an investigation into the ecology, biology, distribution and ......the proportion of ticks on the...
TRANSCRIPT
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A N I N V E S T I G A T I 0 N I N T 0 T H E E C 0 L 0 G Y ,
B I 0 L 0 G Y, D I S T R I B U T I 0 N A N D C 0 N T R 0 L
0 F H A E M A P H Y S A L I S L 0 N G I C 0 R N I S
N E U M A. N N , 1 9 0 1 .
A thesi s presented i n par t i al fulfilme nt
of the requ ireme n t s for the degree of
Master of Ve terina& Science at
Massey Uni versi t y .
Fre deri ck Jame s Alexander Ne ilson B . V . Sc .
1 980
<J
A B S T R A C T
In 1 974 , que sti onnai res were di stribute d t o farmer s i n the
Eas t Coast and Hawke� Bay areas of the Nor th Island of
New Zealand . The t i ck Haemaphysalis longi corni s Neumann 1 90 1 was pre sent on 59% o f farms i n the East Coast-Nor thern
Hawk�s Bay are a and 7% of farms in the remainde r of t he Hawke�
Bay are a . In the former area the t i ck appeare d to have spread
rapidly be tween 1 96 4 and 1 974 .
In the East Coas t -Nor thern Hawkes Bay are a , approx imately one
third of all farme r s consi dere d that the t i ck was a
signi f i cant prob lem on their farm . In t he Cen t ral and Sou t hern
Hawk�s Bay are a the t i ck was not conside r e d a problem and
cond i t i ons were probab ly margi nal for t i ck surv ival .
The di s tribution o f the t i ck was relate d to temperature ,
rainfall and alti tude . Almo st all farms where t i cks we re
pre sent were si tua t e d at less than 300 me tres above sea leve l .
The d i s tribution o f t i ck counts of she e p were posi t i vely
skewed and i t was s hown that the data should be normalized b y
transforming t o logari thms or square roo t s . S quar e roo t s
repre sent the easi e s t me thod o f transformat ion .
A compar i son betwe e n t i ck counts of the l e f t ear , right ear ,
both e ars and the b ody , showe d that overall ear counts
cont r i bute to nearly 50% o f t he to tal t i ck count . Howeve r ,
the propor tion o f t i cks on t he ears compare d wi t h on the b ody
varied over the count ing period and e ar counts were not hi ghly
c orrelated with body counts ( highe s t c or re lat i on , r = 0 . 38 ) .
The diamide , ami tra z , showe d a higher i n i t ial e f ficacy
against H . longi c orni s compared wi th Chlorfenv i nphos , but the
lat t e r appeare d to have a longer period of re sidual acti v i t y .
i i
0
In t he Northern Hawke� Bay and East Coas t are a most (�4%) she e p
owners dip be twe en January and March and over half ( 54%) dip i n
January o r March and t h i s period does no t coincide w i th the
adu l t and larva l peaks .
Inc reasing she ep numbers from 3 per 1 000 m2 ( equi valent to 2
30 per hec tare ) to 3 per 500 m ( e quivalent to 60 per he c tare ) re sul ted in lower t i ck survival in the more heavily s tocked
are as .
An examinat ion of the water balance of t he unfe d s tage s showed
that larvae were very susce p t i b le to de s i c cation at humi di t i e s
be low 80% R . H . Adu l t s we re more re si stant to desiccation than
nymphs . Larvae and nymphs re gain water rapi dly af ter
de siccati on . The cri t i cal e quilibrium a c t i vities for the unfed
s tage s was found to be approximately 0 . 8 , 0 . 7 and 0 . 9 for
larvae , nymphs and adults re spe c tive l y .
Immersion of unfed and engorge d stage s i n water indi cated t hat
t he former survive i mmersion for � 1 8 days whi le t he latter
showed lowe r survival .
Evidence i s pre se nted to sugge st H. longi corni s can cause
deaths from anaemia i n young Re d De er .
i i i
A C K N 0 W L E D G E M E N T S
The i nvestigations reported in this the s i s were carried ou t
f rom 1 9 74 - 1 980 whi le the author was a ve terinary offi cer wi t h
t h e Mini stry of Agri cul ture and Fi sheri e s . Some experimental
work was carried out at Wallaceville Animal Re search Centre and
t he remainder on farms in the Eas t Coast and Hawk�s Bay are a .
I am grateful to t he dire c torate ( Dr G . Adlam and
Mr R . Sali sbury ) and t he regional ve terinary officer
(Mr E . H . Shortri dge ) o f the Animal Healt h Divi sion , Mini stry
of Agri culture and Fi sheries , New Ze aland , for permi ssion for
this work to be under t aken and for arrangi ng study leave .
I am i ndebted to Dr W . A . G . Charleston and Dr A . C . G . Heat h who
superv i se d the rese arch and provided valuable advi ce ,
cri t i c i sm and encouragement throughou t this study .
I wish t o express my thanks to all past and pre sent staff of
the Animal Healt h Div i sion , M . A . F . from Gi sborne , Wairoa and
Rua toria who assisted wi th fenc ing and t i c k counting . To
Messrs R . de Bors t and M . Venni ng who also assisted with t i ck
coun ting , my grate ful thanks . Mr G . B . Dav i s collated the
tick questi onnai roofrom the central and sou thern Hawk�s Bay
are a and I wish to acknowledge and thank him for this
assistance .
Farmer s i n the Gi sborne are a also ass i s t e d wi th thi s study
and I would like to t hank Mr J . Wilson and Mr W. Condor .
As well I am i ndeb t e d to Mr John Holdswo r th , Waikohu Station ,
who provided s taff and 'ac i l i t i e s , over a considerable period ,
for mustering and spraying sheep and holding sheep for t i ck
count s .
v I w i sh to thank Dr A . Heath for arranging the use of fac i li t i e s
at Wallacevi lle and for hi s collabora t i on wi t h Mr L . M . Morri son
in the statisti cal analysis of the t i ck c oun t s from the
i nse c t i c i dal experiment .
iv
V
I also appreci ate the assi stance o f the se ni or supervi sor ,
Dr Charles ton , for hi s adv i ce on the pre s e ntation of t hi s thesi s .
Fi nal ly , t o Mr s A . WiRepa , my hear tfe lt thanks for typ i ng t he
dra f t and final copy o f thi s thesi s .
F . J . A . NEILSON
De cember, 1 980
PRE F A C E
Be t we e n 1 9 70 and 1 974 th e range and pre valence o f
Haemaphysal i s longi c o rn i s appeare d t o b e i nc r e a s i n g o n farms i n
t h e Ea s t Coa s t and Nor t he r n Hawkes Bay are a . Be cause o f t h i s
appare n t i ncre ase i n t i ck numb e r s a ce nsu s was p o s t e d t o farm e r s
i n t he a r e a wi t h t he a i m o f mappi ng t i ck d i s t r i b u t i o n . The n b y
a p roce ss o f i nduc t i ve re asoning i t was hope d t o exam i ne var i ou s
fac t o r s t h a t mi ght i nf lu e nce t h i s di s tr i b u t i on. The C e n t r a l
Hawke� Bay area w a s i nc luded i n t he c e n s u s a s o nl y a f e w t i ck s
h a d b e e n r e p o r t e d f r o m t hi s are a .
Some f arme r s i n the Eas t Coa s t and Northern H . B . area c o n s i de r e d
t h a t the t i ck was e con omi cally i mportant so se l e c t e d farm
p r a c t i c e s (e . g . s t ocki ng rate , t i me o f d i p p i ng or showe ring ,
c h o i c e of i nse c t i c i de) were i nve s t i ga t e d as i t was hop e d t h i s
m i gh t prov i de i nforma t i o n o n wh i c h re comme nd a t i o ns f o r the
c o n t r o l o f the t i ck c ou l d be base d .
Wa t e r balance i s e s se n t i al for the surv ival of all animal
spe c i e s but i t is cru c i a l to t he exis t e n c e of t i cks be cause of
the ir surface to vo lume r a t i o . A s the wa t e r rela t i o ns o f e ggs
and e ngorge d s tage s o f H . longi corn i s hav e b e e n t h orough ly
i nv e s t i ga t e d (He a t h , 1 974 ) so i t was d e c i d e d to i nves t i ga t e
t h i s relat i o nship i n t h e unfed s tage s . It was hop e d that thi s
m i gh t lead t o a b e t t e r unde r s t anding o f the survi val and he n c e
t h e d i s tr i b u t ion o f t h e t i ck .
"The t i ck i s ge nerate d f rom c ouch grass . "
Ar i s to tle i n H i s t o r i a Ani mal i um , c i r ca 300 B.C.
vi .
"Af t e r trea tmen t t he r e w i l l be no sore s and the wool wi l l be more
ple n t i fu l and i n be t te r cond i t i on and the r i ci ni ( t i c ks ) w i l l no t
be troub le some" .
M . Por c i u s Cata 200 B . C .
T A B L E 0 F C 0 N T E N T S
Abst rac t
Acknowle dge m e n t s
Pre face
1 . Re v i e w o f the l i tera t ur e
1 • 1 1 . 2 1 . 3
Ge neral i n trod uc t i o n
Tax o nomy o f t i ck s
The ge nus Haemap h ysal i s
1 . 4 Taxo nomy o f d i s t r i b u t i on o f Hae maphysali s
longi c orni s
1 . 6
Morpho logy o f t i ck s
1 .5 . 1 1 .5 . 2
Gene ral
Morpho logy o f H. longi c o r ni s
Ge ne t i c s o f H . l o ngi c orni s
1 . 7 I n t roduc t i o n o f H. longi c or ni s i n t o New Ze aland
and Au s t r a l i a
1 . 8 The e s tabli shme n t , spre ad and pre se nt
Page
i i
i v
v i
1 2 4
5 1 1 1 1
1 2 1 6
1 9
di s t r i bu t i o n o f H . longi c orni s i n New Ze aland 23 1 . 9 1 . 10
1 . 1 1
1 . 1 2
Ti ck fauna o f th e Ne w Ze aland sub-regi o n
The s i gni fi cance and e conomi c i m p o r t ance o f t i cks
1 . 1 0 . 1 B i o l ogy
1 . 1 1 . 1 1 . 1 1 . 2 Ec o l ogy
1 . 1 2 . 1 1 . 1 2 . 2 1 . 1 2 . 3 1 . 1 2 . 4 1 . 1 2 .5
1 . 1 2 . 6
The s i gni fi cance o f H . l ongi c o r n i s
o f t i c ks
B i o logy o f H . longi c or n i s
Se asona l i t y o f H . l o nsi c orni s
of t i c k s
The t e mperature r e la t i o n s of t i cks
Te mpera ture re l a t i ons o f H . l o ngi c orn i s
The wa t e r re la t i on s o f t i cks
The wat e r re lat i ons o f H . lo ngi corni s
The i�f luence o f v e ge ta t i o n o n the
surv i va l , act i v i t y , d e ve lopme n t and
d i s t r i bu t i on of t i ck s
The i n f luence o f v e ge t a t i o n o n t he
survival , deve lopmen t a c t i vi t y and
d i s t r i bu t i on of H . longi co rn i s
1 . 1 3 Hosts o f H . l o ngi corni s
26 27 30
33 39
43 48 48 50
56 63
67
70
75
v i i .
1 . 1 4 The c o n trol of t i ck s
1 . 1 4 . 1 The c on tro l of H . l o ngi corni s
Exp e r i me ntal Se c t i o n
2 .
3 .
Ti c k que s t i o n naire
2 . 1 Int r o du c t i on
2 . 2 Mate r i al s and me t ho ds
2 . 3 Re su l t s
2 . 4 Di scu s s i on
Ti c k coun t i ng . Di s t r i b u t ion o f t i ck s counts o f s he e p
3 . 1 In tro d u c t i on
3 .2 Mat e r i al s and me thods
3 . 3 Re su l t s
3 . 4 Di s c u s s i on
4 . Ti ck count i ng: the re la t i onshi p be twe e n ear and body
c ou n t s o f H . longi corni s on she e p
4 . 1 4 .2 4 . 3 4 . 4
In t r o duc t ion
Mat e r ials and me thods
Re s u l t s
Di scuss i on
5 . Exam i nat i o n of ind i vi dual t i c k coun ts from she e p for
e v i d e nce of r e s i s t ance to i nfe s t a t i on
6 .
5 . 1 In tr oduc t i on
5 . 2 Mat e r i als and me t hods
5 . 3 Re sul t s
5. 4 Di s c u ss i o n
Chem i cal c o n trol o f H . longi corni s on she e p:
Compari son o f the e f f i cay o f two i n se c t i c i d e s
6. 1 6 . 2
6.3 6 . 4
In tr oduc t ion
Mate r i al s and me t ho d s
Re su l t s
Di s c u s s i o n
7 . Chemi cal c on t rol of H . long i c orni s: i nf orma t i o n from
the Ne w Ze a land She e p R e turns o n the me thod a nd t i m i ng o f
dippi ng i n the Eas t Coast Northern Hawke s Bay ar e a
7. 1 fn t r oduc t i on
7 .2 Mat e r i als and me thods
7 . 3 Re sul t s
7 . 4 Di s c u s sion
v i i i .
Page
77· 79 8 4 84 84 8 4 86 9 4
109 109 1 09 1 10 1 1 8
1 20 120 1 20 1 2 1 1 2 6
1 2 8 1 2 8 1 28 1 30
1 30
1 33
1 33 1 33 1 35 1 38
1 40
1 40 1 40 1 40 1 42
8 . The i nflue nce o f stocking r a t e on t i c k survival
8 . 1
8 . 2
8 . 3 8 . 4
Introdu c t i o n
Mat e r i a l s and m e t ho d s
Re sul t s
Di sc u ssion
9 . The water b alance of u nfed larvae, nymphs and adu l t s
1 0 .
o f H . longi corni s
9 . 1 Introdu c t i on
9 . 2 Mate r i al s and me t hods
9 . 3 Re su l t s
9 . 4 Di s c u s s i o n
T h e effe c t s o f immer s i o n i n wat er on H . long i c o rni s
1 0 . 1 In trodu c t i on
1 0 . 2 1 0 . 3 1 0 . 4
Ma t e r i als and me t ho d s
Re sul t s
Di scu s s i on
1 1 . S ummary and c onclusi ons
Appe n d i x
1 . Copy of the que st ionna i re p o s t e d to farmers i n
De cemb e r . 1 974 2 . P ho t ograph of a map of the locat i on of f arme r s in t he
Cook County who rep l i e d t o t he 1 974 que s t i onnaire
3 . Pho t ograph of a map of the locat i o n of farmer s i n t he
Page
1 43 1 43 1 43 1 43 1 44
1 46 1 46 1 4 7 1 50
1 59 1 63 1 63 1 63 1 6 4 1 67 1 70
1 73
1 76
Waikohu Coun t y who r e p l i ed to the 1 974 ques t i onnaire 1 77 4 . Pho t ogr aph o f a map o f t he l o c a t i o n of f armer s i n the
Wai apu Count y who repl i e d t o t he 1974 que s t i onnaire
5 . Pho t ograph of a map o f t he lo c a t i o n of f arm e r s in t he
1 78
Wai roa County who re p li e d to t he 1 974 ques t i o nnai re 1 79
( ;
ix •
App e nd i c e s 6 t o 30 are t i ck c o u n t s of sheep refe r r e d
t o i n Se c t i o n s 3 , 4, 5 , 6
6 .
7 . 8 . 9 .
1 0 . 1 1 . 1 2 . 1 3 . 1 4 . 1 5 . 1 6 . 1 7 . 18 . 1 9 . 20 . 2 1 . 2 2 . 23 . 2 4 .
25 . 2 6 . 2 7 .
1 8 . 2 9 . 30 . 3 1 .
32 .
3 3-
Ti c k coun t s of A0 .03 " " " "
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" Cont r o l group
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day " " 11
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0 and day 7 "
1 3 "
27 "
0 "
1 3 "
27 "
0 0
1 3 "
2 7 "
0
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1 3 "
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2 7 " "
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20 "
3 4 "
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20 "
34 "
7 7
20 "
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7
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A naemia and deaths i n Red De e r assoc iate d w i t h heavy
i nfe s tat i on s of H. longic orni s
Bib l i o graphy
x.
Page,
1 80 1 8 1 1 8 2 1 83 1 8 4 1 85 1 86 1 8 7 1 8 8 1 89 1 90 1 9 1 192 1 93 1 94
1 95
196 1 9 7 198
1 99 200 20 1 202 203 204
205 206
207
2 1 1
T a b l e
1 . 1
1 . 2
1 . 4
1 . 5
L I S T 0 F T A B L E S
T axono m i c re l at ion sh i p s of t i cks
Wo rld di s t r i b u t i o n s of H. l o ngi c o r n i s and
H. b i spi nosa
Compar i so n of H. l ongi c orni s and H. b i sp i nosa
Approx i m a t e size range s o f H. longi corni s
F i e l d and l aborat o r y d a t a o n t he b i o logy o f
H . longi c orni s
1 . 6 Proposed r e l a t io nship b e t we e n t e mp e rate and b i o logy
of H. longi corni s
1 . 7 D i stri but i o n o f H. l o ngi corni s i n Ne w Ze a land and
A u s t r a l i a in r e l a t i o n t o cli ma t i c i nd i ce s
1 . 8 S o i l t e mpera tu re and wa t e r measureme n t s i n t he
e nvi ro nme n t of rye grass and paspalum pas t u re s
1 . 9
1 . 1 0
H o s t s of H. longi c o r ni s
Summary o f i nse c t i c i d a l t r i a l s agai ns t
xi
Page
3
9
1 0
1 5
40
5 1
55
74
76
H. longi corni s on c a t t le and she ep i n New Zealand 8 1
2 . 1 Length of t i me H. longi corni s pre s e n t on farms i n
t he Northern H. B. a nd Eas t Coas t are a
2 . 2 A l t i tude, rainfall and annual mean t e mpera t u re s for
t he Cl im ato logi cal S t a t i o n s in the are a m ap p e d for
t i ck d i s t r i b u t i o n
3.1 Chi -squar e d value s f r o m t e s t i ng goodne ss o f f i t o f
ac tual t i ck counts t o a normal d i s t ribu t i o n
Chi-squar e d value s f r o m t e s t i ng goodne ss o f f i t o f
a c tual t i ck count + 1 t ransform e d to logar i t hms t o
a normal d i s t r i bu t i o n
8 7
1 0 0
1 1 7
1 1 7
xii
Table Page
3 . 3 Chi-squar e d value s from t e s t i ng goodne ss o f f i t o f
ac t ual t i ck c ou n t s trans formed t o square r oo t s t o
a normal d i s t r i bu t i o n
4 . 1 Compar i son by ANOVAR o f le f t, r i g h t and comb i ned
ear c ou n t s and body c o u n t s o f 302 sheep o n day 0
4 . 2 Compar i so n by ANOVAR o f t o tal le f t , r i ght a n d
c o mb i ne d e ar coun t s a n d b o d y cou n t s o f t i ck s from
98 she e p o n days 0 , 7 , 13 , 20 , 2 7 and 34
Compar i so n b y ANOVAR o f comb i ne d e ar coun t s w i th
body c ou n t s o f 98 she e p o n days 0 , 7 , 1 3 , 20 , 27
and 3 4
4 . 4 Ear and body c ou n t s o f t i cks at i nd i vi dual
4 . 5
observa t i o n t i me s f o r a l l untre a t e d she e p
Correla t i on be twe e n c ombi ne d ear a n d b o d y c o u n t s
5 . 1 Cumula t i ve freque n c y d i s t r i b u t i o n o f t o t a l t i ck
c ou n t s of 302 she e p o n day 0
5 . 2 ANOVAR of t i ck c ount s o f she e p whi c h had b e e n
ass i gn e d t o one o f 3 groups o f t he bas i s o f t he
i ni t ial t i ck count
6 . 1 A NOVAR o f t o t al t i ck c o u n t s for days 0 , 7 and 1 3
f o r 3 t re a t me nt group s and a c o n t r o l group
6 . 2 A NOVAR o f t o tal t i ck c o u n t s for days 20 , 2 7 and 34
f o r 3 t r e a t m e n t group s and a c o n t r o l group
7 . 1 Mai n d i p p i ng me t ho d o n farms i n t h e Eas t Coas t and
Nor thern H.B. area
7 . 2 Mon th o f d i p pin g nomi na t e d b y She e p-owner s i n t he
Sas t C�a s t and Nort he r n H.B. are a
1 1 8
1 2 1
1 22
1 2 3
12 4
1 2 5
1 2 9
1 3 1
1 36
1 37
1 4 1
1 42
Tab l e
8 . 1
8 . 2
Nymphal count� o f she e p i n p addo c k s A , B, C and D
Adu l t count s o f sh e e p i n p addo cks A, B, C and D
9 . 1 Me an we i ght c hange s of u nfed larvae, nymphs and
adu l t s of H . longi corni s de s i c c a t ed for var yi ng
p e r i ods
1 0 . 1
10 . 2
3 3.1
33-2
Effe c t o f i mme r s i o n i n wa t e r on e ngorged s t a ge s of
H . l o ngi corni s
Effe c t o f i mme r si o n i n wa t e r on u nfed st age s o f
H . longi c ornis
H ae mato logi c a l exam i na t i o n of 4 fawns
Normal value s for c e l l u lar cons i tue n t s of Red De er
xiii
Page
144
144
1 50
1 66
208
209
xiv
L I S T 0 F F I GURES
F i gure
1 . 1 Wor l d d i s t r i b u t i on of H . l ongi c or n i s and H . b i sp i nosa 7
1 . 2 H . l ongi c or n i s from c a t t le - i nfe r t i le ma l e 1 3
1 . 3
1 . 4
1 . 5
1 . 6
1 . 7
11
11
11
Di s t ri b ut i on
L i f e c y c l e o f
11 " - s l i gh t ly engorge d female
11 " - nymph
" " - larva
of H . l on �i c orni s w i t hi n Ne w Ze aland
i x od i d t i ck s
1 . 8 Di agramma t i c a l re pr e se n t a t i on of t he seas ona l i t y of
H . l ongi c orni s
1 . 9 S e a s onal di s t r i but i on of p re c ip i t a t i on ex c e e d i ng 50 mm
1 . 10
1 . 1 1
1 . 1 2
pe r mon t h
The range o f t empe r a t u r e s a n d s a t ur a t i on de f i c i t s
f a vourab le f or survi va l and de ve l opme nt of n on
paras i t i c s t a ge s of H. l ongi c orn i s
Cumula t i ve we i ght l oss of e ggs and e ngorge d s t age s
of H . l ongi c orni s e x p os e d t o d r y a i r at 2 5°C
Range of t e mperature a n d re la t i ve humi d i t y f ou n d t o
b e favourab l e f or t he e ggs , engor ge d lar vae and
nymphs of H . l ongi c or ni s
1 . 1 3a Pe r c e n tage of i mpr ove d land c on t a i n i ng paspalum i n
t h e pas t ure
1 3
1 4
1 4
2 4
38
44
4 6
5 2
6 5
6 6
72
1 . 1 3b Pr op or t i onat e change i n p aspalum c on t e n t 72
2 .1 Approx i ma t e are a of d is tr ib ut i on of q ue s tionnaire 8 5
2 . 2 Op i ni on s of farme r s i n t h e Eas t C oa s t and N or t he r n
H . B . as t o t he si gn i f i c a n ce o f H. l ongi c or n i s 8 7
Figur e Page
2 . 3 Di s tribut io n o f farms in Ce n tral H . B . on which
t i c k s were r e p o r t e d t o be pre se n t
2 . 4 A r e a from whi c h re p l i e s t o the que s t i o nnai re were
r e c e ive d by t he Gi sborne o f f i ce of t he M . A . F .
2 . 5 Distr i b u t i o n o f prope r t i e s on whi c h no t i ck s we re
r e p o r t e d to be pre sent
2 . 6 Di s t r i b u t i o n o f prope r t i e s on t i ck s we re pre s e n t
b u t n o t c o n s i de re d a p r o b l e m
2 . 7 Di s trib u t i on o f proper t i e s where t i cks wer e pr e se n t
a n d c ons i d e r e d a prob l e m
2 . 8 M e a n rai nfa l l and rai n f a l l for Nove mber, De c e mb e r
January and Fe bruary ( Manu tuke Cl imat ologi c a l
S t a t i o n )
2 . 9 M e a n tempe rature and t e m p e ra t ure f or June, Ju l y,
A ugu s t and S e p tember ( Manu tuke C l i ma t ol ogi c a l
S t a tion)
2 . 10
2 . 1 1
2 . 1 2
2 . 1 3
3. 1
3. 2
3-3
3. 4
3-5
3. 6
Clima tologi c a l S t a t i o n s i n .the are a in whi ch t i ck
dis t r i b u t i o n was map p e d
M e a n annual rainfall i n C e n tral and Sou the r n H.B.
Soil t ype s o f Cook, Wai k o hu , Wair o a and Wai apu
Cou n t i e s
Me a n annual rai nfall i n t he Ea s t Coast and
N o r thern H . B . are a
Fre que nc y d i s t r i bu tio n o f t i c k c o u n t s - d a y 0
" " " " " " 7
" " " " " " 1 3 � " " ,, " " " 20
" " " " " " 2 7
" " ,, " " " 34
8 8
90
9 1
92
9 3
9 8
9 9
102
1 0 5
10 6
1 1 1
1 1 2
1 1 3
1 1 4
1 1 5
1 1 6
XV
Figure
9. 1 a M e a n we i ght c hange s o f une ngorge d l arvae o f
H . l ongi corn i s d e s i c c a t e d f o r 4 hou r s the n
xvi
t rans f e r r e d t o 6 d i f f e r e n t R .H . 's 1 5 1
9 . 2a & 9 . 2 b Me an we i ght change s o f unengorged nymphs of
9.3a
9 . 3 b
9-5
9 . 6
H . longi corni s d e s i c c a t e d for 28 hours t he n
trans f e rre d t o 6 d i f f e r e n t R .H .'s
Me an we i ght change s o f unengorged ffema l e s
o f H . l o ngi c orni s d e s i c c a t e d f o r 24 ho ur s the n
tran s f e r r e d t o 6 d i f f e r e n t R .H . 's
Me an we i ght change s o f une ngorged f e m al e s of
H. lo ngi corni s d e s i c ca t e d f o r 48 ho u r s the n
tran s f e rre d t o 6 d i f f e r e n t R .H . 's
Regr e s s i o n of % c hange i n p o s t-de s i c c a t e d
b o d y we i gh t o f u n f e d H . l o ngi corni s larvae
on R .H . %
Re gr e s s i on o f % change i n p o s t-de s i c c a t e d
b o d y we i ght o f u n f e d H . longi corni s nymphs
on R .H . %
Regr e s s i o n o f % c ha nge i n p o s t -de s i c c a t e d b o d y
we i gh t of u nf e d H . l o ngi c orni s female s o n
R .H . %
,.
152
1 5 3
1 5 3
1 56
1 5 7