| dc.description.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. | en_US |
