Population dynamics of linseed budfly (Dasyneura lini Barnes) in linseed (Linum usitatissimum Linn.)

Introduction

Population dynamics, an essential component within the field of population ecology, involves examining the factors that drive fluctuations in population sizes. Variations in seasonal weather patterns and ongoing changes in climate directly influence the adaptations and evolution of insect species. It is crucial for entomologists to comprehend how these factors interact to shape insect populations. Insects, being poikilothermic creatures, show sensitivity to precipitation and exhibit fluctuations in response to environmental cues. These variations stem from their inherent traits, which are directly shaped by environmental conditions impacting their physiology and behaviors (Parmesan, 2007; Bale et al., 2002) [2,3] . The degree of impact from different environmental elements dictates the scale of fluctuations in insect population sizes.

In India, Madhya Pradesh holds first rank in terms of area and production; however, in terms of productivity, Bihar ranks first. Linseed covered an area of over 0.23 lakh hectares in Uttar Pradesh and production was about 0.11 lakh tons, with the maximum productivity level being 4.75 q/ha (FAOSTAT, 2020) [8] . Linseed crop is attacked by a number of insect pests at various phases of its growth. Among which linseed budfly, Dasyneura lini Barnes is a major pest causing 88 per cent yield losses (Mukherji et al. 1999) [9] . Budfly lay their eggs in the calyx of flower buds. The maggots that come out of eggs feed the flower and as a result, the infested buds become hollow and unproductive.

Materials and Methods

The experiment was conducted during the Rabi season at the research cum instructional farm of the College of Agriculture, IGKV, Raipur (C.G), over two consecutive Rabi seasons: 2020-21 and 2021-22. The Neelum variety was planted in the last week of November during both experimental years, with a plot size of 1 acre. Weekly observations on the incidence of linseed budfly were recorded on 10 randomly selected plants. Infestation percentages were calculated by counting the number of infested buds against the total number of buds. The population dynamics of the budfly were analyzed based on standard meteorological data, which included maximum and minimum temperature, relative humidity I and II, and rainfall throughout the cropping season. These weather parameters were then correlated with the budfly population. The relationship between the linseed budfly and the weather parameters was examined using Microsoft Excel 2021 software for correlation calculations.

Results and Discussion

Linseed budfly began appearing up during the bud formation stage and continued until it reached maturity. The linseed budfly is active during the duration of the crop. The mean population of D. Lini started in 2020-21 at 5.27% during the 2 nd SMW, which corresponds to the second week of January with the peak population of 30.96% during the 10 th SMW, which corresponds to the first week of March. The maximum temperature showed significant positive correlation (r=0.717*) with the mean population of D.lini and negative but significant correlation were found with relative humidity I (r=-0.788*) while, positive nonsignificant correlation were found with minimum temperature (r=0.411) and rainfall (r= 0.124) and negative non-significant correlation were found with relative humidity II (r=-0.398). The correlation of maximum temperature was found positive significant and the correlation of relative humidity I was found negative significant whereas, all the other parameters showed the positive and negative non-significant correlation with the mean population of D. Lini. During 2021-22, the D. Lini population started at 4.65% during the 2 nd SMW, i.e., the second week of January and reached its peak 35.54% during the 10 th SMW, i.e., the first week of March. The seasonal mean of Rabi 2020-21 and 2021-22 were 14.82 and 20.11%. The maximum temperature showed significant positive correlation (r=0.868*), relative humidity I showed significant negative correlation (r=-0.876*) and relative humidity II showed significant negative correlation (r=-0.870*) with the mean population of D.lini population whereas, positive and nonsignificant correlation were shown with minimum temperature (r=0.073) whereas, negative and non-significant correlation were shown with rainfall (r=-0.559). The correlation of maximum temperature was found positive significant and the correlation of relative humidity I and II was found negative significant whereas, all the other parameters were found to be positive and negative nonsignificant correlation with the mean population of D.lini. The average of both the years 2020-21 and 2021-22, indicated that the mean population of D.lini 4.96% during the 2 nd SMW, i.e., the second week of January and reached its peak 33.25% during the 10 th SMW, i.e., the first week of March. Throughout the cropping season, the mean budfly population were 17.47%. The maximum temperature showed significant positive correlation (r=0.793*) and relative humidity II showed significant negative correlation (r=-0.832*). whereas, rainfall (r=-0.218) and relative humidity II (r=-0.346) exhibited non-significant negative correlation, while minimum temperature (r = 0.242) exhibited non-significant positive correlation. The correlation of maximum temperature was found positive significant and correlation of relative humidity I and II was found negative significant whereas, the other weather parameters exhibited non-significant negative and positive correlation with the mean population of D.lini. The findings of the current study corroborate those of Malik et al. (1998) Malik who reported that bud infestation commenced from the 3 rd to 4 th week of January during the years 1989-90 and 1990-91, with budfly infestation ranging from 0.74% to 1.71%. This infestation progressively increased to cumulative levels ranging from 16.07% to 50.28% at the harvesting stage. The peak bud infestation, reaching 11.82% and 10.22%, respectively, occurred during the last week of February to mid-March on the cultivar Neelum. This result is found to be in close association with result obtained by Gupta and Katlam (2013) [11] who recorded that the linseed budfly appeared in the 2 nd standard week with the 1.4% bud damage. The maximum cumulative damage by budfly was recorded in 10 th standard week with bud damage of 34.16% in Neelum. These findings are also supported by Sahoo (2016 a) [14] who reported that the budfly infestation with the age of the crop which was maximum during 10 th standard meteorological week. Similar observations are also reported by Rizwan et al. (2018) [12] who evaluated the incidence of budfly was recorded as bud damage from second week of January and continued till last week of march. The maximum per cent damage was recorded in the third week of march in Neelum. Present result is also similar to past finding by Malik et al. (1998) [10] who recorded that the average temperature of 16-20 °C and relative humidity of 60-75% were most favourable for the multiplication of the Dasyneura lini. These observations are in confirmation with Gupta (2012) [13] who investigated that there is a positive significant correlation with budfly infestation with maximum temperature of (r=0.865) and negative non-significant correlation with rainfall on Neelum. This study aligns with Sahoo (2016) [14] research, which documented a notable positive correlation (r=0.731*) between maximum temperature and budfly infestation in linseed crops. Moreover, he noted that both maximum and minimum relative humidity levels exhibited a significant negative impact on the damage inflicted by the linseed budfly. Additionally, the study observed a progressive increase in budfly infestation with the crop's age, peaking during the 10 th standard meteorological week (5th to 11th March). Present study agreed with the result of earlier finding reported by Malik et al. (2000) [15] who found that temperature 17-20 ֯ C (Maximum 23-28 °C and minimum 9-12 °C) and relative humidity 60-70% (morning 65-75% and evening 57-65%) were congenial for budfly multiplication.

Conclusion

The first week of March was found to be the most favourable period for the multiplication of the budfly. The correlation study unveiled significant values, indicating a significantly positive correlation with maximum temperature and a negative correlation with relative humidity I and II. From this, it can be inferred that the combined effect of all-weather parameters did not exert a significant influence on budfly population dynamics, except for maximum temperature and relative humidity I and II. None of the individual weather factors alone demonstrated a substantial impact on the budfly population.

Acknowledgement

AcknowledgementsAuthor is highly thankful to department of Entomology of I.G.K.V, College of agriculture Raipur for providing the necessary facilities during the research work.

References

1. Karuppaiah V, Sujayanad GK. Impact of climate change on population dynamics of insect pests. World J Agric Sci. 2012;8(3):240-246.
2. Parmesan C. Influence of species, latitudes and methodologies on estimates of phonological response to global warming. Global Change Biol. 2007;13:18601872.
3. Bale JSB, Masters GJ, Hodkinson ID, Awmack C, Bezemer TM, Brown VK, et al. Herbivory in global climate change research: direct effects of raising temperature on insect herbivores. Global Change Biol. 2002;8:1-16.
4. Rowland GG, McHughen A, Bhatty RS, Mackenzie SL, Taylor DC. The application of chemical mutagenesis and biotechnology to the modification of linseed (Linum usitatissimum L.). Euphytica. 1995;85:317-21.
5. Tadesse T, Parven A, Singh H, Weyessa B. Estimates of variability and heritability in linseed germplasm. Int J Sustain Crop Prod. 2010;5(3):8-16.
6. Gill KS. Linseed. Indian Council Agric Res, New Delhi. 1987;10:24-28.
7. Srivastava RL. Research and development strategies for linseed in India. In: National Symposium on Vegetable Oils Scenario: Approaches to Meet the Growing Demands. 2009;24-26.
8. Food and Agriculture Organisation. 2020. Available from: http://fao.org/faostat/
9. Mukherji KG, Dubey OP, Upadhyay R. Insect pests of linseed, IPM system in Agriculture Oilseed crops. Oilseed crops. 1999;5:250-263.
10. Malik YP, Singh B, Pandey ND, Singh SV. Infestation dynamics of linseed bud fly Dasyneura lini Barnes in relation to weather factors under irrigated conditions in central Uttar Pradesh. Ann Plant Protec Sci. 1998;6(1):80-83.
11. Gupta H, Katlam BP. Seasonal incidence of linseed insect pests and their natural enemies. J Res ANGRAU. 2013;41(3):7-11.
12. Rizwan M, Chandra U, Deshwal R, Imran M, Singh G, Kumar A. Population dynamics and management against bud fly, Dasyneura lini Barnes in linseed (Linum usitatissimum Linn.). Int J Curr Microbiol App Sci. 2018;7:3377-3381.
13. Indira Gandhi Krishi Vishwavidalaya, Raipur. 2012;85-90.
14. Sahoo SK. Effect of climatic variability on population dynamics of insect pests and natural enemies in linseed (Linum usitatissimum L.). Int J Bio-resource Stress Manag. 2016;7(2):247-251.
15. Malik YP, Hussain K, Singh SV, Srivastava RL. Development of management module for bud fly, Dasyneura lini in linseed. Indian J Ent. 2000;62(3):260269.