Compilation of canthariphilous insects

A list of insects attracted to cantharidin is given. Most canthariphilous insects are found within the heteromeran beetle family Anthicidae with 190 species in the three subfamilies Anthicinae (184), Lemodiinae (1) and Tomoderinae (5). Further cantharidin baited species are known from the beetle families Endomychidae (5), Cleridae (4), Chrysomelidae (3), and Staphylinidae (1). In the beetle family Pyrochroidae 23 species from the subfamily Pedilinae and 6 species of the Pyrochroinae are canthariphilous. The insect order Diptera is represented by the families Anthomyiidae (3), Cecidomyidae (2), Ceratopogonidae (22) Chloropidae (1), Platystomatidae (1) and Sciaridae (5). Many species from the heteropteran family Miridae (29) are known to be attracted by cantharidin, also one species from the families Lygaeidae and Tingidae respectively. Parasites of the hymenopteran family Braconidae (6) show a positive reaction to cantharidin as well as species from the subfamily Diapriinae of the family Diapriidae. Chemical analyses of a fulgorid and a cicadid species revealed that also species of Homoptera may contain cantharidin.

In meloid and oedemerid beetles cantharidin is used as an effective haemolymph poison (Ca v il l & C l a r k 1971, C a p in e r a et , Ca r r e l et al. 1986, B l o d g e t t et al. 1991, NlCHOLLS et al. 1990, HOLZ et al. 1994, which protects the adults as well as larval stages and eggs. A n o th er in terestin g p h en o m en o n in co n n ectio n w ith can th arid in is its attractan cy on o th er in sects, w h ich perceive this in secticid e p artly o ver g reat d istan ces (GÖRNITZ 1937, WlRTH 1980, YOUNG 1984. M a n y o f th ese so -called can th arip h ilo us in sects in g est can th arid in w ith o u t an y o b vio us dam age. This paper gives a compilation of insects attracted to cantharidin on species level. Cantha riphilous species are known from following orders and families: Coleóptera (Anthicidae, Cleridae, Chrysomelidae, Endomychidae, Pyrochroidae, Staphylinidae), Diptera (Anthomyiidae, Cecidomyidae, Ceratopogonidae, Chloropidae, Platystomatidae, Sciaridae), Heteroptera (Miridae, Lygaeidae, Tingidae), and Hymenoptera (Braconidae, Diapriidae), Analysis of Homoptera species proved, that cantharidin containing species can also be found in these order of insects.

Coleóptera
Most canthariphilous species are found in the beetle family Anthicidae with 190 recorded species. Mostly Notoxus and A.ulacoderus species are attracted. Conspicuous in many anthicid genera associated with cantharidin are notches at the tips of the elytra in males which function as test organs. Females bite into these structures and choose their sexual partner by the amount of cantharidin a male has taken up (SCHÜTZ & D e t t n e R 1992). Ingested cantharidin is stored in the reproductive organs of the males and transmitted to females during copulation. The nuptial gift is secreted into eggs and thus provides protection for the offspring.
From the family Cleridae Vallenothriocera mfimembris is attracted to the terpenoid cantharidin (FlEMP et al. 1999b). Also single specimens of other clerid species were collected in cantharidin traps put out in southern Europe. Further clerids were suggested to be canthariphilous (CHANDLER 1976, BOLOGNA & FlAVELKA 1984 or reported to contain cantharidin (JUANJIE et al. 1995, DETTNER, in prep.). Gland-like structures on the elytra of male Pallenothriocera rufimembris suggests an analogous cycle as found in anthicids. Specimens of a up to now unidentified clerid species attracted to cantharidin baits near Nairobi, Kenya were observed to remain several hours in the open traps, attacking there other arriving canthariphilous species (mostly Notoxus sp.), killing and feeding on them. Remaining elytra of the preys showed that one clerid often fed more than 10 Notoxus during the dav hours.
Canthariphilous pyrochroid beetles show a similar cycle for cantharidin as discussed above for anthicids (HOLZ et al. 1994, EISNER et al. 1996b. Test organs for cantharidin titees are present on the head of the male in form of grooves (EISNER et al. 1996a). As in anthicid beetles the females bite into these structures to inform themselves about the amount of cantharidin the would-be partner has taken up.
For all other beetles families (Chrysomelidae, Endomychidae, Staphylinidae) with canthariphilous species only the phenomenon that members are attracted to the natural product cantharidin is known. No investigations have been undertaken up to now to illuminate life cycles and function of cantharidin for these insects.

Diptera and Heteroptera
Ceratopogonids are an ever present group as soon as cantharidin is put out. Studies on the function of cantharidin in the biology of canthariphilous ceratopogonids have been made by FRENZEL & DETTNER (1994). Both sexes of the investigated canthariphilous gnats are attracted to cantharidin, ingesting the terpenoid readily. Maximal concentrations in tissues of ceratopogonids analysed are similar to those detected in the cantharidin producing species of the heteromeran beetle families Meloidae and Oedemeridae. High concentrations of cantharidin in the haemolymph of European ceratopogonids proved to deter Empididae, which prey on these gnats.

Hymenoptera
Braconids are parasitoids of other insects. Females are capable of sensing their host for egg-deposition via kairomones. This may also be the case in canthariphilous species that are attracted by the cantharidin smell of their hosts as suggested for Veriltiusplumicornis which is a parasite of the anthicid Notoxus monoceros (GÖRNITZ 1937).

Homoptera
First results in analysing cantharidin contents in fulgorids suggest, that there are also members in the order Homoptera associated with cantharidin. The latern fly Ipycorma clelicatula proved to contain cantharidin, which probably was taken up by host plants (FENG et al. 1988, Dettner 1997. There was also suggested the Cicadidae species Huechjs sanguínea (De GEER) would contain cantharidin (JUANJIE et al. 1995).