1Division of Entomology, School of Agricultural Sciences, Karunya Institute of Technology and Sciences, Karunya Nagar, Coimbatore-641 114, Tamil Nadu, India.
2School of Agricultural Sciences, Amrita Vishwa Vidyapeetham, Coimbatore-642 109, Tamil Nadu, India.
*Corresponding Author: S. Sumaiya Parveen, Division of Entomology, School of Agricultural Sciences, Karunya Institute of Technology and Sciences, Karunya Nagar, Coimbatore-641 114, Tamil Nadu, India. Email: ssumaiyasaleem@gmail.com
Fenugreek is an important winter-season legume crop in South India; however, very limited information is available on the spatial dynamics of its key sucking pests and associated natural enemies. Understanding the influences of local microclimate on pest abundance is very essential for developing site-specific and sustainable management strategies.
An open field experiment was carried out to study the spatial dynamics of major pests of fenugreek and their natural enemy fauna under two different geographical locations of Tamil Nadu (Thondamuthur, Coimbatore and Kangeyam, Tiruppur) during the Rabi season, 2022–23. Monthly observations were recorded on major sucking pests (aphids, thrips and whitefly) and natural enemies (spiders and coccinellids) from early vegetative growth to seed maturity. Meteorological data (temperature, relative humidity, rainfall, sunshine hours and wind speed) were used to determine their correlations with pest populations.
The incidence of pest infestations started at the early vegetative stage and continued until the seed maturity. The aphids were predominant throughout the crop growth phase, although their intensity varied and a higher abundance was noticed during February with 19.88 to 25.85 aphids per 10 cm apical shoot under the experimental field of Thondamuthur (Coimbatore) and Kangeyam (Tiruppur), respectively; while the thrips population appeared to its peak during February in Thondamuthur (7.35 per three leaves) and Kangeyam (8.45 per three leaves). Meanwhile, the peak infestation of whitefly was recorded as 6.65 and 8.45 per three leaves in the experimental plots of Thondamuthur and Kangeyam, respectively. The prevailing maximum temperature was found to have an adverse effect on the population growth of fenugreek pests (r = -0.84, -0.46, -0.59 and -0.68, -0.12, -0.08 against aphids, thrips and whitefly, respectively). The bright sunshine and wind speed have shown a positive association in both of the experimental areas. The natural enemy population controls the pest abundance significantly at both the experimental areas. Spatial distribution indicates a comparatively higher aphid density under the experimental plots of Thondamuthur (Coimbatore), compared to the plots from Kangeyam (Tiruppur), in comparison to that of the whitefly and thrips populations.
Aphid infestation, Environmental factors, Fenugreek pests, Natural enemies, Spatial variation, Sustainable pest management
