EVALUATION OF THE VERTICAL DISTRIBUTION METHOD IN SURVEYING IMMATURES OF THE SILVERLEAF WHITEFLY, Bemisia argentifolii BELLOWS & PERRING, ON FOUR PLANT HOSTS. | ||||
| Journal of Plant Protection and Pathology | ||||
| Article 3, Volume 25, Issue 10, October 2000, Page 6543-6555 PDF (873.03 K) | ||||
| Document Type: Original Article | ||||
| DOI: 10.21608/jppp.2000.259639 | ||||
 View on SCiNiTO | ||||
| Author | ||||
| N. F. Abdel-Baky, | ||||
| Economic Entomology Department, Faculty of Agriculture, Mansoura University, Mansoura-35516, EGYPT. | ||||
| Abstract | ||||
| Field experiments were conducted during the two seasons of 1997 & 1998 to evaluate the vertical distribution method in surveying the silverleaf whitefly (SLWF) immature stages on the four hosts, cotton, cucumber, cantaloupe and cabbage. The results revealed that the vertical distribution of eggs and nymphs was similar on the four hosts. The majority of eggs were found on the newly formed leaves followed by upper-middle and middle leaves. The lowest number was recorded on lower and middle-lower leaves. The percentages of eggs on the top and upper-middle leaves ranged from 31.43 to 40.61, 23.93 to 26.24% in 1997 and 34.40 to 38.07, 25.11 to 27.42% in 1998, respectively, on various plant hosts. Meanwhile, the corresponding percentages were 3.35-10.06 and 5.13-7.05% on the lower leaves during 1997 and 1998. The same trend was observed with the nymphs on the lower to upper leaves of the plant. The high population densities per sample were recorded on the lower leaves with percentages varying from 35.33 to 41.07 in 1997 and 35.93 to 40.28 in 1998. The densities on the middle-lower leaves came next, being 27.91 to 28.54% in 1997 and 27.47 to 30.86 in 1998. There were no nymphs on the new-formed leaves of all four hosts except cabbage plant. The distribution of nymphal instars of SLWF, on the same plant, was discussed. The immature counts from the different combinations of top, top-middle, middle, middle-lower and lower leaves of the whole-plant were compared with those sampled as an indication of immature levels within field population. The results proved the efficiency of vertical distribution in surveying SLWF immature stages. Field experiments were conducted during the two seasons of 1997 & 1998 to evaluate the vertical distribution method in surveying the silverleaf whitefly (SLWF) immature stages on the four hosts, cotton, cucumber, cantaloupe and cabbage. The results revealed that the vertical distribution of eggs and nymphs was similar on the four hosts. The majority of eggs were found on the newly formed leaves followed by upper-middle and middle leaves. The lowest number was recorded on lower and middle-lower leaves. The percentages of eggs on the top and upper-middle leaves ranged from 31.43 to 40.61, 23.93 to 26.24% in 1997 and 34.40 to 38.07, 25.11 to 27.42% in 1998, respectively, on various plant hosts. Meanwhile, the corresponding percentages were 3.35-10.06 and 5.13-7.05% on the lower leaves during 1997 and 1998. The same trend was observed with the nymphs on the lower to upper leaves of the plant. The high population densities per sample were recorded on the lower leaves with percentages varying from 35.33 to 41.07 in 1997 and 35.93 to 40.28 in 1998. The densities on the middle-lower leaves came next, being 27.91 to 28.54% in 1997 and 27.47 to 30.86 in 1998. There were no nymphs on the new-formed leaves of all four hosts except cabbage plant. The distribution of nymphal instars of SLWF, on the same plant, was discussed. The immature counts from the different combinations of top, top-middle, middle, middle-lower and lower leaves of the whole-plant were compared with those sampled as an indication of immature levels within field population. The results proved the efficiency of vertical distribution in surveying SLWF immature stages. | ||||
|
Statistics Article View: 35 PDF Download: 143 |
||||
