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411
POPULATION DYNAMICS, BIOLOGY OF COTTON APHID, APHISGOSSYPII (GLOVER) AND ITS ASSOCIATED NATURAL ENEMIES IN
VADODARA, GUJARAT
*Ruchika Kataria & Dolly Kumar
Corresponding author email: [email protected]
ABSTRACTThe population dynamics study of Aphis gossypii Glover (Hemiptera: Aphididae), a serious pest in Vadodara, India wereconducted during 2008-2011. The results show that the aphid population is higher in the months of January to March oncotton (Gossypium hirsutum L.).Whereas maximum population of aphid were seen in the month of February on Cotton(Gossypium hirsutum L.) host plants. The correlation of aphid population was done with abiotic and biotic parameters. Theaphid population was showing positive correlation with higher temperature and negative correlation with lowertemperature and humidity. The associated insects such as coccinellids and ant showed positive correlation with relativehumidity. Further the biology of the Aphis gossypii Glover was studied on Gossypium hirsutum (L.) under the laboratoryconditions. Aphis gossypii Glover have a complex life cycle with cyclic parthenogenesis. It is difficult to scan the aphidmales because their life cycle continues on the secondary host. The results on different biological parameters showed thatthe total life duration of female ranged from 28-44 days. The fecundity rate was 1499± 458.2 days. The longevity of femaleaphid on an average was 8.1 days with a maximum of 22 days. Hence, the information contained in this paper lead to theidentification of proper management practices during effective reproductive period for Aphis gossypii Glover management.
KEY WORDS: Population dynamics, Aphis gossypii, Biological studies, Cotton plant.
INTRODUCTIONCotton assumes a place of pride in Indian economy as it isone of the most important cash crops in India and plays adominant role in industrial and agricultural economy ofthe country (Tomar, 2010). Worldwide, the Aphis gossypiiGlover is a major threat to agriculture and horticulture inmany tropical, sub-tropical and temperate countries (Sataret al., 1998) which was found to attack a large number ofplant species including crops (Cereals, Pulses andOilseeds), vegetables, fruits, ornamental plants, weeds andwild Plants (Mifsud et al., 2011). They were attacking 220host plant species belonging to 46 different familiesthroughout the world (Patil, 2013) which makes it apolyphagous pest. However, the evidence of aphid wasreported from almost all over India (Singh et al., 2014).Due to a large number of host range, aphids seem to bepresent throughout the year (Razaq et al., 2011). TheAphis gossypii Glover causes yield loss by directlyinfesting leaves, stems, fruits, roots and also cause damageindirectly by secreting honey dew which causedevelopment of sooty mold as well as attracting ant astransporting agents of the aphid to the different host plants(Patil, 2013). The Cotton aphids mainly damage the cottonleaves, tender shoots, cotton balls and finally the wholecrop. In 2002, the cotton aphid was regarded as the sixthmost damaging pest of US cotton. The aphid infested70.3% of US cotton, causing a 0.119% reduction in yieldin 9,307,757 infested acres, resulting in a loss of 31,450bales (Anwar et al., 2007). Heavy infestations may resultin stunted leaves with distortions and curling. The aphidsdeposit sticky honeydew on leaves and cotton balls. Black
mold growing on this honeydew can lower the quality ofthe lint (Steinkraus et al., 1991). Propensity to causedamage to various host plants and its association withvarious natural enemies motivated us to take thepopulation dynamics and biological study of aphids.Application of these studies will be helpful during properimplementation of various control measures against thispest.
MATERIALS & METHODSRecord of aphid populationObservations on population dynamics of aphids and itsassociated insects were recorded from the selectedagricultural sites in Vadodara. The population of aphidswas recorded on 10 cm apical shoot length from 2008 to2011 at weekly interval from randomly selected twentyplants. Similar pattern was followed for associated insects.The relation between an aphid population, its associatedinsects and weather parameters was also worked out(Hanchinal et al., 2010).Record of biological parametersThe biology of Aphis gossypii Glover was studied on theinfested cotton leaves at room temperature at 25±1ºC, 60±10% RH, Photoperiod of 16:8hr (L:D) in the laboratory.The twig of Cotton branch harbouring Aphis gossypiiGlover colonies were plucked from the field and broughtinto the laboratory. The aphids present on such twigs weregently removed with the help of camel hair- brush andreleased on the clean cotton leaves in the plastic boxes(35× 20 cm). Ten such plastic boxes having 10-12 cottonleaves with 30 -60 aphids released in them were
Division of Entomology, Department of Zoology, The Maharaja Sayajirao University of Baroda, Vadodara, – 390002
Biology of cotton aphid, Aphis gossypii & its associated natural enemies in Vadodara
412
maintained in the laboratory. Rearing method was similarto that used by (Kedar et al., 2011). Newly hatchedcrawlers obtained from the ovipositing females of thelaboratory culture were picked up with the help of camelhair-brush and placed onto the cotton leaves at the rate ofone crawler/cotton leaf. Such cotton leaves were kept inopen petri plates. There are total 25 replicates containing 1crawler/leaf. Daily observations were made on the ecdysisof nymphs to determine the instar and its duration. Thereproductive period, post reproductive period, fecundityand longevity of adult females were also recorded. All thestages are observed under stereomicroscope and thenidentified using standard manuals.Statistical AnalysisThe raw data of all the sampled sites from the field diaryof the three consecutive years were transferred in anelectronic format in a spreadsheet layout (Microsoft excel,2007). The data was finally analyzed to calculateimportant value indices from all the sampling sites.Further correlation was calculated by using Minitab 16Statistical Software (Pennsylvania state university, USA,2011) with the biotic (associated insects) and abioticfactors (weather parameters) which are affecting thepopulation of aphids.
RESULTSA) Population dynamics and its correlation with weatherparametersIn agriculture fields of Vadodara, Aphis gossypii Gloverinfestation started appearing in the month of Septemberwhich progressively increases on host plants, cotton(Gossypium hirusutum L.). Observations were made onincreased infestation as crop growth advanced in all thethree consecutive years 2008-09, 2009-10 and 2010-2011.The correlation factors were also recorded in respect withweather parameter in all the three years (Table 4). Duringthe year 2008-09 of study period, the Cotton aphidpopulation was 0.45/10 cm apical shoot in the 39th
meteorological week and progressively increasedthroughout the season. The population reached to 120.00/10 cm apical shoot in the fifth meteorological week ofJanuary and thereafter increased suddenly to reach175.00/10cm apical shoot in the first week of February.Later on, the infestation of aphids declined gradually andreached to 130.00/10cm apical shoot in the 14th
meteorological week. In general, population of itsassociated insects was low during the cropping season.The maximum population of coccinellids and ants were0.20 and 0.22 per plant, respectively in the third and thefirst week of December during this season. (Table 1;Figure. 1, Figure. 2, Figure. 3).
*Standard week (1-31) in X-axis – Refer Table 1to3 (Meteorological weeks 36 to 14; September to March Months)FIGURE. 1 Population Dynamics of Aphis gossypii (Graph showing mean population of aphids collected from 10 cm
Apical shoot of the cotton crop at equal interval of time in the three years of study)
*Standard week (1-31) in X-axis – Refer Tables 1to 3 (Meteorological weeks 36 to 14; September to March Months)FIGURE 2: Population Dynamics of Coccinellid beetles (Graph showing mean population of predators, Coccinellidscollected from 10 cm Apical shoot of the cotton crop at equal interval of time in the three years of study)
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*Standard week (1-31) in X-axis – Refer Table 1to3 (Meteorological weeks 36 to 14; September to March Months)FIGURE 3: Population Dynamics of Ants (Graph showing mean population of associated natural enemies, ants collectedfrom 10 cm Apical shoot of the cotton crop at equal interval of time in the three years of study)
Aphid population was significantly and positivelycorrelated with maximum temperature (0.350) andnegatively correlated with other parameters (minimumtemperature, relative humidity I and II and rainfall).Among predators, there was a significant correlationbetween coccinellid population and relative humidity I(0.437), relative humidity II (0.481). The other parameterswere non-significant. Moreover, it has been observed thatthere was a positive correlation between the population ofants and relative humidity I (0.523), relative humidity II(0.496) but a negative correlation with othermeteorological parameters (Table 4). During 2009-10 ofstudy period, the Cotton aphid population was 0.30/10 cmapical shoot in the 43rd meteorological week andprogressively increased throughout the season. Thepopulation reached to 102.10 /10 cm apical shoot in thethird week of February and thereafter increased suddenlyto reach 178.00/10cm apical shoot in the first week ofMarch. Later on, the infestation of aphids declinedgradually and reached to 145.00/10cm apical shoot in the14th meteorological week. In general, the predatorpopulation was low during the cropping season. Themaximum population of coccinellids, and ants were 0.20and 0.24 %, respectively in the fourth and the second weekof December during this season (Table 2; Figure. 1,Figure. 2, Figure. 3). The aphid population showedpositive correlation with maximum temperature (0.0541)and a negative correlation with other parameters(minimum temperature, relative humidity I and II andrainfall). A significant correlation was observed betweencoccinellid population and relative humidity I (0.034),relative humidity II (0.174). The other parameters werenon-significant. Moreover, there was a positive correlationbetween the population of ants and rainfall (0.062),relative humidity I (0.156) and relative humidity II (0.311)whereas the other meteorological parameters showednegative correlation. (Table 4)During the year 2010-11 of study period, the Cotton aphidpopulation was 0.15/10 cm apical shoot in the secondweek of September and progressively increased throughoutthe season. The population reached to 110.60 /10 cmapical shoot in the first week of January. The peakpopulation of aphids suddenly to reach 178.20/10cm
apical shoot in the third week of January. Later oninfestation of aphids declined gradually and reached to120.50/10cm apical shoot in the 14th meteorological week.The maximum population of coccinellids and ants were0.24 and 0.24 per plant, respectively in the third and fourthweek of November during this season. (Table 3; Figure. 1,Figure. 2, Figure. 3)The aphid population showed positive correlation withmaximum temperature (0.020) and a negative correlationwith other parameters (minimum temperature, relativehumidity I and II and rainfall). A positive correlation wasobserved between coccinellid population and relativehumidity I (0.020), relative humidity II (0.169). The otherparameters were non-significant. Moreover, there was apositive correlation between the population of ants andrelative humidity I (0.152) and relative humidity II (0.292)whereas the other meteorological parameters showednegative correlation (Table 4). Hence, in all the threeconsecutive years the maximum temperature showspositive correlation in the case of aphid population andrelative humidity shows positive correlation in case of itsassociated insects such as coccinelids and ant population.B) Study of Biological Parameters of Aphis gossypii(Glover)The data recorded on different biological parameters aregiven in (Table 5). The life cycle of aphid was very muchunusual. Three different stages are found in aphid cycle,namely eggs, nymphs, and adults. The development fromeggs to adult form takes 15 days. Female undergo 4-5molts. Winged, wingless forms are also present. It wasevident that the mean duration were 3.88±1.69, 4.48±2.51,3.16±1.57, 3.28±1.62 and 8.28±1.90 for the first, second,third, fourth and fifth nymph females of A. gossypii,respectively.For the males, aphid cycle is quite complicated becausewhen winter approaches, some of the females gettransformed into males (Pilgrim, 2010). The males aregenerally found on the secondary host plant so it is quitedifficult to scan their life forms. The adult female had pre-reproductive and post-reproductive period of 11.24±3.28and 17.80±4.0 days, respectively.
Biology of cotton aphid, Aphis gossypii & its associated natural enemies in Vadodara
TA
BL
E 1:
Population dynam
ics ofA
phis gossypii(Cotton aphid), C
occinellids (Ladybird beetles) and A
nts on apical shoot of host plant, Cotton (G
ossypiumhirsutum
L.) in
Agricultural fields of V
adodara during 2008-09.M
onthStandardW
eeksM
aximum
temperature
(ºC)
Minim
umtem
perature(ºC
)
Relative hum
idity(%
) (8.30 a.m.)
Relative
humidity
(%)
(7.30 p.m.)
Rainfall
(mm
)A
phids/ 10
cm
Apical
shoot
Coccinellids
per plantA
nts perplant
September
3636.3
25.670
1515
0.000.00
0.0037
34.524.7
7928
280.00
0.000.00
3832.1
23.894
69.869.8
0.000.00
0.0239
33.224.3
610
00.45
0.020.02
4036.2
2469
22
0.500.02
0.04O
ctober41
3825.1
580
00.62
0.040.02
4237.6
21.638
00
0.680.06
0.0643
35.820.1
520
00.80
0.020.08
4434.8
20.152
00
0.880.08
0.10N
ovember
4534.8
17.661
00
0.920.12
0.1246
34.617
640
01.20
0.140.16
4731.7
1792
00
2.540.18
0.1848
33.115.7
710
05.24
0.060.20
Decem
ber49
34.818.1
810
07.82
0.040.22
5034
16.982
00
10.280.10
0.1651
32.718.8
890
014.54
0.200.15
5232.4
13.387
00
18.240.12
0.141
31.412.8
890
022.54
0.100.10
January2
28.213.6
440
034.24
0.060.08
333
16.748
00
64.200.04
0.064
32.316.1
440
098.20
0.020.06
533.1
13.749
00
120.000.02
0.04Febuary
633.3
14.646
00
175.000.04
0.087
32.614.3
500
0164.00
0.040.04
837
17.439
00
142.000.06
0.029
38.918.8
420
0140.00
0.020.06
March
1038.1
19.255
00
138.000.02
0.1011
38.718.7
320
0136.72
0.020.02
1237.6
21.358
00
134.200.02
0.0213
38.722.2
330
0132.10
0.000.00
1442.1
24.638
00
130.000.00
0.02*M
ean of 20 Plants
414
I.J.S.N., VOL.6 (3) 2015: 411-420 ISSN 2229 – 6441
TA
BL
E 2:
Population dynam
ics ofA
phis gossypii(Cotton aphid), C
occinellids (Ladybird beetles) and A
nts on apical shoot of host plant, Cotton (G
ossypium hirsutum
L.) in
Agricultural fields of V
adodara during 2009-10.M
onthStandardW
eeksM
aximum
temperature
(ºC)
Minim
umtem
perature(ºC
)
Relative
humidity
(%)
(8.30 a.m.)
Relative
humidity
(%)
(7.30 p.m.)
Rainfall
( mm
)A
phids/ 10
cm
Apical
shoot
Coccinellids
per plantA
nts per
plant
September
3633.8
23.493
953.6
0.000.00
0.0037
35.425.7
9399
00.00
0.000.00
3836.6
2593
900
0.000.00
0.0039
36.825.7
9058
00.00
0.000.00
4039
24.580
600
0.000.00
0.00O
ctober41
34.723.3
8569
00.00
0.000.00
4235.7
22.981
650
0.000.00
0.0043
36.717.9
8759
00.30
0.020.02
4435.8
19.382
540
0.420.02
0.02N
ovember
4536.6
1970
610
0.520.02
0.0446
31.218.6
8871
13.20.68
0.040.08
4731.4
14.882
710
0.980.06
0.1248
32.316.8
8977
01.20
0.100.16
Decem
ber49
31.517
9081
03.40
0.120.20
5032.9
1696
870
5.280.14
0.2451
31.318
9288
2.27.94
0.160.18
5230.5
15.481
590
10.240.20
0.141
31.414
7549
012.34
0.140.10
January2
29.712.9
5946
015.28
0.100.08
331.2
11.466
490
17.480.08
0.104
32.313.5
6752
023.50
0.060.08
532.3
14.461
490
33.480.04
0.06Febuary
634.1
15.262
590
65.280.06
0.067
31.615
6949
089.20
0.040.04
836
14.355
400
102.100.02
0.029
35.816.8
7246
0130.00
0.020.06
March
1036.2
18.586
550
178.000.04
0.0211
39.220.1
7437
0154.00
0.020.02
1242.7
20.777
350
150.200.00
0.0213
38.921.9
7932
0148.00
0.000.00
1439.5
22.480
380
145.000.02
0.02
*Mean of 20 P
lants
415
Biology of cotton aphid, Aphis gossypii & its associated natural enemies in Vadodara
TA
BL
E 3:
Population dynam
ics ofA
phis gossypii(Cotton aphid), C
occinellids(L
adybird beetles) and Ants on apical shoot of host plant, C
otton (Gossypium
hirsutum L
.) inA
gricultural fields of Vadodara during 2010-11.
*Mean of 20 P
lants
Month
StandardW
eekM
aximum
temperature
(ºC)
Minim
umtem
perature(ºC
)
Relative
humidity (%
)(8.30 a.m
.)
Relative
humidity
(%)
(7.30 p.m.)
Rainfall
( mm
)A
phids / 10cm
apical
shoot
Coccinellids
per plantA
nts perplant
September
3632.3
25.192
9832
0.000.00
0.0037
31.424
9298
1180.15
0.000.00
3834.1
25.192
9121
0.360.02
0.0239
36.324
9275
10.52
0.020.04
4038.5
24.182
620
0.600.04
0.06O
ctober41
37.924
8570
10.64
0.020.08
4237.4
24.183
650
0.760.04
0.1043
35.323.3
8661
00.96
0.060.12
4436.3
19.482
580
1.460.10
0.12N
ovember
4533.5
19.368
470
3.280.14
0.1646
34.923.5
8876
27.28
0.160.18
4733.8
18.586
7719
8.480.24
0.2048
31.219.4
8975
113.72
0.200.24
Decem
ber49
30.215.7
7761
014.72
0.160.16
5028.2
11.262
660
23.740.10
0.1251
29.111.3
6449
036.48
0.080.10
5229.5
12.479
590
58.260.12
0.081
28.410.7
8052
094.28
0.100.06
January2
2910
6442
0110.60
0.080.04
329.9
10.568
450
130.000.06
0.084
32.611.8
8048
0178.20
0.040.04
530.2
13.869
500
152.200.04
0.02Febuary
634.8
15.182
460
140.000.02
0.027
34.916.2
8044
0138.20
0.020.02
832.5
13.671
420
134.600.06
0.029
35.816.8
5033
0132.20
0.040.00
March
1037.3
17.482
350
130.000.02
0.0011
39.716.8
5231
0128.74
0.020.00
1240.7
20.173
390
126.200.00
0.0213
35.820.9
7737
0124.24
0.000.00
1437.2
21.179
390
120.500.00
0.00
416
I.J.S.N., VOL.6 (3) 2015: 411-420 ISSN 2229 – 6441
TA
BL
E 4:
Correlation
coefficient between w
eather parameters and seasonal fluctuations of A
phids and its associated natural enemies, predator (C
occinellids)and A
nt onC
otton crop during three consecutive years.
Param
etersM
eteorologicalV
aluesC
orrelation coefficient between
weather param
eters and Aphids
population
Correlation coefficient
between w
eather parameters
and Coccinellid populations
Correlation coefficient betw
eenw
eather parameters and A
ntspopulations
2008-09M
aximum
temperature (º C
)42.1
0.350*-0.418
-0.390M
inimum
temperature (º C
)12.8
-0.241-0.452
-0.527R
ainfall (mm
)69.8
-0.240-0.285
-0.287R
elative humidity I (8.30a.m
.)98
-0.578**0.437
0.523R
elative humidity II (7.30p.m
)94
-0.6380.481
0.4962009-
10M
aximum
temperature (º C
)42.7
0.0541-0.701
-0.650M
inimum
temperature (º C
)12.9
-0.020-0.621
-0.586**R
ainfall (mm
)13.2
-0.173-0.013
0.062R
elative humidity I (8.30a.m
.)96
-0.3160.034
0.156R
elative humidity II (7.30p.m
)99
-0.6620.174
0.3112010-11M
aximum
temperature (º C
)40.7
0.020-0.379
-0.287M
inimum
temperature (º C
)10
-0.590-0.225
-0.016R
ainfall (mm
)118
-0.295-0.179
-0.198R
elative humidity I (8.30a.m
.)92
-0.5010.020
0.152R
elative humidity II (7.30p.m
.)98
-0.7800.169
0.292*D
iffers significantly (P =
0.05) **Differs significantly (P
= 0.001)
417
Biology of cotton aphid, Aphis gossypii & its associated natural enemies in Vadodara
418
The duration of the adult reproductive period is about 15days, and the post-reproductive period five days (Capinera2009). In the present studies, the total life duration offemale ranged from 28-44 days. The fecundity rate was1499±458.2. Aphids have both Apterous and wingedforms. In Apterous form, the nymphal period ranges from4-24 days, the longevity of aphid on an average was 9.1days with a maximum of 41 days. A female with anaverage laid 15 nymphs with maximum of 95. In winged
form, the nymphal period ranges from 5 to 22 days at anaverage of 10.1. The longevity of aphid on an average was8.1 days with a maximum of 22 days. The fecundity ofaphid was 9 nymphs (Table 6). Ullah (1980) also reportedthe similar observations for apterous and winged forms.The results indicated that the pest reproduced bothasexually (parthenogenetically) and sexually. Aphids havemany generations in each year.
TABLE 5: Biological parameters of Aphis gossypii Glover on Gossypium hirsutum (L.) under laboratory conditionsBiological parameters Number
observedMean± SD Range
Incubation period 25 3.21±0.93 2-4(A) Female Eggs (hatches) Development from egg to adult is of 15 days*Nymphal duration (7days)First instar 25 3.88±1.69 3-6Second instar 25 4.48±2.51 3-6Third instar 25 3.16±1.57 3-6Fourth instar 25 3.28±1.62 3-6
Fifth instar (Adult virgin female ) 25 8.28±1.90 6-7Pre- reproductive period (days) 25 11.24±3.28 7-15Post reproductive period (days) 25 17.80±4.0 15-20*Fecundity (No. of eggs laid / female ) 25 1499±458.2 500-2375*Adult longevity (days ) 25 22.56±1.58 21-28Total life cycles ( days) 25 28.72±1.06 28-44
*Value of Mean of 25 replicates ± SD
TABLE 6: Developmental stages of Apterous and Winged forms of AphidsDevelopmental Stages Apterous form Winged form
Range Average Range AverageNymphal period 4-24 days 9.8 5-22 10.1Adult logevity 1-41 days 9.1 1-24 days 8.1Fecundity 1-95 nymphs 15 1-35 nymphs 9
DISCUSSIONThe importance of the study of population dynamics ofinsect pests in agricultural fields is helpful for assessingthe pesticide productivity and timing of pesticideapplication. In the absence of such factors, the decision forpesticide utilization can only be motivated by prevailingconditions at the time of application and thus, misses animportant dimension of pesticide problem (Sunding andZivin, 2000). The aphid population was observed fromSeptember 2008 to April 2011. The aphid population wasseen on the cotton crop in the second week of Septembertill April in all the three consecutive years. The peakincidence of aphid population was in the months ofDecember – February. There are 5-6 associated insectsrecorded, namely, Coccinellid beetles, Spiders, Syphridwasp, Hover flies, Ants etc. The ladybird beetles act as abiocontrol agent, though a predator of aphids. The strongAphid – Ant association was seen on the cotton crop. So,the population dynamics of these two associated insectswere calculated. The peak population of associated insectssuch as ladybird beetles and ants was also observed fromSeptember till April. The study on Aphis gossypii Gloverduring study period of 2008-2011 in Cotton fields ofChanni, Vadodara. The cotton crop, grown over a half acrearea in unprotected field, found that aphid infestationstarted appearing in the month of September and graduallyincreased with the advancement of crop growth. The
maximum population of aphids was observed in themonths of November to February which gradually startsdecreasing in the months of March. The aphid populationdisappears totally in the month of April to reappear againin September (Kataria and Kumar, 2013). Karim et al.(2001) also reported that the aphid population startedgrowing from August, reached highest in January andalmost vanished in April. The average population reachedto 120.00/10 cm apical shoot in the 5th meteorologicalweek of January and thereafter increased suddenly that itreached to an average of 175.00/10 cm apical shoot in the1st week of February. Later on, infestation of aphidsdeclined gradually and reached to an average of 130.00/10cm apical shoot in a 14th meteorological week during2008-09. The correlation factors were recorded in respectwith weather parameters, studies concluded that aphidpopulation was significantly and positively correlated withmaximum temperature (0.350) and negatively correlatedwith other parameters. Hasen et al. (2009) also reportedthat among the different environmental factors maximumtemperature, dew point and sun shine hours werepositively correlated with aphid population and minimumtemperature, relative humidity and wind speed werenegatively correlated with aphid population. There waspositive correlation among the aphids with maximumtemperature, whereas negative correlation was observedwith relative humidity and rainfall in Madhya Pradesh. All
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the meteorological parameters influenced of aphids onokra agro- ecosystem in Chitrakoot region, MadhyaPradesh where aphid showed negative correlation withminimum (r = - 0.2930), and mean temperature (r = -0.2120), rainfall (r = -0.3802), maximum (r = -0.5378) andminimum (r =- 0.5109) relative humidity whereas, positivecorrelation with maximum (r = -0.0384) and coccinellids(r = 0.7438) (Singh et al., 2013). Shivanna et al. (2011)reported that the maximum temperature was positivelycorrelated with aphid population and negatively correlatedwith other parameters. Devi et al. (2010) reported that theaphid predators such as Coccinellids show positivecorrelation with relative humidity. The foraging activity ofTapinoma indicum Forel over a period of 72 hoursrevealed that their activities were negatively correlatedwith environmental temperature, but positively correlatedwith relative humidity (Chong and Lee, 2006). In Punjab,the population of predators had a significant positivecorrelation with maximum, minimum, mean temperature,sunshine and vapour pressure (Soni et al., 2013). Anexperiment was conducted during 1983-91 at Anand(Gujarat) to study the outcome of weather factors on theactivity of Aphis gossypii Glover infesting okra (Patel etal., 1997a). Hence, today it is gaining major concern forthe study. The study of its biology is important forunderstanding the form and extent of its populationgrowth. Since, under field condition due to interference ofbiotic and abiotic factors, it is difficult to study the lifehistory and pattern of biological activities of Aphisgossypii Glover. Hence, study was conducted underlaboratory condition. The studies on the biology ofaphid, Aphis gossypii (Glover) on isabgol were carried outin laboratory condition at Department of AgriculturalEntomology, C. P. college of Agriculture, S. D.Agricultural University, Sardar Krushi Nagar during 2008-2009. It was found that the average longevity of the adultwas recorded as (16.36±0.54) days and the total life spanof Aphis gossypii Glover was (23.76±0.65) days (Patil andPatel, 2013). Similarly, studies on the biology and ecologyof the cabbage aphid, Brevicoryne brassicae Linn. underlaboratory conditions at the D.D.U. Gorakhpur University,Gorakhpur, Uttar Pradesh found that one cabbage aphidgeneration develops in 7-10 days (Pal and Singh, 2013).Research work conducted on biological studies of otherspecies of aphids belonging to the same family, Sugarcanewoolly aphid, Ceratovacuna lanigera (Zehntner) reportedthe average longevity of apterous and alatae adults was 36and 8.3 days, 20.5 and 24.1 days. The average fecundity ofapterous adult was 60 aphids, while it was 10 aphids inalatae. The rate of reproduction under laboratoryconditions varied from 3 to 5 nymphs per day, with a totalfecundity of 41 to 56.6 aphids (Joshi and Viraktamath,2014). The study of biology of aphid provides informationregarding longer life span of adults and higher foodrequirements leading to the visibility of the pest andsymptoms, respectively, on the crop and is thus utilized forproper assessment for use of control measures in the field.Hence, this information will be helpful during thedevelopment of successful Integrated Pest Managementprogram (IPM) for Aphis gossypii Glover control.
CONCLUSIONThe presence of large host range and high reproductiverate of Aphid, Aphis gossypii (Glover) causes itspersistence throughout the year. This makes them a greateconomic threat in agricultural fields of Vadodara. Thepresent study on biology of aphid, Aphis gossypii (Glover)give the understanding of mode and degree of itspopulation growth. Hence, this information will be helpfulduring the development of successful Integrated PestManagement program (IPM) for Aphis gossypii (Glover)which is considered as the polyphagous pest in the world.
ACKNOWLEDGEMENTWe acknowledge Anand Agricultural University, Anand,for the identification of aphid species. The authorsacknowledge the vital suggestions and comments of Prof.Bonny Pilo, Ex–Dean, Department of Zoology, M. S.University of Baroda, Vadodara, Gujarat. The authorsthank the farmers of the fields who gave the permissionfor field study. One of the author thankful for financialsupport from Department of Environmental Science,M.S.University of Baroda, Vadodara.
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