Study on the Effects of Multiple Matings in Coccinella transversalis for its Behaviour and Reproduction

The evolution and maintenance of multiple mating (repeated mating or polyandry) in predaceous ladybird beetles (Coleoptera: Coccinellidae) is an adaptive puzzle; since a single ejaculate of male often provides enough sperm to female for her lifetime egg production. Despite numerous studies on multiple mating evaluating reproductive attributes, there are negligible studies that investigated changes in behavioural patterns in ladybirds during multiple mating. In the present study, effects of multiple mating on mating behavioural pattern of males and reproductive attributes of females have been assessed using Coccinella transversalis as an experimental ladybird species. Results revealed that during copulation behaviour, time for the commencement of mating, latent period, wriggling movement duration, number of bouts and mating duration decreased with increase in number of mating; whereas interval between successive bouts increased significantly. Moreover, fecundity and egg viability of females increased with increase in number of mating.

Enantiomorphs and taxonomy of three conchological species in flat-shelled snails Trichocathaica (Pulmonata, Camaenidae)

Biomodal (flat/globular or slender/tall) shell/body shapes are associated with dichotomous (simultaneous reciprocal or non-reciprocal) modes of copulation behaviour in the fully-shelled stylommatophoran snails. In flat-shelled groups that copulate simultaneously reciprocally, no study has found an example of enantiomorphism that persists within a population. However, the original description of a flat camaenid snail, Trichocathaicaamphidroma, noted that it is dextral- or sinistral-coiled. By examination of shell surface morphology, we found that shell specimens classified as those of this species include shells of three different morphological species. Namely, T.amphidroma, Trichocathaicavestita (Pilsbry, 1934), comb. n., and Trichocathaicamacrosquamata Páll-Gergely, sp. n. In each of the three species, both sinistral and dextral shells have been collected from presumably one area. Ethanol-fixed soft bodies of single dextral and sinistral individuals of T.vestita, which were available for the first time for interchiral comparison of genital morphology in the present genus, differed from each other in the pattern of penial microsculpture. They might represent enantiomorphs that have recently diverged in allopatry instead of enantiomorphism within a population or species. However, their shell and genital differences were not discrete enough to divide them taxonomically into two morphologically distinct species. Our results demonstrate the importance of evaluating individual variation relative to differences between incipient species in penial morphology, especially between conchologically indistinguishable enantiomorphs in the flat groups. We revise the taxonomy of the genus Trichocathaica including the above-mentioned new species, and Trichocathaicaputeolata Páll-Gergely, sp. n.

Mating behaviour of Simulium erythrocephalum (De Geer, 1776) (Diptera: Simuliidae) in Zaragoza (Spain)

Simulium erythrocephalum (De Geer, 1776) es una especie altamente antropofílica responsable de brotes de mosca negra en España. Así, se realizaron observaciones sobre el comportamiento de apareamiento de S. erythrocephalum en condiciones naturales en España, incluyendo la formación de enjambres, el reconocimiento, abordaje y la finalización de la cópula y el comportamiento post cópula. Los resultados obtenidos demostraron que la actividad de cópula tiene lugar durante la tarde. Observamos como el ser humano representa un marcador de orientación atractivo para los enjambres de machos, cuya formación está relacionada con el período de actividad de búsqueda de hospedador por parte de las hembras. Este estudio representa el primer estudio sobre el comportamiento de cópula de simúlidos en España, ampliando el conocimiento general sobre este comportamiento en las moscas negras. Simulium erythrocephalum (De Geer, 1776) is a highly anthropophilic species that is responsible for blackfly outbreaks in Spain. Thus, field observations of the mating behaviour, including swarm formation, recognition and chasing, copulation, termination of copulation and post-copulation behaviour of S. erythrocephalum were conducted in a natural habitat in Spain. The obtained results demonstrated that mating activity occurs during the evening hours. We observed the human host represents an attractive orientation marker of male swarms, whose formation is related to the host-seeking activity period of females. This study represents the first report about the mating behaviour of Simuliidae species in Spain, increasing the general knowledge about this behaviour of blackflies.

The recently described parasitoid braconid wasp, Napo townsendi (Hymenoptera: Braconidae: Euphorinae: Dinocampini), forms leks and deters predators in the Ecuadorian cloud forest

In the Ecuadorian cloud forest, males of the parasitoid braconid waspNapo townsendiShaw displayed facultative lekking, appearing both singly and in groups of 2–7 on the leaf tops of various plant species. To attract females, they constantly employed a stereotypical, spread-winged calling behaviour, apparently releasing a sex pheromone combed from the lateral metasomal exocrine glands and applied to the wings and hind legs. Aggregated males used the same posture in conspecific agonistic displays, often leading to physical fighting. While female wasps were attracted to and mated with displaying singletons, they also made a choice among aggregated males. When females approached, males vibrated their wings in a brief courtship and mounted. Details of copulation behaviour, which lasted on an average of 3–4 min, are described. Without apparent physical weaponry, the displaying wasps successfully warded off attacks from an assortment of predatory arthropods, particularly salticid spiders. We present case studies of repeated unsuccessful predation attempts by salticids. Here, we postulate that calling and release of sex pheromone may double as both an intrasexual agonistic display and an aposematic advisory to predators that the wasps employ a chemical defence.

Distinct copulation positions in Drosophila pachea males with symmetric or asymmetric external genitalia

Left-right asymmetric genitalia have appeared multiple times independently in insects and have been associated with changes in mating positions. However, there is little experimental data on how the evolution of genital asymmetries may have affected the evolution of mating positions or vice versa. As opposed to its closely-related species, Drosophila pachea has a conspicuous asymmetry in its male genitalia external lobes, with the left lobe being 1.49 ± 0.08 (SD) times longer and thinner than the right lobe. In a laboratory stock, we found that 20% of the males possess fully symmetric lobes. To better understand how asymmetric genitalia may affect mating, we compared D. pachea copulation behaviour between these mutant males and wildtype males. We found that D. pachea wild-type males adopt a one-sided mating posture with the male always one-sided 8.55° ± 1.79° (SD) towards the female’s right side. Within 45-min recordings, all wild-type males did mate whereas 39% of symmetric mutants failed to form a stable mating complex and did not mate. In successful copulations, symmetric mutants also adopted a right-sided mating posture but the angle between male and female bodies was significantly more variable compared to wild-type males. Our results suggest that lobe size asymmetry is required for the formation of a stable mating complex and for the positioning of the male according to a precise angle on the female. However, lobe size asymmetry is not required for D. pachea right-sided mating posture.

Perception of male–male competition influences Drosophila copulation behaviour even in species where females rarely remate

Males in many taxa are known to exhibit behavioural plasticity in response to the perceived intensity of sperm competition, reflected in Drosophila melanogaster by increased copulation duration following prior exposure to a rival. We tested the prediction that males do not adjust their copulation effort in response to the presence of a competitor in Drosophila species where there is little or no sperm competition. Contrary to expectations, male plasticity in copulation duration was found in both Drosophila subobscura and Drosophila acanthoptera , species in which females rarely remate. These results are discussed in relation to the adaptive basis of plasticity in these species.

Copulation, mating system and sexual dimorphism in an Australian millipede, Cladethosoma clarum

Investigations of millipede mating dynamics have focussed primarily on Old World or North American species. In contrast, data for the diverse and abundant polydesmid millipedes of Australia are lacking. Here I examine copulation, behaviour and sexual dimorphism in an Australian millipede, Cladethosoma clarum. In this species, copula position is best described as ‘in parallel’. Both females and males mated with two or more individuals of the opposite sex, and average copulation duration was 4.7 min. Behavioural observations revealed differences between the sexes in patterns of behaviour. Specifically, females devoted most of their time to feeding, whereas males were more mobile and were observed walking more often than females. The sexes also exhibited marked sexual dimorphism in that females exhibited greater body width and body mass compared with males, whereas males had longer legs relative to females. In millipedes, longer legs allow an individual to walk faster. Consequently, male C. clarum appear to be capable of relatively rapid locomotion. As Australian millipede densities are spatially unpredictable, the increased mobility of males likely reflects an active mate-location strategy. Furthermore, the occurrence of multiple mating by females suggests that male leg length may have evolved as an adaptation for rapid mate location under scramble competition polygyny.