Aphidicidal activity of hot and cold water extracts of some indigenous plants, Azadirachta indica A. Juss (neem), Calotropis procera (Aiton) W.T. Aiton (akanda), Polygonum hydropiper L. (biskatali) and Ipomoea sepiaria J. Koenig ex Roxb.(bankalmi), were tested against the bean aphid, Aphis craccivora Koch. Hot water extract of P. hydropiper and A. indica was found to be the most eVective (87.6-94.5 and 80.47-89.6% mortality respectively, P < 0.01) among all the extracts. Other hot and cold water extracts also appeared to be useful (59.5-87.5% mortality) as pesticides for A. craccivora. The highest yield (3.25 kg per plant) was obtained using hot water extract of P. hydropiper followed by hot water extract of A. indica (3.15 kg per plant). The lowest yield (0.32 kg per plant) was recorded from the control block. All the phytoproduct treatments had signiWcantly (P < 0.01) better yield than the control block.

Impact of planting dates on Aphis gossypii Glover infestation and yields of eggplants was studied in the field. The aphid population was very low (4.75-31.05 aphids/plant) on the first planted crops. Yield of first planting dates were higher (1.56-3.58 kg/plant), however; aphid population on the successive late planting crops gradually increased and reached to peaks at third planting dates (15.51- 96.46 aphids/plant). Yield of eggplant gradually decreased on successive late planting crops and lowest yield recorded for third planting crops (1.06-1.88 kg/plant).DOI: http://dx.doi.org/10.3329/bjz.v39i2.10585 Bangladesh J. Zool. 39(2): 187-194, 2011

Context: Intrinsic rate of natural increase (rm) of Aphis gossypii is important factor to know the actual increase of population which is governed by physical factors of environment. Objectives:The aims of this study were to determine the intrinsic rate of natural increase (rm) of A. gossypii which is the basic knowledge of IPM program. Materials and Methods:The nymphal duration, pre-reproductive period, reproductive period, fecundity, longevity, etc. were observed within the glass chimneys. The newly born nymphs were considered as F1 generations. Similarly, the first progeny of F1 generation were released in other glass chimneys to have F2 generation. In this way, F3, F4 and F5 generations were obtained. Data for duration between birth of a nymph and its first laid progeny (d) and number of progeny (Md) per female were recorded. Altogether data of 8 replications were considered for the calculation of intrinsic rate of natural increase (rm) of A. gossypii infesting brinjal plants.Results: Intrinsic rate of natural increase (rm) value was highest (0.322 ± 0.005) for the F1 generation, followed by F2 (0.317 ± 0.003) and it was lowest (0.303 ± 0.002) for F5 generation. Temperature influenced the rm significantly (r= 0.903, p<0.05). Dew point also influenced the rm of A. gossypii significantly (0.882 P<0.05). Relative humidity played insignificant role (r= 0.428) on the rm of A. gossypii. Conclusion:The results obtained in this study are essential to know the actual populations increase which important to pest control.

Context: Lipaphis erysimi have different type of preference to settle on different varieties of mustard. Pest preferential movement is important for ecofriendly pest control. Objectives:The aim of this study was to determine the L. erysimi resistance varieties of mustard to get more yields by lower cost and avoid most aphid infesting varieties for higher cost Materials and Methods: Two criteria were used to determine the varietal preference of L. erysimi, viz. (i) dispersal of aphids by cutting the base of host plants and enforce to settle on different varieties of three species of Brassica under free choice conditions, and (ii) suitability of those varieties based on the aphid infestation in the field crop condition at same season. Results:The preferential movement of L. erysimi on ten varieties of Brassica showed significant differences (P<0.01). The variety, Bari sharisa-6 showed highest (90.00 ± 7.21) aphid settlement followed by the variety, Rai-5 (89.00 ± 5.69). The variety, Bari sharisa-10 showed lowest (10.00 ± 0.58) aphid settlement followed by the variety, Bari sharisa-11 (19.00 ± 3.61). Naturally infested aphid population on first sowing date was recorded highest (2.1 ± 0.79) on the variety Bari Sarisha-8, followed by Bari Sarisha-6 (1.93 ± 0.88). The lowest (0.19 ± 0.09) number of aphids recorded on Bari Sarisha-12. In second sowing date, Bari Sarisha-7 showed highest (19.5 ± 6.51) aphid population, followed by Bari Sarisha-8 (15.42 ± 5.72). The lowest (1.2 ± 0.38) aphid population found on the variety, Bari Sarisha-11. In third sowing date, highest (14.69 ± 5.69) number of aphids was recorded on the variety, Bari Sarisha-6, followed by the variety, . Lowest number (6.06 ± 2.30) of aphids was found on the variety, Bari Sarisha-12. In the fourth sowing date, highest (15.54 ± 5.72) aphid population recorded on the variety, Bari Sarisha-8, followed by Bari Sarisha-7 (14.39 ± 5.70); and the lowest (4.41 ± 1.75) number of aphids recorded on the variety, Bari Sarisha-9.