164
Observations on the Biology of Ornithodorus papillipes Birula
larvae which emerged on each day were noted.
The data from five such history cards showed
that the minimum duration of the egg stage is 15
days and the maximum 31 days (average 19 days).
The largest numbers of larvae emerged on the
18th, 19th and 20th days.
Observations on the larval stage
The duration of the larval as well as of the
nymphal stage is calculated from the date of their
first feed, for changes for the next stage start only
after this feed. Unfed larvae or nymphs have
never been observed to moult or reach the next
stage.
Mortality among larvae
The percentage of mortality among larvae of
O. papillipes ranged between 36 and 47. The
majority of the larvae were observed to hatch out
in a moribund condition, while some, though
apparently in good condition immediately after
emergence, remained active only for a few days
and died before they were a week old. It has
been observed that such larvae refuse to feed
when put on a host. A larva that has fed usually
attains the adult stage. Actually, the mortality
in the nymphal and adult stages is almost
negligible.
Number and duration of nymphal stage
Some of the progeny of one of the females were
reared individually up to the adult stage in order
to determine the number and duration of the
nymphal stages and the observations are sum-
marized in Table IV.
TABLE IV
Duration of nymphal stages (at 25°C.)
Stage
Egg to larva . . .
Larva to No. Inymphal stage
No. I to No. II nymphal stage
No. II to No. III nymphal
stage.
No. III to No. IV . .
to Male
.
.
.
.
to Female . . .
No. IV to No. V . . . .
to Male
.
.
.
.
to Female . .
No. V to No. VI . . .
to Male
.
.
.
.
to Female . . .
No. VI to No. VII . .
to Male . . . .
to Female . . .
Duration in days
Maxi-
mum.
31
19
27
35
36
43
31
42
54
49
Mini¬
mum.
15
12
15
17
18
18
18
22
21
21
Average
19.6
14.7
18.2
21.7
22.5
24.7
23.7
28.6
30.1
26.5
Number
or
indivi-
duals
observed
787
360
170
167
78
45
23
5 24
45
Observed only in one case and the
duration was 40 days.
... 60
...
...
... 28
...
...
... 37.5
... ...
Nil
4
Nil
Nil
Observed only in one case and the
duration was 71 days.
As already shown earlier in this article, some of
the eggs remained unhatched and a large propor¬
tion of the larvae died without reaching the adult
stage, so that the total number of adults raised
amounted, roughly speaking, to 50 per cent of the
eggs deposited. As an example of the ratio of
sexes, there were 69 males and 73 females in a
batch of 142 adults reared from eggs.
The number of ecdyses undergone by nymphs
before reaching maturity varied as shown in
Table V.
TABLE V
Ecdyses in O. papillipes
Number of cedyses
4 . . .
5 . . .
6 . . .
7
.
.
.
Percentage
of males
65.21
34.78
Nil
Nil
Percentage
of females
31.5
61.64
5.48
1.38
As will be seen, males appeared after the fourth
and fifth ecdyses, while females appeared after
the fourth, fifth, sixth and seventh. The majority
of males appeared after the fourth ecdysis and
the majority of females after the fifth. The
number of moults varied from four to seven, the
minimum period for metamorphosis being 77 days.
The mean minimum periods required for meta-
morphosis from egg to adult stage are 96 and 124
days in males and 95, 120 and 160 days in females,
according to whether the male undergoes four
or five and the female four, five or six moults.
Preparatory to the emergence of the next stage,
the nymphal skin usually splits laterally as far
as the anterior edge of the spiracle.
The periods mentioned above are longer by an
average of 28 days than in the case of O. moubala
reared at 22°C.
It is of interest to observe that, unlike those of
O. coriceus, O. moubata and O. savignyi, the larva
of O. papillipes is active and takes a feed before
it moults into a first stage nymph. Sexually
mature specimens of O. papillipes were kept alive
for long periods but no individual was observed
to undergo ecdysis once it had reached the adult
stage.
SUMMARY
The average period taken by a female O. papil-
lipes for a complete feed on its host is one hour.
The larvae feed for 10-20 minutes at each meal,
whilst the duration of feed in the first, second and
third nymphal stages is 15-25, 35-45 minutes
respectively and that in the fourth and fifth
nymphal stages 45-60 minutes. Copulation