Male mate choice in a sexually cannibalistic species: male escapes from hungry females in the praying mantid Tenodera angustipennis

The chromosome-level genome of Chinese praying mantis Tenodera sinensis (Mantodea: Mantidae) reveals its biology as a predator

BACKGROUND

The Chinese praying mantis, Tenodera sinensis (Saussure), is a carnivorous insect that preys on a variety of arthropods and small vertebrates, including pest species. Several studies have been conducted to understand its behavior and physiology. However, there is limited knowledge about the genetic information underlying its genome evolution, digestive demands, and predatory behaviors.

FINDINGS

Here we have assembled the chromosome-level genome of T. sinensis, representing the first sequenced genome of the family Mantidae, with a genome size of 2.54 Gb and scaffold N50 of 174.78 Mb. Our analyses revealed that 98.6% of BUSCO genes are present, resulting in a well-annotated assembly compared to other insect genomes, containing 25,022 genes. The reconstructed phylogenetic analysis showed the expected topology placing the praying mantis in an appropriate position. Analysis of transposon elements suggested the Gypsy/Dirs family, which belongs to long terminal repeat (LTR) transposons, may be a key factor resulting in the larger genome size. The genome shows expansions in several digestion and detoxification associated gene families, including trypsin and glycosyl hydrolase (GH) genes, ATP-binding cassette (ABC) transporter, and carboxylesterase (CarE), reflecting the possible genomic basis of digestive demands. Furthermore, we have found 1 ultraviolet-sensitive opsin and 2 long-wavelength-sensitive (LWS) opsins, emphasizing the core role of LWS opsins in regulating predatory behaviors.

CONCLUSIONS

The high-quality genome assembly of the praying mantis provides a valuable repository for studying the evolutionary patterns of the mantis genomes and the gene expression profiles of insect predators.

Increased male mating success in the presence of prey and rivals in a sexually cannibalistic mantis

Precopulatory sexual cannibalism—or cannibalism without mating—is expected to promote the evolution of male strategies that enhance mating success and reduce the risk of cannibalism, such as preferentially approaching feeding females. Sexual selection on male competitiveness has the potential to alter male mating decisions in the face of cannibalism risk, but such effects are poorly understood. We investigated the effect of prey availability and male–male competition on mating incidence in the highly cannibalistic Springbok mantis, Miomantis caffra. We found that matings were initiated more rapidly and more often in the presence of prey, suggesting that females distracted with foraging may be less of a threat. Competition between males also hastened the onset of copulation and led to higher mating success, with very large effects occurring in the presence of both prey and competitors, indicating that intrasexual competition may intensify attraction to foraging females. Taken together, our results suggest that precopulatory cannibalism has selected for male preference for foraging females and that males adjust their mating strategy to both the risk of competition and the threat of cannibalism.

Population Structure, Movement Patterns, and Frequency of Multiple Matings in Tenodera sinensis (Mantodea: Mantidae)

Models of the evolution of sexual cannibalism show that the frequency of male mating opportunities has significant impact on male choice and male risk aversion. In this study, we examined ecological components that should affect opportunities for multiple mating in wild populations of the Chinese mantid (Tenodera sinensis Saussure). While conducting mark-recapture studies of two field populations over the course of two seasons, along with Global Positioning System data on locations of individuals, we collected data on population densities, movement patterns, and individual ranges to estimate the overlap of adult males and female mantids. Our results show that local populations of mantids range from 89 to 161 individuals and occur at densities ranging from 10 to 39 mantids per 1,000 m2. Males move greater distances daily compared with females, giving males larger home range sizes. The ranges of male mantids overlapped with multiple females, thus offering the potential for multiple mating by males. We directly observed 11 encounters between male and female T. sinensis, including one multiple mating by an individual male. The overall mate encounter rate for males was 12.5%. We also provide additional observations of interspecific sexual attraction between T. sinensis and Mantis religiosa Linne (Mantodea: Mantidae). Mantids were most commonly found within the top 20% of two flowering plants, goldenrod (Solidago Linnaeus spp. (Asterales: Asteraceae)) and mugwort (Artemisia vulgaris Linnaeus (Asterales: Asteraceae)), which should place them in prime locations for capturing flying pollinators.