MYRMECOPHILOUS CRICKET (ORTHOPTERA:GRYLLIDAE)I GREGG H ENDERSOI\ and ROGER D

J. E:\TO~1()1. Soc BRI"I COLLI~IBI , \ ti 3 ( 19S6). DI.C 31. 1986

MORPHOLOGY OF MYRMECOPHILA MANNI, A MYRMECOPHILOUS CRICKET (ORTHOPTERA:GRYLLIDAE)I GREGG H ENDERSOI\ and ROGER D. AKRE Departmcnt of Enlomolog) Was hington State Univcr!>ity Pullman. WA 99164-6432

ABSTRACT Scanning electron microscopy showed that the myrlllccoph il ous cricket. MI'nIlCC0l'ili/1i 1I/(lIlIli Schimmer. retains many structural features CO lll mon to typical gryllid, and ha, reV. of the Illorphological Icatures often associated with myr111 ccophily. Howeve r. the 1110uth parts. particularl) the labrum and epipharynx. arc highly 1110dified for strigilation and trophallaxis. The structurc of the ov ipm.itor is unique in that it can expand greatly to permit the passage of large eggs. This cri cket al so dillers from typi cal gryll ids in having stemmata instead ofcol1lpound eyes. a feature probably re lated to its life in side dark ant nests where it docs not need good vision. Behavioral. ra ther than morphological. attributes arc probabl\ more important in adapting the crickets for life with ant s.

INTRODUCTION RESUI:r s AN D DISCUSSION Four species ofM."nlll'col'ili/a Latrei lle. small C .3-4.0 Sensory Apparatus 111m ). apterous crickets. arc found in North America (Hebard 1920). Ml'rlllccopili/a are the only l11 yrmecophi Thc SEM showed that M. 1III/IIIIi ha s morphological lous cric ket> known. Inquil ines. especially myrme features cOllllllonly foun d in the rami I) Gryllidae . How cophiles. often share a number of characteristics that cver. some pec ula rities of M. 1IIllllili n1

Fig. I . Highly ma~nifi e d SE M show ing scape (sc) of the an tenna and stel11 mata (stc) . Note the row of ha irs along the scapc.

F i ~. 2. Typical arrangemcnt of se nsory hairs that are found on eac h ofthe44 + seg ment s of th e antenn

Fig. 3. Diagram , howing the oriclllatH)J1 of Ihe ccrn" to the re,t of the hody. Two major Iype, of hair' arc located here . The lOp in .,c n shows filamentous hairs that detect soun d or vihration . The,e hairs arc located oYer moSi of the ccreal surhlCc. The second t\ pe of hair. located onlv along the tir,ttwo hasal ,egillenb. arc hal loon hair' whie!. help Ihe in,eel orient to gravit~ (Bi,hof 19 7-+).

Fig. -+. The lCeding mechanism or M. I//(///ll i is modified to increasc the c nic icncy olliS keding habilS . Lahrum (lhn . Ephiphal) nx (cphy). Galea (ga). 60 J. ENTOMOL SOC BRIT. COLlIMRI,\ X3 ( I YR 6). D EC ~ I . 19X6

Fi g. S. SEM shows the top of the head . cervix. and pronotul11 of M. !/I III I II i. The arrow points to a sing le hair scalc. its se rrated natu re is shown. greatly enla rged. to the right.

Fig. 6. SEM reveals the expandi ng nature of the ov iposit or of M. !/IanJli. This a ll ows for ovipositi on of large eggs. The fi rst valvul ae (I vi v) can spread apart and the spiraled egg guide (e.g.) can unspi ral, inc reasi ng the total surrace area . The thi rd val vu lae (3 vlv) are fu seu and wrap around the sclerotized ti ps of the second valvulae (2 vlv). .I. E:--: I()~I()I Soc BIU! COLl \1 KIA ~:; ( 19N6 J. DI.c. .\ I. 1<)X6 6t

and trophallaxi,. The length of thc al1!ennae aids the and arc posi tioned to sw<:er an) panicle, scrared by the cr icket in mim icking thc:-,c ~ignaJ:.. \\ hich a ll ()w~ til l' mandible, inlO th e epiphary nx. Highl) lllodified mouth crlc!-"ct. in a ~cn~~, (() para~i t i/c ib ho~l. In addition. rarts abo occur among th o~c inquili n l'~ which arc \\el l oh~cr\'alion~ ~ho\\ that M. JIll/III/; u.... t:\ ib antennae and intcgrated In{() ant colonies (c'.g .. Psdaphidae. Akrc and ce rci in elahorate di~play~ during ma ting and intra~peci Hill 19131. fi c agg r c~ .... inn (Hcndcr .... on 19 ~5). Cereal shahing ha .... a 1... 0 becn observed In I'ield crickcb a nd Illay aid in di rcCling tlw lcillaic into proper rosition for copulat ion (Alexander Odor Camouflage 1961 ) M. lllillilli arc all ac~ed b) ant s. bu t the) arc abo found The cyes llf M. 1I/ll1111i arc nm cO fllpound. '" in 1ll0,t at thL very heart of the ant nesl. the brood chamber cricket'. hut are comr(l,cd of I R to 20 , tcnlfllata located ( Hender,on 1985 I. Onc means by which Ihe cricket ahove each anlenna. Vi,ual pe rception f()r thi, type of eyc allain, entrance int o the chamber i, through behavioral i, believed to be ofa co,u',e Ill,,,aic that can only diflcren mimicry. Odor eamonll age may be another mcan". M. ti ate ,hares and ,harpl~ cont rast ing images (Dcthicr lIIillllli arc covered with ,errated sealc, on the dorsum of 19·n. Me)er Rocho\\' 197-+). Morphological regres,ion th e hcad. thora\. and abdomen th at lIlay be used to of the eye, is a"ociatcu wi th Ill) rmecorhily (Wilson acquire odors (Figs. 5). Acquisition ofthc nl',t odor b) 1971). and although ,temmata arc not a rcgre"cd form of my rlllccophile, through mechanical means is COlllmon. compound c)e. the cnd rcsult i, much the ,amc. Fi nc Host odors are transferred by hi sterid beetles a"ociatcd visua l acuit) i, probably not ncce"ar) since thc crickets with army ants by rubbin g their tibial bru,hes on the ants spcnu most of th ei r li\'es inside a dad, ne,1. (Rettenllleycr 1961. Akrc 19(8). The Illyrmccophilous bectle M r nll('<"l/ph"dill.\ ('x("(/\'IIlico/li,\ (Bl anc hard) (Scarabaeidae) has rccentl y heen found 10 acquire spe LOl:O Jll otory Apparatus eie'-'pecifi e hydrocarbons from it, host by contacl. b) M. II/allili arc both ,altatorial ano cur,orial. thus they groo min g behavior. and by i n gc~ti()n of r~gurg.ita t cd ant re tain thc jumpin g and running abilitie, typical o f G ry ll i postpharyngcal g land cnntents (Vander 1..,1cer and Wojick dac. With M. 1IIIIIIIIi retaining sensilla to allow for pe rcep 19X ~). The ,erratcd ,cale, on M. IIltllllli might scrape ti on of a pproach ing anls. it follows that the) ,hould re tain pa rtic le, oil the walls and galleries of the ant nest during the ir ' pced and jumping abilit\ to alk)\\ for escarc. the cricket's tra\c1s. Wheeler ( 1900) repon ed that the Wheeler ( 1900) belic\·cd that the complicated fig-zag wall, and gallerie, of ant ne, t, arc co\ered with cutic ular path 01 M l'nllcclI!,hi/li was the major l;lCtor in allowing lipids deposited b) the con,tant travcl or the ants. Al thcm to li\e \\ it h anls. OINo' rvati o ns in the l aborator~ th ough att ack~ h~ an l ~ on thei r cricket glle~b ~lIggcsllhat revealed th at M. 1Illlllili aho retain, the ahi lit y tn lo,e a h"'t hydrocarbon acquisition is not full y cflective . acqui hind leg if ,eized by an ant. Steincr ( 196R) was thc first to s it ion o f e\·en a sma Ii amount of h",t hydrocarbons may recognize thi~ ~ I dap tat ioll in field cr i ckL' t ~ a~ we ll i.I~ ~() Ill e help in the c ri cket\ l'ommcnsal existence. grasshoppers a, a possihle mean, of ",cape. M. 1I/IIIIIIi appeared 10 function norlllall) with a leg Illis,ing and Reproductive .~ lllrph() l og .' lived as long a, intact Mrnlll'c(j/Jhi/a (He nderson 1985). Schimmcr ( 1909) found that the m'irmitor of M\TII/(' ("1I!,hi/" has unique aniculatillit as a rcsult of e longation <.Ind fusinn oj' th \~ eigh th and ninth Icrga rlur~t1I ~. Feeding A pparat", Gorokhov (19RO) suggestcd that the colulllll gavc th e The mouth pan, of M. 1IIlIIIIIi arc of the general oni1or (\\ ip",itnr the ahilit) to e\tcnd and retract: a necc"an tc rall t} pC' \\ ith a large numbe r of chc/1lo ..... cn...,nr) ~c n ~i ll a abilit\ si nce the in ,eCl (lVipo,Slts eggs nearly one-thi rd as on the tir' of th e labia l and ma\il la n pa lpi. Hl)\\cver. long a, its bod). SEM ,howed that the mClllbranou, cgg SEM revealed that the cpiphar) nx and lahrum arc lllodi guide i, 'riraled (Fig 6) . Thc ,pirallng permit, expansion fied in M. 1IIIIIIIIi The labru m i, reduccd and th e of' the egg gdid~. and \\~ ~uggC\t that th is abo is ar. cpipharyn\ protrudc's from heneath it in finger-like pro adapialillll for lay ing propLlrtionatcl)' large cgg\. 1\:-, til ... lection,. fused pro\imall) and ,Iightl~ sera rate distalh egg Ira\'cl~ dtw, n the egg gu iue th e :-.piral opcn~ lip gi\'lIlf, (Fig. -+ 1. Epirhar~ ngeal rrojectilHl, ofthi, type arc some the egg the area it needs v.:hiIL ~Idl providing a :-,mooth time, fo und IJ1 aquatic in,cct, (Haliplidae. Cllicopte ra. patl",·a\ rer,. ob,cn. 1 and arc probahl~ meu lor ,craping food I()o~(' Irom \arinu:-. ~lIh~ l ratc~ . M . lJIaf/lli ... trigilate an'" and engage thclll in lr()pha l~ Summar. la\i,. The brush-l ike erirharyn\ appears to be a adapta ,\1. 11/(111111 i, morrhologicall) \\cll c4u ipned for myr tion for taking this lood, mec·orhih. The antennae and c~rci are dcnsch c1.lthell The protruding eplphar) n\ Innea,c, the surface arc; \\ ith ,cn,or) hair, that qui<'~I~ detcct approaching allis that comes In contact \\ ith the ball of liquid rcgurgitated This carl~ warning s),stel11. Cllurlcd with the rropcnslt\ b) the anI. Thc ,urface ten,ion of the liqUid i, e

tions. coupled with appropriate behavior. permit these These small crickets have used a mi nimum of morpho crickets to integrate into the colonies of their host ants logical adaptations and a maximum of behavioral mod if i without mu ch difficulty. Also imponant is their small size cations to integrate themselves in to colon ies of the ir host (2.3 t04.0 mm) which makes them difficult 10 catch even ants. The number of crickets in th ese colonics (one nest with a determined allack by an ant. harbored over 300 crickets) suggests that they are at least Well integratecl mynnecophiles freq ucntly have greatly as successful as myrmccoid inquilines. modifieclmouth pans to take advantage of food within the ACKNOWLEDGEMENTS ant colony. and these crickets arc no exception . Their brush -type epipharynx probably helps sweep food into We sincerely thank E.P. Call s and P.c. Schroeder fo r the buccal cavit y when the c ri cket is strigilating an ant. advice on many aspects of this project. We arc grate ful to During trophallaxis the large and irregular surface of th e J. Jenkins. J. We ll s. and M.G. Means for assistance in epipharynx may aid in the transfer of the regurgitated coll ecting cri ckets. We also thank E. P. CallS. P.c. Sch liquid . Much more importantly. it appea rs that the mim roeder. R.W. Sites. and R.S. Zack for critically rev iewin g icking of recognition signal s of the ants cnables the the manuscript and for making numerous suggesti ons for cricket to tap a nearly unlimited resource. the contents of improvement. A. Mudge provided untiring technical as the crops of foraging workers. sistance in the fina l prepa ration of the manuscript.

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