Courtship behavior of the mosquitoSabethes cyaneus (Diptera: Culicidae)

Unlike any other mosquito reported, Sabethes cyaneus(Fabricius) displays an elaborate courtship before and during copulation. A male approaches a female suspended from a horizontal stick, suspends himself in front of her as he grasps her folded wings, and proceeds with a series of discrete stereotyped behaviors that involve proboscis vibration and movement of iridescent blue paddles on his midlegs. The sequence of these behaviors is as follows: freeleg waving, swinging, copulation attempt, superficial coupling, waving, genital shift, waggling, and release. Insemination occurs after genital shift. The only overt reciprocation by the female is abdomen lowering during the male's swinging. Courtship is often unsuccessful, and males are usually rejected during freeleg waving. The relation between male performance and mating success remains obscure.     

Electronic mosquito repellers induce increased biting rates in Aedes aegypti mosquitoes (Diptera: Culicidae)

Studies have demonstrated that electronic mosquito repellers are useless and that some of them could even increase the attraction of mosquitoes. While testing some electronic repellers, we noted that they also promoted an increase in biting rates. The present work has evaluated three commercial devices and a computer program working on five different sound frequencies. In a test chamber, the number of Aedes aegypti L. bite attempts was computed during four cycles of 3 min each by alternately turning the devices off and on. The mosquito biting rates for five sound frequencies (ranging from 9.6 kHz to 18.2 kHz) initially demonstrated a significant increase (ranging from around 20% to 50%), which decreased from 8.3% to 25.1% when the repellers were turned off. The biting rate significantly increased at 11.8 kHz (33.7%) when the device was turned on again. The danger of using electronic repellers and the role of sound frequencies stimulating mosquito biting are discussed.     

意大利蝗交配行为观察

通过昆虫行为观测仪与室外饲养观察,分析意大利蝗Calliptamus italicus的交配行为,阐明交配经历和温度对意大利蝗交配持续时间的影响。结果发现:(1)意大利蝗的交配行为包括相遇和交配两个阶段。相遇行为包括避让、打斗和交配3种类型,其中打斗多发生在雄雄相遇、雄虫与一对正在交配成虫相遇情况。避让和交配则多发生在雌雌相遇、雌雄相遇、雌虫与一对正在交配成虫相遇情况。雄虫在交配过程中占据主动。意大利蝗的交配行为包括曲腹、爬背、抱对和交配4个过程,平均时间为11.25±1.40 min。(2)雌雄虫初次交配的持续时间(12.88±0.67 min)显著长于雌雄虫均有交配经历的时间(10.47±0.39 min)(P0.05);初次交配雌虫和有交配经历雄虫的交配持续时间(11.00±0.75 min),与初次交配雄虫和有交配经历雌虫的时间(12.12±0.67 min)无显著差异(P0.05)。(3)随温度升高意大利蝗的交配持续时间缩短,27℃时交配持续时间最长(15.93±2.25 min),且与36℃、42℃时的时间差异显著(P0.05),42℃时的交配持续时间最短,为6.01±0.43 min,与36℃时的时间(7.47±0.52 min)差异不显著(P0.05)。     

Spermatophore feeding and mating behaviour in praying mantids (Mantodea: Liturgusidae)

In a number of insects, males transfer sperm to females via an externally attached spermatophore, which females subsequently remove and consume. Here I report the first study of spermatophore feeding in a praying mantid. While studies of praying mantid mating behaviour have largely focused on sexual cannibalism, this behaviour is not known in the genus Ciulfina . The general patterns of mating behaviour and spermatophore feeding are described for four species: Ciulfina rentzi , Ciulfina klassi , Ciulfina biseriata and Ciulfina baldersoni . Copulation duration and postcopulatory spermatophore attachment duration were found to vary both inter- and intraspecifically. Ciulfina rentzi exhibited a considerably longer mean copulation duration and a considerably shorter mean postcopulatory spermatophore attachment duration than the other Ciulfina species. Smaller males copulated for longer durations in C. rentzi and C. klassi . For C. baldersoni , both copulation duration and postcopulatory spermatophore attachment duration increased with female mass. The genus Ciulfina is highlighted as an intriguing new system in which to test hypotheses surrounding the function of spermatophore feeding and the significance of copulation duration.     

Dynamics of mating success in experimental groups ofDrosophila melanogaster (Diptera: Drosophilidae)

Determinants of male courtship success in Drosophila melanogasterwere examined in groups of five males sequentially presented with five individual females. Thirty-three percent of males never mated, while approximately half of the males mated two or three times. Rapid courtship initiation was associated with male success in early matings only. Male size was important for courtship outcome, but the size distributions of mating and nonmating males and their progeny numbers indicate balancing rather than directional selection on size- dependent courtship success.     

Mating behavior and male mating success in wildAnastrepha Ludens (Diptera: Tephritidae) on a field-caged host tree

Mating behavior and factors affecting mating success of males were studied using wild Anastrepha ludens on a fieldcaged host tree. The most common courtship sequence had five components: (1) male calls from the underside of a leaf, (2) female arrives to the maleoccupied leaf, (3) male orients to female and stops calling, (4) one or both approach to a face-to-face position 1–3 cm apart, and (5) male mounts female after 1–2 s. Courtship behavior was almost identical to that of laboratoryculture flies observed previously under laboratory conditions. Most malefemale encounters occurred at a height of 1–2m, well inside the outer canopy of the tree. Differential mating success by males occurred. No male mated more than once per day, owing possibly to a very short sexual activity period. Factors favoring mating success of males were survival ability and tendency to join male aggregations and to fight other males. Thorax length and age (9–11 days difference) had no effects on male copulatory success. Overall win/loss percentage was not related to mating success because the males that were most successful at mating fought mostly among themselves, driving their win/loss percentage down. However, these successful males (at mating) won most of their fights against less successful males. Results confirmed a lek mating system: males aggregated, called, and defended territories; territories did not contain femalerequired resources; and females exercised mate choice, apparently through selection of sites within leks.     

Effect of body size on swarming behavior and mating success of maleAnopheles freeborni (Diptera: Culicidae)

We examined whether body size affects the swarming behavior and mating success of male Anopheles freeborninear California rice fields. Swarms formed after dusk and persisted for approximately 30 min. The proportion of males in 33 swarms sampled n=6028 ranged from 100 to 92% but decreased over time (r=0.73, t=6.03, P<0.001).On average, swarming males (n=1058) were larger than males sampled from the resting population (n=735, H=35.6, P<0.0001),indicating that some males never swarm at all. Males swarming early were significantly smaller than those swarming during the peak (H=6.71, P=0.009)or final minutes of the swarm (H=4.86, P=0.002). Mated males returned to the swarm after mating, and larger males enjoyed greater mating success than did smaller ones (n=398, H=16.1, P=0.0005).     

Mate discrimination in Littorina littorea (L.) and L. saxatilis (Olivi) (Mollusca:Prosobranchia)

The ability of males of Littorina littorea and L. saxatilis to discriminate between mates of different sex, species and size was examined. In partner choice experiments males of L. littorea had the possibility to initiate a copulation with either a female or a male. The males did not show a preference for either sex. There was therefore no evidence that they could determine the sex of a conspecific prior to copulation. The duration of intrasexual copulation was considerably shorter than for intersexual copulation, both in the field and in laboratory experiments. For the two species, intersexual copulations were far more frequent than intrasexual ones. This can partly be explained by the difference in copulation time.Few interspecific copulating pairs were found on the shore. This may reflect a low interspecific encounter rate rather than a mechanism of species recognition. On all of these occasions, however, the active male was of L. saxatilis. It is argued that selection against precopulatory species and sex recognition is a more likely explanation than an hypothesis that states that the required mutations for precopulatory mate identification has not yet occurred. L. littorea males copulated longer with large than with small females. Copulation time was short with parasitized females, which are sterile or of low fecundity. The allocation of mating effort by males is discussed.     

Assessment of Aedes albopictus (Skuse) (Diptera: Culicidae) clutch size in wild and laboratory populations

Aedes albopictus (Skuse) is an invasive mosquito species found across the southern U.S. with range expansion into many northern states. Intra‐ and interspecific larval competition have been evaluated for Ae. albopictus with respect to subsequent adult size, immature and adult survivability, and its capacity to vector pathogens as an adult. However, limited data are available on egg production as related to larval rearing conditions. Because Ae. albopictus is a container‐inhabiting mosquito that oviposits in resource‐limited habitats, it is found under variable density‐dependent conditions. Therefore, we examined the impact of specific rearing conditions on Ae. albopictus clutch size and adult body size; comparing the egg production values and wing lengths from known developmental densities to those from field‐collected populations. Field populations varied significantly among collection sites in mean clutch size (23 to 46). These clutch sizes were comparable to the mean clutch sizes of females reared at the larval densities of nine (20 eggs) and three (53 eggs) larvae per 3 ml of water in the laboratory. Field populations experienced density‐dependent effects impacting adult mosquito size. Mosquitoes from the four sample sites had mean wing lengths of 1.99, 2.47, 2.51, and 2.54 mm, which were less than the mean wing length of mosquitoes reared at larval densities of three larvae per 3 ml of water (2.57 mm).     

Influence of previous mating experience on future mating success in maleLucilia cuprina (Diptera: Calliphoridae)

Receptive and virginL. cuprina females were placed with a virgin male and an experienced male that had mated between one and five times previously. The experienced males secured significantly more matings than virgin males. Males with previous matings also gained experience in competing with males. Males directed mating attempts at each other, seemingly in the context of intrasexual competition. Experienced males directed more mating attempts at virgin males than vice versa. As their number of previous matings increased, experienced males made the first mating attempt at females more often and directed more mating attempts at females compared with virgin males. Females did not actively discriminate against experienced males, even though the proportion of matings secured on the first attempt by experienced males declined with increasing mating experience. Alternative behavioral explanations are discussed.     

Relationship between age and colour of hatched eggshells of Ochlerotatus vigilax (Skuse) (Diptera: Culicidae) on an Australian saltmarsh

Abstract The presence of aedine mosquito eggshells in soil has recently been used to delineate oviposition patterns in coastal wetlands. However, the colour of eggshells may reveal information about the oviposition activity of mosquitoes that is not evident from the density and distribution of eggshells alone. This study describes the rate of colour change of newly hatched eggshells of Ochlerotatus (Ochlerotatus) vigilax , the common saltmarsh mosquito. In March 1996, eggshells were buried in soil of five mosquito-breeding sites on Kooragang Island, NSW. Eggshells were graded by colour using Munsell^® soil-colour charts. Seventy-five percent of newly hatched eggshells were black and 25% were dark brown in colour. Black eggshells faded quickly to lighter shades of brown, so that none were recovered 20 months after commencement of the study. Eggshells faded to a median of dark brown after 13 months and medium brown after 2 years. In another study, significant differences in colour frequency between existing saltmarsh and two recently created oviposition sites were found; the latter site being characterised by numerous black and dark-brown eggshells and very few light-brown eggshells. The results suggest that active and inactive oviposition sites may be identified using the frequency distribution of eggshell colours based on large numbers of eggshells, whereas the colour of individual eggshells only coarsely reflects age since eclosion.     

Chromosomal Evidence on the Sporogony of Amblyospora californica (Microspora: Amblyosporidae) in Culex tarsalis (Diptera: Culicidae)

ABSTRACT. Amblyospora californica is a polymorphic, eukaryotic microsporidian. Three types of sporogony producing three types of spores occur in male larvae and female adults of its mosquito host, Culex tarsalis , and an alternate copepod host, Acanthocyclops vernalis. Development of A. californica in male larvae includes merogony and sporogony. Karyogamy and meiosis was observed in sporogony in male larvae but not in the female adult or in the copepod. Chromosomal evidence showed that sporogony included two consecutive meiotic divisions and a subsequent mitosis forming an octosporont, ultimately containing eight haploid, uninucleate mature spores. In this species, the haploid number of chromosomes is nine. Macrosporoblasts and macrospores, containing 1, 2 or more nuclei, can be seen in infected male larvae. The stage of sporogony in which cytokinesis was arrested seems to determine the number of nuclei. Those with only one nucleus, we believe are due to failed nuclear division at meiosis. Although A. californica displayed a process of karyogamy and meiosis similar to that of the species from Cx. salinarius , they may not be the same species because of the difference in their chromosome numbers.     

Aedes albopictus (Diptera: Culicidae) oviposition response to organic infusions from common flora of suburban Florida

We evaluated the oviposition response of gravid Aedes albopictus (Skuse) to six organic infusions. Laboratory and field‐placed oviposition cups baited with water oak (Quercus nigra L.), longleaf pine (Pinus palustris P. Mill), or St. Augustine grass (Stenotaphrum secundatum (Walt.) Kuntze), as well as binary infusion mixtures of each, were used. In addition, a triple‐cage, dual port olfactometer was used to measure upwind response of gravid individuals to these infusions. We found that Ae. albopictus deposited more eggs in infusion‐baited cups compared with water alone. Moreover, significantly more eggs were laid in the water oak and a water oak‐pine mixture as compared with the St. Augustine grass infusion in laboratory bioassays. However, a negative upwind response was observed with longleaf pine infusion in the olfactometer. In field cages, significantly more eggs were deposited in infusion‐baited cups as compared with water alone and a greater percentage of eggs were deposited in cups containing a water oak and the water oak‐longleaf pine mixture as compared with cups containing single infusions or their mixtures.     

Distribution of the eggs of Aedes punctor (Diptera: Culicidae)

ABSTRACT.

• 1 Eggs of the mosquito Aedes punctor Kirby were found to be aggregated in a horizontal band within woodland depressions.
• 2 The height of the peak of egg density above the lowest point in the depression varied from 24 to 39 cm in six transect studies.
• 3 One depression, 2 m in diameter, was analysed in detail and found to contain a total of 9231 eggs with a maximum density of 944 eggs in a 250 cmz area.

     

Cost of mating in male Menochilus sexmaculatus (Fabricius) (Coleoptera: Coccinellidae)

Mating and reproduction not only provide benefits but can also incur substantial costs. An increasing number of recent studies have indicated that mate searching, mating, and ejaculate production requires large amount of energy which can result in high cost to males. Here, we examine the effect of number of matings of males and mating duration on mating and reproductive success in Menochilus sexmaculatus (Coleoptera: Coccinellidae) by subjecting them to 3 consecutive matings of 30, 60, 90 min, and complete mating (a) with no interval and (b) with interval of 24 hr between the matings. The results reveal a reduction in reproductive performance for both the setup and reduction is more when mating is consecutive without gap. This shows that between subsequent matings males require time to recuperate the sperm/ejaculate. As a male engages in a greater number of matings, the time it takes to begin mating when paired with a female increases and the overall duration of mating decreases. However, frequent mating attempts made by males result in reduction in their body weight. Thus, in this ladybird beetle mating and related physiological process consume lots of energy and the body weight of males tend to decrease which further modifies their reproductive performance. The study helps us to identify the cost of mating from male's perspective and indicates that males need to rejuvenate between the matings.     

酪蝇的羽化节律和交配行为

【目的】为了明确酪蝇Piophila casei的羽化节律和交配行为,为深入研究酪蝇的性信息素打下基础。【方法】在室内条件[温度(27±1)℃,光周期L︰D=14︰10]下观察了酪蝇的羽化节律和交配行为。【结果】结果表明,化蛹后第8天成虫羽化最多,羽化高峰期出现在由暗期进入光期的前后,雄虫略早于雌虫羽化。观察结果表明,当雄虫接近蛹壳时会表现出"触摸"、"经过"、"扑"、"抱握"等动作,而雌虫仅有"触摸"、"抱握"的动作。当遇到同性成虫或者已交配雌虫时,雄虫会"追逐"对方,当接触到对方时雄虫会表现出"抱握"、"触摸"动作以进行识别,被识别雄虫会"翘起腹部末端"使对方离开,已交配雌虫则猛烈"摆动身体"使对方离开。当遇到处女雌虫时,雄虫跳跃到雌虫背上迅速进行交配。雌虫羽化后1 min即可交配,雄虫羽化后30 min可交配,交配平均持续时间10 min。雄虫间会有交配竞争行为发生,后来者会跳跃到先来者背上,向下弯曲腹部试图越过先来者与雌虫交配。【结论】酪蝇的羽化高峰出现在进入光期前后。成虫对蛹壳有显著趋性,雄虫主动追逐识别异性,较雌虫表现出更强烈的交配欲望。