Chalkbrood - Status Today and Hopes for Control' - Golden Rule Honey

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Attempts to infect small and large larvae from uncapped cells rvith
A. apis
First rve sought ,to determine rvhether A. apis causes chalkbroocl
discrase or is simply a secondar.y invader oI lanrae killecl or irriur:e,cl bl'
other errents. Evidence for thc latter might be supportecl by grot'th of
the fungus on dead larwae. We also s'ished to deterrnine rl'hether munrmification
arises from infection b-v both vegetative and sporulatecl strains
ancl rvhether A. opis can invade larr.ae through the cuticle ancl/or. per os.
In acldition, u,e rvished to deternrine g'hetlicr vourlg an,cl olcl lan'ae are
equally susceptible to infection.
The u'ater removal technique of ClATl.Y et al. (1.961) u'as ernplol'ed
rvithout removing any cappings from l,he cells. Thus, the larr.ae rvere
rvashed from a cornb onto sterile a,bsorbent paller. T'hen each lan-ae
rvas individlrally picked up on the polished end of a glass tube attachecl
to a $rater suction devi,ce. while held 'to the glass tube, each sras u.ashed
3 times u'ith sterile clistilled lvater from a plastic sqlleeze bottle.
The larva,e rvere ,divicled into trvo age groups. srnall and large, on
the basis of size. The small }ar.r.ae were 3--4 davs old (average u'eight
54 mg). ancl the large iar-r,-ae were 4.5-b.5 dal's old (average u.eight
134 rrng). The treatmen,t groups of larvae are ,shorvn in Table 1.
Lan'ae in the ((alive" treat'ment groups u,ere indir.idualh' pracecl
in sterile vial caps in sterile glass petri dishes that contained a piece of
filter paper kept rnoist u'ith sterile distilled rrater. Eight-l0 larvae
leceiving the same treatment ,ll'ere placed in the same petri clish. Larvae
in the ((dead" treatment groups u'ere placed in sterile r,'ierl caps and
petri dishes and ,were killed r,vitJr dly ice.
A drop of the approp'iate homogenate \\:as place.d eithe. on the
mouthparts or ,on the dolsal side of the larr.ae. We confirmeC consulrption
of the homogenate by direct observation. The clishes rvere placec
in a 25rC inc,ubator. Letrr.ae u'ere o,bservecl clail1" for 10 da1-s tvith a
clissecting rni'closcope fol moveurent, fungal grou'th, discoloratiorr, and
nrunrrnif icaticn.
'I'he lesults are shon'n in Table 2. Eler-en urLrrnnties u'ere fornrecl
in control tleatment grollps leceiving cleacl ..1. c7ri.s. These Iarvae rnaliravc
httcl trtttut'al itrfec'tions u'hich r,r":re inarJ'liralent lrnl.il thc lan'ac t'(:r.e
inc'r.rbaterl. Iloq'cver'. trorre of the colclnies frou'r ri-hic'h lalr.uc rr-ct'e obtained
r:ontainec anv larvae thiit u'cre r-isibl.r' iulectecl l-ith ;1. rrpi.s. Nol
wet-e altv rntturntics for:nil at. the err.rtltrncc or on the bottciurs of these
colonies. T'hr:r'efore. sorne l>ec r'olonics or lalvae rlav harbor'-1. cpis
$'ithor.tt sltorving sigrts cll cliscitsc. Snr:rll larviie tirat u'err: natur-allf ilfcctecl
recluilecl 5'*7 da1's of incubation to lnunrntifr- : tire large l;u.r-ae
requ irccl 6-B da1's.
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