Eurycoma longifolia Jack (Simaroubaceae), commonly known in Malaysia
as tongkat Ali, grows wild in rainforests of South East Asia (Osman
et al., 2003; Hussein et al., 2005;
Musa et al., 2005). Although, E. longifolia
roots have been used in traditional medicine and as a health supplement for
decades, scientific evidence of its potential use as alternative medicine is
fairly recent. E. longifolia has been reported to have a range of medicinal
properties including anti-malarial (Ang et al., 1995;
Chan et al., 2004), anti-ulcer (Tada
et al., 1991) and anti-pyretic (Chan et al.,
1995) properties. It has also been reported to show certain cytotoxic effects
on human cancer cells (Kuo-Ping et al., 2003)
and aphrodisiac properties (Ang and Ngai, 2001; Ang
and Lee, 2002). These fairly recent awareness of the multitude of medicinal
benefits of E. longifolia resulted in extensive extraction of
E. longifolia roots from the natural forest and the species has
been threatened with extinction due to indiscriminate collection and over exploitation
(Hasnida et al., 2001).
Atteva sciodoxa (Lepidoptera: Yponomeutidae) is a common pest of E.
longifolia in Brunei Darussalam, Indonesia, Malaysia and Thailand. In Malaysia,
the pest is found both in lowland and montane areas (Robinson
et al., 1994). The recent onset of tongkat Ali plantations has led
to widespread outbreaks of A. sciodoxa (Musa
et al., 2005). This study reports on the morphology, development times
and ovipositional aspects of different metamorphic stages of A. sciodoxa.
MATERIALS AND METHODS
This study was conducted at University Putra Malaysia, Serdang-Malaysia in 2007-08. Fourth instar larvae of A. sciodoxa were collected from seedlings in the nursery and reared to adult stage in wooden cages (34x34x60 cm) with wire mesh (1.5 mm2). They were fed on E. longifolia leaves and maintained in the laboratory at 27± 2°C, 80± 5% relative humidity with 12 h photoperiod. Pupae were collected and transferred to cylindrical containers (40x30 mm diameter) until adult emergence.
Four pairs of newly emerged adults were released on each seedling in a wooden rearing cage containing 10% honey placed on a cotton swab. The honey was replenished on alternate days. The leaves were checked daily for eggs, which were then transferred in cylindrical plastic containers (40x30 mm diameter) until hatching.
Upon hatching, each first instar larva was carefully transferred onto tender leaves of E. longifolia placed upright in cylindrical plastic containers (40x30 mm diameter) containing 10 mm of moistened sterilized sand which was then covered with Whatman® filter paper and capped with a lid. This set up maintained a relative humidity of 80± 5% besides keeping the leaflets fresh for 24 h. The first and second instars were fed on young leaves, while the 3rd to 5th instars on semi-mature leaves. The containers were cleaned and leaves replaced daily. For the 3rd instar larvae onwards, medium sized cylindrical containers (66x40 mm diameter) were used. Pupae were separated according to sex using a stereomicroscope and kept singly in plastic containers (40x30 mm diameter).
For adult rearing and recording of oviposition parameters, cages were set up for single pairs. Sterilized moistened sand was levelled to a depth of 10 mm in a 10 cm petri dish and covered with Whatman® filter paper. Fresh E. longifolia shoot with 4-5 leaflets was inserted upright through the centre of each set up. These leaflets were then placed in cylindrical containers (8x12 cm diameter). Three drops of 10% honey were placed on the inside base of the container and then inverted. Single pairs of virgin adults were introduced in each container and two drops of honey were added on alternate days. The adult moths were transferred to different containers whilst cleaning the experimental containers and adding drops of honey. Observations were made on the time as well as duration of copulation, number of eggs laid per day and also longevity of the adult moths. Leaves bearing eggs were transferred to new containers (66x40 mm diameter) to record hatchability.
The morphological measurements of the egg, larval stages, pupa and adult moth
were recorded using a stereomicroscope equipped with an image analyzer. Larval
head capsules were collected following every moult to determine the head capsule
width. To measure the larval body length, larvae were immobilized by subjecting
to low temperature of 10°C for10 min. Calculated head capsule width and
ratio of increment was calculated as described by Dyar (1890).
The difference between observed and calculated head capsule width, development
periods and morphological measurements between males and females were compared
using the unpaired two tailed t-test.
RESULTS AND DISCUSSION
Adult morphology: Atleve sciodoxa adults are small golden brown
moths bearing white spots of variable size on the tergum and fore-wings (Fig. 1a). The white spots are bigger towards the anal margin and the vertex region
is white. The fore-wings are elongate and slightly triangular at the apex. The
antennae are long and filiform. The hind-wings are broad, dark grey with short,
light brown fringe. The dorsal part of the abdomen is orange, while the ventral
light yellow with white transverse bands. Adults are feeble fliers. The sexes
can be differentiated based on the abdominal tip and genital orifice. The male
abdomen is long and pointed distally with a narrow slit while, the female abdomen
is blunt with a prominent genital orifice bordered by white scales (Fig. 1b,
The mean wing span of the adult is 22.97± 0.2 mm, where that of the
female is 24.28± 0.2 mm and the male 21.63± 0.2 mm. The results
indicate a significant difference (p<0.01) between the wing span of the two
sexes (Table 1).
||Adult moths of A. sciodoxa, (a) dorsal view of female
moth (0.65x), (b) ventral view with male genital orifice (20x) and (c) ventral
view with female genital orifice (20x)
|| Wing span of adult A. sciodoxa under laboratory conditions
||Survivorship curves of adult A. sciodoxa at 27±
2°C and 80± 5% relative humidity with 12 h photoperiod
||Reproductive parameters of A. sciodoxa at 27±
2°C and 80± 5% relative humidity with 12 h photoperiod
|n = 30 females
Adult lifespan: The female lifespan ranged between 6-19 days with a
mean of 14.8± 0.6 days while that of the adult male ranged between 7-16
days with a mean of 11.6± 0.6 days. In terms of longevity, the female
adult lived significantly longer than the male (p<0.01). The survivorship
curve for the male, female and combined population is shown in Fig.
2. The difference in mortality rate between male and female populations
was more pronounced after day 7 of emergence. The cumulative mortality over
time for A. sciodoxa depicts a type II survivorship curve as described
by Southwood (1978).
Ovipositional aspects: Mating activity usually commenced at dawn and may occur more than once. Initial copulation took place after 3-4 days of adult emergence and lasted for 2-3 h, while the second copulation, generally lasted for 10-12 h. Mating time varied with age. There was a 1:1 sex ratio of male to female. Pre-oviposition period varied between 4 to 9 days with a mean of 6.20± 0.2 days.
On average, a single female laid 106.1± 4.9 eggs during its lifespan.
The minimum number of eggs laid per female was 50, while the maximum was 171.
The maximum number of eggs laid per female per day was 20.1± 0.5 (Table
2) and the mean number of eggs per female per day during the oviposition
span was 12.6± 0.5. The fecundity curve showed that the most productive
period was from day 8-15 of post emergence with a peak on day 12 (Fig.
||Mean number of female offsprings per female (± SE)
of A. sciodoxa at 27± 2°C and 80± 5% relative humidity
with 12 h photoperiod
||Eggs of A. sciodoxa, (a) typical distribution of freshly
laid eggs, (b) chorion and (c) mature egg, 24 h prior to hatching
||Egg and pupal dimensions of A. sciodoxa under laboratory
Egg: Atteva sciodoxa egg is ovoid and yellow in colour when freshly laid. The mean length and width of the egg was found to be 1.19± 0.02 and 0.86± 0.02 mm, respectively (Table 3). Eggs were laid singly and preferentially on young leaves, along the mid rib and also towards the tip of leaflets (Fig. 4). Fertile eggs were also observed on the surface of rearing containers. The eggs turned grey and eventually darkened near hatching time. The incubation period was 5.70± 0.1 days with a hatchability of 81.1± 0.6% (Table 2).
Larva: Newly hatched larvae were dark grey in colour with black hairs
on the dorso-lateral positions of the thorax and abdomen.
||Dimensions of larval instars of A. sciodoxa and application
of Dyars Rule on head capsule
|*Observed mean head capsule and **Calculated head capsule
||Development periods of different metamorphic stages of A.
sciodoxa at 27± 2°C and 80± 5% relative humidity with
12 h photoperiod
The head was reddish-brown in colour. The body colour turned yellowish-green
in 2-3 days. Prior to the first moult, the thoracic and last three abdominal
segments turned to a creamy colour. The mean head capsule width and body length
were 0.55± 0.1 and 4.71± 0.7 mm, respectively (Table 4). The calculated
head capsule width was 0.54 mm. There was a 1.8% difference between observed
and calculated head capsule widths. The ratio of increment of head capsule was
0.62. The lifespan of the 1st instar ranged between 3-5 days with a mean of
4.00± 0.1 days (Table 5). The first moult took place between 24-36 h.
For the second instar, the mean head capsule width and body length was 0.89±
0.01 and 8.64± 0.12 mm, respectively, while the calculated head capsule
width was 0.87 mm (Table 4). The difference between observed
and calculated head capsule width was 2.2% and the ratio of increment of head
capsule was 0.73. The head of the second instar was also brown in colour. The
body turned greenish-yellow, particularly at the terminal segments of the abdomen
whilst the dorsal region of the abdomen was dark green. One pair of small black
dots appeared on the dorso-lateral position of each thoracic and abdominal segment.
|| Full grown 5th instar larva of A. sciodoxa (0.65x)
The mean duration of the 2nd instar was 3.10± 0.1 days. Prior to moulting,
the entire body turned yellowish-orange in colour. The second moult took place
between 24-30 h.
The mean head capsule width and body length of the third instar was 1.23± 0.02 and 12.87± 0.1 mm, respectively, while the calculated head capsule was 1.2 mm. There was a 2.4% difference between observed and calculated head capsule width. The ratio of increment of head capsule was 0.77. The head was reddish brown. The dorso-lateral black dots increased in size and the body turned green. The mean duration of the 3rd instar was 3.80± 0.1 days. Prior to moulting, the body turned orange in colour. The 3rd moult took place between 20-24 h.
The mean head capsule width and body length of the 4th instar was1.53± 0.02 and 16.29± 0.1 mm, respectively. The 4th instar was similar to the 3rd instar in appearance except increased body size and the black spots on the dorso-lateral margin of the tergites increased in size. The difference between observed and calculated head capsule width was 2.0% and the ratio of increment of head capsule was 0.74. The 4th instar period lasted between 4-5 days (mean 4.1± 0.1 days).
The mean head capsule width of the 5th instar was 1.9-2.3 mm while the body length of the full grown 5th instar was 20.1-24.2 mm. There was a 0.5% difference between observed and calculated head capsule widths. The 5th instar larvae were dark yellowish-green. The black spots coalesced on the tergites to form conspicuous black bands (Fig. 5).
The mean 5th instar duration was 5.7± 0.1 days. Prior to pre-pupation,
the larvae turned bright orange in colour. The larvae ceased feeding and attach
themselves to silken webs spun around leaves or other objects in the vicinity.
There was a distinct quiescent pre-pupation stage which lasted for 24-36 h.
||Pupa of A. sciodoxa (a) dorsal view of pupa; (b) male
g enital orifice and (c) female genital orifice
The overall mean ratio of increment of head capsule for the five larval stages was 0.72. The mean overall larval period of A. sciodoxa was 20.7± 0.2 days, ranging between 19-22 days. The shortest larval period was of the 2nd instar (3.1 days), while the longest was of the 5th instar (5.7 days). The difference in developmental periods between the 1st and 4th instar as well as between the 2nd and 3rd instars were marginal (0.1 and 0.7 days, respectively).
Pupa: Upon pupation, A. sciodoxa appeared orange in colour and
turned reddish brown prior to adult emergence. Paired black dots were present
dorsally on each thoracic and abdominal segment. There were paired black dots
aligning both sides of the ventro-lateral margins of the 5th, 6th and 7th sternites.
The male genital orifice was apparent on the middle of the ninth abdominal sternite,
bordered by elevations. In the female pupae, the genital orifice was located
ventro-anteriorly of the eighth abdominal sternite (Fig. 6a, b).
Similar external differences in the location of the genital orifice have been
documented in other lepidopterous pests such as Paliga (syn Pyrausta/Eutectona)
machaeralis (Misra, 1975) and P. damastesalis
(Intachat, 1999). The mean pupal body length and width
was 10.80± 0.1 and 2.42± 0.1 mm, respectively. The female pupal
body was 11.26± 0.2 mm long and 2.72± 0.1 mm broad while that
of the male was 10.36± 0.1 and 2.17± 0.1 mm, respectively. There
was a significant difference between the female and male body length and width
(p<0.01). The duration of the pupal stage ranged between 5-7 days with a
mean of 6.2± 0.1 days. The female pupa survived significantly longer
(p<0.01). than the male (6.5± 0.1 and 5.5± 0.1 days, respectively.)
Atteva sciodoxa completed its life cycle between 34-52 days with a mean of 45.68± 0.6 days. There was a significant difference (p<0.01) in the developmental period and life cycle between males and females. The mean male life cycle was 43.6± 0.7 days ranging between 34-50 days while that of the female was 47.8± 0.7 days, with a range between 38 to 52 days.
Atteva sciodoxa are small golden brown moths with a mean wing span of 22.97 mm. The fore-wings and tergum has white spots. The adult lifespan ranged between 5-19 days. The eggs are ovoid, yellow and laid singly. The larval period ranges between 19-22 days with five instar stages. A pair of black dots aligns each dorsal thoracic and abdominal segments of the 2nd to 4th instar larvae. The 5th instar larvae are yellowish-green with black spots on tergites coalesced to form conspicuous black bands. The larval period ranges between 19-22 days. The pupa is orange with black dots and turns reddish-brown prior to adult emergence. The mean body length is 10.80 mm. The pupal stage ranged between 5 to 7 days. The oviposition period is 8.5 days, during which a female lays on average 106 eggs. Atteva sciodoxa completes its life cycle between 34 to 52 days.
The authors wish to acknowledge the Pakistan Forest Institute, Peshawar and also University Putra Malaysia, for their support for Mr. Ghulam Ali Bajwa to undertake this research as part of his PhD. study.