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DAMACE ASSESSMENT ON STORED MUNGBEAN AND SOYBEAN BY THE COMMON BEAN WEEV1L

TABLE1

Effecis of Callosobruchus maculatus infcstation on four varieties of mungbcan in storage

Parameter	No. of weevils'				% damaged grain				% germination
Storage Period	1	3	5	Mean^2	1 *	3	5	Mean	1	3	5	Mean
(mths.)
Variety EG. Glabrous	235	2972	3526	2133.2b	14.3	100	100	71.45a	84	0	0	28.0a
MG. 50-10A	185	3750	3987	2487.2a	11.5	100	100	70.5 la	84	0	0	28.Oa
V 1968	183	2771	3335	2096.2b	5.8	100	100	68.66b	91	0	0	30.22a
U Thong	101	2749	3602	2150.2b	6.0	100	100	68.58b	89	0	0	29.56a
^:*Mean	I76a	3060.5b	3612.5c		9.4a	lOOb	lOOb		87a	Ob	Ob

¹    Dala includes maturę and immature insects

²    Values wiihin columns follbwed by the same leuer are not significandy different at P=.05 by DMRT ⁵Values wiihin rows followed by the same letier are not significandy different at P = .05 by DMRT'

C. maculatus in soybean wasdue to the presenceof saponins which inhibit larval development (Applebaum etai 1965).Saponinsmay beregarded as specific metabolic defense mechanisms of soybean which have evolved against insects.

The percentage ofdamaged grain isconsider-ed Iow (<8%)for all the varieties. During the one-month storage period, no damaged grains were re-corded (based on the presence of emergence holes). HoweandCurrie (1964) reported that the development period (larval to adult) and survival (percentadultemergence) of C. maculalusvłasIow on soybean and that body size was smaller, which explains the Iow increase in the number of C.

maculatus and the Iow percentage damaged soy-beansobserved in ourstudy.

Generally, the percentgermination decreased during storage up to the fifth month. Variety KS 437 had the lowest average percent germination (15%) while vari ety Palmet to had the highestaver-age (83.3%). The lattervariety supported the lowest population of C. maculatus and suffered the least grain damage. It isadvisable then for soybean food manufacturersand farmerstoselect Palmetto if the soybean is to be stored for about 6 months.

Compared to m u ngbean, soybean appeared to be morę resistant to a t tac k by C. maculatus, resulting in a lower increase in numbersand damaged grain.

TABLE2

Effecis of Callosobruchus maculatus infestation on five varieties of soybean in storage

Parameter	Density increase^1				% damaged grain				% germination
Storage Period (mths.)	1	3	5	Mean^2	1	3	5	Mean	1	3	5	Mean
Var. ety Disoy	20	36	63	39.7a	0	3.28	8.16	3.81a	71	49	26	48.67 b
KS 437	20	29	51	33.33a	0	1.65	4.96	2.20ab	30	9	6	14.89c
Jupiter	20	28	28	25.33a	0	0.73	2.75	1.16ab	54	5	10	19.78c
Palmetto	20	24	32	25.44a	0	0.54	0.54	0.79b	97	95	58	83.30a
Acadian	20	22	22	21.33a	0	0.24	0.24	0.31b	79	20	22	40.44b
*Mean	20a	27.8a	39.2b		Ob	1.29b	3.33a		66.2a	35.6b	24.1 lc

Data includes maturę and immature insects

-Yalues within columns followed by the same letter are not significandy different at P=.05 by DMRT *Values within rows followed by the same letter are not significandy different at the P-.05 by DMRT

PERTANIKA VOL. 14 NO.l. 1991 29