Females cannibalizing males
In this study, we recorded frequent occurrence of females predating on conspecific males. We found 12 (42.9%) cases in Anisoptera represented by species Erythemis simplicicollis (9 cases) and Orthetrum sabina (3 cases). In Zygoptera 19 cases (50%) were observed in nine species (Agriocnemis femina , Ceriagrion coromandelianum ,Coenagrion puella , Ischnura sp, Ischnura elegans ,Ischnura graellsii , Ischnura ramburii , Ischnura verticalis , and Lestes alacer ) where females predate on males (Supplementary Table 1-3, Fig. 2). The predation of male odonates by females odonates can be an act of sexual cannibalism Cordero (1992). Sexual cannibalism (eating of male by female) has been shown in other insect system such as spiders, and praying mantis where consuming males has been shown to benefit fitness of the species (Nishimura & Isoda, 2004; Mitchell & Walls, 2008; Segoli et al., 2008). However, further experimental studies are required in case of odonates to determine fitness cost and benefit for the species. Sexual cannibalism is common in many arthropod species and several hypotheses have been proposed by researchers to explain the drivers that induce the sexual cannibalism (Nishimura & Isoda, 2004; Mitchell & Walls, 2008; Segoli et al., 2008). Females predate on males during low food availability when male are easy to consume (Newman & Elgar, 1991). As a result of extreme mate choice, females’ prey on undesirable rejected males (Elgar & Nash, 1988). Failed to recognize conspecific males could lead to the consumption of males (Gould, 1984). It occurs due to the inheritance of high aggressiveness in females (Arnqvist & Henriksson, 1997; Schneider & Elgar, 2002). Sexual cannibalism also represents male monogamy, as in some spider species males initiate the cannibalism process by placing their abdomen in front of female mouthparts during copulation and sacrificing themselves to females to gain reproductive success (Segoli et al., 2008). In Odonates, mating harassment is a common phenomenon and costly for female fitness. Traits such as conspicuous colour and cryptic behavior have evolved in species to avoid male mating harassment (Khan, 2019). Simultaneously, the wheel position and male sperm translocation have been evolved in odonates to avoid sexual cannibalism (Rivas-Torres, 2019). Female predation on males can be an evolutionary strategy to avoid male mating harassment (Fincke 1987; Xu & Fincke, 2022). To avoid sexual cannibalism the future studies should focus to determine what drives female odonates predate on male odonates.