ToXdeat . Vol . 24, No . 9, PP. 950- 954, 1986 . 0011- 0101/ 60 . 00+ . 00 Pr i nt ed in OFWHrl nl n. Per pmon Jour nal s Lt d . HORNET VENOMS: LETHALI TI ES AND LETHAL CAPACI TI ES J USTI N O . SCHMI DT, ' SOI CHI YAMANE, MAKOTo MATSUURA3 and CHRI STOPHER K . STARR ' Sout hwest ern Bi ol ogi cal I nst i t ut e, 1961 W . Br i cht a, Tucson, AZ 85745, U.S.A., Tacul t y of Educat i on, I bar aki Uni ver si t y, M ito 310, Japan, Tacul t y of Agr i cul t ur e, M ie Uni ver si t y, 1515 Kam i hama, Tsu 514, Japan, and ' Depart ment of Bi ol ogy, De La Sal l e Uni ver si t y, P.O. Box 3819, Mani l a, Phi l i ppi nes ( Accept ed f or publ kat i on 14 May 1986) J . O . Sct i mnrr, S. YAmANE, M . MATsuuaAand C. K. STAaR . Hor net venoms : l et hal i t i es and l et hal capaci t i es. Toxkon 24, 950- 954, 1986 . - The i .v . 1. Dp val ues to m i ce of pur e venoms of Vesper nr aedar l ni a j aponi ca, V . sl mW i nm xant hopt em, V . t r opka dwMa and V . l . hi ct uaw wer e, r espect i vel y, 4 . 1, 3 . 1, 2.8 and 1.6 mg/ kg . The m zyxwvutsrqponmlkjihgfedc val ue of 1 .6 mg/ kg di st i ngui shes t he venomof V . hwht aw as t he mos t l et hal known was p venom . To measur e t he absol ut e l et hal i t y of a si ngl e st i ng, a new i ndex, cal l ed l et hal capaci t y, based on t he amount of venom possessed by an i ndi vi dual and its l et hal i t y is pr esent ed . V . mandaJi ni a and V . t r opka ar e t he mos t venomous known i nsect s, with a l et hal capaci t y of one st i ng f r om V . mandar *t d del i ver i ng an Lo (i .V.) dosage of venom to 270 g of mous e . The l et hal capaci t y f or an ent i r e hor net col ony, cal l ed col ony l et hal capaci t y, f or V . t r opka is 94 kg of mouse/ col ony . HORNETS in t he genus Vespa ar e t he l ar gest st i ngi ng i nsect s in t he worl d . These of t en conspi cuousl y col or ed speci es at t r act bot h l ay and sci ent i f i c i nt er est , ar e somet i mes ser i ous pr edat or s of honey bees ( MATSUURA and SAKAQAMI , 1973 ; I SHAY et al ., 1967) and t hei r st i ngs can i nduce al l er gi c r eact i ons in hyper sensi t i ve i ndi vi dual s ( ORI and HI YAMA, 1977 ; ABE, 1985 ; see SCHMI DT, 1986b, f or gener al di scussi on) . Ext ensi ve l i t er at ur e per t ai ni ng t o t he genus Vespa ( SPRADBERY, 1973 ; EDWARDS, 1980; MATSUURA and YAMANE, 1984) and speci f i cal l y to t he f our speci es of Vespa used in t hi s st udy ( MATSUURA, 1984 ; KOJ I MA and YAMANE, 1980; KOJI I MA, 1982) is avai l abl e . W ith a f ew except i ons (e.g . KAWAI et al ., 1980; ABE et al ., 1982; ABE and KAwAI , 1983) , little is known about t he venoms of t he hor net s of east er n Asi a and t hei r venom l et hal i t i es ar e unknown . We r epor t her e t he r esul t s f r om f our di ver se East Asi an speci es and det er m i ne t hei r capaci t i es as def ensi ve agent s . Wor ker hor net s of V . mandari ni a j aponi ca Radoszkowski , V . si m illima xant hopt er a Camer on and of V . t r opi cs deust a L. epel et i er and V . 1. l uet uaw de Saussur e wer e col l ect ed, r espect i vel y, 11- 13 August 1980 in Hi t achi Dai go and M i t o, Japan, 17 August 1980 in Yuasa, Wak ay ama Pr ef ect ur e, Japan, and 1 June 1985 in I nang, Sor sogon Pr ovi nce, Phi l i ppi nes . I mmedi at el y upon col l ect i on t he wor ker s of al l speci es wer e pl aced on i ce. Venomwas ext r act ed f r om col d- anest het i zed l i ve hor net s or f r oml i ve f r ozen ( - 10° to - 20° C) i ndi vi dual s . Al l venoms wer e col l ect ed as pur e f l ui ds expr essed f r omt he st i ng tip i nt o 5 or 10 pl m i cr ocapi l l ar y t ubes . The m i cr ocapi l l ar y t ube cont ent s wer e t hen empt i ed 950