8342937087

Pertanika 14(1), 27-30 (1991)

Damage Assessment on Stored Mungbean Vigna radiota (L.) Wilczek and Soybean Glycine max L. Merr Infested with the Common Bean Weevil, Callosobruehus

maculatus (F. )(Coleoptera:Bruchidae)

NOORMA OSMAN. ROHANIIBRAH1M

and

ABANG BOHARI ABANG JOHARI

Department ofPlant Prolection, Faculty oJAgńculture.

Universiti Pertanian Malaysia 43400 L JPMSerdang, SelangorDartilEhsan, Malaysia.

Keywords: Calosobruchus maculatus, mungbean, soybean, damage assessment

ABSTRAK

Taksiran kerugian oleh Callosobruehus maculatus (F.) keatas empat varieti kacanghijau dan lima vańeli hacang soya telah ditentukan. Seratus gram tiap-tiap satujenis dan vańeti kekacangini di simpan dałam bekas plastik yang lutsinar bersama 20 ekordeiuasaC. maculatus. Para meter yang di teliti ialah kenaikan populasi, peratus bijirin rosak dan peratuspercambahan. Pada kacanghijau, bilangan ku mbangdewasa adalahfmling tinggi dałam vańeti MG 50-10A dan rendah dałam vańeti V1908(P<0.05). Kesemuakacanghijau rosakselepas 3bulandisimpan. Oleh itu kadar percambahan tidak dapat ditentukan. Pada kacangsoya, bilangan kumbangdewasa meningkat 20-215 % dałam kesemua uarieli melainkan A ta dian. Pada umumnya peratus kacangsoya yang rosak adalah rendah (<8%) manakala peratus percambahan yangpalingtinggi terdapat dałam uarieti Palrnetto (P<0.05). Dibandingkan dengan kacang hijau, kacang soya menghasilkan kurang kenaikan populasi, peratus bijirin rosak yang rendah dan peratus percambahan yang tinggi. Kacang soya adalah lebih sesuai untuk disimpan selama 3-5 bulan tanpa mendapat serangan he.bat dań perosak i ni.

ABSTRACT

Damages to thegrains by Callosobruehus maculatus (F.) on fourvańeties oj mungbean and Jive oj soybean were assessed. One hundred grams ojeach type and vańety of beans plus 20 adults oJC. maculatus were placed in a transparent plastic Container. The paramateres measured were weevil density, percentage oj damaged grains and percentageseedgermination. In mungbean, thenumberojadult weeiul was highest in vańety MG 50-1OA andlowest in \ 1968 (P< 0.05). Germination ratę could not be assessed as beans were 100 % da maged after 3 rnonths ojstorage. In soybean, weevil density inereased Iry 20-215 % in all nańeties except Acadian. The percentage oj damaged grain was Iow (<8%) Jor all nańeties. The percentage oj germination is significantly highest in v ariety Palrnetto (P<0.05). Compared to mungbean, soybean had a lower populalion inerease, lower percentage damaged grain and higher jur cent age germination. Soybean can be stored Jor 3-5 rnonths with minor infestation frorn this fiest.

INTRODUCTION

I he bruchid, Callosobruehus maculatuscommonly known as common bean weevil isan importantpest ol stored cowpea, Vigna unguiculata Walp. and other tropical grain legumes. Crop damage by C. maculatus Ai harvest is usually less than 10% but infestation could build up rapidly during seed storage. Thirty seven to 60% o! the seeds may exhibit emergence holes within 4-6 rnonths of storage (Jotwani 1964). Losses in seed weight and qualityareconsiderable under poor conditionsof storage, a situation common in developing countries.

In 1986', Malaysia imported 284,584 tons of beans, worth 166,705 thousand ringgit (Anon. 1986). This figurę is expected to inerease in the followingyears. Data on crop loss assessment under Malaysian conditions is not available. In India, Yadar etai( 1968) recorded a weight loss of 15% in grams and 16% in * kabul gram* (Cicer ańetinum).