Well-developed antennae are crucial for many insects, but especially for scramble competitors, who race to find their mates using female sex cues. In these systems, the ability of males to locate females quickly is thought to be under strong selection. A rarely tested assumption is that males with more sensory structures are able to locate females faster. In the present study, we used the false garden mantid Pseudomantis albofimbriata to investigate male antennal morphology and its effect on male efficiency in finding a mate. We used scanning electron microscopy to describe the major sensilla types and their arrangement along the length of male antennae. We also conducted field enclosure trials relating male antennal morphology to scramble competition in this system. We identified six different types of antennal sensilla (cheatic, trichoid, basiconic, grooved peg, ceolocapitular and campaniform) on male P. albofimbriata antennae. As expected, males who had more trichoid sensilla located females quicker than did males with fewer sensilla. Results of the current study suggest that antenna morphology plays a significant role in mate location and hence scramble competition in the P. albofimbriata mating system.

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Strategic ejaculation is a behavioural strategy shown by many animals as a response to sperm competition and/or as a potential mechanism of cryptic male choice. Males invest more mating resources when the risk of sperm competition increases or they invest more in high quality females to maximize their reproductive output. We tested this hypothesis in the false garden mantid Pseudomantis albofimbriata, where females are capable of multiply mating and body condition is an indicator of potential reproductive fitness. We predicted male mantids would ejaculate strategically by allocating more sperm to high quality females. To determine if and how males alter their ejaculate in response to mate quality, we manipulated female food quantity so that females were either in good condition with many eggs (i.e. high quality) or poor condition with few eggs (i.e. low quality). Half of the females from each treatment were used in mating trials in which transferred sperm was counted before fertilisation occurred and the other half of females were used in mating trials where fertilisation occurred and ootheca mass and total eggs in the ootheca were recorded. Opposed to our predictions, the total number of sperm and the proportion of viable sperm transferred did not vary significantly between female treatments. Male reproductive success was entirely dependent on female quality/fecundity, rather than on the number of sperm transferred. These results suggest that female quality is not a major factor influencing postcopulatory male mating strategies in P. albofimbriata, and that sperm number has little effect on male reproductive success in a single mating scenario.

Multiple mating by females is a common phenomenon in nature. Polyandrous females may benefit from genetically diverse progeny that may survive better in a changing environment. Males in polyandrous systems, however, may not achieve their maximum paternity. Therefore, males are predicted to carry traits that prevent or reduce female polyandry. Praying mantids are predatory insects in which females can mate multiple times, predicting the evolution of male counter-strategies. However, the rate of polyandry and male strategies against polyandry are rarely studied in these insects. In the current study, we used false garden mantids Pseudomantis albofimbriata to quantify the rate of multiple mating when several males are present within close visual range of an unmated female. We further determined how long mated females stay unattractive after mating. We found that in a scramble scenario, the subsequent males stay with a copulating pair and attempt mating once the first male has completed copulation. These second copulation attempts are often successful. If only one male is attracted as a result of the initial pheromone plume, then polyandry is unlikely because the female will remain chemically unattractive for 8 days on average (thus preventing subsequent male attractions), which is longer than the usual latency to lay the first egg sac. From previous studies, we know that single male attraction is the most common scenario in this system in both natural and semi-natural contexts. Therefore, polyandry depends on the number of males attracted to the initial pheromone plume of the female and is likely to be a relatively uncommon phenomenon in this system.

The Funding section is incorrect. The complete, correct Funding statement is: The Joyce W. Vickery Scientific Research Fund from the Linnean Society of NSW (http://linneansocietynsw. org.au/grants.html) funded this research. The funder had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.