisexual species of rock lizard belonging to the Darevskia genus. Most works devoted to the study of reticulate evolution in lizards have used genetic and morphological approaches rather than behavioural observations. The study of the proximal mechanisms of evolution is important in understanding how evolution occurs. The results indicate that even in ecologically similar species, social and sexual selection tend towards separation of the species rather than mixing, although they are able to coexist peacefully.

Reproductive Interference in an Introduced Bumblebee: Polyandry may Mitigate Negative Reproductive Impact.

As a signature of reproductive interference (RI), we reviewed hybrid production in eusocial bumblebees in Japan, by comparing introduced Bombus terrestris with native B. ignitus in Honshu (main island of Japan) and with native B. hypocrita sapporoensis in Hokkaido (northern island of Japan). In this review, we present additional new data showing hybrid production between introduced B. terrestris and native B. ignitus in Honshu. Interspecific mating with introduced B. terrestris disrupts the reproduction of native B. h. sapporoensis and B. ignitus, which belong to the same subgenus of Bombus, through inviable egg production. This interference appears to facilitate species replacement on Hokkaido. Simultaneously, the mating frequencies for queens of B. terrestris have increased, suggesting that polyandry might evolve in response to the extent of RI between B. terrestris and B. h. sapporoensis. To suppress the population size of B. terrestris in Hokkaido, two methods have been proposed: the mass release of B. h. sapporoensis males to induce RI between the two species and the spraying of insecticides against foraging workers so that the workers will carry the insecticides back to their colonies, killing the immature bees within the colonies. A candidate insecticide type is insect growth regulator, which may disrupt larval development without any apparent effect on foraging workers.

Mate choice in a changing world

Human activities by altering environmental conditions are influencing the mate choice of animals. This is by impacts on: (i) the production and expression of traits evaluated by mate choosers; (ii) the transmission of information about potential mates to choosers; (iii) the reception and processing of the information by choosers; and (iv) the final mate choice. Here, I first discuss how these four stages of the mate-choice process can be altered by environmental change, and how these alterations, in turn, can influence individuals, populations, and communities. Much evidence exists for human-induced environmental changes influencing mate choice, but the consequences for the fitness of courters and choosers are less well known, and even less is known about the impact on population dynamics, species interactions and community composition. More evidence exists for altered mate-choice systems influencing interspecific matings and thereby community composition and biodiversity. I then consider whether plastic adjustments and evolutionary changes can rescue adaptive mate-choice systems, and reflect on the possibility of non-adaptive mate-choice systems becoming less maladaptive under environmental change. Much evidence exists for plastic adjustments of mate-choice systems, but whether these are adaptive is seldom known, as is the contribution of genetic changes. Finally, I contemplate the possibility of mate-choice systems rescuing populations from decline in changing environments. I explain how this is context dependent with both positive and negative outcomes possible. In summary, while much evidence exists for human-induced environmental changes influencing mate-choice systems, less is known about the consequences for ecological and evolutionary processes. Considering the importance that mate choice plays in determining individual fitness and population viability, the effects of environmental change on mate-choice systems should be considered in studies on the ecological and evolutionary consequences of human disturbances to habitats.

Rapid Loss of Resistance to Satyrization in Invasive Mosquitoes and the Effects of Age on Interspecific Mating Frequency.

In several areas where Aedes aegypti (L.) (Diptera: Culicidae) and Aedes albopictus (Skuse) (Diptera: Culicidae) have come in contact following successful invasions, Ae. aegypti have been rapidly displaced by Ae. albopictus. Recent work has confirmed that mating interference, in the form of satyrization, is likely a driving factor in these competitive displacements. However, in sites of sympatry, Ae. aegypti females evolve resistance to satyrization, and in the laboratory, satyrization-susceptible Ae. aegypti can evolve resistance within a few generations of cage exposure to Ae. albopictus. The resistance trait may be costly to maintain, as satyrization-resistant females have been shown to invest more time in mate selection. Here, we show that increased satyrization-resistance does not persist in the absence of satyrization pressure, confirming a cost to maintaining this trait. Ae. aegypti lines that had been previously selected for increased satyrization-resistance demonstrated rapid decreases in this trait over eight generations. Support for the hypothesis that condition-dependent mate preferences lead to variation in mating choice among individuals of differing quality within a population has been accumulating. Here we examine how age-related changes in reproductive effort or reproductive value may result in age-dependent mate choice. We hypothesize that older, lower quality individuals may be more likely to accept a subpar mating, in this case an interspecific mating. Our results demonstrate that mosquito age significantly affects interspecific mating rates with older mosquitoes (male and female) engaging in interspecific mating more frequently than younger counterparts (26.32 vs 9.41%). We discuss the possibility of age-related signal variation causing the breakdown of mating barriers with age.

Spermathecal Filling in Aedes aegypti and Aedes albopictus: Effects of Female and Male Body Sizes and Species.

The mosquitoes Aedes aegypti (L.) (Diptera: Culicidae) and Aedes albopictus (Skuse) (Diptera: Culicidae) are ecologically similar species that have evolved independently in their native ranges, Ae. aegypti in Africa and Ae. albopictus in Asia. Where their invasive ranges overlap, interspecific mating is facilitated by both species swarming to mate around bloodmeal hosts during daylight. Here, we test hypotheses to account for variation in spermathecal filling in females of Ae. aegypti and Ae. albopictus, particularly, the effect of mosquito size on the number of spermathecae containing sperm after intraspecific and interspecifc matings of these two species. Results show that significantly more spermathecae contained sperm in large than in small Ae. albopictus females, but there was no effect of Ae. aegypti female body size on the average number of spermathecae filled. Among inseminated females, there was no effect of male size or cross-type on number of spermathecae with sperm. Differences in the effect of female size on the number of spermathecae that store sperm in Ae. aegypti and Ae. albopictus imply differences in the mating biology of these two species.

Deciphering Hybrid Larch Reaction Norms Using Random Regression.

The link between phenotypic plasticity and heterosis is a broad fundamental question, with stakes in breeding. We report a case-study evaluating temporal series of wood ring traits of hybrid larch (Larix decidua × L. kaempferi and reciprocal) in relation to soil water availability. Growth rings record the tree plastic responses to past environmental conditions, and we used random regressions to estimate the reaction norms of ring width and wood density with respect to water availability. We investigated the role of phenotypic plasticity on the construction of hybrid larch heterosis and on the expression of its quantitative genetic parameters. The data came from an intra-/interspecific diallel mating design between both parental species. Progenies were grown in two environmentally contrasted sites, in France. Ring width plasticity with respect to water availability was confirmed, as all three taxa produced narrower rings under the lowest water availability. Hybrid larch appeared to be the most plastic taxon as its superiority over its parental species increased with increasing water availability. Despite the low heritabilities of the investigated traits, we found that the expression of a reliable negative correlation between them was conditional to the water availability environment. Finally, by means of a complementary simulation, we demonstrated that random regression can be applied to model the reaction norms of non-repeated records of phenotypic plasticity bound by a family structure. Random regression is a powerful tool for the modeling of reaction norms in various contexts, especially perennial species.

Partial replacement of Rainbow Lorikeets Trichoglossus haematodus moluccanus by hybrid lorikeets in Hobart, Tasmania

The Eastern Rainbow Lorikeet Trichoglossus haematodus moluccanus recently became established in Tasmania. This study presents opportunistic observations of the species in Hobart from March 2007 to August 2018. During the first 6 years, flocks of more than four Rainbow Lorikeets were seldom seen. However, during the middle of 2013 larger flocks of up to 14 birds were observed repeatedly. Following this, five birds were trapped and removed in August 2013 and another four in May 2014. Thereafter, only five observations of more than a single Rainbow Lorikeet were made, suggesting that trapping may be effective at controlling their populations locally. However, following the trapping sessions, apparent hybrids between Rainbow Lorikeets and native Musk Lorikeets Glossopsitta concinna became more common and more diverse in appearance. Four morphotypes of hybrids were observed, with one of these almost certainly the result of interspecific mating in the wild. Rainbow Lorikeets and hybrids foraged predominantly from flowers of Swamp Gum Eucalyptus ovata and at bird-feeders. Hence, Rainbow Lorikeets could possibly have impacts on Musk Lorikeets through interbreeding and, if they become more common, on these and other species of birds through competition for nectar and pollen of eucalypts.

Strong, but incomplete, mate choice discrimination between two closely related species of paper wasp.

Paper wasps (genus Polistes) are one of the most species-rich genera of social insect. Prior studies have found that male coloration, male colour pattern, territory choice and female caste are potential drivers of intraspecific mate choice in paper wasps. However, there has been no formal assessment of interspecific mate choice in this group; therefore, the mechanism driving diversification in paper wasps remains an open question. In this study, we measured interspecific and intraspecific mating behaviour between two closely related species of paper wasps, Polistes fuscatus and Polistes metricus. These two species have ample opportunity to interbreed because P. fuscatus and P. metricus forage, nest and mate in the same habitats. We tested the strength of reproductive isolation between these species using no-choice and choice mating trials. Our results show strong, symmetric, prezygotic isolation between P. fuscatus and P. metricus. Males discriminated between conspecifics and heterospecifics but attempted to mate with females of the other species in ~10% of heterospecific mating trials. Female wasps were more discriminating than males and probably evaluated species identity and male quality through visual or olfactory cues. We additionally report sexual dimorphism in P. metricus body size.

Killing two bugs with one stone: a perspective for targeting multiple pest species by incorporating reproductive interference into sterile insect technique

The sterile insect technique is an environmentally friendly method to control and even eradicate agricultural and veterinary insect pests without using chemical pesticides in excess. However, the continuous production and release of sterile insects is economically costly and eradication programs using sterile insects have not always been successful owing to the incomplete mating ability of the sterile insects. Here we focus on the theory and empirical findings of interspecific negative mating interaction, known as reproductive interference, to develop a more cost-effective and value-added pest management program. We suggest that sterile insects can be used for simultaneous control of both wild-type conspecifics and closely related pest species by taking advantage of the fact that, when species recognition abilities are incomplete, courtship and mating are often misdirected toward heterospecies. This new approach might help mitigate economic damage and human health crises caused by pest insects. © 2018 Society of Chemical Industry.

Rapid evolution and the genomic consequences of selection against interspecific mating.

While few species introduced into a new environment become invasive, those that do provide critical information on ecological mechanisms that determine invasions success and the evolutionary responses that follow invasion. Aedes albopictus (the Asian tiger mosquito) was introduced into the naturalized range of Aedes aegypti (the yellow fever mosquito) in the United States in the mid-1980s, resulting in the displacement of A.aegypti in much of the south-eastern United States. The rapid displacement was likely due to the superior competitive ability of A.albopictus as larvae and asymmetric mating interference competition, in which male A.albopictus mate with and sterilize A.aegypti females, a process called "satyrization." The goal of this study was to examine the genomic responses of a resident species to an invasive species in which the mechanism of character displacement is understood. We used double-digest restriction enzyme DNA sequencing (ddRADseq) to analyse outlier loci between selected and control lines of laboratory-reared A.aegypti females from two populations (Tucson, AZ and Key West, Florida, USA), and individual females classified as either "resisted" or "mated with" A.albopictus males via mating trials of wild-derived females from four populations in Florida. We found significant outlier loci in comparing selected and control lines and between mated and nonmated A.aegypti females in the laboratory and wild-derived populations, respectively. We found overlap in specific outlier loci between different source populations that support consistent genomic signatures of selection within A.aegypti. Our results point to regions of the A.aegypti genome and potential candidate genes that may be involved in mating behaviour, and specifically in avoiding interspecific mating choices.

Reproductive interference between two serious pests, oriental fruit flies Bactrocera carambolae and B. dorsalis (Diptera: Tephritidae), with very wide but partially overlapping host ranges

Bactrocera carambolae and B. dorsalis (Diptera: Tephritidae) are extremely destructive pests of fruits and vegetables in the Asia-Pacific region. Earlier reports have described that B. carambolae and B. dorsalis, respectively, use mainly star fruit and mango, suggesting a certain level of host partitioning which can be ascribed neither to differences in larval food qualities nor host-specific parasitoid mortality. This study specifically examined reproductive interference (antagonistic sexual interaction) between B. carambolae and B. dorsalis as a potential factor strongly affecting their host partitioning. We observed mating behaviors, especially interspecific courtships and mating, by cohabiting the conspecific and heterospecific pairs together. Consequently, we quantified their effects on the reproductive success of females. Males of both species frequently courted their own females, but they also courted females of other species. Courtship refusal by females was not selective in males of either species. This incomplete discrimination of both sexes led to frequent occurrences of interspecific sexual interactions in both species, but only B. carambolae females showed reduced reproductive success. These results suggest that B. dorsalis, superior in reproductive interference, can occupy high-quality mango, whereas B. carambolae, inferior in reproductive interference, must use low-quality star fruit.