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Revista da Sociedade Brasileira de Medicina Tropical 3 7 ( 2 ) :1 8 9 -1 9 1 , mar-abr, 2 0 0 4
Pathogenicity of
Evlachovaea
sp ( Hyphomycetes) , a new species
isolated fr om
Triatom a sordida
, in Chagas’ disease vector s
Patogenicidade de
Evla cho va e a
sp ( Hyphomycetes) , uma nova espécie
isolada de
Tria to m a so rdida
, para vetores da doença de Chagas
Chr istian Luz1, Luiz Fer nando Nunes Ro cha1 and Io nizete Gar cia Silva1
ABSTRACT
Evlac ho vaea sp wa s te ste d o n n ym phs o f 5 Tr iato ma spp 5 Rho dnius spp, Panstr o ngylus her r er i a n d Dipe talo gaste r maximus a t 25 ° C, 75% hu m i di ty a n d hu m i di ty > 98%. Mo st spe c i e s sho we d su sc e pti b i li ty to f u n ga l i n f e c ti o n a t hi gh hu m i di ty. Mo rta li ty wa s re du c e d a t 75% hu m i di ty. Fu n ga l de ve lo pm e n t wa s o b se rve d o n 69.5% o f c a da ve rs.
Ke y-words:Evlac ho vaea. Tri a to m i n a e . Pa tho ge n i c i ty. Ve c to r c o n tro l.
RESUMO
Evlac ho vae a sp f o i te sta d a e m n i n f a s d e 5 Tr iato m a sp p , 5 Rho dnius sp p , Panstr o ngylus he r r e r i e Dipe talo gaste r m axim us a 2 5 ° C, 7 5 % u m i d a d e e u m i d a d e > 9 8 %. A m a i o ri a d a s e sp é c i e s f o i su sc e tí ve l à i n f e c ç ã o e m u m i d a d e a lta . Mo rta li d a d e f o i re du zi da a 75% de u m i da de . O f u n go de se n vo lve u e m 69.5% do s c a dá ve re s.
Palavr as-chave s:Evlac ho vaea. Tri a to m i n a e . Pa to ge n i c i da de . Co n tro le de ve to re s.
1 . Institute o f Tr o pic al Patho lo gy and Pub lic He alth, Fe de r al Unive r sity o f Go iás, Go iânia, GO, B r azil
This wo r k was suppo r te d b y CNPq Ce ntr o - Oe ste ( Co nse lho Nac io nal de De se nvo lvime nto Cie ntífic o e Te c no ló gic o ) .
Addr e ss to: Dr. Chr istian Luz. Unive r sidade Fe de r al de Go iás, Caixa Po stal 1 3 1 , 7 4 0 0 1 - 9 7 0 Go iânia, GO. Te l: 5 5 6 2 2 0 9 - 6 1 1 3 , Fax: 5 5 6 2 5 2 1 - 1 8 3 9 .
e -mail: wo lf@ iptsp.ufg.b r
Re c e b ido par a pub lic aç ão e m 3 0 /6 /2 0 0 3 Ac e ito e m 3 /2 /2 0 0 4
Ento mo patho genic fungi suc h as Be a u ve ri a b a ssi a n a and
Me ta rh i zi u m a n i so p li a e we r e sho wn to b e ac tive against triato mine bugs under labo rato ry c o nditio ns2 4. Ho wever, o nly
a fe w fie ld te sts have b e e n r e po r te d, and the r e is almo st no pub lishe d info r matio n ab o ut patho ge nic fungi iso late d fr o m fie ld- c o lle c te d tr ia to m in e c a da ve r s . Pa r a m e s wa r a n a n d Sankar an ( 1 9 7 9 ) r epo r ted B. b a ssi a n a o n the tr iato mine b ug
Lin shc o ste u s sp in India. Rec ently another fungus identified as a ne w spe c ie s o f Evla c h o va e a,a ge nus de sc r ib e d in Russia1,
was found on a dead Tria to m a so rdida nymph in c entral B razil, a nd its pa tho ge nic ity wa s do c um e nte d a ga ins t Tri a to m a i n f e sta n s3. He r e in we r e po r t r e sults o n the patho ge nic ity o f
the Evla c ho va e a sp in o ther triato mine spec ies.
All tr iato mine s te ste d, 5 Tri a to m a spp, 5 Rho dn i u s spp,
Pa n s tr o n gylu s h e r r e r i, a n d Di p e ta lo ga s te r m a x i m u s, o r iginate d fr o m the Institute o f Tr o pic al Patho lo gy and Pub lic Health, Go iânia, B r azil. Insec ts wer e r ear ed at 2 5 ± 0 .5 ° C, 7 5 ± 5 % relative humidity ( RH) , and a photoperiod of 1 2 :1 2 ( L:D) h. The y we r e b lo o d-fe d o n c hic k e ns at 2 -we e k inte r vals. The fungus was c ultivated o n c o mplete medium and inc ub ated fo r
1 5 days at 2 5 ± 0 .5 ° C, 7 5 ± 5 % RH, and a photoperiod of 1 2 :1 2 ( L:D) h3. Fo r the te sts, c o nidia we r e suspe nde d in 1 0 ml o f
ste r ile 0 .1 % Twe e n 8 0 and adj uste d to 3 .3 x1 06, 1 07, 3 .3 x1 07,
1 08, 3 .3 x1 08 and 1 09 c o nidia/ml, c o r r e spo nding to b e twe e n
2 .4 x1 03 and 8 .0 x1 05 CFU ( c o lo ny-fo r ming unit) /c m2 tr e ate d
sur fac e4. Te n r e c e ntly mo lte d and unfe d thir d instar nymphs
( N3 ) o f the var io us spe c ie s we r e dir e c tly spr aye d with 5 ml o f e ac h c o nc e ntr atio n using a Po tte r spr ay to we r ( B ur k ar d Ltd., He r tfo r dshir e , UK) . Co ntr o l inse c ts we r e tr e a te d with 0 . 1 % Twe e n 8 0 o n ly. N3 we r e pla c e d o n filte r pa pe r in pla s tic Pe tr i dis h e s ( 9 0 x 1 5 m m ) a n d th e n in c ub a te d in a te s t c h a m b e r ( 3 3 x 3 7 x 2 2 c m) at RH 7 5 % , humidity c lo se to saturation ( RH> 9 8 % ) , 2 5 ± 0 .5 ° C and a photoperiod of 1 2 :1 2 ( L:D) h. Humidity of 7 5 % inside the test c hamber was regulated with a satur ate d so lutio n o f NaCl. Inse c ts we r e no t fe d dur ing the assays. Mo r tality o f nymphs was mo nito r e d daily. Le thal c o nc e ntr atio ns to k ill 5 0 % and 9 0 % ( LC
5 0 and LC9 0) we r e
1 9 0
Luz C e t al
Fungal emergenc e of Evla c ho va e a sp on c adavers and external c onidiogenesis were examined daily.
Mo st tr iato mine spe c ie s te ste d we r e fo und susc e ptib le to the Evla c ho va e a sp isolate at RH> 9 8 % . Susc eptibility of insec ts was c le ar ly influe nc e d b y humidity. At RH 7 5 % mo r tality was distinc tly r e duc e d fo r all spe c ie s. Re sults sho we d a ge ne r al relationship between dosage and fungal ac tivity against insec ts. This was also o b se r ve d fo r T. i n f e sta n s3. Fir st inse c ts o f mo st
tr iato mine spe c ie s suc c umb e d to the fungus 5 -7 days afte r applic atio n o f
≥
3 .3 x1 07 c o nidia/ml independently o f humiditytested. Mo r tality o f T. vi tti c e ps and T. de lpo n te i initiated after 8 and 9 days inc ubatio n at RH> 9 8 % , respec tively, and the first de ad N3 o f T. p i c tu ra ta e xpo se d to RH 7 5 % we r e fo und 1 2 days after treatment. Total mortality was observed at the highest do se s ( 3 .3 x1 08 and 1 09 c o nidia/ml) and humidity c lo se to
satur atio n, exc ept fo r T. vi tti c e ps, T. pi c tu ra ta and T. so rdida
whic h had mo r tality r ates o f 1 0 % , 6 0 % and 8 0 % , r espec tively, 2 0 days after exposure at RH> 9 8 % . Values of LC5 0, and LC9 0 are
presented in Table 1 . LC
5 0, 1 5 days after inc ubation at RH> 9 8 % ,
varied from 3 .1 8 x1 03 CFU/c m2 (R. n e gle c tu s) to 4 .3 4 x1 05 CFU/
c m2 (T. so rd i d a) . At RH 7 5 % o nly P. h e rre ri ( 1 .3 7 x1 05 CFU/
c m2) and R. e c u a d o ri e n si s ( 3 .1 1 x1 05 CFU/c m2) pr e se nte d
suffic ient mortality to c alc ulate the LC
5 0. After 2 0 days inc ubation
a t h um idity c lo s e to s a tur a tio n m o r ta lity o f T.d e lp o n te i,
R. n e gle c tu s, R. n a s u tu s a n d D. m a x i m u s we r e to o h igh to c a l c u l a te LC
5 0 a n d va r i e d b e twe e n 2 . 9 3 x 1 0
3 CFU/c m2
(R. p ro li x u s) and 1 .4 4 x1 05 CFU/c m2 (
T. p i c tu ra ta) fo r the o the r spe c ie s. At RH 7 5 % LC
5 0 2 0 days afte r inc ub atio n was
1 .1 2 x1 05 CFU/c m2,1 .6 8 x1 05 CFU/c m2 and 3 .7 1 x1 05 CFU/c m2 for P. h e rre ri, R. e c u a d o ri e n si s and D. m a x i m u s, r e spe c tive ly ( Table 1 ) . Control mortality at both humidities was
≤
1 0 % during the assay, ir r e spe c tive o f the spe c ie s.Am o ng a ll c a da ve r s r e ga r dle ss o f tr ia to m ine spe c ie s, h um idity o r do s e te s te d, 5 0 . 8 % o f th e c a da ve r s s h o we d outgrowth of Evla cho va e a sp only, 1 8 .7 % were found with mixed develo pment o f Evla c ho va e a sp and o ther s a pr o ph ytic fun gi,
Ta b le 1 - Le tha l c o nc e ntra tio ns ( LC50 a n d LC90) ( CFU/c m2) a nd re spe c tive c o nfide nc e inte rva ls ( 95% C.I.) o f Evlac hovaea sp. c a lc ula te d fo r tria to m ine third insta r nym phs, 15 a nd 20 da ys a fte r e xpo sure a t 75% a nd > 98% re la tive hum idity a nd 25° C1.
Time after inoc ulation ( days)
1 5 2 0
LC5 0 LC9 0 LC5 0 LC9 0 Spec ies Humidity ( % ) ( CFU x 1 05/c m2) ( 9 5 % C.I.) ( CFU x 1 05/c m2) ( 9 5 % C.I.)
Tri a to m a de lpo n te i 7 5 * * * *
> 9 8 0 .2 0a,b ( 0 .0 5 -0 .5 5 ) 5 .0 2b,c ( 1 .3 6 -4 0 2 .0 ) * * * *
Tria to m a le c tic u la ria 7 5 * * * *
> 9 8 0 .8 9b,c
( 0 .3 2 -2 .2 8 ) 1 .5 4b,c
( 1 .0 7 -2 .6 1 x1 04
) 0 .2 0 c ,d
( 0 .1 2 -1 .0 6 ) 0 .5 2a,b
( 0 .2 7 -2 7 9 .0 )
Tri a to m a p i c tu ra ta 7 5 * * * *
> 9 8 1 .6 6c
( 0 .8 4 -8 .3 0 ) 9 .9 0b,c
( 3 .2 7 -7 9 6 .0 ) 1 .4 4 d
( 0 .7 4 -5 .7 3 ) 8 .4 4a,b
( 2 .9 3 -2 9 0 .0 )
Tri a to m a so rd i d a 7 5 * * * *
> 9 8 4 .3 4c
( 1 .7 4 -3 0 ) 6 7 .4 0c
( 1 3 .8 0 -6 .9 1 x1 03
) 1 .0 8 d
( 0 .6 0 -2 .6 9 ) 6 .9 7a,b
( 2 .7 9 -5 1 .2 0 )
Tria to m a vittic e ps 7 5 * * * *
> 9 8 * * * *
Pa n stro n gylu s h e rre ri 7 5 1 .3 7c
( 0 .6 9 -5 .2 6 ) 8 .7 7b,c
( 2 .9 5 -2 3 5 .0 ) 1 .1 2d
( 0 .5 1 -5 .3 6 ) 1 2 .3a,b
( 3 .2 1 -6 8 2 .0 )
> 9 8 0 .0 6a
( 0 .0 2 -0 .1 3 ) 0 .6 3a,b
( 0 .2 8 -3 .8 9 ) 0 .0 5a,b
( 0 .0 2 -0 .0 9 ) 0 .2 7a ( 0 .1 3 -1 .6 4 )
Rh o d n i u s e c u a d o ri e n si s 7 5 3 .1 1c
( 1 .2 9 -2 7 .6 ) 5 9 ,3 0c
( 1 1 ,0 -3 .4 x1 04
) 1 .6 8d
( 0 .7 0 -6 .6 6 ) 3 3 .5 0a,b
( 7 .8 5 -4 2 9 .0 )
> 9 8 0 .3 3a,b
( 0 .1 8 -0 .5 5 ) 0 .9 3b
( 0 .5 6 -4 .6 2 ) 0 .1 3b,c
( 0 .0 7 -0 .2 1 ) 0 .3 7a ( 0 .2 2 -1 .3 8 )
Rh o d n i u s n a su tu s 7 5 * * * *
> 9 8 0 .0 4a
( 0 .0 2 -0 .1 2 ) 0 .6 4 a,b
( 0 .2 2 -4 .4 5 ) * * * *
Rh o d n i u sn e gle c tu s 7 5 * * * *
> 9 8 0 .0 3a
( 0 .0 1 -0 .0 6 ) 0 .1 1 a
( 0 .0 6 -0 .5 5 ) * * * *
RRh o d n i u s p ro li x u s 7 5 * * * *
> 9 8 0 .0 6a ( 0 .0 1 -0 .1 9 ) 0 .5 7 a,b( 0 .1 9 -6 .3 4 ) 0 .0 3a ( 0 .0 1 -0 .0 5 ) 0 .0 8a ( 0 .0 5 -1 1 .1 )
RRh o d n i u s ro b u stu s 7 5 * * * *
> 9 8 0 .3 5b
( 0 .2 2 -0 .5 8 ) 0 .7 8 a,b
( 0 .5 -2 .7 6 ) 0 .2 2b,c
( 0 .1 3 -0 .4 4 ) 0 .3 8a ( 0 .2 6 -1 5 .1 )
Di pe ta lo ga ste r m a xi m u s 7 5 * * 3 .7 1d ( 1 .0 2 -6 .5 9 x1 02) 1 .6 8 x1 02 b ( 1 7 .0 -1 01 6)
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Revista da Sociedade Brasileira de Medicina Tropical 3 7 ( 2 ) :1 8 9 -1 9 1 , mar-abr, 2 0 0 4
2 5 % with unide ntifie d sa pr o phytic fungi, a nd 5 . 5 % sho we d n o e x te r n a l fun gi. R e s ults un de r lin e th e n e e d to s tudy e n to m o pa th o ge n ic fun gi fo r c o n tr o l o f tr ia to m in e b ugs .
ACKNOWLEDGEMENTS
Autho r s thank Car me c i N Elias fo r te c hnic al suppo r t, and Ric har d A Humb er fo r the c r itic al r eview o f the manusc r ipt.
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