Assassin Bugs are medium-sized insects. They have an oval-shaped abdominal area, over which is superimposed overlapping wings that create the appearance of an "X" on the back. They are variously colored, and have a small narrow head that projects outward from the body. The front two pairs of legs are longer and more powerful than the hind legs: they are used to grab and hold insect prey. Assassin bugs actively hunt and feed on a variety of insects, sucking out their bodily juices. They occasionally lurk near flowers to feed on bees and other insects.
Known prey organisms
Based on studies in:
Costa Rica (Carrion substrate)
This list may not be complete but is based on published studies.
- L. F. Jiron and V. M. Cartin, 1981. Insect succession in the decomposition of a mammal in Costa Rica. J. New York Entomol. Soc. 89:158-165, from p. 163.
Evolution and Systematics
The antennae of Rhodnius bugs detect heat from their potential victims using numerous sensitive, hairlike thermoreceptors.
"Rhodnius bugs are large, blood-sucking insects found throughout the Americas. They live in close proximity to their victims, in nests or burrows, and detect potential victims -- small, warm-blooded creatures such as mice -- by sensing their body heat. A Rhodnius bug has its own built-in thermometers on its antennae in the form of numerous exceedingly sensitive hairlike thermoreceptors, which can detect air that has been warmed by its prey's body heat." (Shuker 2001:38)
Learn more about this functional adaptation.
- Shuker, KPN. 2001. The Hidden Powers of Animals: Uncovering the Secrets of Nature. London: Marshall Editions Ltd. 240 p.
Molecular Biology and Genetics
Statistics of barcoding coverage
Specimens with Sequences:1201
Specimens with Barcodes:980
Species With Barcodes:197
The Reduviidae are a large cosmopolitan family of the order of "true bugs" or Hemiptera. They are slightly unusual among the Hemiptera because almost all are terrestrial ambush predators (most other predatory Hemiptera are aquatic). The main examples of non-predatory Reduviidae are some blood-sucking ectoparasites in the subfamily Triatominae. Though there are spectacular exceptions, most members of the family are fairly easily recognisable: they have a relatively narrow neck, sturdy build and formidable curved proboscis (sometimes called a rostrum). Large specimens should be handled with caution, if at all, because they sometimes defend themselves with a very painful stab from the proboscis.
The Reduviidae are members of the suborder Heteroptera of the order Hemiptera. The family are almost all predatory, except for a minority that are blood-sucking species of importance as disease vectors. About 7000 species have been described, making it one of the largest families in the Hemiptera.
The name Reduviidae is derived from the type genus, Reduvius. That name in turn comes from the Latin reduvia, meaning "hangnail" or "remnant". Possibly this name was inspired by the lateral flanges on the abdomen of many species.
Among others, the family include the assassin bug genera:
Some genera and subfamilies have more particular common names that are reasonably widely recognised, such as:
- ambush bugs (subfamily Phymatinae)
- thread-legged bugs (subfamily Emesinae, including the genus Emesaya)
- Kissing or cone-headed bugs Triatominae. This subfamily is unusual in that most species are blood-suckers and several are important disease vectors.
- wheel bugs (Arilus cristatus)
Adult insects range from about 4 to 40 mm, depending on the species. They most commonly have an elongated head with a distinct narrowed neck, long legs, and prominent, segmented, tubular mouthparts, most commonly called the proboscis, but some authors use the term "rostrum". Most species are bright in color with hues of brown, black, red, or orange.
The most distinctive feature of the family is that the tip of the rostrum fits into a groove in the prosternum, where it may be used for stridulation by rasping it against ridges in the groove. The structure of ridges is a stridulitrum, or stridulatory organ to produce sound, a tactic often used to discourage predators. If harassment continues, many species can deliver a painful stab with the proboscis, injecting venom or digestive juices. The effects can be intensely painful and the injection from some species may be medically significant.
Predatory Reduviidae use the long rostrum to inject a lethal saliva that liquefies the insides of the prey, which are then sucked out. The saliva contains enzymes that predigest the tissues they swallow. This process is generally referred to as extra-oral digestion, or EOD. The saliva is commonly effective at killing prey substantially larger than the bug itself.
The legs of some Reduviidae have areas covered in tiny hairs that aid in holding onto their prey while they feed. Others, members of the subfamily Phymatinae in particular, have forelegs that resemble those of the praying mantis, and they catch and hold their prey in a similar way to mantises.
As nymphs, some species will cover and camouflage themselves with debris or the remains of dead prey insects, which forms a very effective camouflage. The nymphal instars of the species Acanthaspis pedestris present one good example of this behaviour where they occur in Tamil Nadu in India. Another well-known species is Reduvius personatus, known as the masked hunter because of its habit of camouflaging itself with dust. Some species tend to feed on pests such as cockroaches or bedbugs and are accordingly popular in regions where people regard their hunting as beneficial. Reduvius personatus is a case in point, and some people breed them as pets and for pest control. Some assassin bug subfamilies are adapted to hunting certain types of prey. For example, Ectrichodiinae eat millipedes, and feather-legged bugs eat ants. A spectacular example of the latter is Ptilocnemus lemur, an Australian species in which the adult attacks and eats ants, but the nymph waits until the ant bites the feathery tufts on its hind legs, upon which it whips round and pierces the ant's head with its proboscis, and proceeds to feed.
Some research on the nature of the venom from certain Reduviidae is under way. The saliva of Rhynocoris marginatus showed some insecticidal activity in vitro, in tests on lepidopteran pests. The effects included reduction of food consumption, assimilation and utilization. Its anti-aggregation factors also affected the aggregation and mobility of haemocytes.
The saliva of the species Rhynocoris marginatus (Fab.) and Catamirus brevipennis (Servile) have been studied because of their activity against human pathogenic Gram-negative bacteria (including strains of Escherichia coli, Pseudomonas aeruginosa, Proteus vulgaris, Salmonella typhimurium) and the Gram-positive (Streptococcus pyogenes).
Some species are blood suckers rather than predators, and they are accordingly far less welcome to humans. Triatoma species and other members of the subfamily Triatominae, such as Rhodnius species, Panstrongylus megistus and Paratriatoma hirsuta, are known as kissing bugs, because they tend to bite sleeping humans in the soft tissue around the lips and eyes. A more serious problem than their bites is the fact that several of these haematophagous Central and South American species transmit the potentially fatal trypanosomal Chagas disease, sometimes called American trypanosomiasis.
Current taxonomy is based on morphological characteristics. The first cladistic analysis based on molecular data (mitochondrial and nuclear ribosomal DNA) was published in 2009 and called into question the monophyly of some current groups, such as the Emesinae.
- Weaving, Alan; Picker, Mike; Griffiths, Charles Llewellyn (2003). Field Guide to Insects of South Africa. New Holland Publishers, Ltd. ISBN 1-86872-713-0.
- Sahayaraj, Kitherin; Kanna, Ayyachamy Vinoth; Kumar, Subramanian Muthu (2010). "Gross Morphology of Feeding Canal, Salivary Apparatus and Digestive Enzymes of Salivary Gland of Catamirus brevipennis (Servile) (Hemiptera: Reduviidae)". Journal of the Entomological Research Society 12 (2): 37–50. Retrieved 14 December 2012.
- Bulbert, Matthew W. Herberstein, Marie Elisabeth. Cassis, Gerasimos. Assassin bug requires dangerous ant prey to bite first. Volume 24, Issue 6, pR220-R221, 17 March 2014. Current Biology DOI: http://dx.doi.org/10.1016/j.cub.2014.02.006 
- Kitherin, Sahayaraj; Muthukumar, S. (2011). "Zootoxic effects of reduviid Rhynocoris marginatus (Fab.) (Hemiptera: Reduviidae) venomous saliva on Spodoptera litura (Fab.)". Toxicon 58 (5): 415–425. doi:10.1016/j.toxicon.2011.06.001.
- Weirauch, Christiane; Munro, James B. (October 2009). "Molecular phylogeny of the assassin bugs (Hemiptera: Reduviidae), based on mitochondrial and nuclear ribosomal genes". Molecular Phylogenetics and Evolution (Elsevier) 53 (1): 287–299. doi:10.1016/j.ympev.2009.05.039. PMID 19531379.
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