Male Scorpionflies Research Articles

Evolving longer for a mate: A new scorpionfly (Mecoptera: Panorpoidea: Panorpidae) with exaggeratedly elongated male abdominal segments

Male scorpionflies often evolve exaggeratedly elongated abdominal segments (EEAS) that are used as a sexual display to the females, and a combat weapon in intra-sexual disputes. EEAS have independently evolved several times since the Jurassic till the present day in at least eight genera and four families. In this paper, Neopanorpa exaggerata sp. n. with EEAS is described from Yunnan Province, China. Through comparisons among extinct and extant species, our current knowledge is summarized for the evolution, copulatory mechanism, and biogeography of the scorpionflies with EEAS. Also discussed are the trade-offs between the benefits of "looking sexy" and the negative impacts associated with a long abdomen. Additionally, further clarification is provided on the multiple origins of EEAS in Panorpoidea.

Evolution of sexual conflict in scorpionflies.

Sexual conflict - opposite reproductive/genetic interests between sexes - can be a significant driver of insect evolution. Scorpionflies (Insecta: Mecoptera) are models in sexual conflict research due to their large variety of mating practices, including coercive behaviour and nuptial gift provisioning. However, the role of palaeontology in sexual conflict studies remains negligible, namely due to the paucity of well-preserved fossils. Here, we describe three male scorpionflies from Cretaceous and Eocene ambers. The structure of notal and postnotal organs is analysed in extant and extinct forms; a depression below the base of the notal organ in different panorpid species spatially matches the anterior fold of the female's wing. Based on disparate abdominal configurations and correlations in extant relatives, we posit that each new fossil taxon had a different mating approach along a nuptial gifting-coercive spectrum. The Eocene specimen possesses extreme female clamping abdominal armature, suggesting a degree of sexual coercion greater than in any other known scorpionfly, extinct or extant. The fossil record of abdominal modifications in male scorpionflies documents a relatively late evolution (Eocene) of long notal organs indicating oppressive behaviour toward a female during mating. Our findings reveal a wider array of mating-related morphological specialisations among extinct Panorpoidea, likely reflecting more diversified past mating strategies and behaviours in this group, and represent first steps towards gaining a deep-time perspective on the evolution of sexual conflict over mating among insects.

Atypical mating in a scorpionfly without a notal organ

Firm coupling of genitalia is critical for copulation in most groups of insects. To counter female resistance that usually breaks off genital connection, male scorpionflies (Mecoptera: Panorpidae) usually provide nuptial gifts for the female and seize their mates with grasping devices. The notal organ, a modified clamp on tergum III of male scorpionflies, plays a significant role in seizing the female wings and helping maintain mating position during copulation. The mating behaviour remains unknown for the scorpionfly Furcatopanorpa longihypovalva (Hua and Cai, 2009) whose male lacks a notal organ. In this paper, we first attempt to study the mating behaviour of F. longihypovalva. The results show that the male provides liquid salivary secretion through a mouth-to-mouth mode for the female, and maintains copulation mainly by continuous provision of salivary secretion rather than by seizing the female with grasping devices. Thus the male copulates with the female in an atypical O-shaped position, with only their mouthparts and genitalia connected to each other. The salivary glands exhibit remarkable sexual dimorphism: short and bifurcated in the female, but well-developed and multi-furcated in the male. The extremely developed salivary glands of the male lay a structural foundation for the male to continuously provide liquid salivary secretion, and to help the male to mediate female resistance, being likely to serve as a compensation to his absence of the notal organ. We also investigated the functional morphology and copulatory mechanism of the male and female genitalia. The evolution of the atypical mating pattern of F. longihypovalva is putatively discussed as an adaptation in the context of sexual conflict.

The role of male's anal horns in copulation of a scorpionfly

AbstractSexual conflict drives evolution of sexually antagonistic adaptations that give advantages to the bearer. As a consequence of sexual conflict, male scorpionflies (Mecoptera: Panorpidae) provide nuptial gifts for the female and use grasping organs to repress female resistance. These organs, except notal organ, have not been satisfactorily studied. In this paper, the mating behavior of Dicerapanorpa magna (Chou) was investigated to reveal the role of the anal horns (a pair of posterior processes on tergum VI) of males. The males initiate copulation through grasping the female with the notal organ and anal horns, prolonging copulation by providing salivary masses to the female as nuptial gifts and maintaining copulation after the female consumed the salivary masses. The results of a manipulative experiment show that the anal horns play a significant role in the mating success for the males of D. magna by promoting male domination in copulation through increasing the duration of pre‐ and post‐gift‐providing copulatory stages against female resistance and by avoiding wasting of nuptial gifts. The anal horns of male D. magna seem to be a male adaptation evolved to overcome female mating resistance.

Structural evidence why males of Panorpa liui offer prey rather than salivary mass as their nuptial gift

AbstractMa, N. and Hua, B. 2011. Structural evidence why males ofPanorpa liuiofferprey rather than salivary mass as their nuptial gift. —Acta Zoologica(Stockholm)92: 398–403.The scorpionflies are considered as ideal model animals for the study of matingsystems in insects. The males generally offer both prey and salivary mass asnuptial gifts to the females during copulation. Our field observations show thatPanorpa liuiis peculiar because the males offer only prey rather than salivarysecretions as nuptial gift. Through anatomical and histological examinations, thesalivary glands ofP. liuiwere found to be devoid of sexual dimorphism inPano-rpa for the first time. Both the male and femaleP. liui bear simple salivaryglands, which are only composed of a common duct and two short sac-likeglands. This is the first attempt to explore the relationship between the salivaryglands and the mating tactics from the structural aspect inPanorpa, speculatingthat the simple structure of the male salivary glands inP. liuimight be responsi-ble for its failing to produce salivary mass as a nuptial gift during copulation.Compared with Boreidae, Meropidae, Bittacidae and Panorpidae, we presumethat the absence of sexual dimorphism ofthe salivary glands might represent aplesiomorphy inP. liui. The origin and evolutionary process of the nuptial giftbehaviour are tentatively speculated inPanorpa.Baozhen Hua, Entomological Museum, Northwest AF Engqvist and Sauer2001). Most of the recent studies have related to the selectivepressures responsible for the maintenance or behind the evo-lutionary elaboration of nuptial gifts (Vahed 1998).The scorpionflies in the genusPanorpa(Mecoptera: Pano-rpidae) are relatively weak flyers, only feeding upon soft-bod-ied dead arthropods (mainly insects) as scavengers (Byers andThornhill 1983), and have been used as model animals for thestudy of insect mating system (Carpenter 1931; Thornhill1981; Byers and Thornhill 1983; Engqvist and Sauer 2003).In general, male scorpionflies may obtain mating in threealternative ways, offering salivary masses, offering prey giftsor copulations with no gifts (Thornhill 1981; Byers andThornhill 1983). Generally, the third alternative is forceful,but in some European species copulation without gifts maytake place without force when the food resource is limited(Engqvist and Sauer 2003). In the males ofPanorpa, bothnuptial preys and salivary masses are used as mating effort toentice females to copulate. Females discriminate against malesthat are unable to produce salivary masses and⁄or to offer adead arthropod (Thornhill 1981; Bockwinkel and Sauer1994). Nuptial gifts inPanorpa also function to maximizeejaculate transfer. The duration of copulation is considerablylonger for the males that offer nuptial gifts (Bockwinkel andSauer 1994) and is also positively related to the number of sal-ivary masses provided by a male (Thornhill 1981; Thornhilland Sauer 1991; Saueret al.1998).

Mating Effort and Cryptic Sperm Choice in Scorpionflies: Male Investment Strategy vs. Female Control

AbstractIn this study, we examined which sex controls sperm transfer during copulation in scorpionflies. Therefore male scorpionflies were doubly mated to females of high and low fecundity to explore whether they allocate sperm according to female quality. While mating order had no effect males transferred sperm at higher rates when mating with low‐quality instead of high‐quality females. As there is no obvious benefit from providing low‐fecundity females with more sperm, we suggest a condition‐dependent female ability to counteract sperm transfer. Therefore, we disabled females at the beginning of copulations using the insecticide Propoxur which leads to total paralysis caused by tremors. While the provoked muscle contractions led to significantly smaller numbers of sperm transferred, Propoxur treatment had no effect on males. We suggest female counteracting of sperm transfer to be adaptive by decreasing the relative amount of sperm transferred by low‐quality males and increasing the proportion of offspring sired by high‐quality males.

Influence of Nutrition on Courtship and Mating in the ScorpionflyPanorpa cognata(Mecoptera, Insecta)

AbstractScorpionflies have been used as model organisms for the study of alternative male mating tactics as well as sexual conflict and coercive mating. Here we describe the courtship and mating behaviour of the scorpionflyPanorpa cognataat different levels of nutrition. Alternative mating tactics in scorpionflies involve nuptial food gifts, and we expected an effect of nutrient availability and male individual condition on the relative frequency of these mating tactics. Subsequent to female attraction by means of male pheromonal emission (calling) and a conspicuous pairing prelude, the majority of matings were initiated by male secretion of one relatively large salivary mass on which females feed during copulation. Usually, males produced only a single salivary mass per mating, and the copulation was terminated after the female had consumed the salivary mass. Alternatively, in 40% of the copulations, males offered females a dead arthropod as nuptial gift. However, these matings were neither preceded by male calling nor by the pairing prelude. Copulations with no gifts were extremely rare, and forced copulations were absent. The manipulation of the clamp‐like notal organ used by male scorpionflies in coercive matings had no effect on the duration of copulation, suggesting thatP. cognatamales are not able to enforce longer matings. Copulations involving salivary mass gifts were significantly longer than copulations with prey provided as gifts. Although contrary to our expectations, nutrition had no effect on the relative frequency of the different male mating tactics, it had several effects on courtship and mating. First, well‐fed individuals copulated significantly more often, both with prey and salivary secretions, than individuals with limited nutrient resources available. This was true for both sexes, although the effect was stronger for males. Higher availability of nutrients decreased the time until male and female sexual maturity and increased male calling duration per day. Furthermore, high nutrient availability decreased the duration of the pairing prelude, and consequently pairs started copulating earlier at night in the high nutrient treatment.

A life-history perspective on strategic mating effort in male scorpionflies

In species with high male mating effort, there is a trade-off between mating effort spent in a current mating and resources left for future matings. Consequently, to maximize their reproductive success, males have to invest strategically, saving resources in matings with low reproductive gain for future, more valuable matings. However, as males age, the expected future reproductive success constantly declines. Thus, the importance of resource rationing may drastically change during a lifetime. Males of the scorpionfly Panorpa cognata offer females a costly nuptial gift before copulation, which functions as male mating effort. Resources for the production of these salivary masses are severely limited for males in poor condition. We found that males invested more in copulations with high-quality females than in copulations with low-quality females. However, males ceased to discriminate as they became older. Old males, with a relative small number of expected future matings, did not invest differentially in copulations with high- versus low-quality females. In copulations with low-quality females, males invested more in late than in initial matings, whereas in matings with high-quality females, time of mating had no influence on mating effort. These results imply that males adaptively change their resource allocation strategy during the course of the season. Initial matings seem to be characterized by male prudence; in later matings, males seem to adopt a more opportunistic mating strategy.

Sex Attractant of Male Scorpion Flies

IT is well known that in mecopteran flies of the family Panorpidae courtship and mating behaviour fall into a distinctive pattern1. In the case of the Bittacidae, the recorded observations2–4, although suggestive, have been insufficient to reveal clear-cut feeding and mating patterns.