studies on the biology of sugarcane early ... preliminary attempt to develop the bean based...

International Journal of Social Science & Interdisciplinary Research__________________________________ ISSN 2277 3630 IJSSIR, Vol. 2 (9), SEPTEMBER (2013) Online available at indianresearchjournals.com

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STUDIES ON THE BIOLOGY OF SUGARCANE EARLY SHOOT BORER,

CHILO INFUSCATELLUS SNELLEN ON ARTIFICIAL DIET IN NORTH

COASTAL REGION OF ANDHRA PRADESH, INDIA

BHAVANI B

SENIOR SCIENTIST (ENTOMOLOGY)

REGIONAL AGRICULTURAL RESEARCH STATION,

ANAKAPALLE, ANGRAU, ANDHRA PRADESH, INDIA

ABSTRACT:

Studies on the biology of sugarcane early shoot borer, Chilo infuscatellus Snellen on bean based

artificial diet (in vitro) under laboratory conditions at R.A.R.S., Anakapalle, Andhra Pradesh,

India revealed that the ESB moth laid eggs on the ventral surface of the leaf, close to the midrib.

The fecundity of female ranged from 368 to 384 and the incubation period ranged from 4.0 to 4.1

days. The larva passed through four moults with five instars and the total larval period ranged

from 16.0 to 16.3 days. Pupation occurred in the outermost leaf sheath in a silken cocoon and the

pupal period varied from 6.3 to 6.6 days. Longevity of male and female moths varied from 3.5 to

3.6 and 4.0 to 4.2 days, respectively. The sex ratio of male: female was 1:2.28. The total life

cycle was completed in 30.2 to 30.7 days. The peak period of activity of the pest was observed

from March to May. The present studies clearly indicated that the biology of ESB when reared

on bean based artificial diet (in vitro) was not significantly different from the biology on the

plant (in vivo) and the artificial diet can be used for rearing ESB under in vitro conditions.

KEY-WORDS: Sugarcane, early shoot borer, Chilo infuscatellus Snellen, biology and artificial

diet.

It is a part of Ph.D thesis submitted to the Acharya N.G.Ranga Agricultural University

(ANGRAU), Hyderabad, Andhra Pradesh

Sugarcane is a long duration crop with luxuriant vegetative growth and is damaged by a number

of insects during its crop growth. Among the insect pests, shoot borer (ESB), Chilo infuscatellus

Snellen (Crambidae; Lepidoptera) is a serious pest in peninsular regions of India and more vital

in early stages of crop growth causing economic loss (Avasthy and Tiwari,1986). In Andhra

Pradesh, ESB starts infestation from germination as shoot borer and continues as internode borer

after stalk formation, if not controlled in the early stages of the crop growth under rainfed

conditions. It destroys 26 to 65 per cent of mother shoots (Khan and Krishnamurthy Rao 1956)

and causes losses from 22 to 33 per cent in cane yield, 12 per cent in sugar recovery and 27 per

cent in jaggery (Patil and Hapse,1981). In Andhra Pradesh, due to borer incidence maximum

yield loss could go even up to 42% when the incidence was at 60 days age of the crop

(Lakshminarayana, 1983). It destroys 58% of shoots in different states, causing reduction of 10.1

to 34.4 tonnes / ha in cane yield and 0.25 to 3.0 units in sugar recovery (Chaudhary, 1973).


71

To evaluate sugarcane germplasm against ESB, C. infuscatellus under optimum insect pest

populations in field conditions and to study the resistance mechanisms involved under in vitro

and in vivo conditions, artificial infestation of ESB larvae is needed to ensure uniform and

sufficient level of pest infestation at desired stage of crop growth. Mass rearing of ESB larvae on

the natural host (sugarcane shoot) is time consuming due to regular change of plant material and

also involves more man power. Not only a lot of plant material is wasted but also frequent

handling of the culture results in high mortality of the insects. These drawbacks have led to

evolve artificial diet for ESB, C. infuscatellus. Mukunthan and Jayanthi (2001) has

made preliminary attempt to develop the bean based artificial diet for the rearing of sugarcane

early shoot borer larvae round the year under laboratory conditions at Sugarcane Breeding

Institute (SBI), Coimbatore. A preliminary study on the biology of the ESB, C. infuscatellus was

made on bean based artificial diet (in vitro) under laboratory conditions at R.A.R.S., Anakapalle,

Andhra Pradesh, India and compared with the biology of ESB on plant (in vivo) under net house

conditions using the sugarcane variety, 93 A145 to find out the variation in the biology of C.

infuscatellus reared under in vitro (artificial diet) and in vivo (on plant) conditions, if any.

Materials and methods

ESB, C. infuscatellus rearing on artificial diet

The ESB, C. infuscatellus larvae obtained from field were reared on bean based artificial diet

under laboratory conditions (Mukunthan and Jaynathi, 2001) at the Integrated Pest Management

(IPM) laboratory, Regional Agricultural Research station (R.A.R.S), Anakapalle. The newly

hatched larvae were released on to the bean based artificial diet impregnated with shoot powder

of the susceptible check, 93 A 145(Plate 1).

For the preparation of shoot powder, shoots of sugarcane ( 93 A 145) were collected from 60

days old plants raised under field conditions and dried in a hot air oven at 800 C for two days

and powdered to <80 mesh size. The different ingredients utilised for preparation of the

artificial diet were listed in Table 1. All the ingredients of fraction A (Table 1) except the

sugarcane shoot powder were blended for 1 minute. Field bean seeds (100 gm) were soaked in

water for 24 hours and extruded manually from the seed coat and cooked before use. It was

mixed with other ingredients of the medium (Fraction-A) except agar-agar, ascorbic acid,

sugarcane shoot powder and ground to a paste. Agar was melted in 80 ml of water (Fraction –B)

and sugarcane shoot powder was added to it and poured into the blender containing Fraction-A.

All the constituents were blended for three minutes and were autoclaved. Ascorbic acid was

dissolved in 30 ml of water and formaldehyde was added to medium just before it began to

solidify and poured into a plastic container of 250 gm capacity. After cooling for 2-3 hours in the

laboratory, neonate larvae were released on to the artificial diet using a fine brush.

The plastic containers were kept in the rearing room in dark for 2 days, as first instar larvae have

a strong photopositive behaviour and settle better on the diet in darkness. In the rearing room,

temperature was maintained at 28 + 10

C, relative humidity at 60 to 70 per cent and light was

provided for 12 hours. The lab culture were supplemented with field collected larvae frequently.

The diet was changed for two times at 15 days interval for completion of the total life cycle of

early shoot borer.

Duration of larval period was recorded in terms of number of days from the release in large cup.

The pupae were sexed on the basis of their relative size and genital openings. Duration of pupal


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period was recorded in terms of number of days from pupation till adult emergence. For this

purpose, each pupa was kept on a moist blotting paper in petriplate for moth emergence. The

males and females were released in net cases in which potted young sugarcane plants were kept.

Observations were recorded on oviposition period, fecundity, incubation period, per cent hatch,

egg measurements, larval duration, larval length, width and capsule width of 1st to 5

th instar

larva; pupal duration, per cent pupation; length, width of male and female pupa; length, wing

span of male and female adults; adult longevity.

Table 1 List of ingredients of artificial diet used for rearing of C. infuscatellus

in the laboratory

S.No. Ingredients Quantity

1 Shoot powder 50.0 g

2 Field bean 100.0 g

Fraction- A Casein 50.0 g

Yeast 16.0 g

Vitamin capsules 8.0 g

Salt mixture 5.0 g

Ascorbic acid 1.0 g

Sorbic acid 0.5 g

MPH 1.0 g

Fraction –B Agar agar 8.0 g

Formalin 1.0 ml

Distilled water 470 ml

Source: (Mukunthan and Jayanthi 2001)

ESB, C. infuscatellus rearing on plant (in vivo) under net house conditions

In order to study the biology of the ESB, C. infuscatellus under in vivo conditions, pot

culture of the sugarcane variety, 93 A 145 was maintained in the net house. Sugarcane plants

(93 A 145) were grown in medium size plastic pots (Plate ). The potting mixture consisted of red

soil and FYM (2:1). Before planting, SSP and MOP were applied @ 100g per pot and one three

budded sett planted in each pot. Urea was applied @ 10g per pot after germination. The plants

were watered daily as per the need. The newly hatched larvae were released on the 21 days old

sugarcane plants using a camel hair brush. After pupation, the pupae were collected and placed

on a moist blotting paper in petri dishes for moth emergence. After moth emergence, the males

and females were released in pairs in net cages in which potted young sugarcane plants were

kept.

Observations were recorded on oviposition period, fecundity, incubation period, per cent

hatch, egg measurements, larval duration, larval length, width and capsule width of 1st to 5

th

instar larva; pupal duration, per cent pupation; length, width of male and female pupa; length,

wing span of male and female; adult longevity.


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Estimation of oviposition

To study the period of maximum egg laying by ESB, C. infuscatellus, egg counts were made

once in three days. All the plants in the net house were carefully examined and the number of

egg masses / 10 plants at fortnightly interval commencing from January to December were

recorded.

Site of oviposition

The numerical position of the leaf with the egg mass in a plant was recorded on 50 randomly

selected plants. The leaves on the plant were numbered from the youngest visible leaf to the

oldest. The number of egg masses found on the leaves was separately recorded with reference to

each leaf. Concurrently with this, the location of each egg mass on every leaf was recorded. This

was done by dividing a leaf into three parts, namely the bottom one third, the middle one third,

and the distal one third.

Number of egg masses laid by adults in captivity

Moths that were emerged from bulk rearing of the ESB in the laboratory were separated into

males and females. One male and one female moth were introduced in net cage in which potted

young sugarcane plants were kept and allowed to mate and lay eggs. The number of egg masses

laid by each female after copulation was recorded with dates.

Number of eggs in an egg mass

The egg masses collected from potted plants in net house were brought to the laboratory and the

number of eggs per single egg mass was counted under a stereoscopic binocular microscope.

Description of different developmental stages

To study and describe different developmental stages ( i.e egg, larva, pupa and adult) change in

their colour pattern and size etc., were observed daily on artificial diet. To get accurate

measurements, various developmental stages were fixed in KAAD (Kerosine oil 1 part, absolute

alcohol 10 parts, glacial acetic acid 2 parts and dioxane 1 part). The eggs and larvae of first two

instars were measured under microscope with the help of ocular and stage micrometer scale.

However, stage of later larval instars, pupae and adults were measured with the help of vernier

calipers and scale having accuracy to measure up to 0.5 mm, in each case 10 specimens were

measured.

Results and discussion

Studies on biology of sugarcane early shoot borer, C. infuscatellus were carried out on bean

based artificial diet impregnated with dry shoot powder of sugarcane variety, 93 A 145

under laboratory conditions (in vitro) and compared with biology of ESB on the sugarcane plant

(in vivo) under net house conditions during March to May, 2008.

Observations were made on oviposition, preferred site for oviposition under field conditions ;

morphological features, duration and morphometrics of different life stages of ESB, C.

infuscatellus viz., egg, larval instars, pupa, adult, fecundity, sex ratio and fecundity of the pest

under in vitro and in vivo conditions and the data were presented in tables from .


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Oviposition/ Fecundity

Under field conditions, the oviposition commenced from the middle of January and continued up

to the end of August (Table 2). Highest numbers of egg masses were laid during the second

fortnight of April (21 egg masses) and the oviposition was reduced after first fortnight of August,

thereafter, no oviposition was found except for stray incidence in September and November.

Table 2 Number of egg masses laid by C.infuscatellus in each fortnight

under net house conditions

However, early shoot borer, C. infuscatellus could be reared in the laboratory throughout the

year and oviposition occurred throughout the year and the average number of egg masses laid by

a moth was found to be 4.64 under in vivo conditions (Table 3). Under in vitro conditions (on

artificial diet), the number of eggs laid per female ranged from 368 to 384, with an average of

376.67 ± 5.85 eggs whereas, under in vivo conditions (plant), the fecundity of female ranged

from 328 to 380, with an average of 347.22 ± 14.14 eggs (Table ). The fecundity of the ESB was

reported as 429 eggs by Khan and Singh (1942a), 179 eggs by Agarwal and Haque (1955), 400

eggs by Garg and Chaudhary (1979), 338 eggs by Hasabe and Khaire (1994), 262.5 eggs by

Venugopal Rao (1998) and 337 eggs per female by Sunil kumar (2003). The variations in

fecundity may be ascribed to the fluctuations in the ambient temperature and availability of food.

Heavy egg deposition by the ESB moth has observed during April and May, when the average

maximum and minimum temperatures ranged from 34.5 0

C to 35.8 0

C and 24.2 0

C to 25.80

C,

respectively. The mean relative humidity in the morning during the period varied between 78.5

per cent and 82.87 per cent. The maximum per cent hatching and larval pupation was observed in

April followed by May and June as reported by the earlier workers at Anakapalle (Platinum

Jubilee Souvenir, 1988).

Month/Year No. of egg masses

1st fortnight 2nd fortnight

Jan, 08 Nil 1

Feb, 08 4 6

Mar, 08 9 19

Apr, 08 18 21

May,08 18 16

Jun, 08 13 11

Jul, 08 9 13

Aug, 08 11 5

Sep, 08 1 Nil

Oct, 08 Nil Nil

Nov, 08 1 Nil

Dec, 08 Nil Nil


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Table 3 Number of egg masses laid by C. infuscatellus adults in captivity under net house

conditions

Date/Year

Total No. of

female moths

under

observation

Number of adults laying

One mass Two

masses

Three

masses

Four

masses

Five

masses

Six masses

& above

17th

Mar, 2008 5 - - - - 3

2

4th

Apr, 2008 5 - 3 2

21th

Apr, 2008 6 - - - 2 2 2

5th

May, 2008 5 - - 2 3

24th

May, 2008 6 - - - 1 3 2

4th

Jun, 2008 6 - - - 1 3 2

15th

Jun, 2008 3 - - - - 2 1

30th

Jun, 2008 4 - - - - 2 2

4th

Jul, 2008 5 - - 1 2 1 1

23th

Jul, 2008 4 - - - 1 2 1

4th

Augt, 2008 3 - - - - 2 1

21st Aug, 2008 2 - - 1 1 -

4th

Sep, 2008 3 - - - 1 1 1

19th

Sep, 2008 2 - - - 1 1 -

3rd

Oct, 2008 1 1 - - - - -

20th

Oct, 2008 1 1 - - - - -

3rd

Nov, 2008 1 1 - - - - -

20th

Nov, 2008 2 1 1 - - - -

6th

Dec, 2008 2 2 - - - - -

23rd

Dec, 2008 1 2 - - - -

20th

Jan, 2009 2 1 - - 1 - -

Total 69 7 3 1 11 28 20

Average number of egg masses per adult : 4.64


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Site of preference for oviposition on leaf

Under field conditions, adult female laid eggs in masses, generally on the first three lower

green leaves of the plant. Within the leaf, middle portion was more preferred for laying of eggs

as evidenced by the data (Table 4). It was very clear that, out of the total 74 egg masses laid by

the female moth, 50 egg masses were laid on the middle part of the leaf, 14 egg masses on the

lower part of leaf and 10 egg masses on the upper part of the leaf. Maximum percentage of egg

laying (67.57%) was recorded on the middle part of the leaf, whereas lowest percentage of egg

laying (13. 51%) was observed on the upper part of the leaf. In the middle part of the leaf, it was

clear that eggs were always located on ventral surface near the midrib. The preference nearer to

the midrib may be attributed to the protection of eggs against mechanical injuries. Generally, the

oviposition choice by the ESB female might be for egg survival rather than for a suitable host for

the larvae, to enable the dispersal. Choosing smooth, low sites with a crease for oviposition may

help protect eggs from desiccation and dislodgement. These findings are in conformity with the

findings of Gupta (1940), Usman et al. (1957), Siva Rao and Kamalakar Rao (1963) and Roome

et al. (1977 who reported that the eggs were laid nearer to the midrib. Venugopala Rao (1998)

reported that the females preferred to lay eggs to an extent of 60.94 per cent in the middle one

third portion of the leaf.

Number of eggs in the egg mass

Under field conditions, the number of eggs in an egg mass ranged from 29 to 102, the

average being 60.28. Highest number of eggs were observed in an egg mass during the second

week (102) and fourth week (100.40) of May whereas lowest number of eggs per mass (29) were

observed during the last week of December (Table 5).


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Table 4 Site of ovipositional preference by ESB, C. infuscatellus under

net house conditions

Sl. no.

of the

Plant

Number of egg masses on leaf

blade Total number of egg

masses

Lower

1/3rd

Middle

1/3rd

Upper

1/3rd

1 - 1 - 1

2 1 2 1 4

3 2 2 - 4

4 - 2 1 3

5 2 3 - 5

6 1 2 1 4

7 - 2 - 2

8 2 3 1 6

9 1 3 1 5

10 1 2 - 3

11 - 3 - 3

12 - 4 1 5

13 - 3 - 3

14 - 2 1 3

15 - 3 1 4

16 1 2 1 4

17 2 4 - 6

18 1 3 - 4

19 - 3 - 3

20 - 2 1 3

Total 14 50 10 74 (Grand Total)

18.92% 67.57% 13.51%


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Table 5 Average number of eggs in an egg mass laid by ESB,C. infuscatellus females on

93 A 145 under net house conditions

Dates/Year No. of egg masses

collected

Total No. of eggs Average number

of eggs per mass

12th Mar, 08 5 320 64.00

27th Mar, 08 6 412 68.67

12th Apr, 08 6 495 82.50

27th Apr, 08 5 423 84.60

12th May, 08 6 612 102.00

27th May, 08 5 502 100.40

11th Jun, 08 3 268 89.33

26th

Jun, 08 4 169 42.25

11th Jul, 08 4 278 69.50

26th Jul, 08 5 347 69.40

10th Aug, 08 3 173 57.67

25th Aug, 08 4 210 52.50

09th Sep, 08 3 137 45.67

24th Sep, 08 2 91 45.50

09th Oct, 08 2 83 41.50

24th Oct, 08 3 129 43.00

08th Nov, 08 2 87 43.50

23th Nov, 08 3 116 38.67

08th Dec, 08 1 36 36.00

23th Dec, 09 1 29 29.00

TOTAL 73 4917 Mean 60.28


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Egg

The eggs of ESB, C. infuscatellus were oval, dorsoventrally flattened, looked like a scale

of fish. Eggs were laid in masses in a three to four overlapping rows resembling tiles on a roof

and were found to be glued on to the moth during oviposition on the under surface of the leaves.

They were creamy white in colour, when freshly laid and gradually changed to yellowish with

pin head size spot after 24 hours of egg laying. Empty egg shells were white and remained

attached to the leaf. On artificial diet (in vitro), measured on an average 0.89 ± 0.009 mm in

length, 0.63 ± 0.007 mm in width whereas, an individual egg measured on an average 0.90 ±

0.02 mm in length, 0.63 ± 0.02 mm in width under in vivo conditions (Table 7).

Incubation period/ Hatchability

In the present studies, the egg period ranged from 4 to 4.1 days with an average of 4.06 ±

0.05 days on artificial diet ( in vitro) whereas under in vivo (on plant) conditions, it ranged from

4 to 4.3 days with an average of 4.14 ± 0.11 days (Table 6). These are in close proximity with

Karla and Sunil kumar (1966), Habase and Khaire (1994), Venugopala Rao (1998) and Sunil

Kumar (2003) who reported the egg period as 4-7 days, 3-6 days, 3.7 days and 4.39 days,

respectively whereas Chandy et al. (1964) reported 3 -11 days egg period in Tamil Nadu.

Under field conditions, the incubation period was found to be least during the last week

of March to second week of April (60-72 hours). It seemed to increase progressively later on.

The per cent hatch was more from second week of March to last week of May (93.8 to 99.6%).

Incubation period ranged from72.0 to 96.0 hours from May to first week of October whereas, in

the winter months (October to December) it was 96-120 hours (Table 6).

On artificial diet (in vitro), the per cent egg hatching varied from 65.5 per cent to 90 per

cent with an average of 81.83 ± 9.56 per cent while under in vivo ( on plant) conditions it ranged

from 69.5 to 94.5 per cent with an average of 87.33 ± 3.35 per cent (Table 7). These results are

similar to the findings of Agarwal and Haque (1955), Hasabe and Khaire (1994), Venugopala

Rao (1998) and Sunil kumar (2003) who recorded hatching percentage of 88.57 and 83.57, 81.56

and 84.46 ± 3.83, respectively. The variation in egg period and hatchability might be attributed

to variation in the atmospheric temperature and relative humidity in that location.


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Table 6 Per cent hatch and incubation period of eggs of C. infuscatellus on

susceptible check (93 A 145) net house condtions

Egg masses

collected on

No of

eggs/mass

Total No. of eggs hatched per mass Percent

hatch

60-71

hours

72-84

hours 85-96

hours

97-120

hours

12th Mar, 08 64 - 7 53 - 93.8

27th Mar, 08 68.67 - 14 53 - 97.6

12th Apr, 08 82.5 - 17 62 - 95.8

27th Apr, 08 84.6 - 12 69 - 95.7

12th May, 08 102 - 11 89 - 98.0

27th May, 08 100.4 - 12 88 - 99.6

11th Jun, 08 89.33 - 3 69 - 80.6

26th

Jun, 08 71.25 - 21 32 - 74.4

11th Jul, 08 69.5 - 11 41 - 74.8

26th Jul, 08 69.4 - - 47 - 67.7

10th Aug, 08 57.67 - - 39 - 67.6

25th Aug, 08 52.5 - - 35 - 66.7

09th Sep, 08 45.67 - - 28 - 61.3

24th Sep, 08 45.5 - - 23 - 50.5

09th Oct, 08 66.5 - - 24 - 84.2

24th Oct, 08 73 - - - 35 83.6

08th Nov, 08 43.5 - - - 32 66.7

23th Nov, 08 38.67 - - - 23 54.3

08th Dec, 08 36 - - - 25 52.8

23th Dec, 09 29 - - - 18 44.8


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Heavy egg deposition by the ESB moth has observed during April and May, when the

average maximum and minimum temperatures ranged from 34.5 0

C to 35.8 0

C and 24.2 0

C to

25.80

C, respectively. The mean relative humidity in the morning during the period varied

between 78.5 per cent and 82.87 per cent. The maximum per cent hatching and larval pupation

was observed in April followed by May and June as reported by the earlier workers at

Anakapalle (Platinum Jubilee Souvenir, 1988).

Larva

First instar larva was active, grayish white in colour with black head and immediately

after hatching moved fast in search of the food material. Under in vitro (on artificial diet)

conditions, it measured on an average 1.85 ± 0.03 mm in length, 0.2 ± 0.01 mm in width of the

body and the head capsule was 0.23± 0.01 mm in width whereas, the length and width of the

body and width of the head capsules was 1.84 ± 0.03mm, 0.21 ± 0.01mm and 0.24 ± 0.01mm on

an average, respectively under in vivo (on plant) conditions (Table 7).

The second instar larva was dirty white in colour with prominent dark stripe on mid

dorsal portion and impressions of the stripes were found on the body. Under in vitro conditions,

the length of the second instar larva was on an average 5.26 ± 0.052 mm, 0.49 ± 0.008 mm in

width and the head capsule was 0.4 ± 0.004 mm. Under in vivo conditions, it measured on an

average 5.23 ± 0.13 mm in length, 0. 48 ± 0.01 mm in width of the body and the head capsule

was 0.38± 0.02 mm in width (Table 7).

The third instar larva was dirty white in colour with dark black head. Black spots on

tubercles were absent. Under in vitro conditions, the average length, width of the body and width

of the head capsule were 12 ± 0.005 mm, 1.98 ± 0.003 mm and 1.33 ± 0.007 mm whereas

average length, width of the body and width of the head capsule were 11.95 ± 0.09 mm, 1.95 ±

0.02 mm and 1.30 ± 0.02 mm, respectively under in vivo conditions. (Table 7).

The fourth and fifth instar larva was also dirty white in colour with dark brown head. The

body possesses five violet stripes, one on dorsal surface, one pair each on the sub-dorsal and

lateral surfaces of the body (Plate 2). Black spots were observed on the tubercles which were

present on the eight abdominal segments. Under in vitro conditions, it measured on an average

17.1 ± 0.01 mm in length, 2.88 ± 0.009 mm in width of the body and the head capsule was 1.8 ±

0.007 mm in width. Under in vivo conditions, the body measured on an average 17.07 ± 0.03

mm length, 2.83 ± 0.07 mm width, whereas the width of head capsule was 1.8 ± 0.02 mm

(Table 7 ).


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Table 7 Morphometrics of the life stages of the ESB, C. infuscatellus in vivo (plants) and in

vitro (artificial diet) conditions

S.

No. Stage of the insect

in vivo in vitro

Mean(mm)* range (mm) ± SD Mean (mm)

* range (mm) ± SD

1 Egg

a. Length 0.89 0.88-0.9 0.02 0.90 0.87- 0.94 0.02

b. Width 0.63 0.62-0.64 0.02 0.63 0.6 - 0.65 0.02

2 I instar larva

a. Length 1.85 1.84- 1.86 0.03 1.84 1.8 - 1.88 0.03

b. Width 0.20 0.2-0.22 0.01 0.21 0.19 - 0.24 0.01

c. Width of the Head capsule 0.23 0.23-0.24 0.01 0.24 0.23 - 0.26 0.01

3 II instar larva

a. Length 5.26 5.2- 5.3 0.05 5.23 5 - 5.4 0.13

b. Width 0.49 0.48-0.5 0.01 0.48 0.46 - 0.5 0.01


4 III instar larva

a. Length 12 11.99-12 0.01 11.95 11.96 – 12 0.09

b. Width 1.98 1.97-1.98 0.01 1.95 1.92 - 1.98 0.02


5 IV instar larva

a. Length 17.1 17.08-17.11 0.01 17.07 17.04- 17.11 0.03

b. Width 2.88 2.86-2.89 0.01 2.83 2.8 - 2.9 0.07


6 V instar larva

a. Length 23.88 23.8-23.9 0.04 23.92 23.85 – 24 0.07

b. Width 3.49 3.48-3.5 0.01 3.49 3.47 - 3.5 0.01


7 Pupa(Male)

a. Length 12.49 12.48-12.5 0.01 12.49 12.47 - 12.5 0.01

b. Width 2.22 2.2-2.23 0.01 2.23 2.21 - 2.23 0.01

Pupa(female)

a. Length 17.2 17.19-17.2 0.01 17.19 17.18 -17.21 0.01

b. Width 3.26 3.24-3.26 0.01 3.26 3.2 - 3.29 0.03

8 Adult(Male)

a. Body length 9.92 9.9-9.92 0.01 9.92 9.9 - 9.95 0.02

b. Wing span 22.05 21.99-22.1 0.05 22.01 21.96 - 22.1 0.05

Adult(Female)

a. Body length 13.46 13.4-13.5 0.05 13.46 13.4 - 13.5 0.05

b. wing span 25.42 25.4-25.43 0.01 25.41 25.36 - 25.43 0.02

*Mean of 10 individuals SD: Standard Deviation


83

Under in vitro conditions, the average length of the fifth instar larva was 23.88 ± 0.04

mm, 3.49 ± 0.008 mm in width of the body and the head capsule was 1.92 ± 0.02 mm in width

whereas under in vivo conditions, the average measurement of fifth instar larva was 23.92 ± 0.07

mm length, 3.49 ± 0.01 mm width and 1.89 ± 0.03 mm width of head capsule (Table 7).

The earlier biology studies on ESB indicated that the full grown larvae measured about

20-25 mm in length (Ramakrishna Ayyar and Margbandlu, 1935, Gupta, 1940), whereas in the

present study it was 23.88 to 23.91 mm in length and 3.49 to3.54 mm in width. These findings

are in agreement with the earlier findings in respect to the size of mature larvae (Gupta, 1940,

Venugopal Rao, 1998 and Sunil Kumar, 2003). The findings on the duration of five larval

instars in the present study are in conformity with reports of Chandy et al.( 1964), Venugopala

Rao (1998) and Sunil Kumar (2003).

The young larvae immediately after hatching crawled to the tip of the leaf and suspended

themselves by a silken thread and has reached the base of the shoot. It has also observed that

the newly hatched larvae were observed first feeding on the leaf sheaths as a miner and only after

attaining second instar stage, started boring into the shoot. The larva has been observed to feed

on the growing point and consequently unopened spindle leaves were found to be damaged at the

base and finally the ‘deadheart’ formation occurred in about 10 days after the entry of borer into

the plant. Similar behaviour of larvae was observed by Khan and Singh (1942b), Gupta (1957),

Usman et al. (1957), Siva Rao (1960), Karla and Sunil Kumar (1966) and Venugopala Rao

(1998)

Larval period

On artificial diet (in vitro), the total larval period ranged from 16 to 16.3 days with an

average of 16.1 ± 0.11 days. The duration of first instar larva ranged from 2.1 to 2.2 days with

an average of 2.14 ± 0.05 days. The duration of second instar larva was 3 to 3.10 days with an

average of 3.04 ± 0.05 days. The duration of third instar larva ranged from 3 to 3.2 days with an

average of 3.16 ± 0.05 days and that of fourth instar larva ranged from 3.2 to 3.3 days with an

average of 3.21 ± 0.03 days. The fifth instar larva took about 4.5 to 4.6 days, with an average of

4.54 ± 0.05 days to enter into pupation (Table 8).

On plant (in vivo), the larval period ranged from 16.4 to 17.2 days with an average of

17.03 ± 0.23 days. The duration of first instar larva was ranging from 2.1 to 2.3 days with an

average of 2.19 ± 0.09 days. The duration of second instar larva was 3.1 to 3.4 days with an

average of 3.21 ± 0.09 days. The duration of third instar larva ranged from 3.2 to 3.5 days with

an average of 3.31 ± 0.11 days and that of fourth instar larva ranged from 3.5 to 3.7 days with an

average of 3.6 ± 0.07 days. The fifth instar larva took about 4.7 to 4.9 days, with an average of

4.72 ± 0.11 days to enter into pupation (Table 8). The response on artificial diet could be

exploited for quicker screening of sugarcane cultivars against the borer pest. These results are in

close conformity with those of Khan and Singh (1942a), Chandy et al. (1964), Venugopala Rao

(1998) and Sunil Kumar (2003).


84

Pupa

Pupa was ‘obtect’ type. The newly formed pupae were grayish in colour. The integument

transparent, turned light brown in colour on the second day and subsequently turned to dark

brown. The female genital aperture is situated on the eighth abdominal segment in the form of a

slit while the male genital aperture was situated on raised oval sclerite with linear depression in

the middle of ninth abdominal segment. Under in vitro conditions, male pupa measured on an

average 17.2 ± 0.005 mm in length and 3.26 ± 0.008 mm in width. Under in vivo conditions, the

average size of the male pupa was 12.49 ± 0.01 mm in length and 2.23 ± 0.01mm in width. The

female pupa was slightly bigger in size and was 17.19 ± 0.01 mm in length and 3.26±0.03 mm in

width (Table 7 and Plate 4). These findings are comparable with the findings of Gupta (1940 and

1959), Venugopala Rao (1998) and Sunil Kumar (2003) who reported the approximate length of

male pupa as 13 mm and that of female as 17 mm.

Pupal period

On artificial diet (in vitro), the pupal period ranged from 6.3 to 6.6 days with an average

of 6.43 ± 0.13 days whereas it ranged from 6.8 to 7 days, with an average of 6.91 ± 0.08 under

in vivo (on plant) conditions (Table 8).

These results are comparable with the observations of earlier workers with reference to

C. infuscatellus in different states of India. The pupal period varied from 7-13 days at Lyallapur

(Khan and Singh,1942), 8-10 days in Uttar Pradesh (Gupta, 1953), 12-24 days in Bihar (Agarwal

and Haque,1955), 7-8 days (Usman et al.,1957), 7-13 days in Tamil Nadu (Chandy et al., 1964),

5-8 days in Rajasthan (Karla and Sunil Kumar, 1966), 8-10 days in Haryana (Garg and

Chaudhary,1979), 7 days (Patil and Hapase,1981) and 5-9 days in Maharastra (Hasabe and

Khaire,1994), 7.7- 19.2 days in Assam (Saikia et al., 1996) and 6 – 10 days with an average of

7.2 days in Andhra Pradesh (Venugopala Rao,1998). The larvae pupate within the shoot itself

generally at its base. Before pupating, a larva cuts a slanting hole leading outside the shoot and

plugs it with its fros to facilitate emergence of the adult moth later.

Adult

The female adult moth was light straw to brownish in colour without any dark markings

on the outer edge of the forewings and the hind wings were grayish white in colour (Plate ). The

male moths were light straw to brownish grey coloured forewings with dark markings on the

outer edge and grayish white hind wings (Plate 4). Female moths were observed to be slightly

bigger in size than male moths. Under in vitro conditions, male adult measured an average body

length of 9.92 ± 0.009 mm with wing expansion of 22.01 ± 0.05 mm whereas female adult

measured 13.46± 0.05 mm body length and 25.41 ± 0.009 mm wing expansion. Under in vivo

conditions, the body length of the male moth was 9.92 ± 0.02 mm, while the female was 13.46 ±

0.05 mm on average. The average wing expanse in males was 22.01 ± 0.05 mm while that of

female was 25.41 ± 0.02 mm (Table 7). These measurements are almost similar to those recorded

by Isaac and Misra (1933), Gupta (1940, 1959), Venugopala Rao (1998) and Sunil Kumar (2003)

who reported that the size of moth after wing expanse varied from 19-26 mm in male and 25-33

mm in female.


85

Adult longevity

The longevity of adult male moths, which were reared on artificial diet (in vitro) ranged

from 3.5 to 3.6 days with an average of 3.57 ± 0.05 days, while that of the females ranged from 4

to 4.2 days with an average of 4.13 ± 0.1 days. Under in vivo conditions, the longevity of male

and female moths ranged from 3.6 to 4 days with an average of 3.73 ± 0.13 days and 4.3 to 5

days with an average of 4.57 ± 0.33 days, respectively (Table 8) which are in close conformity

with the findings of Habase and Khaire (1994), Venugopala Rao (1998) and Sunil kumar

(2003)..

Higher percentage of viable eggs (376.67 ± 5.85) per female were obtained from the moths

reared on artificial diet compared to those obtained from the moths reared on sugarcane plant

(347.22 ± 14.14).

Total life cycle

The data collected on life history indicated that the ESB, C. infuscatellus on artificial diet

(in vitro) completed its life cycle with in a period of 30.2 to 30.7 days with an average of 30.44

± 0.22 days whereas on plant (in vivo) it ranged from 31.15 to 32.55 days with an average of

32.22 ± 0.28 days (Table 8) and the results were more or less in agreement with reports of

Gupta (1940), Khan and Singh (1942a), Siva Rao and Kamalakara Rao (1963), Chandy et

al.(1964), Garg and Chaudhary (1979), Habase and Khaire (1994), Venugopala Rao (1998) and

Sunil kumar (2003).

Sex ratio

From the data in table 9, it was evident that more female moths emerged compared to

male moths and the ratio of males to females was 1:2.28 under in vitro conditions ( on artificial

diet) whereas, it was 1:2.08 under in vivo (on plant) conditions (Table 9 ). This is in agreement

with Usman et al. (1957 ), Venugopal Rao (1998) and Sunil kumar (2003) who reported the male

to female sex ratio as 1:2.0, 1:1.98 and 1:1.92, respectively.

The present studies on biology of ESB have clearly indicated that the biology of ESB

reared on bean based artificial diet (in vitro) was not significantly different from the biology of

the ESB reared on plant (in vivo). Hence, the bean based artificial diet could be used for the mass

rearing of ESB, C. infuscatellus under laboratory conditions.


86

Table 8 Duration of different developmental stages of ESB, C. infuscatellus in vivo and

in vitro conditions

S. No Stage of the insect in vitro in vivo

Mean* range (days) ± SD Mean* range (days) ± SD

1 Incubation period 4.06 4 - 4.1 0.05

4.14 4-4.3 0.11

2 Larval period

A I instar 2.14 2.1 - 2.2 0.05

2.19 2.1 - 2.3 0.09

B II instar 3.04 3.0 - 3.1 0.05

3.21 3.1 - 3.4 0.09

C III instar 3.16 3.0 - 3.2 0.05

3.31 3.2 - 3.5 0.11

D IV instar 3.21 3.2 - 3.3 0.03

3.60 3.5 - 3.7 0.07

E V instar 4.54 4.5 - 4.6 0.05

4.72 4.7 - 4.9 0.11

Total larval period 16.10 16 - 16.3 0.11

17.03 16.4 -17.2 0.23

3 Pupal period 6.43 6.3 - 6.6 0.13

6.91 6.8 – 7 0.08

4 Adult longevity

A Male 3.57 3.5 - 3.6 0.05

3.73 3.6 – 4 0.13

b. Female 4.13 4 - 4.2 0.10

4.57 4.3 – 5 0.33

Average 3.86 3.75 - 4.2 0.05

4.14 3.95 - 4.4 0.17

5 Total life cycle 30.44 30.2 -30.7 0.22

32.22 31.15 - 32.55 0.28

6 Fecundity (No.) 376.67 368 -384 5.85

347.22 328 – 380 14.14

7 Per cent hatching(%) 81.83 65.5 - 90 9.56 87.33 69.5 - 94.5 3.35

* Mean of 10 individuals

SD: Standard deviation


87

Table 9 Sex ratio of ESB, C. infuscatellus reared under in vitro and in vivo conditions

in vitro in vivo

S. No Number

of pupae

observed

Male Female Sex ratio S. No Number

of pupae

observed

Male Female Sex ratio

1 14 4 10 1 : 2.50 1 12 4 9 1 : 2.25

2 17 5 12 1 : 2.40 2 10 4 6 1 : 1.50

3 10 3 7 1 : 2.33 3 14 4 10 1 : 2.50

4 13 4 9 1 : 2.25 4 10 4 7 1 : 1.75

5 15 5 10 1 : 2.00 5 13 5 8 1 : 1.60

6 10 3 7 1 : 2.33 6 10 3 7 1 : 2.33

7 12 4 8 1 : 2.00 7 8 2 6 1 : 3.00

8 10 3 7 1 : 2.33 8 12 4 9 1 : 2.25

9 13 4 9 1 : 2.25 9 10 3 7 1 : 2.33

10 14 4 10 1 : 2.50 10 12 4 8 1 : 2.00

Total 128 39 89 1 : 2.28 Total 111 37 77 1 : 2.08


88

Acknowledgements

The authors are thankful to the Director of Research, ANGRAU, Associate Director of Research,

RARS, Anakapalle and Professor & Head, College of Agriculture, Rajendranagar for providing

facilities during the research work.

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DECLARATION

I, Dr. B. BHAVANI, Senior Scientist (Entomology), Regional Agricultural Research Station,

Anakapalle hereby declare that the Research article entitled “Studies on the Biology of

Sugarcane Early Shoot borer, Chilo infuscatellus Snellen under in vitro and in vivo

conditions in North Coastal Region of Andhra Pradesh, India” is an original research work

done by me as a part of my Ph.D work at Regional Agricultural Research Station, Anakapalle,

Andhra Pradesh. It is further declared that this article or any part thereof has not been published

earlier in any manner.

B.BHAVANI

studies on the biology of sugarcane early ... preliminary attempt to develop the bean based...

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