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Relative Occurrence and Abundance of Mustard Aphid, Lipaphis erysimi (Kalt.) and Their Predators on Rainbow and Oscar Canola Varieties
J. Asia-Pacific Entomol. 7(2): 215 -219 (2004) www.entomology.or.kr
Relative Occurrence and Abundance of Mustard Aphid, Lipaphis erysimi (Kalt.l and Their Predators on Rainbow and Oscar Canola Varieties Muzaffar A. Talpur* and Rab Dino Khuhro Faculty of Crop Protection, Sindh Agriculture University Tandojam- 70060, Sindh, Pakistan
Abstract The studies on the relative occurrence and
aphid, canola, Lipaphis erysimi, occurrence, predators
importance that attack the brassica crop include the cabbage aphid, Brevicoryne brassicae Linn., mustard aphid, Lipaphis erysimi Kalt., cabbage butterfly, Pier is brassicae L., painted bug, Bagrada hilaris Fab., army warm, Agrotis ypsilon Rott. and cabbage semilooper, Tarache notabilis Walker. Among all the insects pests, the aphid is a serious pest (Talpur et al., 1991; Saljoqi et al., 2001; Syed et al., 1999). The extent of seed yield damage caused alone by the cabbage aphid, B. brassicae on variety RL-18 (B. napus) was estimated as 66.8% in an unsprayed treatment (Prasad and Phadke, 1983) from India. The losses due to mustard aphid accounted for 60 to 90% in Delhi, 70% in Bihar, 27.5 to 65.3% in Haryana, 90% in west Bengal, 43% in Orisa and 50.0% in Punjab (Singh and Sidhu, 1958). Since the canola is a recently introduced crop in Pakistan and many varieties are grown under Sindh agro-ecological conditions. No information on pest attack on canola crop has been reported so far. Therefore, it is essential to investigate the pest problems of this newly introduced crop. This basic information will be useful for researchers, farmers and Integrated Pest Management (IPM) specialists for the management of aphids on oil seed crops in future.
Introduction
Materials and Methods
The canola belongs to genus Brassica of the family Cruciferae and is recently introduced as oilseed crop in Pakistan. The canola oil is free of odour and bitterness and is very popular amongst the health conscious people due to low erucic acid <2% and <30% micro mig, low acid glucosinolates and devoid of cholesterol (Beversdorf and Hume, 1990). Rapeseed and mustard are sown on an area of 0.32 million hectares in Pakistan with annual production of 0.05 million tons. The brassica crops occupy 80% ofthe total area under oilseed crops in Pakistan (Larik, 2002). A number of insects pest species of economic
The experiment was conducted at Oil Seed Section, Agriculture Research Institute, Tandojam, Sindh, Pakistan to investigate the relative occurrence and abundance of aphid species and their predators on Rainbow and Oscar canola varieties. The canola varieties were sown on November 15,2000 in a plot size of 100 X 100 sq. ft. Recommended cultural and agronomic practices from sowing till harvest for these varieties were adopted. No insecticide was sprayed in and around the experimental plot to provide natural environment for aphids attack, their multiplicationand predators on both the canola varieties. The observations on the incidence and population buildup ofaphids were started from the seedling stage and continued till maturity of the plants. The data were recorded during morning hours (09-11 a.m.) twice per week. For this
abundance of mustard aphid, Lipaphis erysimi (Kalt.) revealed that aphid appeared on leaves during 3rd week of January and on the inflorescences during 2nd week of February and continued up to harvesting on both the varieties. The peak populations (42.7) and (28.7) per leaf on Rainbow and Oscar varieties were recorded. Whereas, the peak populations (7.5) and (6.6) per inflorescences were recorded on these varieties. The higher mean population ranges (9.2 to 28.7) and (25.1 to 42.7) per leafon Oscar and Rainbow and (3.9 to 6.6) and (2.3 to 7.6) per inflorescence were recorded from February 15 to March 5. The temperature range of 16.5 to 20.6°C, seems to have favored the pest multiplication. The predator species such as, green lacewing beetle, Chrysoperla carnea (Stephens), eleven-spotted ladybird beetle, Coccinella undecimpunctata (Linn.) and seven-spotted ladybird beetle, Coccinella septempunctata (Linn.) were recorded when the pest population of aphids was sufficiently developed on the canola varieties. Key words abundance,
*Corresponding author. E-mail: [email protected] Tel: +92-221-765901; Fax: +92-221-765300 (Received December 1, 2003; Accepted June 7, 2004)
216
J. Asia-Pacific Entomol. Vol. 7 (2004)
purpose, twenty five plants were selected at random from each variety. During vegetative growth stage, five leaves per plant i.e., two from bottom, two from mid and one from top portion were scanned thoroughly for aphid counts. However, during flowering stage, one inflorescence (4 inches long) per plant was scanned at random from 25 plants each on both varieties and number of aphids was counted. The observations on prevalence of(predators) on randomly selected 25 plants were also recorded. Both, immature and adult beetles on 25 randomly selected plants were collectedand broughtto the laboratoryfor identification. The records of meteorological data were obtained from Nuclear Institute of Agriculture, Tandojam. The data obtained on aphids were subjected to statistical analysis. The means of aphid populations per leaf and per inflorescence were compared using paired-t test.
Thereafter, the aphid population decreased gradually upto harvest. The maximum population of aphids (6.6) per inflorescence was recorded on Oscar variety on February 22 whereas, the maximum population of a~hids (7.6) per inflorescence was recorded on March 5 h on Rainbow variety. This shows that the aphid population on leaf and inflorescence was higher on Rainbow variety as compared to Oscar variety. The data in Figs. 1 and 2 also shows that these were two peaks from February 19 to March 5 indicate two overlapping generations. The data in Figs. 1 and 2 further indicate that the maximum population of aphids on both varieties ranged between February 22 to March 5 with a temperature range of 16.6 to 20.7°C which seems favourable for the pest multiplication. The ANOVA of data in Table 1 indicate that the seasonal means (1.4±0.12) and (2.1 ± 0.23) per leaf on Oscar and Rainbow were highly significant by using T-Value. The means (1.7±0.19) and (l.8 ± 0.19) per inflorescence were non-significant.
Results The results of the present study on relative occurrence and abundance of the mustard aphid, Lipaphis erysimi (Kalt.) and their natural enemies (predators) on Oscar and Rainbow canola varieties are presented in Figs. 1-5. The data in Fig. 1 depict that aphids appeared on the leaves during 3rd week of January and on inflorescences during 2nd week of February (Fig. 2) on both varieties and continued upto harvesting. On Oscar variety, that pest population on leaves increased gradually from February 2nd week and reached to its peak (28.7) per leaf on February 19 with appearance of predator, C. carnea. The pest population showed other peak of (24.2) per leaf on March 5th, after which the pest population decreased gradually due to maturity of the crop. Whereas, on Rainbow variety, the pest population increased gradually with maximum population of (42.7) per leaf on February 22.
45,---------------40
Predators During the study three predator species were recorded i.e., C. carnea, C. septempunctata and C. undecimpunctata. The data in Fig. 3 indicate the all predators population was higher on Rainbow than Oscar variety. The maximum population of predators on Rainbow (7.8) per 25 plants was recorded on February 19 whereas, maximum population (8.0) was recorded on Oscar on March 22. The seasonal mean of all predators was higher (2.1) on Rainbow as compared with Oscar variety (l.8). The reason for higher population of predators on Rainbow variety might be due to maximum population of aphids (prey) on same variety. The data in Fig. 4 depict the weekly predator prey curves. The aphid populations increased gradually from 1st week of February and reached to
----,
__ Oscar
_0"", Rainbow
B
........Rainbow
35 30
J: .E
to
o!--_ _e¥«'~ . .'V
Fig. 1. Relative mean population of aphids on Oscar and Rainbow canola (Brassica napus) varieties recorded from January to March 2001.
-_-.---::~~±="'*"'_J '),fQ
$~ ,.f-#
-tf#
-cq;~1t
'1,,');~1t "''O~w
Observation dates
Fig. 2. Relative mean population of aphids on Oscar and Rainbow canola (Brassica napus) varieties recorded from February to March 2001.
Mustard aphid, Lipaphis erysimi and their predators
",------------------~30
-e-oecer 8
......... Rainbow
te
- - Chrysaperla camea
25
....... ccccoese seplempllnctafa
.i
14
. :l
6
ill
i -
5
'0
3
217
:;
12
~
10
-.-Caccinella undecimpunetata __ Temp."C 20
i
4
'0
£
~
oLL~~~~~~~~~,....:J /////~~~///////~/////
Jan-3rd
4th
Feb-1st
2nd
3rd
4th
March-1st
2nd
Weeks
Ob••rvetrondetee
Fig. 3. Relative population of all predator species on Oscar and Rainbow canola (Brassica napus) varieties from January to March 2001.
350r-----------------_ .......Predator 300
...... Prey
1l i
250
200
150
~
ci 100
Z
50
Jan-arc
4th
Fetl-1st
2nd
3rd
4th
MarctJ.1sl
2nd
3rd
W•• k,
Fig. 4. Predator-prey ratio observed on Oscar and Rainbow canola (Brassica napus) varieties from January to March 2001. Predators include Chrysoperla carnea, Coccinella septempunctata and Coccinella undecimpunctata beetles and prey is mustard aphid.
their peak (318.4) per plant of both varieties during fourth week of February. Thereafter, the pest population decreased upto 4th week of March. The predators population also increased gradually (1.9) from February 2nd week and reached to its peak (7.6) in 1st week of March. However, the increased population of all the predators was recorded during February 2nd week to March 1st week. Thereafter, the predators population decreased with the decrease in prey populations. This shows that the predator's populations were increased when the aphid populations were maximum on both the canola varieties. However, the number of predators could not bring the prey population under control due to their low population on the crop. The results of present study are in agreement with those of Panda et al. (2000) who reported that the aphid population reached to its peak (302.1) per plant when the canola variety, Brassica juncea L. was 70 days old crop. The natural enemies recorded were Menochilus sexmaculatus (Fabr.), C. septempunctata, Coccinella repanda
Fig. 5. Population abundance of various predators under different weekly fluctuate temperatures (OC) from JanuaryMarch 2001.
(Thun.) and Diaeretiella rapae (M'Jntosh) which influenced the aphid population during their activity period from January to February. The data in Fig. 5 reveals that three species of predators were recorded i.e., C carnea, C septempunctata and C undecimpunctata. The weekly populations of predators are correlated with temperature. During January 3rd week, the predator C. carnea appeared on the canola varieties which were infested already with the aphids. It multiplied gradually and reached to its peak (16.9) per 25 plants. Thereafter, its population decreased during 1st week of March. The weekly temperatures during January 3rd week to February 4th week ranged between 14.1 to 19.9°C, which seems favourable for the predator, C. carnea population. At the same time the pest population was also high during February 19 to 1st week of March. Later, with the increase in weekly temperatures of 20.7 to 27.5°C decreased the population of predator C. carnea. The Fig. 5 further depict that two species of lady bird beetle, C. septempunctata and C. undecimpunctata multiplied with the increase in weekly temperatures 20.7 to 24. 5 °C, seems favourable for both predatory beetle populations. Thereafter, the crop reached to its maturity and their population decreased. The ANOVA in Table 1 showed that C. carnea was highly significant in Rainbow with 3.4 T'-value. However, predatory green lacewing beetle, seven-spotted ladybird beetle and eleven-spotted ladybird beetle were statistically non-significant on both the cultivars of canola varieties. The results of present studies are in agreement with those of Panda et al. (2000) who reported that maximum temperature between 24.9 to 29.0°C were found to be congenial for the proper development of aphid population. The natural enemies recorded were M sexmaculatus, C. repanda, C. septempunctata and D. rapae influenced the aphid population during January - February. The results of present studies are in agreement with those of Syed et al. (1999) who reported that peak populations of
J. Asia-Pacific Entomol. Vol. 7 (2004)
21S
Table 1. Comparison of mean aphid populations and their predators per leaf and per inflorescence on Oscar and Rainbow canola (Brassica napus) varieties. Oscar(Mean ± S.E)
Rainbow(Mean ± S.E)
T-Value
Leaf
1.4 ± 0.12
2.2 ± 0.23
2.51 HS
Inflorescence
1.7 ± 0.19
I.S ± 0.19
1.32
Chrysoperla carnea
O.S ± 0.10
1.2 ± 0.13
3.36
Coccinella septernpunctata
0.5 ± 0.07
0.5 ± 0.06
O.IS
Coccinella undecimpunctata
0.7 ± 0.09
0.6 ± O.OS
LSI NS
Parameters
NS HS
NS HS NS
= Non-significant = Highly-significant
aphids on all 12 canola varieties was recorded in 4th week of February. There was also a significant negative correlation between aphid infestation and yield of canola varieties. The results are also in agreement with those of Saljoqi et 01. (2001) who conducted experiment on effect of sowing dates and cultivar test of canola varieties against aphid population and found that Rainbow was highly infested with 23.8 aphids per plant and Oscar showed an intermediate infestation of 19.0 aphids per plant. The results are also in agreement with those of Kulkarni and Patel (2001) from India who reported that aphid incidence occurred between the first week of January to fourth week of February with high incidence during first week of February. The difference in peak periods could be due to ecological conditions at India.
Discussion The studies on relative occurrence and abundance of aphid showed that aphid population was maximum from February 15th upto March 5th with a range of 9.8 to 28.2 and 25.1 to 42.7 per leaf on Oscar and Rainbow canola varieties. This shows that the pest population remained maximum after 75 days after sowing of both varieties. The results of present study agree with those of Panda et 01. (2000) who reported maximum population of 302.1 per plant on 70 days old on B. juncea in Rajpur, Madhya Pradesh, India. However, the maximum temperature ranged between 24.9 to 29.0°C in India. Whereas, in Pakistan weekly temperature was 16.5 to 27.5 'C. The minor temperature differences could be due to agro climatic differences in India and Pakistan. This is the crucial period for the pest attack on crop and needs regular monitoring of the crop and control measures. The present study also indicates that there is potential of natural enemies and three species of predators i.e.,
C. cornea, C. septumpunctata and C. undecimpunctata appeared two months after sowing and population ranged from 0.2 to 1.8 per week on Oscar and from 0.4 to 5.2 on Rainbow varieties, respectively. This shows that C. cornea appeared when pest number was at peak on leaves and inflorescences on both varieties. Similar observations in a lab experiment are reported by Singh and Kumar (2000) from India that there is a potential in C. cornea in suppressing the mustard aphid population. However, lady bird beetle predators appeared at later stage of the crop when there was maximum population of aphids on the crop and could not control the pest effectively. Appearance of two Coccinellid natural enemies at later stage of crop with maximum population of aphids with a temperature range of 18.4 to 27.5 'C was favourable for Coccinellid predators. The results of present studies also confirm with those of Singh and Kumar (2000) who reported that on average 11.5, 79.5 and 83.0 aphids were consumed by 1st, 2nd and 3rd instar larvae of C. cornea, respectively. Similarly, Seema and Singh (1999) reported that larvae of C. septumpunctata consumed 111.6 aphids per individual in February and 141.0 in March and adults consumed were on an average of 518.0 aphids per individual in February and 528.1 in March. The data in Figs. I and 2 indicate that maximum mean number of aphids was recorded during February 2nd week to March 2nd week on both varieties with a temperature range of 19.9 to 22.8°C and the agro climatic conditions seems to have favored the pest buildup. The results of present studies are in partial agreement with those of Saharia (1984) and Pandey at el. (1986) who reported from India, that aphid population peaked from mid January and mid February whereas, in the present study aphid population peaked during February 3rd week to March 1st week. The delay could be due to climatic differences. The results of present study are also in agreement with those of Ram and Gupta (1987) who reported that the development of aphid population on mustard crop was favoured by maximum and
Mustard aphid, Lipaphis erysimi and their predators
minimum temperatures of 21.4 to 22.8 and 5.9 to 7.6°C and relative humidity of 80.2 to 83.0% and 31.2 to 40.9%, respectively. The occurrence of both Coccinellid predators was maximum at temperature range of 20.65 to 27.54 °C, which shows that above temperature range along with pest population and plant phenology were favourable for the development of the predators. However, the predators could not control the pest effectively. The present study also indicates that February 2nd week to March l st week remained favourable for the aphids on this crop (Figs. 1 and 2). Keeping the results of the present study in view it is suggested to take preventive measures against aphids when they reach economic injury levels i.e., 5 aphids per leaf on both the varieties of canola.
Literature Cited Beversdorf, WOO and D.J. Hume. 1990. Registration of 'Winfield' rapeseed. Crop Science 30: 1356. Kulkarni, A.V and 1.S. Patel. 2001. Seasonal abundance of mustard aphid (Lipaphis erysimi) and associated bioagents in Indian mustard (Breassicajuncea) crop. Indian J. Agric. Sci. 10: 681-682. Larik, N.M. 2002. Year Book of Statisties of Pakistan. Published by Ministry of Food, pp. 59-60. Agriculture and Livestock, Islamabad. Panda, D., B.S. Thakur and B. Patro. 2000. Population dynamics of Lipaphis erysimi (Kalt.) on Brassica juncea
219
L. at Raipur, Madhya Pradesh. Plant Protection Bulletin (Faridabad). 52: 28-30. Pandey, K.P., A. Kumar and c.P.M. Tripathi. 1986. Population ecology of Lipaphis ervsimi (Kalt.) on Brassica campestris. Rev. Appl. Entomo!. 75: 1228. Prasad, S. K and K. G. Phadke. 1983. Effect of mustard aphids, Lipaphis erysimi (Kalt.) infestation on the seed yield of different varieties of brassica species. Rev. App!. Entomol. 73: 854. Ram, Sand M. P. Gupta. 1987. Effect of weather conditions and time of sowing on the incidence of mustard aphid, Lipaphis erysimi Kalt. Rev. App!. Entomo!. 76: 5245. Saharia, D. 1984. The population dynamics of the mustard aphid, Lipaphis erysimi Kalt. on Brassica juncea crop. Rev. App!. Entomo!. 75: 5497. Saljoqi, A.U.R., S. Moeez-ud-Din., S. Ahmed and Karimullah. 2001. Effect of sowing dates and cultivar test of canola against aphid population. Sarhad J.Agric. 17: 623-628. Seema, K and 1.P. Singh. 1999. Predation potential of Coccinella septempunctata var divaricata olive on mustard aphid, Lipaphis erysimi (Kalt.) infesting mustard crop. Madras Agric. J. 86: 370-372. Singh, N.N and M. Kumar. 2000. Potentiality of Chrysoperla carnea (Stephens) in suppression of mustard aphid population. Indian J. Entomol. 62: 323-326. Singh, Sand S. Sindhu. 1958. Control of mustard aphid by synthetic insecticides. Indian Oilseed J. 2:24.30. Syed, T.S., A. Makorani and G.H. Abro. 1999. Resistance of different canola varieties against aphid, Lipaphis erysimi Kalt. Proc. Pak .Cong .Zool. 19: 45-49. Talpur, M.A., T.Hussain., G.H.Nizamani and H.B.Baloch. 1991. Relative resistance of some Oliferous brassica to mustard aphid, Lipaphis erysemi Kalt. Proc. Pak. Congo Zoo I. 11: 125-129.
Relative Occurrence and Abundance of Mustard Aphid, Lipaphis erysimi (Kalt.l and Their Predators on Rainbow and Oscar Canola Varieties Muzaffar A. Talpur* and Rab Dino Khuhro Faculty of Crop Protection, Sindh Agriculture University Tandojam- 70060, Sindh, Pakistan
Abstract The studies on the relative occurrence and
aphid, canola, Lipaphis erysimi, occurrence, predators
importance that attack the brassica crop include the cabbage aphid, Brevicoryne brassicae Linn., mustard aphid, Lipaphis erysimi Kalt., cabbage butterfly, Pier is brassicae L., painted bug, Bagrada hilaris Fab., army warm, Agrotis ypsilon Rott. and cabbage semilooper, Tarache notabilis Walker. Among all the insects pests, the aphid is a serious pest (Talpur et al., 1991; Saljoqi et al., 2001; Syed et al., 1999). The extent of seed yield damage caused alone by the cabbage aphid, B. brassicae on variety RL-18 (B. napus) was estimated as 66.8% in an unsprayed treatment (Prasad and Phadke, 1983) from India. The losses due to mustard aphid accounted for 60 to 90% in Delhi, 70% in Bihar, 27.5 to 65.3% in Haryana, 90% in west Bengal, 43% in Orisa and 50.0% in Punjab (Singh and Sidhu, 1958). Since the canola is a recently introduced crop in Pakistan and many varieties are grown under Sindh agro-ecological conditions. No information on pest attack on canola crop has been reported so far. Therefore, it is essential to investigate the pest problems of this newly introduced crop. This basic information will be useful for researchers, farmers and Integrated Pest Management (IPM) specialists for the management of aphids on oil seed crops in future.
Introduction
Materials and Methods
The canola belongs to genus Brassica of the family Cruciferae and is recently introduced as oilseed crop in Pakistan. The canola oil is free of odour and bitterness and is very popular amongst the health conscious people due to low erucic acid <2% and <30% micro mig, low acid glucosinolates and devoid of cholesterol (Beversdorf and Hume, 1990). Rapeseed and mustard are sown on an area of 0.32 million hectares in Pakistan with annual production of 0.05 million tons. The brassica crops occupy 80% ofthe total area under oilseed crops in Pakistan (Larik, 2002). A number of insects pest species of economic
The experiment was conducted at Oil Seed Section, Agriculture Research Institute, Tandojam, Sindh, Pakistan to investigate the relative occurrence and abundance of aphid species and their predators on Rainbow and Oscar canola varieties. The canola varieties were sown on November 15,2000 in a plot size of 100 X 100 sq. ft. Recommended cultural and agronomic practices from sowing till harvest for these varieties were adopted. No insecticide was sprayed in and around the experimental plot to provide natural environment for aphids attack, their multiplicationand predators on both the canola varieties. The observations on the incidence and population buildup ofaphids were started from the seedling stage and continued till maturity of the plants. The data were recorded during morning hours (09-11 a.m.) twice per week. For this
abundance of mustard aphid, Lipaphis erysimi (Kalt.) revealed that aphid appeared on leaves during 3rd week of January and on the inflorescences during 2nd week of February and continued up to harvesting on both the varieties. The peak populations (42.7) and (28.7) per leaf on Rainbow and Oscar varieties were recorded. Whereas, the peak populations (7.5) and (6.6) per inflorescences were recorded on these varieties. The higher mean population ranges (9.2 to 28.7) and (25.1 to 42.7) per leafon Oscar and Rainbow and (3.9 to 6.6) and (2.3 to 7.6) per inflorescence were recorded from February 15 to March 5. The temperature range of 16.5 to 20.6°C, seems to have favored the pest multiplication. The predator species such as, green lacewing beetle, Chrysoperla carnea (Stephens), eleven-spotted ladybird beetle, Coccinella undecimpunctata (Linn.) and seven-spotted ladybird beetle, Coccinella septempunctata (Linn.) were recorded when the pest population of aphids was sufficiently developed on the canola varieties. Key words abundance,
*Corresponding author. E-mail: [email protected] Tel: +92-221-765901; Fax: +92-221-765300 (Received December 1, 2003; Accepted June 7, 2004)
216
J. Asia-Pacific Entomol. Vol. 7 (2004)
purpose, twenty five plants were selected at random from each variety. During vegetative growth stage, five leaves per plant i.e., two from bottom, two from mid and one from top portion were scanned thoroughly for aphid counts. However, during flowering stage, one inflorescence (4 inches long) per plant was scanned at random from 25 plants each on both varieties and number of aphids was counted. The observations on prevalence of(predators) on randomly selected 25 plants were also recorded. Both, immature and adult beetles on 25 randomly selected plants were collectedand broughtto the laboratoryfor identification. The records of meteorological data were obtained from Nuclear Institute of Agriculture, Tandojam. The data obtained on aphids were subjected to statistical analysis. The means of aphid populations per leaf and per inflorescence were compared using paired-t test.
Thereafter, the aphid population decreased gradually upto harvest. The maximum population of aphids (6.6) per inflorescence was recorded on Oscar variety on February 22 whereas, the maximum population of a~hids (7.6) per inflorescence was recorded on March 5 h on Rainbow variety. This shows that the aphid population on leaf and inflorescence was higher on Rainbow variety as compared to Oscar variety. The data in Figs. 1 and 2 also shows that these were two peaks from February 19 to March 5 indicate two overlapping generations. The data in Figs. 1 and 2 further indicate that the maximum population of aphids on both varieties ranged between February 22 to March 5 with a temperature range of 16.6 to 20.7°C which seems favourable for the pest multiplication. The ANOVA of data in Table 1 indicate that the seasonal means (1.4±0.12) and (2.1 ± 0.23) per leaf on Oscar and Rainbow were highly significant by using T-Value. The means (1.7±0.19) and (l.8 ± 0.19) per inflorescence were non-significant.
Results The results of the present study on relative occurrence and abundance of the mustard aphid, Lipaphis erysimi (Kalt.) and their natural enemies (predators) on Oscar and Rainbow canola varieties are presented in Figs. 1-5. The data in Fig. 1 depict that aphids appeared on the leaves during 3rd week of January and on inflorescences during 2nd week of February (Fig. 2) on both varieties and continued upto harvesting. On Oscar variety, that pest population on leaves increased gradually from February 2nd week and reached to its peak (28.7) per leaf on February 19 with appearance of predator, C. carnea. The pest population showed other peak of (24.2) per leaf on March 5th, after which the pest population decreased gradually due to maturity of the crop. Whereas, on Rainbow variety, the pest population increased gradually with maximum population of (42.7) per leaf on February 22.
45,---------------40
Predators During the study three predator species were recorded i.e., C. carnea, C. septempunctata and C. undecimpunctata. The data in Fig. 3 indicate the all predators population was higher on Rainbow than Oscar variety. The maximum population of predators on Rainbow (7.8) per 25 plants was recorded on February 19 whereas, maximum population (8.0) was recorded on Oscar on March 22. The seasonal mean of all predators was higher (2.1) on Rainbow as compared with Oscar variety (l.8). The reason for higher population of predators on Rainbow variety might be due to maximum population of aphids (prey) on same variety. The data in Fig. 4 depict the weekly predator prey curves. The aphid populations increased gradually from 1st week of February and reached to
----,
__ Oscar
_0"", Rainbow
B
........Rainbow
35 30
J: .E
to
o!--_ _e¥«'~ . .'V
Fig. 1. Relative mean population of aphids on Oscar and Rainbow canola (Brassica napus) varieties recorded from January to March 2001.
-_-.---::~~±="'*"'_J '),fQ
$~ ,.f-#
-tf#
-cq;~1t
'1,,');~1t "''O~w
Observation dates
Fig. 2. Relative mean population of aphids on Oscar and Rainbow canola (Brassica napus) varieties recorded from February to March 2001.
Mustard aphid, Lipaphis erysimi and their predators
",------------------~30
-e-oecer 8
......... Rainbow
te
- - Chrysaperla camea
25
....... ccccoese seplempllnctafa
.i
14
. :l
6
ill
i -
5
'0
3
217
:;
12
~
10
-.-Caccinella undecimpunetata __ Temp."C 20
i
4
'0
£
~
oLL~~~~~~~~~,....:J /////~~~///////~/////
Jan-3rd
4th
Feb-1st
2nd
3rd
4th
March-1st
2nd
Weeks
Ob••rvetrondetee
Fig. 3. Relative population of all predator species on Oscar and Rainbow canola (Brassica napus) varieties from January to March 2001.
350r-----------------_ .......Predator 300
...... Prey
1l i
250
200
150
~
ci 100
Z
50
Jan-arc
4th
Fetl-1st
2nd
3rd
4th
MarctJ.1sl
2nd
3rd
W•• k,
Fig. 4. Predator-prey ratio observed on Oscar and Rainbow canola (Brassica napus) varieties from January to March 2001. Predators include Chrysoperla carnea, Coccinella septempunctata and Coccinella undecimpunctata beetles and prey is mustard aphid.
their peak (318.4) per plant of both varieties during fourth week of February. Thereafter, the pest population decreased upto 4th week of March. The predators population also increased gradually (1.9) from February 2nd week and reached to its peak (7.6) in 1st week of March. However, the increased population of all the predators was recorded during February 2nd week to March 1st week. Thereafter, the predators population decreased with the decrease in prey populations. This shows that the predator's populations were increased when the aphid populations were maximum on both the canola varieties. However, the number of predators could not bring the prey population under control due to their low population on the crop. The results of present study are in agreement with those of Panda et al. (2000) who reported that the aphid population reached to its peak (302.1) per plant when the canola variety, Brassica juncea L. was 70 days old crop. The natural enemies recorded were Menochilus sexmaculatus (Fabr.), C. septempunctata, Coccinella repanda
Fig. 5. Population abundance of various predators under different weekly fluctuate temperatures (OC) from JanuaryMarch 2001.
(Thun.) and Diaeretiella rapae (M'Jntosh) which influenced the aphid population during their activity period from January to February. The data in Fig. 5 reveals that three species of predators were recorded i.e., C carnea, C septempunctata and C undecimpunctata. The weekly populations of predators are correlated with temperature. During January 3rd week, the predator C. carnea appeared on the canola varieties which were infested already with the aphids. It multiplied gradually and reached to its peak (16.9) per 25 plants. Thereafter, its population decreased during 1st week of March. The weekly temperatures during January 3rd week to February 4th week ranged between 14.1 to 19.9°C, which seems favourable for the predator, C. carnea population. At the same time the pest population was also high during February 19 to 1st week of March. Later, with the increase in weekly temperatures of 20.7 to 27.5°C decreased the population of predator C. carnea. The Fig. 5 further depict that two species of lady bird beetle, C. septempunctata and C. undecimpunctata multiplied with the increase in weekly temperatures 20.7 to 24. 5 °C, seems favourable for both predatory beetle populations. Thereafter, the crop reached to its maturity and their population decreased. The ANOVA in Table 1 showed that C. carnea was highly significant in Rainbow with 3.4 T'-value. However, predatory green lacewing beetle, seven-spotted ladybird beetle and eleven-spotted ladybird beetle were statistically non-significant on both the cultivars of canola varieties. The results of present studies are in agreement with those of Panda et al. (2000) who reported that maximum temperature between 24.9 to 29.0°C were found to be congenial for the proper development of aphid population. The natural enemies recorded were M sexmaculatus, C. repanda, C. septempunctata and D. rapae influenced the aphid population during January - February. The results of present studies are in agreement with those of Syed et al. (1999) who reported that peak populations of
J. Asia-Pacific Entomol. Vol. 7 (2004)
21S
Table 1. Comparison of mean aphid populations and their predators per leaf and per inflorescence on Oscar and Rainbow canola (Brassica napus) varieties. Oscar(Mean ± S.E)
Rainbow(Mean ± S.E)
T-Value
Leaf
1.4 ± 0.12
2.2 ± 0.23
2.51 HS
Inflorescence
1.7 ± 0.19
I.S ± 0.19
1.32
Chrysoperla carnea
O.S ± 0.10
1.2 ± 0.13
3.36
Coccinella septernpunctata
0.5 ± 0.07
0.5 ± 0.06
O.IS
Coccinella undecimpunctata
0.7 ± 0.09
0.6 ± O.OS
LSI NS
Parameters
NS HS
NS HS NS
= Non-significant = Highly-significant
aphids on all 12 canola varieties was recorded in 4th week of February. There was also a significant negative correlation between aphid infestation and yield of canola varieties. The results are also in agreement with those of Saljoqi et 01. (2001) who conducted experiment on effect of sowing dates and cultivar test of canola varieties against aphid population and found that Rainbow was highly infested with 23.8 aphids per plant and Oscar showed an intermediate infestation of 19.0 aphids per plant. The results are also in agreement with those of Kulkarni and Patel (2001) from India who reported that aphid incidence occurred between the first week of January to fourth week of February with high incidence during first week of February. The difference in peak periods could be due to ecological conditions at India.
Discussion The studies on relative occurrence and abundance of aphid showed that aphid population was maximum from February 15th upto March 5th with a range of 9.8 to 28.2 and 25.1 to 42.7 per leaf on Oscar and Rainbow canola varieties. This shows that the pest population remained maximum after 75 days after sowing of both varieties. The results of present study agree with those of Panda et 01. (2000) who reported maximum population of 302.1 per plant on 70 days old on B. juncea in Rajpur, Madhya Pradesh, India. However, the maximum temperature ranged between 24.9 to 29.0°C in India. Whereas, in Pakistan weekly temperature was 16.5 to 27.5 'C. The minor temperature differences could be due to agro climatic differences in India and Pakistan. This is the crucial period for the pest attack on crop and needs regular monitoring of the crop and control measures. The present study also indicates that there is potential of natural enemies and three species of predators i.e.,
C. cornea, C. septumpunctata and C. undecimpunctata appeared two months after sowing and population ranged from 0.2 to 1.8 per week on Oscar and from 0.4 to 5.2 on Rainbow varieties, respectively. This shows that C. cornea appeared when pest number was at peak on leaves and inflorescences on both varieties. Similar observations in a lab experiment are reported by Singh and Kumar (2000) from India that there is a potential in C. cornea in suppressing the mustard aphid population. However, lady bird beetle predators appeared at later stage of the crop when there was maximum population of aphids on the crop and could not control the pest effectively. Appearance of two Coccinellid natural enemies at later stage of crop with maximum population of aphids with a temperature range of 18.4 to 27.5 'C was favourable for Coccinellid predators. The results of present studies also confirm with those of Singh and Kumar (2000) who reported that on average 11.5, 79.5 and 83.0 aphids were consumed by 1st, 2nd and 3rd instar larvae of C. cornea, respectively. Similarly, Seema and Singh (1999) reported that larvae of C. septumpunctata consumed 111.6 aphids per individual in February and 141.0 in March and adults consumed were on an average of 518.0 aphids per individual in February and 528.1 in March. The data in Figs. I and 2 indicate that maximum mean number of aphids was recorded during February 2nd week to March 2nd week on both varieties with a temperature range of 19.9 to 22.8°C and the agro climatic conditions seems to have favored the pest buildup. The results of present studies are in partial agreement with those of Saharia (1984) and Pandey at el. (1986) who reported from India, that aphid population peaked from mid January and mid February whereas, in the present study aphid population peaked during February 3rd week to March 1st week. The delay could be due to climatic differences. The results of present study are also in agreement with those of Ram and Gupta (1987) who reported that the development of aphid population on mustard crop was favoured by maximum and
Mustard aphid, Lipaphis erysimi and their predators
minimum temperatures of 21.4 to 22.8 and 5.9 to 7.6°C and relative humidity of 80.2 to 83.0% and 31.2 to 40.9%, respectively. The occurrence of both Coccinellid predators was maximum at temperature range of 20.65 to 27.54 °C, which shows that above temperature range along with pest population and plant phenology were favourable for the development of the predators. However, the predators could not control the pest effectively. The present study also indicates that February 2nd week to March l st week remained favourable for the aphids on this crop (Figs. 1 and 2). Keeping the results of the present study in view it is suggested to take preventive measures against aphids when they reach economic injury levels i.e., 5 aphids per leaf on both the varieties of canola.
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