Blister beetles

Blister beetles have wide range of ecological value. Due to their unique biology and relationship with other insects, they have been studied from various aspects. Agronomists study to explore information on crop infestation and ecologists study parasitoid nature of larva.

1. Blister Beetles
Shreeram Ghimire
Department of Zoology, Amrit Campus
Thamel, Kathmandu
www.shreeramghimire.com
Email: [email protected], [email protected]

2. Introduction
•BlisterbeetlesareimportantmemberoforderColeopteraandspecifically
aretermedasfamilyMeloidae.Thesebeetlesarestatedasblisterdueto
secretionofachemicallyblisteringagent‘Cantharidin’.Thatsecretionis
defensiveinnature.
•Itisestimatedthatblisterbeetleshavemorethan2500speciesin
approximately120genera.
•Thesebeetlesarephytophagous.Theyfeedonplantleavesandflowersof
alfalfa,soyabean,otherbeans,potatoesandotherhorticulturalplants.
•Theseanimalsaremostlydiurnalbutveryfewarenocturnaltoo.
•Adultsliveinorganizedgroupsandarecolorful.
•Allblisterbeetlelarvaearespecializedpredators.Larvaeofmostofthe
speciesenterthenestsofwildbeesandfeedonimmaturebeesand
reservedprovisions.Sometimes,larvaealsoconsumeeggsofgrasshoppers

3. General Anatomy
•Adults range from half to one inch long. The
body is narrow and elongated with wider
head than protonum. (protonum: the dorsal
sclerite of the prothorax).
•Wing covers are flexible and rounded over the
abdomen. The color of these cover varies
from black to gray to brown.
•Elytra are leathery and soft, rather than rigid,
and the foresings cover the abdomen.
•Antennae is filiform.
Epicuta puncticollis

4. Blister Beetles as Pest
•Blisterbeetlesarerecordedaspesttovariouscropslikealfalfa,
potatoes,beans,sugarbeetsandotherleafyplants.Thesebeetles
damageleavesandflowers.
•Blisterbeetlesalsoaffectlivestockdigestivesystemwhentheyare
ingested.Thesebeetlesareregardedastoxicevenpotentiallylethal
duetoproductionofcantharidinbytheinsects.Variousscholars
mentionedtheimpactsonhorse,sheepandcattle.Animalsmaybe
poisonedbyeatingcrushedbeetlesincuredhay.Cantharidinaffects
digestiveandurinarytract.
•ChemistryofCantharidin:fromchemicalsafetypointofview,itis
acutetoxicandirritant.Itisamonoterpenoidwithanepoxy-bridged
cyclicdicarboxylicanhydridestructure.Itisdeclaredaspoisoninlarge
doses.

5. Biology
•Femalebeetleslayclustersofeggsinthesoilinlatesummer.The
small,activelarvaethathatchfromtheseeggscrawloverthesoil
surfaceenteringcracksinsearchforgrasshoppereggsdepositedin
thesoil.
•Afterfindinggrasshoppereggsorbeeegg,blisterbeetlelarvae
becomesimmobileandspendstherestoftheirdevelopmentaltime
asleglessgrubs.
•Theuniquefeatureofthisbeetleistriungulinlarva.Thefirstinstar
larvadevelopstoleglessgrubandisparasiticinnature.
•Thelarvaepupateandemergesasadults.
•The species become active during summer season.

6. Ecology
•Larvaofthisbeetlefeedsoneggsofgrasshopperandbees.Blister
beetleslarvaarethusparasitoidinnature.So,itisrecordedthat
higherthenumberofgrasshopperinparticularhabitatmeanshigher
thechanceofbristlebeetlestoflourish.So,thesebeetleshelpto
controlthegrasshopper,usefulforsomecropsinsomeinstance.
•Cantharidinisusedinbothdefenseaswellasmeanofchemical
communicationamongblisterbeetles.
•Blisterbeetlesarephytophagousandarepesttowiderangeofcrop
speciesliketomato,onion,tobacco,citrus,spinachandothercrops.
•BlisterbeetlesdevelopMullerianmimicrywithothercoleopteran
familiescreatingbetternaturalfitnessduetoadvancedaposematism.

7. Nepal
•Basedonsearchingooglescholarandotheronlineplatforms,no
specificresearchrelatedtoblisterbeetleshavebeenrecordedyetin
thecaseofNepal.
•FewIndianscholarshavetriedtocointheterminologyduetopest
significanceratherthanonecologicalsignificance.
•Nepal,duetoitswiderangeofecosystem,mayharborgooddiversity
ofthesebeetles.
•Basedonmybaselinesurvey,Ihavecollected4species:Mylabris
pustulata,Mylabrisguerini,EpicutapuncticollisandMylabris
variabilis.
•ThereisaongoingsurveyofBlisterbeetlesinKathmanduvalleyand
surroundingdistrictsledbypresenteroftheseslides.Thefindingwill
besharedsoon.

8. Scientific Leader of Blister Beetle Research
•MarcoA.Bologna:Heisthetowering
figureofBlisterBeetleResearch.Hehas
widerangeofpublicationfrom
systematics,taxonomyanddiversityto
economicsignificance.HeisItalianby
nationality.Byprofession,heis
professorofzoologyinRomaTre
UniversityofItaly.
•Hedidhisresearchedinentomology,
herpetology,conservationbiologyand
zoogeography.

9. References
•Carrel,J.E.,McCairel,M.H.,Slagle,A.J.,Doom,J.P.,Brill,J.,and
McCormick,J.P.1993.Cantharidinproductioninablister
beetle.Experientia,49(2):171-174.
•Bologna,M.A.,andPinto,J.D.2001.Phylogeneticstudiesof
Meloidae(Coleoptera),withemphasisontheevolutionof
phoresy.SystematicEntomology,26(1):33-72.
•Ghoneim,K.2013.Agronomicandbiodiversityimpactsoftheblister
beetles(Coleoptera:Meloidae)intheworld:Areview.Int.J.Agri.Sci.
Res.,2:21-36
•Nikbakhtzadeh,M.R.,andTirgari,S.2002.Blisterbeetles(Coleoptera:
Meloidae)inNahavandcounty(Hamedanprovince,Iran)andtheir
ecologicalrelationshiptoothercoleopteranfamilies.IranianJournal
ofPublicHealth,55-62.