Origin, transfer and distribution of cantharidin-related compounds in the blister beetle Hycleus scabiosae

Cantharidin provides chemical protection for the coleopteran families Meloidae and Oedemeridae. In the present study, it was observed that cantharidin concentration in Hycleus scabiosae was slightly decreased from mated females (mean = 0.011 mg/mg of dry weight) to males (mean = 0.010 mg/mg) and considerably diminished in relation to virgin females (mean = 0.005 mg/mg). Significant concentrations of palasonin (21.69 ng/mg among virgins and 17.49 ng/mg in mated females) and palasoninimide (14.62 ng/mg in virgins and 9.17 ng/mg in mated females) were found in H. scabiosae. Palasonin, palasoninimide and cantharidinimide content of eggs were measured as 5.61, 7.69 and 7.80 ng/mg respectively. Surprisingly, males showed no trace of cantharidin-related compounds (CRCs); therefore CRCs in H. scabiosae could not be transferred from males to females and based on experiments employing its deuterated form, cantharidin is probably independently synthesized in females from the male nuptial transfer. An inseminated female incorporates about 38.5 ng of cantharidin (0.34 percent of the maternal content), 196.35 ng of palasonin (91.82 percent of maternal content) and 269.15 ng of palasoninimide (96.70 percent maternal content) into each egg mass during oviposition. It seems that eggs of this meloid species exploit a different array of protective chemicals by increasing the ratio of CRCs versus cantharidin. CRCs are less toxic than cantharidin; therefore, such compounds might have been deposited in eggs as a safer substitute for cantharidin to provide effective protection, but does not simultaneously harm the susceptible embryo.(AU)

Medically important beetles (insecta: coleoptera) of Iran

This study focused on coleopteran species that are responsible for the emergence of recent cases of dermatological manifestations in Iran. To the best of our knowledge, five species of the family Meloidae and nine species of the genus Paederus are by far the only beetles recognized as medically important in Iran. The staphylinids consists of Paederus ilsae, P. iliensis, P. fuscipes, P. kalalovae, P. balcanicus, P. lenkoranus, P. littoralis, P. carpathicus, P. nigricornis, while the meloids are Mylabris impressa, M. guerini, Muzimes iranicus, Alosimus smyrnensis and Epicauta sharpi. Most cases of linear dermatitis in this country occur in areas bordering the Caspian Sea. This problem is caused by beetles of the genus Paederus which are present as adults from mid-April to October with particularly high incidences from May to August. Fars (in southern Iran) ranks second in number of cases of insect-induced dermatitis. The third major region in which this type of dermatitis has been recorded is Hamedan Province, in the west of the country. Meloid dermatitis showed its highest severity in 2001, when a considerable number of patients sought medical help in Toyserkan and Nahavand counties. New cases of skin blistering were reported along the Persian Gulf coast and the agent was identified as Epicauta sharpi (Coleoptera: Meloidae). In all these regions, it was observed that recorded cases of lesions coincided precisely with the yearly peaks of the beetles. Paederus fuscipes and P. kalalovae are the predominant species along the Caspian Sea shore. It appears that P. fuscipes is homogeneously distributed throughout the Caspian Sea region while the distribution of the other species is more irregular. Paederus fuscipes is probably the major agent that causes linear dermatitis in northern Iran. Whereas this disease is a rural difficulty in the south, mainly in villages or small towns, it is an urban problem in northern provinces along the Caspian Sea shore. Meloid dermatitis has been registered only in western and southern Iran. It is not as widespread as linear dermatitis and remains a minor rural health problem.

Medically important beetles (insecta: coleoptera) of Iran

This study focused on coleopteran species that are responsible for the emergence of recent cases of dermatological manifestations in Iran. To the best of our knowledge, five species of the family Meloidae and nine species of the genus Paederus are by far the only beetles recognized as medically important in Iran. The staphylinids consists of Paederus ilsae, P. iliensis, P. fuscipes, P. kalalovae, P. balcanicus, P. lenkoranus, P. littoralis, P. carpathicus, P. nigricornis, while the meloids are Mylabris impressa, M. guerini, Muzimes iranicus, Alosimus smyrnensis and Epicauta sharpi. Most cases of linear dermatitis in this country occur in areas bordering the Caspian Sea. This problem is caused by beetles of the genus Paederus which are present as adults from mid-April to October with particularly high incidences from May to August. Fars (in southern Iran) ranks second in number of cases of insect-induced dermatitis. The third major region in which this type of dermatitis has been recorded is Hamedan Province, in the west of the country. Meloid dermatitis showed its highest severity in 2001, when a considerable number of patients sought medical help in Toyserkan and Nahavand counties. New cases of skin blistering were reported along the Persian Gulf coast and the agent was identified as Epicauta sharpi (Coleoptera: Meloidae). In all these regions, it was observed that recorded cases of lesions coincided precisely with the yearly peaks of the beetles. Paederus fuscipes and P. kalalovae are the predominant species along the Caspian Sea shore. It appears that P. fuscipes is homogeneously distributed throughout the Caspian Sea region while the distribution of the other species is more irregular. Paederus fuscipes is probably the major agent that causes linear dermatitis in northern Iran. Whereas this disease is a rural difficulty in the south, mainly in villages or small towns, it is an urban problem in northern provinces along the Caspian Sea shore. Meloid dermatitis has been registered only in western and southern Iran. It is not as widespread as linear dermatitis and remains a minor rural health problem.(AU)

Detection of cantharidin-related compounds in Mylabris impressa (Coleoptera: Meloidae)

Cantharidin is mainly found in the beetle families Meloidae and Oedemeridae (Insecta: Coleoptera) which are the natural producers of this terpene anhydride. Most studies to date have focused on cantharidin distribution in blister beetles, with few reports on recently found cantharidin-related compounds (CRCs). Using gas chromatography-mass spectrometry (GC-MS), the present work reported cantharidin and two CRCs, palasonin and cantharidinimide from Mylabris impressa stillata (Baudi, 1878) which was collected from Toyserkan county, Hamedan Province, Iran. Ionization provided mass spectra with characteristic fragments of cantharidin at m/z 96 and 128, demethylcantharidin at m/z 82 and 114, and cantharidinimide at m/z 70, 96 and 127. This is the first time that cantharidin and the two CRCs are found in the genus Mylabris which in turn is new to the field of venomous insects.

Detection of cantharidin-related compounds in Mylabris impressa (Coleoptera: Meloidae)

Cantharidin is mainly found in the beetle families Meloidae and Oedemeridae (Insecta: Coleoptera) which are the natural producers of this terpene anhydride. Most studies to date have focused on cantharidin distribution in blister beetles, with few reports on recently found cantharidin-related compounds (CRCs). Using gas chromatography-mass spectrometry (GC-MS), the present work reported cantharidin and two CRCs, palasonin and cantharidinimide from Mylabris impressa stillata (Baudi, 1878) which was collected from Toyserkan county, Hamedan Province, Iran. Ionization provided mass spectra with characteristic fragments of cantharidin at m/z 96 and 128, demethylcantharidin at m/z 82 and 114, and cantharidinimide at m/z 70, 96 and 127. This is the first time that cantharidin and the two CRCs are found in the genus Mylabris which in turn is new to the field of venomous insects.(AU)