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Department of Entomology, S.V. Agricultural College, ANGRAU, Tirupati-517 502.
A fixed plot survey was conducted to study the incidence of sucking insect pests and pink bollworm in cotton fields of Nandyal and Kurnool districts of Andhra Pradesh during 2023-2024 at monthly intervals. Among the sucking insect pests, whitefly (Bemesia tabaci) population recorded 6.66 per three leaves at Dornipadu mandal in Nandyal district during August and crossed the ETL. Whereas, leafhoppers (Amrasca biguttula biguttula), thrips (Thrips tabaci) population was recorded 9.51,
8.75 per three leaves during August at Doddenakeri village of Adoni mandal in Kurnool district and crossed the ETL. Highest incidence of aphid (Aphis gossypii) population was recorded with mean of 6.59 per three leaves at Thumbaleedu village of Alur mandal in Kurnool district and did not crossed the ETL during crop growth period. Pink bollworm (Pectinophora gossypiella) recorded 57.60 per cent green boll damage and 30.00 per cent locule damage at Kanakaveedu village of Yemmiganur mandal during January in Kurnool district.
KEYWORDS: Fixed plot survey, Amrasca biguttula biguttula, Aphis gossypii, Bemesia tabaci, Pectinophora gossypiella, Thrips tabaci, green boll damage, locule damage.
Cotton, Gossypium hirsutum Linnaeus. Which is known as “White Gold” and globally recognized as “King of fibers” which plays a crucial role in both industrial and agricultural economy of the country. Globally, China (329 lakh bales of 170 kg), India (316.76 lakh bales of 170 kg) and Brazil (194.12 lakh bales of 170 kg) are the leading cotton producing countries whereas in India, Andhra Pradesh ranks eighth place with 11.58 lakh bales of 170 kg of production (AICRP on Cotton Annual Report, 2023-24) from which Kurnool (1,55,442 ha) tops the area under cotton production followed by Palnadu (49,600 ha), Anantapuramu (39,727 ha) districts (AP agrisnet Kharif, 2023).
In spite of being the best cotton producing country, India faces a plenty of issues in cotton production out of which damage caused by insect pests attract greater importance. Cotton pests were primarily divided into bollworms and sucking pests. Among the sucking pests the most important insect pests are leaf hoppers (Amrasca biguttula biguttula), aphids (Aphis gossypii), thrips (Thrips tabaci) and whitefly (Bemisia tabaci) (Aslam et al., 2004).
Among the bollworms i.e., American bollworm (Helicoverpa armigera), spotted bollworm (Eariasvitelli) and pink bollworm (Pectinophora gossypiella), severe yield loss of cotton is due to development of resistance in pink bollworm on first and second generation Bt cotton hybrids. Under this circumstances a survey was conducted to know the incidence of sucking insect pests and pink bollworm damage on cotton crop in Nandyal and Kurnool districts.
Fixed plot survey was conducted to study the incidence of sucking insect pests in cotton crop viz., leaf hoppers (Amrasca biguttula biguttula), aphids (Aphis gossypii), thrips (Thrips tabaci) and whitefly (Bemisia tabaci) and pink bollworm (Pectinophora gossypiella) in Nandyal and Kurnool districts. In Nandyal district Allagadda mandal Nallagatla village, Dornipadu mandal Dornipadu village, Koilkuntla mandal Bheemunipadu village and in Kurnool district Yemmiganur mandal Kanakaveedu village, Adoni mandal Doddenakeri village, Alur mandal Thumbaleedu village were selected. In each village five farmers fields were selected to record the incidence of sucking insect pests and pink bollworm in cotton.
Whitefly population was counted in cotton by counting the number of nymphs and pupae on three leaves one at bottom, one at middle and one at top per plant during vegetative and maturity phase. Leafhoppers were counted from cotton by counting the number of hoppers in first two terminal leaves on twenty five plants in the early stage and express as number of hoppers per leaf. Aphids were counted from cotton by counting the number of infested plants in randomly selected plants and arrived at a per cent. Aphids population was taken in numbers instead of per cent because of less incidence and thrips were counted from cotton by counting the number of insects on the top unopened leaves on plants and express as number of thrips per leaf.
The observations on pink bollworm was done by randomly collected twenty five bolls and expressed the per cent boll damage by using following formula.
Per cent boll damage =
Collected bolls were examined for the locule damage by destructing the bolls carefully with a knife and expressed the per cent locule damage by using following formula.
Per cent locule damage =
Simple statistical tools viz., mean and per cent were used to analyse the data on sucking insect pests and pink bollworm using Microsoft excel 2021 Spread Sheet.
Among the sucking insect pests, whitefly (Bemesia tabaci) population was ranged from 2.46 to 6.14 per three leaves during August to November in Nandyal district. Highest whitefly population was recorded (6.66 per three leaves) at Dornipadu mandal during August and crossed the economic threshold level. Less number of whitefly population was recorded (2.10 per three leaves) at Bheemunipadu village of Koilkuntla mandal during November. At Thumbaleedu village of Alur mandal in Kurnool district recorded highest whitefly population (5.90 per three leaves) during August and crossed the economic threshold level. Less number of whitefly population (1.73 per three leaves) was recorded in Kanakaveedu village of Yemmiganur mandal during November month. Whitefly population was ranged from 1.81 to 5.45 per three leaves during August to November.
Similar results were also observed with the Sana et al. (2011) who reported that the peak incidence of whitefly population at 60 days after sowing with 5.78 adults per leaf, there after decline in the population and reached 0.53 per leaf at 120 DAS and also with the Jeyakumar et al. (2008) from which Whitefly population remained higher on 31st, 33rd, 36th and 37th Standard Meterological Week (August and September), in which it crossed more than 3 whitefly adults per three leaves.
In Nandyal district, aphid (Aphis gossypii) incidence was recorded highest (4.11 per three leaves) at Dornipadu mandal during August and did not crossed the economic threshold level. Less incidence (1.07 aphids per three leaves) was recorded at Dornipadu mandal during November and overall mean population of aphids was ranged from 1.21 to 3.66 per three leaves. In Kurnool district, aphid incidence was high (6.59 per three leaves) at Thumbaleedu village of Alur mandal during August and did not cross the economic threshold level during crop growth period. Less incidence (1.09 aphid population per three leaves) was recorded at Kanakaveedu village of Yemmiganur mandal during November. Aphid population was ranged from 1.63 to 5.39 per three leaves, respectively.
Similar results were observed with the Kiruthika et al. (2022) who recorded the highest aphid population at 50 days after sowing of the crop with 18.7 adults per three leaves.
Mean population of thrips (Thrips tabaci) was recorded highest (5.08 per three leaves) at Dornipadu mandal during August and did not cross the economic threshold level during crop growth period. Less number of thrips population (1.07 per three leaves) was recorded at Bheemunipadu village of Koilkuntla mandal during
November and overall mean population of thrips was ranged from 1.34 to 4.60 per three leaves in Nandyal district. Highest incidence of thrips population (8.75 per three leaves) was recorded in Kurnool district at Doddenakeri village of Adoni mandal during August and crossed the economic threshold level. Less number of thrips population (2.07 per three leaves) was recorded at Thumbaleedu village of Alur mandal during November. Thrips population was ranged from 2.63 to 7.40 per three leaves.
Whereas our findings are similar with the findings of Rajasekhar et al. (2023) who observed that the peak incidence was noticed at 45 days after sowing (32.26 thrips per three leaves) and decline gradually to 0.30 per three leaves at 150 days after sowing.
Leafhopper population was ranged from 3.00 to 7.80 per three leaves. Highest leafhopper population (8.78 per three leaves) was recorded at Dornipadu mandal during August and crossed the economic threshold level. Less number of population (2.61 per three leaves) was recorded at Bheemunipadu village of Koilkuntla mandal during November in Nandyal district. In Kurnool district leafhopper population was recorded highest (9.51 per three leaves) at Doddenakeri village of Adoni mandal during August and crossed the economic threshold level. Less number of leafhopper population (3.16 per three leaves) was recorded at Thumbaleedu village of Alur mandal during November and mean population of leafhopper was ranged from 3.67 to 8.61 per three leaves.
Similar results were recorded with the Dhaka and Pareek (2008) who observed that the population increased gradually and reached to its peak (90/30 leaves) in 32nd and 33rd week (August) and also with findings of Arif et al. (2006) who recorded maximum leafhopper population to be 1.85 per leaf during second week of August.
The results on the incidence of pink bollworm on cotton was observed in Nandyal and Kurnool districts during October, November, December and January (2023-2024).
The incidence of green boll damage was ranged from 11.20 to 25.60per cent during October to January.
The highest mean per cent of green boll damage (28.00%) was recorded in Nandyal district at Bheemunipadu village of Koilkuntla mandal during January and less per cent (10.40%) was recorded at Nallagatla village of Allagadda mandal during October. The incidence of green boll damage was recorded highest with mean per cent (57.60%) at Kanakaveedu village of Yemmiganur mandal in Kurnool district during January, lowest mean per cent (12.80%) at Thumbaleedu village of Alur mandal during October with an overall mean per cent of 25.07 to 42.13 per cent.
Similar results were also found by Patil et al. (2002) who observed highest boll damage i.e., 54.45 per cent with 62.56 per cent locule damage.
At Bheemunipadu village of Koilkuntla mandal in Nandyal district recorded the highest locule damage (14.20%) during January, less per cent was observed (4.80%) at Nallagatla village of Allagadda mandal during October with an average boll infestation of 5.07 to 12.60 per cent. In Kurnool district, highest mean per cent of locule damage was recorded (30.00%) at Kanakaveedu village of Yemmiganur mandal during January, less per cent of green boll damage (6.00%) at Thumbaleedu village of Alur mandal during October with an average boll infestation of 12.33 to 22.80 per cent.
Similar results were observed in Shinde et al. (2018) who recorded that the locule damage of 0.44 to 39.08 per cent in non Bt cotton and in Bt cotton from 0.44 to 18.79 per cent. Muttappa and Patil (2019) who recorded the locule damage due to pink bollworm infestation varied from 19.28 to 22.77 per cent. The maximum (22.77%) locule damage was recorded during 4th week of December.
Based on the results obtained through the present investigation on cotton crop revealed that the peak incidence of sucking insect pests recorded during August, then their incidence was declined. In Nandyal district, highest number of whitefly population was recorded whereas highest number of thrips, aphids and leafhopper population was recorded in Kurnool districts. Pink bollworm incidence was low due to use of seed cotton and pheromone traps in large scale from vegetative stage
up to boll maturity stage in Nandyal districts whereas in Kurnool district pink bollworm incidence was more due to commercial cotton growing by farmers.
The author is highly thankful to Acharya N. G. Ranga Agricultural University, S. V. Agricultural College, Tirupati for providing financial support and Associate Director Research for providing facilities at RARS, Nandyal during my research work.
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