Adipokinetic hormone (Pyrap-AKH) enhances the effect of a pyrethroid insecticide against the firebug Pyrrhocoris apterus.
BACKGROUND
Adipokinetic hormones (AKHs) are insect neuropetides controlling stress situations including those elicited by insecticide treatment. The effect of Pyrap-AKH on the mortality of the firebug Pyrrhocoris apterus (L.) treated with the insecticide permethrin (Ambush 25 EC) was studied.


RESULTS
Coinjection of 50 ng permethrin with 80 pmol Pyrap-AKH induced a significant 2.3-fold increase in bug mortality compared with the insecticide alone. The results were confirmed by topical coapplication of both agents (400 ng and 80 pmol respectively). Injections of 50 and 100 ng permethrin elicited a significant increase in the AKH level in CNS and the haemolymph. The results indicate an involvement of AKH in stress response to permethrin. The enhanced effect of insecticide by AKH treatments probably results from the stimulatory role in bug metabolism: carbon dioxide production was increased 3.5- and 2.5-fold respectively 1 and 3 h after permethrin treatment, and 4.3- and 3.4-fold after the permethrin plus AKH cotreatment, compared with the control.


CONCLUSIONS
The elevation of metabolism could intensify the permethrin action by its faster penetration into tissues and by stimulation of biochemically active cells, and could be a reason for enhanced action of permethrin after its cotreatment with Pyrap-AKH.
Kodrík
Dalibor
D
Institute of Entomology, Biology Centre, Academy of Sciences, CZ-370 05 Ceské Budejovice, Czech Republic. kodrik@entu.cas.cz
Bártů
Iva
I
Socha
Radomír
R
D000818:Animals; D002245:Carbon Dioxide / Q000378:metabolism; D002490:Central Nervous System / Q000187:drug effects / Q000378:metabolism; D005260:Female; D006458:Hemolymph / Q000378:metabolism; D020062:Heteroptera / Q000187:drug effects / Q000378:metabolism / Q000502:physiology; D007301:Insect Hormones / Q000097:blood / Q000378:metabolism / Q000494:pharmacology*; D007306:Insecticides / Q000008:administration & dosage; D008297:Male; D009842:Oligopeptides / Q000097:blood / Q000378:metabolism / Q000494:pharmacology*; D026023:Permethrin / Q000008:administration & dosage; D010574:Pesticide Synergists / Q000097:blood / Q000378:metabolism / Q000494:pharmacology*; D011761:Pyrrolidonecarboxylic Acid / Q000031:analogs & derivatives* / Q000097:blood / Q000378:metabolism / Q000494:pharmacology; D013312:Stress, Physiological / Q000187:drug effects
D007301:Insect Hormones; D007306:Insecticides; D009842:Oligopeptides; D010574:Pesticide Synergists; C044833:adipokinetic hormone; D002245:Carbon Dioxide; D026023:Permethrin; D011761:Pyrrolidonecarboxylic Acid