| dc.description | Vegetables are essential and rich source of minerals and micronutrients considering the
aspects of nutritional, financial, and food security in Bangladesh. More than 100
vegetables are produced represented by different species and varieties. Major vegetables
grown in Bangladesh are potato, brinjal, country bean, tomato, cucurbits, yard long bean,
okra, radish, cauliflower, cabbage, aroids, carrot, leafy vegetables etc. However, country
bean, Lablab purpureus (L) is one of the major winter vegetable grown in Bangladesh
(Haq, 1986). It is a good source of protein which contains 4.5% protein in green pods and
about 25% in dry seeds (Rashid, 1976). It also contains appreciable amount of vitamins,
calcium, phosphate, sulphur and sodium (Gopalan et al., 1982). Eventhough 11,000 ha of
land are cultivated during winter season the total production of country bean is still low
and far below the public demand. In the circumstances the production of bean is always
threatened by several insect and mite pests which cause enormous loss and act as a barrier
to fulfill the vegetables demand. Among the arthropod pests, the two-spotted spider mite,
Tetranychus urticae Koch (Acarina: Tetranychidae) is the most important pest and
responsible for significant yield losses in many vegetables including beans, greenhouse
crops (Meyer, 1996), fruit trees (Salman, 2007), ornamental and agronomic crops
worldwide (James and Price, 2002). The developmental rate, survival, reproduction and
longevity of T. urticae may vary in response to changes in temperature, host plant
species, host plant nutrition, cultivar type, phonological stage, exposure to pesticides,
relative humidity, etc. (Sabelis, 1981; Brandenburg and Kennedy, 1987b; Wermelinger et
al., 1991; Wilson, 1994; Dicke, 2000; Marcic, 2003; Skorupska, 2004), Many secondary
metabolites found in plants are responsibile for the development of organisms and the
tolerance levels of bean varieties can be different against the mite. So, screening ‘the mite
redistent bean varieties can be ous of the important strategies to reduce the pest
infestation. Biological knowledge, in particular life table attributes is a significant step to
know the development of a pest. However, little is known about the two-spotted spider
mite’s population growth parameters especially on different bean varieties in Bangladesh
perspectives. So, the present study is designed primarily to provide data on biology and
reproduction of T.urticae on selected five varieties of country bean and also explore the
least preferable bean varieties to mite. | en_US |
| dc.description.abstract | The two-spotted spider mite, Tetranychus urticae Koch (Acarina : Tetranychidae) is one
of the most destructive cosmopolitan pests, which attack many vegetables, horticultural
and greenhouse plants. Biological performance of this mite was studied on five country
bean varieties (Lablab purpureus L.) to find out the mite tolerance varieties. IPSA 2,
BARI seam 1, BARI seam deshi, Deshi (Local variety) and ASA purple varieties of bean
were tested under laboratory conditions (26 - 32°C, RH 70 - 85% and 13: 11 D:L). The
longest longevity period was 15.63 and 19.83 days for female and male, respectively
when the 7. urticae fed on ASA purple. On the contrary, it was the shortest 13.82 and
15.75 days for both the sexes while reared on BARI seam 1. Lifetime fecundity was also
the highest (78.93 + 4.26) on ASA purple and the lowest (54.64 + 7.85) on BARI seam 1.
The sex ratio (proportion of male) was the maximum (0.39) on Deshi (Local variety) and
the lowest (0.17) on BARI seam 1. No significant differences have observed among the
immature development and adult longevity of two-spotted spider mite while fed five bean
varieties. But life time fecundity showed the signifcant differences on the tested hosts.
Life table parameters were analyzed and found the lowest generation time (7= 12.46)
when T. urticae fed on BARI seam deshi, but R, (56.60) was the highest on ASA purple,
rm (0.32) and A (1.38) were also the highest when fed BARI seam deshi. Based on the
fecundity performance of two-spotted spider mite, it could be concluded that the variety
BARI seam 1 was less preferable host as compared to others. A comparison was made for
studying the effect of some pesticides: Omite 57 EC, Kumulus DF and botanical oils:
neem oil, mahogony oil, chilli extract and water on the important mite pest, Tetranychus
urticae. The sublethal concentrations of Omite 57 EC (20 ml/10L), Kumulus DF (4.5
gm/1L), neem oil (5 ml/1L), mahogony oil (5 ml/1L) and chilli extract (10 gm/1L) were
used. The test was conducted in both the semi-field (25-34°C, 65-80% RH and a
photoperiod of 13L: 11D) and laboratory (26 - 32°C, 70 - 85% RH and a photoperiod of
12 - 13: 12 - 11 L: D) conditions using bean variety IPSA 2 with three replications.
Results showed that the highest mortality caused by Omite 57 EC (96.37%, 100%,
99.62%, 100% and 100%), while the lowest mortality in water (23.22%, 2.13%, 0.01%,
3.71% and 0.00%) and control (0.00%) in the field direct toxicity assays after 1°, so
14™ and 21‘ days of spraying. I | en_US |
