EVALUATION OF SOME ESSENTIAL OILS AGAINST PULSE BEETLE ( Callosobruchus chinensis L . ) IN PEA SEEDS
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Date
2015
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ABSTRACT The present investigations on “Evaluation of some essentials oils against pulse beetle (Callosobruchus chinensis L.) in pea seeds” were carried out during 2014-15 in the Department of Seed Science and Technology, College of Horticulture, Dr. Y.S. Parmar University of Horticulture and Forestry, Nauni–solan (H.P). The essentials oils of camphor, wild marigold, cone-bearing sage, eucalypts, lemongrass and sweet flag at 2.5 ml/kg, 1.25 ml/kg , 0.60 ml/kg and 0.30 ml /kg (v/w basis)were evaluated against C. chinensis L. infesting pea seeds. Among the six essentials oils, sweet flag possessed reasonably high and immediate toxicity irrespective of its doses. It resulted in 78.33 percent overall mortality with in a day of treatment, while in 3 days mortality increased to 96.67 percent (2.5 ml/kg and 1.25 ml/kg doses resulted 100 % mortality). After 7 days cent per cent mortality was observed in seeds coated with sweet flag essential oil followed by eucalypts (85.83%) cone - bearing sage (77.50%), camphor (74.17%), lemongrass (71.66%) and wild marigold (61.67%) in decending order. After 10- days of exposure, eucalypts essential oil also resulted complete kill even at lowest dose (0.30ml/kg). On day -15, mortality in control had substantially increased to 67.50 percent. Egg laying was minimum on sweet flag essential oil treated pea seeds (5.25 eggs/5 females) on 7th – day of observations. In untreated pea seeds, increases in egg laying was negligible in 20 – days observations (7th day 94.08- 20th day 101.92). Progeny development from the eggs laid on pea seed traeated with sweet flag essentials oil was (1 beetle). Maximum protection to treated pea seed in terms of reductions in seed damage by C. chinensis was provided by sweet flag essential oil (0.33%) and lemongrass essential oil (3.90%). Next effective treatments were wild marigold (6.81%), camphor (7.86%), cone - bearing sage (7.94%) and eucalypts (11.74%). Pea seeds treated with sweet flag essential oil resulted 92.75 per cent germination followed by lemongrass essential oil (85.58%), camphor (78.33%), cone – bearing sage (43.75%), eucalypts (41.25%) and wild marigold (39.42%). Sweet flag essential oil resulted 1665.19 seed vigour index – I followed by lemongrass essential oil (1440.78), camphor (1193.76) eucalypts (843.69), cone - bearing sage (714.09) and wild marigold (685.30). Maximum seed vigour index –II was recorded in sweet flag essential oil (2115.74) treated pea seeds followed by lemongrass (1681.86), camphor (1524.56), cone -bearing sage (1153.46), eucalypts (1097.59) and wild marigold (799.55). In case of essential oils as grain protectants sweet flag essential oil at 2.5 ml/kg was effective in protecting pea seeds up to 8 months. After 2 months pea seeds treated with sweet flag essential oil resulted 91.11 per cent pulse beetle mortality followed by camphor (42.22%), eucalypts (35.56), lemongrass (33.33%), wild marigold (31.11%) and cone-bearing sage (28.89%). After month-4 mortality recorded in sweet flag essential oil treated pea seeds were significantly high (71.11%) as compared to other treatments. After month 6 only sweet flag essential oil was effective. Minimum egg laying (10 eggs/5 females) was recorded in pea seeds treated with sweet flag essential oil after 2-months of treatment. Pea seeds treated with sweet flag essential oil at 0.30 ml/ kg resulted adult emergence of 2.67 beetles, seed damage (0.70%), weight loss (0.23%) and highest germination (91.33%), seed vigour index-I (1360.65) and seed vigour index-II (1800.32). Mixing of pea seeds with sweet flag essential oil at 0.30 ml/kg provided protection up to 2-months of treatment whereas pea seed treated with 2.5 ml/kg would be effective in protecting pea seed against damage caused by pulse beetle, Callosobruchus chinensis L. up to month -8 of treatment.