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Effects of Methanol Extracts of Neem A. Indica Seed Extracts on Epilachna Beetle

Kh. S. Islam
Department of Entomology, Bangladesh Agricultural University, Mymensingh

B.N Islam
Department of Entomology, Bangladesh Agricultural University, Mymensingh

Abstract/ Executive Summary:

The effects of extracts of neem ( Azedirscht indica A. Juss.) seed kernel, prepared with methanol, on the feeding behaviour and growth responses of larvae. fecundity and egg viability of Epilachna dodecastigma Muls. were investigated. Laboratory studies indicated that the larvae were deterred from feeding on neem seed kernel extract (NSKE) treated leaves. Cessation of food intake increased with higher concentrations. 90% and 75% mortality were observed in first instar larvae when fed on the leaves treated with 0.5% and 0.25 % NSKE. respectively. Later instars were less susceptible. larval weight gains were poor feeding on the NSKE treated leaves. Pupal mortality was also significant. Characteristic discolorations occurred in the fourth ins tar larvae and pupae developed from the larvae fed on NSKE treated plants, Fecundity and viability of eggs reduced significantly when NSKE treated food leaves were offered to both the larvae and adults. Egg laying was almost fourteen times less than those in the control.

Keywords: MethanoI extracts, Neem seed, Beetle

Location: Department of Entomology, Bangladesh Agricultural University, Mymensingh

Start Date:

End Date:

Program Area: Pest Management

Commodity: Insects

Objectives:

To investigate, (i) the effects of neem seed kernel extracts on the feeding rate, growth and development of the larvae of Epilachna dodecastigma Muls. and (ii) the fecundity and egg viability of the adult beetles,

Methodology:

Seeds of A. indica were collected from the northern region of Bangladesh. Fifty gm of neem seed kernels were powdered in an electric grinding machine. The ground neem seed kernels were stirred at room temperature (30°C) by a magnetic stirrer with 1 litre methanol for 3 hours. The mixture was left to stand for 20 hours and again stirred for another hour and filtered. The solvent was allowed to evaporate in porcelain dishes and the residues were dried to a constant weight in an oven at 40°C. A hard brownish wax of Neem Seed Kernel Extract (NSKE) was obtained. The extract was dissolved in 85% aqueous methanol and diluted to prepare 0.01, 0.1, 0.25, and 0.5% concentrations. In the laboratory. the seedlings of rim bed gourd. Luffa eeutenqut (L.) Roxb. were grown in plastic pots. Each pair of beetles. E. dodecestiqme collected from the Horticulture Farm. Bangladesh Agriculture University was reared on the leaf discs of 20-25 days old seedlings of ribbed gourd. Larvae from laboratory stock culture were used for different tests. The ribbed gourd seedlings were sprayed uniformly with four concentrations of the extract separately using 100 ml atomizer. Control seedlings were sprayed with water only. One pair of larvae of each instar was released on a plant and allowed to feed on and this was replicated five times. Feeding responses of the larvae were observed from first to final instars. The area consumed by each larval Instar and also by total larval period was measured by a square millimeter graph paper. The consumption rate per larval instar was examined. The newly moulted larvae were fed on the treated leaves. Data ware also collected on larval duration and larval rnortality. Larval duration of differnt instars was observed at every 1 2 hours and expressed in days. In another experiment. the leaf consumption rate was assessed from same larva during the entire larval per iod. Here weekly sprays were made starting from the time of releasing the larvae immediately after hatching. Weight of last instar larva was recorded only. Abnormalities in larval and pupal stages were noted. Pupal mortality wail also recorded. In determining pupal mortality, the extracts were applied topically on the prepupae and pupae. The surviving adults .emerging from the pupae developed from larvae fed on treated leaves were again provided with N S K E treated leaf discs to feed for three days and allowed to mate. The number of eggs laid by them and the viability of the eggs were determined.

Source of Information: Bangladesh J. Agril. Scl. 15 (1): 27-32, 1988

Article Link (Online Journal):

Funding Source:

Total Budget (Tk.) :

Achievement/Findings:

Laboratory studies indicated that the larvae were deterred from feeding on neem seed kernel extract (NSKE) treated leaves. Cessation of food intake increased with higher concentrations. 90% and 75% mortality were observed in first instar larvae when fed on the leaves treated with 0.5% and 0.25 % NSKE. respectively. Later instars were less susceptible. larval weight gains were poor feeding on the NSKE treated leaves. Pupal mortality was also significant. Characteristic discolorations occurred in the fourth ins tar larvae and pupae developed from the larvae fed on NSKE treated plants, Fecundity and viability of eggs reduced significantly when NSKE treated food leaves were offered to both the larvae and adults. Egg laying was almost fourteen times less than those in the control.

Knowledge Management: Journal