POPULATION DYNAMICS AND EFFICACY OF PLANT EXTRACTS AGAINST THE SPIRALING WHITEFLY, ALEURODICUS DISPERSUS RUSSELL (HOMOPTERA: ALEYRODIDAE)
Date
2012
Authors
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Publisher
HAJEE MOHAMMAD DANESH SCIENCE AND TECHNOLOGY UNIVERSITY, DINAJPUR.
Abstract
The spiraling whitefly, Aleurodicus dispersus Russell (Homoptera: Aleyrodidae) is the most
important and damaging pest of the guava orchards in Bangladesh, Seasonal abundance and
population trends of spiraling whitefly, A. dispersus and their natural enemies were observed.
Toxicity of eight plant extracts against A. dispersus was also studied. The result showed that
September to December was the peak infestation period and almost no damage was caused from April
to June. The abundance of adult, nymph and pupae of 4. dispersus were highest 5.0, 10.0 and 9.0
respectively. from September to December. The number sooty mould infested leaves were highest
(93%) in the month of October to January. Ladybird beetle Scymnus sp. (Coccinellidae: Coleoptera)
and Encarsia sp. (Aphelinidae: Hymenoptera) were also found as the predators of 4. dispersus during
the survey. Laboratory experiments were also conducted to test the efficacy of eight plant extract
against the adult 4. dispersus. Spraying (topical application) and dry film (residue on substrate)
methods were used to measure the toxicity of eight plant extracts. In addition, repellency of eight
plant extracts and their mixture against A. dispersus were also determined. The maximum (100%)
mortality of adults was recorded for neem (ethanol) spraying at 6 hours after treatment being 500
mg/L water with 50% acetone and were followed by nisinda (acetone), ata (acetone), biskatali
(acetone), vad (ethanol), vad (acetone) and akondo (ethanol) at 12 hours after treatment being 500
mg/L. In the residue on substrate experiment, the maximum (100%) mortality were recorded for neem
(ethanol) at 18 hours after treatment being 500 mg/L water with 50% acetone. The mixture of plant
extract neem (ethanol) + akondo (acetone); neem (ethanol) + roktokorobi (acetone) and neem
(ethanol) + ata (ethanol) exhibited a significant synergism against A. disperus. Finally the repellency
test of neem (ethanol) showed best response. All the applied doses has repellency and direct toxicity
effect. Neem (ethanol) possess the repellency class V followed by biskatali (ethanol), biskatali
(acetone) and akondo (ethanol). Therefore. the considerable infestation period of 4. disperus was trom
the month of October to February and plants extract may an alternative control method to suppress the
A. disperus in the guava orchard.
Description
Guava (Psidium guajava: Myrtaceae) is a major fruit crop and getting an important commercial
fruit in Bangladesh. It contains high food value like 36.50g calorie, 0.9-1.0g protein, 0.1-0.5¢ fat,
9.5-10g carbohydrates, 200-4001.U. carotene, 260mg vitamin C, some amount of minerals and
vitamin B complex per 100g edible fruit (Bose et al. 2001). Guava contains 82.5% water, 2.45%
acid, 4.45% reducing sugar, 9.73% total soluble solid, 0.48% ash and 260mg vitamin C per 100g
of fruit (Bose et al. 2001). A daily intake of only 20g fresh guava fruit can fulfill the vitamin C
requirements.
Guava is successfully grown in almost all the regions of Bangladesh. The Kazipiara, a guava
variety was released in Bangladesh in 1984 by Bangladesh Agricultural Research Institute
(BARI). The variety has high yielding potential and year round bearing ability. With the release
of Kazipiara a surprising increase in the guava production has occurred in Bangladesh (Rashid et
al., 1987).
Keywords
plant extracts, repellency