| Reduviidae | |
|---|---|
_with_bee_(Apis_ssp)_prey.jpg) | |
| Assassin bug (Rhynocoris iracundus) with bee prey | |
Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Arthropoda |
| Class: | Insecta |
| Order: | Hemiptera |
| Suborder: | Heteroptera |
| Infraorder: | Cimicomorpha |
| Family: | Reduviidae Latreille, 1807 |
| Subfamilies | |
Bactrodinae | |
TheReduviidae is a largecosmopolitan family of the suborderHeteroptera of theorderHemiptera (true bugs). Among the Hemiptera and together with theNabidae almost all species are terrestrialambush predators; most other predatory Hemiptera are aquatic. The main examples of non-predatory Reduviidae are some blood-suckingectoparasites in the subfamilyTriatominae, with a few species from South America noted for their ability to transmitChagas disease. Though spectacular exceptions are known, most members of the family are fairly easily recognizable: they have a relatively narrow neck, sturdy build, and formidable curvedproboscis (sometimes called arostrum). Large specimens should be handled with caution, if at all, because they sometimes defend themselves with a very painful stab from the proboscis.
The family members are almost all predatory, except for a few blood-sucking species, some of which are important as disease vectors. About 7000 species have been described, in more than 20 recognized subfamilies, making it one of the largest families in the Hemiptera.[1]
The nameReduviidae is derived from thetype genus,Reduvius. That name, in turn, comes from theLatinreduvia, meaning "hangnail" or "remnant". Possibly this name was inspired by the lateral flanges on the abdomen of many species.
Commongenera include:
While members of most subfamilies have nocommon names other thanassassin bugs, some subfamilies have their own common names such as:
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Adult insects range from roughly 12 to 36 mm (0.47 to 1.42 in), depending on the species.[5] 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 colour with hues of brown, black, red, or orange.
The most distinctive feature of the family is that the tip of the proboscis fits into a ridged groove in theprosternum, where it can be used to produce sound bystridulation.[6] Sound is made by rasping the proboscis against ridges in this groove orstridulitrum (stridulatory organ). These sounds are often used to discourage predators. When harassed, 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 lethalsaliva that liquefies the insides of the prey, which are then sucked out. The saliva contains enzymes that digest the tissues they swallow. This process is generally referred to asextraoral digestion.[8] 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 subfamilyPhymatinae in particular, have forelegs that resemble those of thepraying mantis, and they catch and hold their prey in a similar way to mantises.
Asnymphs, some species cover andcamouflage themselves effectively with debris or the remains of dead prey insects. The nymphal instars of the speciesAcanthaspis pedestris present one good example of this behaviour where they occur inTamil Nadu in India. Another well-known species isReduvius personatus, known as the masked hunter because of its habit of camouflaging itself with dust. Some species tend to feed on pests such ascockroaches orbedbugs and are accordingly popular in regions where people regard their hunting as beneficial.Reduvius personatus is an example, 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, theEctrichodiinae eatmillipedes, andfeather-legged bugs eat ants. A spectacular example of the latter isPtilocnemus 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 around and pierces the ant's head with its proboscis, and proceeds to feed.[9]
Some research on the nature of the venom from certain Reduviidae is under way. The saliva ofRhynocoris marginatus showed some insecticidal activityin vitro, in tests on lepidopteran pests. The effects included reduction of food consumption, assimilation, and use. Its antiaggregation factors also affected the aggregation and mobility of haemocytes.[10]
The saliva of the speciesRhynocoris marginatus (Fab.) andCatamirus brevipennis (Servile) have been studied because of their activity against human pathogenic Gram-negative bacteria (including strains ofEscherichia coli,Pseudomonas aeruginosa,Proteus vulgaris, andSalmonella typhimurium) and the Gram-positive (Streptococcus pyogenes).
Some species are bloodsuckers rather than predators, and they are accordingly far less welcome to humans. The blood-feeding habit is thought to have evolved from species that lived in the nests of mammalian hosts. Several species are known to live among bat roosts, includingCavernicola pilosa,Triatoma dimidiata andEratyrus mucronatus.Triatoma species and other members of the subfamilyTriatominae, such asRhodnius species,Panstrongylus megistus, andParatriatoma 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 thesehaematophagous Central and South American species transmit the potentially fataltrypanosomalChagas disease, sometimes called American trypanosomiasis. This results in the death of 12,000 people a year.[11]
The Emesinae live among spider webs.
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 theEmesinae.[12] Reduviidae are monophyletic, and the "Phymatine Complex" is consistently recovered as the sister to the higher Reduviidae, which includes 90 percent of the reduviid species diversity.[13] Reduviidae is suggested to have split from other Cimicomorphs during the Jurassic, based on molecular clock.[14] The oldest fossils of the family are from theLower Cretaceous (Barremian) agedYixian Formation, represented by the genusSimplicivenius, belonging to the subfamilyReduviinae.[15]
