Cannibalism or intraspecific predation is considered as a usual phenomenon in many natural populations of animals (Fox, 1975). Among the arthropods, this behavioral trait has been observed in many insect orders such as Lepidoptera, Odonata, Hemiptera, Mantodea, Orthoptera, Thysanoptera, Trichoptera, Blattodea, Diptera, Neuroptera, Coleoptera, and Hymenoptera (Capinera, 2008; Richardson et al., 2010). Odonata is a well-known predatory insect order, where cannibalism is frequently seen in larval stages (Ilmonen & Suhonen, 2006), but rather rarely documented in case of adults. Till date, in adult Zygoptera, cannibalism has been documented in several species: Ceriagrion melanurum Selys, C. auranticum Fraser, Coenagrion puella (L.), Ischnura elegans (Vander Linden), I. graellsii (Rambur), I. verticalis (Say), I. ramburii Selys, Enallagma civile (Hagen), Pyrrhosoma nymphula (Sulzer), Archilestes grandis (Rambur), Euphaea dispar Rambur, and Hetaerina americana (Fabricius) (Bick & Sulzbach, 1966; Müller, 1972; Utzeri, 1980; Robertson, 1985; Fincke, 1987; Cordero, 1992; Rolff & Kröger, 1997; Reels, 2010). Herein, a case of cannibalism is reported for the first time in Ceriagrion coromandelianum Fabricius from India.

While snapping some insects of a village garden (21°40'19.08"N; 87°34'29.75"E, 7 m.a.s.l.), near Bara Solemanpur village, Purba Medinipur district, West Bengal, India, on January 12^th, 2014, at about 12:30 hs, a female of C. coromandelianum devouring a conspecific male was observed (Fig. 1). They were perched on a Marigold tree (Tithonia sp.) at about 1.5 feet height from the ground. The distance of nearby water body was about 10 m and the place of observation was characterized by flowering plants of Marigold with grassy vegetation. Ceriagrion coromandelianum is a sexually dimorphic damselfly (usually males with citron yellow abdomen and females with olive brown abdomen) widely distributed in the Oriental region (Subramanian et al., 2018). The breeding behavior of this damselfly has also been documented from India (Thaokar et al., 2018), but cannibalism or act of intraspecific predation has never been reported in this damselfly.

According to Fox (1975), factors that trigger the cannibalism are mainly starvation, density, stress, availability of victim and victim’s behavioral pattern. In larval stages of odonates, cannibalism usually occurs due to high population density (Van Buskirk, 1989). In case of adults the reason is still quite vague. Utzeri (1980) first reviewed the instances of cannibalism in adult Zygoptera and in most of the cases tenerals and youngs were involved as prey. According to Utzeri (1980), the instances of cannibalism takes place when intraspecific communication has failed or when the victim is not recognized as conspecific. Thus, he said cannibalism in Zygoptera might be an aspect of ordinary predation. Corbet (1999) has also postulated that, in case of cannibalism in odonates, usually mature adults predate on the teneral males that were unable to perform threat display. Rolff & Kröger (1997) mentioned that cannibalism occurred in adults mostly during or after the cold weather period. As starvation occurred due to the low foraging activities during colder months, that triggers the switch in food selection. The present example was also observed during the colder month of January. But, none of the specimens were examined in the studied area, to confirm whether they were starved or not. So, it will be insignificant to remark the starvation as one of the reasons for cannibalism in the case of the present observation. However, the present observation also supports the hypothesis of sexual cannibalism, which is commonly seen in many species of spiders and mantis (Elgar & Nash, 1988; Lawrence, 1992), where mature females devour the males for the benefit of reproductive success. In Zygoptera, sexual cannibalism was first presented by Cordero (1992) with examples of Ischnura damselflies. Interestingly, in the case of the present observation the mature female was devouring a conspecific male, whose colour was olive brown similar to that of female. Also in Zygoptera, cannibalism involved a mature male predating on its mature conspecific female (Reels, 2010). Thus, in the case of zygopteran cannibalism, both sexes acted as predator and prey. As a consequence, it will be fair enough to explain that cannibalism in zygopterans might be an aspect of ordinary predation, as put forward by Utzeri (1980).

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