The total density of virus vectors is dependent on incidence, their life cycle since from eggs deposition/oviposition till the emergence of young ones from pupae and the adult stage. The Whitefly (Bemisia tabaci) is always as alatae adult so that can cover long distance as virus vectors. Their number on plants is commonly influenced by fluctuations of weather particularly temperature and Relative Humidity (RH). Thus climatic changes play great role. The appearance of whitefly by their numbers is dependent on 25-30°C temperature and 30-50% by relative humidity.
Whitefly (Bemisia tabaci) is one of the important virus vectors. In North India, specially East U.P. due to playing significant role their control is must by their number and density by decreasing frequency of disease spread, yellow sticky trap catches showed high increase in number in March-April but the number is found decreased during rains most probably due to wetting of plant Leaves, so that Whiteflies could not settle down there and wander for proper settlement by moving to long distances. Conditions favouring whitefly build up are variable. The increase in count is correlated with temperature more positively and relative humidity [1,2].
First of all potted plants in replicates are made available and also the plot field is well prepared and selected for the experiment to proceed. The sticky traps of size 12×10 inches are prepared and then wrapped over by yellow polythene as vectors like Whitefly (Bemisia tabaci) are photosensitive for yellow colour. To enhance the trapping smear of vaseline coating is done over the surfaces of traps as well as on under surfaces (Abaxial) of host leaves. The number of Vector is counted in morning, noon and at evening. The traps faces should be in the direction of wind blowing (Table 1).
The experimental datas were collected in suitable bright light conditions for comparative point of view. It has been found that on abaxial surfaces of leaves of different plants, the density is terms of number is maximum as compared yellow sticky traps. This may be probably due to physiological behavioural difference as found between living and non living states. The increased number directly reflects the pattern of incidence of vectors like Whitefly (Bemisia tabaci) and evidence of population, transmission frequency and hence the symptomatic disease appearances. In different plants, there is found difference in the number of Whiteflies through which we can also analysis that vectors are more sensitive towards the attraction of plants rather than traps which may be biologically important in several other aspects [3,4].
By taking different variety of plants for the data obtained for counting of vectors, it can be diagnosed for cultivation point of view the type of plants to be cultivated for better production results.
Table 1: Observations, Findings and Analytical Calculation
| Plants selected | Use of adherent vaseline | No. of Whiteflies | Weather condition | Difference of White fly number in both | |
| Count from Abaxial surfaces of Leaves | Trap counting | ||||
| Bhindi | under surface | 89 | 39 | Bright light | 50 |
| Tomato | under surface | 75 | 41 | Bright light | 34 |
| Mung | under surface | 77 | 35 | Bright light | 42 |
| Cowpea | under surface | 92 | 37 | Bright light | 55 |
| Traps | Front surface | -- | 42 | Bright light | --- |
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