No competition for resources between two tick species at their parapatric boundary

Summary Aponomma hydrosauri and Amblyomma limbatum are tick species with the same major host species, the sleepy lizard Trachydosaurus rugosus, but parapatric distributions in South Australia. Near Mt. Mary one species is abruptly replaced by the other over one kilometre. There is substantial overlap in feeding sites on the hosts. This suggested that interspecific competition, during feeding, may be an important mechanism preventing further overlap of the distributions of the two species. However, in the overlap region there was no resource shortage, and each species infested hosts independently of the other species. Also in laboratory experiments at the highest densities encountered in the field, larvae and nymphs of each species attached and engorged equally well whether alone or mixed with the other species. These data refuted the, hypothesis of interspecific competition between the two species while feeding.     

Mating behaviour in the Australian reptile tick Aponomma hydrosauri

Females of the Australian reptile tick Aponomma hydrosauri make few movements once they are attached to a host. Males move significantly more often on hosts with females attached. Male movement often leads to contact and courtship with females. Movement is most frequent in the early part of the dark phase of a photoperiod. After contact the courtship, both on the host and in experimentally induced off-host situations, follows a stereotyped sequence of positional orientations, here divided into six phases. Copulation does not automatically follow courtship initiation, and in particular successful courtship requires females to respond to male initiation by lifting their hind legs to allow the male to crawl under. Compared to other animal species, the males of A. hydrosauri play an unusually passive role in mate seeking. This may be explained by the extremely patchy distribution of the mate-finding environment, lizards.     

Mating behaviour and reproductive isolation of three species of reptile tick

The mating behaviour of three species of reptile tick, Aponomma hydrosauri, Amblyomma albolimbatum and Amb. limbatum is similar and involves a female sex pheromone which activates males to detach from their hosts and search. After contacting females, a stereotyped six-phase courtship sequence occurs. There are qualitative differences between the species in courtship behaviour at phase 3 (reversal of position by dorsally mounted males) and phase 6 (the copulation position). On-host observations of non-conspecific mating show that females of the three species have species-specific activation pheromones, which is contrary to reports in other species of tick. Such specificity should result in reproductive isolation of the three species; however, under certain circumstances it may not prevent non-conspecific contacts between the sexes. Off-host observations of courtship behaviour show that once males of the three species contact non-conspecific females, they attempt courtship and are persistent with their courtship. Rarely did non-conspecific courtships proceed beyond phase 4 of the courtship sequence, as non-conspecific females did not lift their bodies to allow males venter contact. Differences between the species in leg orientation in the copulation position, together with body size differences, are responsible for a complete barrier to successful non-conspecific copulation. The observations illustrate the role that behavioural mechanisms play in reproductively isolating these three species of tick.     

Niche segregation in reptile ticks: attachment sites and reproductive success of females

Summary This study examined whether the mating or feeding success of females of two tick species, Amblyomma limbatum and Aponomma hydrosauri, is influenced by their site of attachment on a host. Marked interspecific differences were detected in the preferred sites of attachment of females to their common host, the sleepy lizard Tiliqua rugosa, with Amb. limbatum found predominantly in the ears and on the lower back, while Ap. hydrosauri preferred to attach under the forelimbs and on the midback. Data from field surveys suggested that higher proportions of females were mated in the preferred sites for Ap. hydrosauri, and in one of the preferred sites for Amb. limbatum. However, laboratory and field experiments showed that for both species, the mean time before females were mated, mean engorgement time and mean feeding rate were independent of where they were attached to a host. Four hypotheses were considered as explanations of the observed niche segregation; intespecific competition, avoidance of pheromone jamming or adaptations, to maximize mating and feeding, and minimize physical disturbance. These could not totally explain the observed site specificity in either tick species. Site specificity may represent adaptations by each species to other host species encountered within their distributional range.     

Reproductive interactions between two Australian reptile tick species

In South Australia the two tick species Amblyomma limbatum and Aponomma hydrosauri share the same common reptile host species, but have allopatric distributions which abut along a narrow parapatric boundary. Reproductive interference is a mechanism that has previously been suggested could contribute to maintaining the boundary. Populations of each species were established in pens within the range of Aponomma hydrosauri. Pens held either each species alone, or the two species together. The performance of females in those pens was monitored over 28 months. There was no indication that the proportion of attached females which mated and engorged was reduced by the presence of heterospecifics. There was no indication that the time taken to mate, engorge and detach was any longer in the presence of heterospecifics. The experiment did not support the hypothesis that reproductive interference contributes to maintaining the parapatric boundary. However, Amblyomma limbatum in the pens had a shorter season of reproductive activity, and achieved much smaller numbers of reproductive females. This may inhibit successful colonization of cooler habitats to the south of its distribution.     

Proposing a new hypothesis: Rickettsia spp. as a mechanism maintaining parapatry between two Australian reptile tick species

This study investigates two parasitic reptile ticks — Bothriocroton hydrosauri and Amblyomma limbatum — of the sleepy lizard (Tiliqua rugosa) that abut at a 1–2 km wide parapatric boundary in South Australia. Long‐term research has investigated potential mechanisms to explain the maintenance of this boundary but has not uncovered why the distribution of A. limbatum does not extend further south. It has been previously hypothesised that pathogens may be responsible for maintaining parapatric boundaries. Rickettsia spp. has previously been reported in B. hydrosauri ticks. This study explored whether Rickettsia spp. occurs in co‐occurring A. limbatum. We observed that Rickettsia spp. was absent from all A. limbatum ticks and that 83% of examined B. hydrosauri were found to be positive with a spotted fever group Rickettsia strain. This study puts forward the hypothesis that Rickettsia spp. could contribute to the maintenance of the Mt Mary parapatric boundary between these two tick species. Further work is required to determine whether Rickettsia spp. can be transmitted from B. hydrosauri to A. limbatum and — if transmission can occur — to explore whether Rickettsia is lethal to A. limbatum ticks.     

A comparison of the reproductive parameters of females of two reptile tick species

In comparisons of females of two reptile tick species Aponomma hydrosauri and Amblyomma limbatum, Ap. hydrosauri was initially larger, and after mating on the host engorged faster and remained attached for a shorter time before completing engorgement and detaching. Amb. limbatum had a longer period of engorgement, and achieved a greater engorged weight. Engorged Amb. limbatum females laid significantly more eggs than equivalent sized Ap. hydrosauri. Although the two species are ecologically similar and were collected from the same site for this study, their reproductive differences probably reflect adaptations to different conditions in their largely allopatric ranges.     

Interspecific differences in microhabitat choice by two species of Australian reptile tick

The microhabitat choice of all life cycle stages, both unfed and engorged, of two Australian ixodid ticks, Amblyomma limbatum and Aponomma hydrosauri, were compared in the laboratory. When offered a choice between bare soil (or sand) and soil covered with litter, most ticks moved into the litter, except unfed larvae which often took refuge within crevices on the surface of exposed sand. The two species differed in the position they adopted within the litter. Ap. hydrosauri were predominately found at the interface between the soil and litter. Amb. limbatum were more often found higher up in the litter. There were also interspecific differences in the body orientation of ticks within the litter. All life cycle stages of Ap. hydrosauri adopted a position with their dorsal surface facing upwards, whereas unfed stages of Amb. limbatum were more frequently found with their ventral surface facing upwards. The behaviour of each species probably represents a different compromise between two factors, maximizing host detection, and minimizing their exposure to desiccation or predation.     

室内养殖条件下三疣梭子蟹的生殖蜕壳和交配行为

本文采用外部特征观察和红外线摄像,对室内配对养殖三疣梭子蟹(Portunus trituberculatus)的生殖蜕壳和交配行为进行了系统研究。结果发现:近交配季节,雌性三疣梭子蟹腹甲出现蓝黑色并不断加深,游泳足掌节则最终汇聚成一轮红色月牙,这些体表特征集中出现在生殖蜕壳前期,可能是除信息素外,另一类用于交配活动的视觉信号。三疣梭子蟹的交配活动起始于两性间的求偶抱对行为,雌性完成生殖蜕壳便进行软壳交配,这是一个连续的过程,包括随后的抱对守护行为;期间,相对于交配前后的抱对行为,三疣梭子蟹用于实质性交配活动的时间十分有限。然而,这可能是一种生殖策略:一方面,雌性可以采用抱对这种方式确保随后进行的生殖蜕壳及软壳交配过程能在有限的时间内安全有序地完成;另一方面,作为补偿,雄性可通过交配活动在雌性生殖道内生成精子塞来保证父权,减少个体间的竞争。     

Risk of predation for two reptile tick species

Experiments were conducted in the Mount Mary region of South Australia where the distributions of the two reptile-tick speciesAponomma hydrosauri andAmblyomma limbatum narrowly overlap. Engorged larvae and nymphs were placed in boxes with and without access to predators and left for 1 week. At two out of five sites there was greater loss from open access boxes in replicates during warmer periods of the year. Predation by ants appears to be the most likely explanation for the loss of ticks.     

Reproductive and Mating Success in the Small-Mouthed Salamander (Ambystoma texanum) Estimated via Microsatellite Parentage Analysis

Bateman’s principles of sexual selection predict that the sex with “cheaper” gametes may maximize reproductive efforts by mating multiply and so display greater positive covariance between reproductive and mating success. We conducted a semi-controlled breeding experiment to genetically quantify sexual selection in adult Ambystoma texanum, a sexually monomorphic salamander with simple courtship behaviors. We used four polymorphic microsatellite loci to genotype 57 adults enclosed in a breeding wetland and compared their multilocus profiles to that of 862 embryos collected from the enclosure. The molecular data were used to assign parentage, investigate the mating system, and measure sexual selection intensity. Parentage analyses indicated 36% of dams and 93% of sires were genetically sampled via their gametes but physically unsampled, suggesting that a large number of breeders over-wintered within the enclosure and/or some females released into the enclosure were already inseminated. We used the genetic data to generate estimates of individual reproductive and mating success and we interpret these in light of salamander behavior and sexual selection theory. The incidence of multiple mating in females (86%) was considerably higher than in males (32%) and the standardized variance in mating success was significantly greater in females. The correlations between reproductive and mating success were significant and of similar magnitude between the sexes, indicating that both sexes increased reproductive success through increased mating success. This pattern may be a function of differential opportunities for mating success between the sexes. Electronic Supplementary Material The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Multiple lines of evidence supports the two varieties of Halenia elliptica (Gentianaceae) as two species

Delimiting species requires multiple sources of evidence. Here, we delimited two varieties of Halenia elliptica (Gentianaceae) using several lines of evidence, including morphological traits and mating system in a sympatric population, phylogenetic relationships based on nrITS and cpDNA (rpl16) data, and complete chloroplast genome sequences. Comparative analysis of 21 morphological traits clearly separates the two varieties of H. elliptica. Examination of the flowering process and pollination treatments indicate that H. elliptica var. grandiflora produces seeds via outcrossing, whereas H. elliptica var. elliptica produces seeds via mixed mating. Furthermore, hand-pollinated hybridization of the two varieties produced no seeds. Observations of pollinators showed that when bees began a pollination bout on H. elliptica var. grandiflora they preferred to continue pollinating this variety; however, when they began a pollination bout on H. elliptica var. elliptica, they showed no preference for either variety. Phylogenetic analysis confirmed the monophyly of H. elliptica, which was further divided into two monophyletic clades corresponding to the two varieties. A large number of variants from the chloroplast genomes reflected remarkable genetic dissimilarities between the two varieties of H. elliptica. We recommend that the two varieties of H. elliptica should be revised as two species (H. elliptica and H. grandiflora). Our findings indicate that H. elliptica varieties may have split into two separate species due to a shift in mating system, changes in flowering phenology and/or post-pollination reproductive isolation.     

Mating affects reproductive investment into eggs,but not the timing of oogenesis in the flesh fly <Emphasis Type="Italic">Sarcophaga crassipalpis</Emphasis>

We examined the effects of mating on reproductive investment and the timing of oogenesis in the flesh fly Sarcophaga crassipalpis by exposing females to males or not. All females exposed to males were mated within a few days and we found that mating affected reproductive investment. Virgin females not exposed to males produced a large clutch of eggs (∼91), but females exposed to males and mated produced 10% more. There was no effect of mating on egg length or mass. There was also no effect of mating on the timing of oogenesis. Females in both treatments provisioned their eggs at the same rate with yolk first becoming visible in the oocytes on day three of adulthood and complete provisioning of eggs occurring by the seventh day of adulthood. We examined the biochemical basis of egg provisioning by identifying the yolk proteins and quantifying their blood titer during the oogenic period in both, females exposed to males and mated and those not exposed to males. There was no difference in the timing of the first appearance, peak titer, or disappearance of yolk proteins in the blood between the two treatments. However, consistent with our observation of greater egg production in mated females, these females contained a greater peak yolk protein titer.     

Mating preferences of two species of Eccritotarsus (Hemiptera: Miridae)

ABSTRACT

Eccritotarsus spp. are biological control agents that have been sourced from Brazil and Peru to control water hyacinth in South Africa. These agents have been released in over 30 sites and were thought to be the same species. The sequencing of mitochondrial DNA and interbreeding experiments have since confirmed the cryptic species to be separate species. The Brazilian population remains E. catarinensis while the Peruvian population is now E. eichhorniae. This paper assessed the mating behaviour of both species, to investigate behavioural traits that have resulted in reproductive isolation, which could have led to speciation. Mating choices in a form of no-choice, bi-choice and multi-choice tests were conducted within and between species in a 3:1, 2:1 and 1:1 sex ratio. The E. eichhorniae pair had more single and multiple copula incidences, higher average total copula duration and higher copula latency while the E.catarinensis♀×E.eichhorniae♂ pair had less single and multiple copula incidences, lower average total copula duration and lower copula latency. When the E.eichhorniae♀ and E.catarinensis♂ were given their respective choices, they only mated with conspecifics. However, when E.eichhorniae♀ are crossed with E.catarinensis♂ they do not produce offspring. These results suggest that interbreeding will be limited in South Africa.     

Molecular individuality: polymorphism of salivary gland proteins in three species of ixodid tick

Pooled tissue samples are frequently used in biochemical studies involving parasites in order to ensure that there is sufficient material for experimentation. A pooled sample is considered to represent the overall phenotypic characteristics of the investigated population. However, this will not be the case if there is a significant degree of molecular polymorphism among individuals in the sampled population. Here we demonstrate marked differences in the protein profile of salivary glands among individuals from three species of ixodid tick (Rhipicephalus appendiculatus, Amblyomma variegatum, Ixodes ricinus), and show that pooling the tissue of several individuals masks substantial qualitative differences among the individuals. Our observations indicate that much greater caution is needed in general when using pooled samples if the molecular diversity within the population is not clearly defined.     

Host-odour recognition in two tick species is coded in a blend of vertebrate volatiles

The questing behaviour of ixodid ticks serves for identification and localisation of approaching hosts and is evoked by carbon dioxide, vibrations, visual and odour stimuli. In an olfactometer, we examined the specificity of the questing response of larvae of Boophilus microplus, a one-host tick which develops mainly on cattle, and Ixodes ricinus, a three-host tick with a broader host spectrum. While all mammalian odours tested were equally stimulatory for I. ricinus, B. microplus was clearly more activated by bovine odours. A phenolic fraction of bovine odour stimulated B. microplus only. Attractive components of the host odours were identified by exposing the ticks to single chemicals and mixtures. Single chemicals stimulated questing responses only at levels higher than the levels detected in the bovine odour. However, an artificial odour blend of 37 pure chemicals, diluted to concentrations at which the individual components were inactive, proved to be as effective as natural host odour for both tick species. Further fractionation of the blend revealed that the combinatory effect was achieved by only 7 compounds in both species. Although B. microplus responded to the same synergistic mixture of volatiles as I. ricinus, it showed significant higher sensitivity to the cattle-associated compounds 1-octen-3-ol and 2-nitrophenol and this might contribute to its host-specificity. Accepted: 20 March 1999     

Male mating behaviour reduces the risk of sexual cannibalism in an Australian praying mantid

In cases where sexual cannibalism represents a sexual conflict, we should expect to find male traits that reduce the risk of cannibalism. In fact, a wide variety of such traits have been proposed, including elaborate courtship displays, cautious approach behaviours, and opportunistic mating whilst a female is feeding. However, there is very little direct evidence that these behaviours actually reduce the risk of sexual cannibalism for males, and the evidence that does exist comes mainly from spider studies. In this study of Pseudomantis albofimbriata praying mantids we found evidence of various male behaviours that reduced the risk of sexual cannibalism. Most males attempted to avoid detection entirely and others moved in a slow and stealthy manner. We also observed five cases of opportunistic mating, but saw no evidence of any male courtship routine. It seems that mounting from the rear of a female or slowly approaching her from the front, allows many males to go unnoticed and, therefore, substantially reduces the risk of sexual cannibalism in this mating system. Interestingly, we could not identify any female traits that males use to assess the risk of sexual cannibalism. It may be that P. albofimbriata males use alternative means to assess these risks. The presence of these behavioural strategies by males suggests a net cost of being consumed, and that sexual cannibalism is likely to be a female strategy in this system.     

Expression of heat shock proteins and subolesin affects stress responses, Anaplasma phagocytophilum infection and questing behaviour in the tick, Ixodes scapularis

We characterized the effects of subolesin and heat shock protein (HSP) expression on Ixodes scapularis Say (Acari: Ixodidae) stress responses to heat shock and feeding, questing behaviour and Anaplasma phagocytophilum (Rickettsiales: Anaplasmataceae) infection. Ticks and cultured tick cells were analysed before and after subolesin, hsp20 and hsp70 gene knock-down by RNA interference. The results of these studies confirm that HSPs are involved in the tick cell response to heat stress and that subolesin and HSPs are both involved in the tick response to blood-feeding stress and A. phagocytophilum infection. Subolesin and hsp20 are involved in the tick protective response to A. phagocytophilum infection and hsp70 expression may be manipulated by the pathogen to increase infectivity. Importantly, these results demonstrate that subolesin, hsp20 and hsp70 expression also affect tick questing behaviour. Overall, this research demonstrates a relationship between hsp and subolesin expression and tick stress responses to heat shock and blood feeding, A. phagocytophilum infection and questing behaviour, thereby extending our understanding of the tick-host-pathogen interface.     

菲牛蛭交配及卵茧人工孵化初步研究

人工饲养条件下,比较观察了不同养殖模式(水体、土壤)和不同温度(24℃、26℃、28℃、30℃、32℃和34℃)对菲牛蛭(Hirudinaria manillensis)交配率的影响,并进行了不同卵茧质量(＜0.6 g、0.6～1.0 g、1.0～1.5g、1.5～2.0 g、＞2.0 g)及不同温度(22℃、24℃、...     

Asymmetric reproductive interference between two closely related spider mites: <Emphasis Type="Italic">Tetranychus urticae</Emphasis> and <Emphasis Type="Italic">T. turkestani</Emphasis> (Acari: Tetranychidae)

Tetranychus turkestani Ugarov and Nikolskii and Tetranychus urticae Koch RF (red form) (Acari: Tetranychidae) are closely related species. Previously, the two species were found in separate agricultural habitats in Israel. Here, additional collections were undertaken and mixed populations of the two species were found. Manipulation experiments were conducted in order to test whether sexual interactions occur when T. turkestani and T. urticae RF share the same host. Interspecific crosses showed that the two species are capable of producing viable F₁ females, but that these females are sterile as their F₂ eggs failed to hatch. This indicates a post-zygotic reproductive barrier, supporting the current placement of T. turkestani as a separate taxon. Mating behavior parameters revealed that males of both species courted virgin conspecific and heterospecific females at the same rate and readily tried to copulate with them. Female mate recognition seemed to be more reliable in T. turkestani than in T. urticae RF as the number of copulations was significantly higher and their duration significantly shorter in the T. turkestani interspecific (T. turkestani ♀ × T. urticae RF ♂) as compared to the intraspecific crosses, a phenomenon not observed in T. urticae RF. In mixed cultures, a significant reduction in female production was observed for T. urticae RF but not for T. turkestani, suggesting an asymmetric reproductive interference effect in favor of T. turkestani. The long term outcome of this effect is yet to be determined since additional reproductive factors such as oviposition rate and progeny survival to adulthood may reduce the probability of demographic displacement of one species by the other in overlapping niches.