M. R. Amin
Department of Entomology, Bangabandhu Sheikh Mujibur Rahman Agricultural University (BSMRAU), Gazipur, Bangladesh.
M. S. Miah
Department of Entomology, Bangabandhu Sheikh Mujibur Rahman Agricultural University (BSMRAU), Gazipur, Bangladesh.
H. Rahman
Department of Entomology, Bangabandhu Sheikh Mujibur Rahman Agricultural University (BSMRAU), Gazipur, Bangladesh.
N. P. Nancy
Department of Entomology, Bangabandhu Sheikh Mujibur Rahman Agricultural University (BSMRAU), Gazipur, Bangladesh.
M. K. A. Bhuiyan
Department of Plant Pathology, Bangabandhu Sheikh Mujibur Rahman Agricultural University (BSMRAU), Gazipur, Bangladesh.
Eggplant, Insect Pollinator, Foraging, Infestation, Germination, IPM
Field Laboratory of the Department of Entomology, Bangabandhu Sheikh Mujibur Rahman Agricultural University (BSMRAU), Salna, Gazipur, Bangladesh
Pest Management
Insects, Brinjal
The study was conducted during March to August, 2016 in the Field Laboratory of the Department of Entomology, Bangabandhu Sheikh Mujibur Rahman Agricultural University (BSMRAU), Salna, Gazipur, Bangladesh. The soil of the study site is silt clay in texture belonging to Salna series. The area represents the agro-ecological zone of Madhupur tract (AEZ-28) with pH 5.8-6.5, cation exchange capacity of 25.6 and C:N ratio of 3:1 (Haider et al., 1991). Study location and climatic conditions: The study site (BSMRAU, Gazipur) is located at 25°25′ North latitude and 89°5′ East longitude, which is in the middle of Bangladesh.The study area has a subtropical climate having mean maximum and minimum temperature of 360C and 12.70C, respectively, and relative humidity and average annual rainfall were 65.8% and 237.6 cm, respectively.
Collection of eggplant seeds and cultivation of crop: Seeds of eggplant variety BARI Begun 8 were collected from the Horticulture Research Center, Bangladesh Agricultural Research Institute (BARI), Joydebpur, Gazipur, Bangladesh. Seeds of eggplant were sown on 2 March, 2016 in polythene bags. For transplanting seedlings, plots having 3.0 m ×3.0 m followed by randomized complete block design were used. Eggplant seedlings were transplanted 60 cm apart on 21 March 2016, in rows. The distance from row to row was1.0 m. Each plot has three rows and each row contained 5 plants.Fertilizers were applied according to Fertilizer Recommendation Guide (FRG, 2012) (N- 80 kg, P- 24 kg, K- 60 kg, S- 10 kg per hectare). Intercultural operations such as irrigation and weeding were done whenever necessary.
Effect of pollinators on fruit set: To determine the effect of wind and insect pollinators on fruit set, three types of treatments were adopted on the experimental plots. The adopted treatments were (i) open plot (wind and wild insect pollination), (ii) enclosed plot (covered with mosquito net) having 25 supplemented insect pollinators (black ant, honeybee and house fly) per week, and (iii) covered plot (covered with mosquito net) without supplemented pollinators. Each treatment was replicated three times.
Collection of insect and identification of pollinators: Free-living insects were collected from flower initiation to fruit maturation stage using a 30 cm diameter sweep net having 1.5 mm mesh, and attached with a 2 m long rod. Every week sweeping was done in between 09:00 to 11:00 h of the day, and each sample was consisted of 30 sweeps. The collected insects were brought to the Entomology Laboratory of BSMRAU for identification and counting. They were killed by storage in a freezer for a few hours, mounted on points, dried and morphotype. Insect pollinators were identified to species following morphological characters and comparing with museum specimens.
Observation of insect abundance and foraging behavior of pollinators: Landing duration (length of foraging time on a flower) of the insect pollinators on eggplant flowers were measured using a stop watch. Observations were done in between 10:00 to 13:00 h of the day and data were recorded 7 times for each pollinator species. Observation of plant and fruit infestation: During the study, plants were regularly monitored to record their infestation level by different chewing and sucking insects. Infested plants were recorded by observing the symptoms on shoot and leaves and then percent infested plant was calculated. During fruiting, field inspection was done daily to observe the infestation of the fruits by shoot and fruit borer. The damaged and undamaged fruits were counted and percentage of fruit infestation was calculated on number basis.
Germination test: For this purpose, 5 mature fruits were randomly collected from each treatment and the seeds of the fruit were separated. Sixty seeds from each treatment were randomly selected and these were kept for germination test. Trays, each 30 cm × 30 cm × 5 cm (L × W × D), was used for this purpose. A single sheet of paper was placed in the bottom of each tray to cover drainage holes. Each tray was filled with clean and moist sand mixed soil and 20 seeds were sown in 5 rows of 4 seeds. Seeds were sown at the normal seeding depth of 3 cm and were watered every alternate day. Only healthy seedlings were counted after 7 days when the majority of seedlings were emerged. Diseased, discolored, or malformed seedlings were excluded from counts. The total number of healthy seedlings for each treatment was used to determine germination percentage.
Statistical analysis: One-way analysis of variance (ANOVA) followed by Tukey posthoc statisticwas employed for analyzing the data. All the analyses were performed using IBM SPSS 21.0. (IBM SPSS statistics 21, Georgia, USA).
Bangladesh J. Agril. Res. 44(1): 103-113, March 2019 ISSN 0258-7122 (Print), 2408-8293 (Online)
Journal