SPATIAL DISTRIBUTION AND SEASONAL ABUNDANCE OF LEMON BUTTERFLY (Papilio demoleus) ON DIFFERENT CITRUS PLANTS IN SYLHET

Abstract

The study was conducted at Citrus Research Station (CRS) and four villages in Jaintapur, Sylhet in order to explore the spatial distribution and seasonal abundance of lemon butterfly in three citrus orchards viz., Jara lebu, Mandarin and Sweet orange during May to October 2014. Fifteen citrus orchards were selected randomly from five locations viz., CRS, Dowdic, Bagerkhal, Lamashampur and Utlarpar villages of two Unions viz. Nijpat and Fatehpur in Jaintapur. Three orchards were selected from each of the selected five locations. Four plants from each orchard of each location were selected randomly and tagged for data collection. Each plant of the tagged plants was considered one replication. Each tagged plant was divided into five canopy directions viz., north canopy, south canopy, east canopy, west canopy and central canopy to determine the spatial distribution of lemon butterfly. At the stand level, the results of spatial distribution showed that the maximum average leaf infestation (Mean±SD: 22.60±3.65% and 20.47±3.57%) was found in north and west facing canopy respectively and minimum (16.22±2.18% and 16.25±2.71%) in south canopy and east canopy respectively. The moderate level of average leaf infestation (18.06±3.22%) was found in central canopy. At the landscape level, the maximum average leaf infestation (21.35±3.51%) was found in Bagerkhal village, while the minimum (17.80±2.70% and 17.94±2.72%) was found at Citrus Research Station and Dowdic respectively. Besides, the abundance of lemon butterfly in the nursery of Jara lebu, Mandarin and Sweet orange was determined at 15, 30, 45 and 60 days after grafting (DAG) of the seedlings to find out the incidence pattern of lemon butterfly in the nursery. The maximum seedling infestation (57.5%, 70.0% and 82.5%) was found respectively in Jara lebu, Mandarin and Sweet orange at 60 DAG. Conversely, the minimum seedling infestation (5.0%, 12.5% and 20.0%) was found respectively in Jara lebu, Mandarin and Sweet orange at 15 DAG. The seasonal abundance of lemon butterfly on both Jara lebu and Sweet orange was lower in May which gradually increased up to October, with the exception for Mandarin that the maximum seasonal abundance was found only in August, 2014. It may be concluded that the citrus seedlings in the nursery could be protected from the attack of lemon butterfly through the adoption of pest management methods at very initial stage of seedlings in the nursery.