and Integrated Pest Management - part - usaid

IPM OF PLUTELLA XYLOSTELLA (L.) ON
VEGETABLES IN SOUTHEAST ASIA: RATIONALE,
NEED, AND PROSIPECTS
G. S. Lima
Scnior Research Officer
Malaysian Agricultural Research and Development Institute (MARDI)
P.O. Box 12301, Selangor, Malaysia
There are many accounts of the importance of the Diamondback Moth
(DBM), Pltella xylostella (L.) (Lcp: Yponomcutidac) (AVRDC 1986), with at
least 128 countries listing it as a pest of concern (CIE 1967, Salinas 1972).
Prominent among these are the Southeast Asian countries. In this region in
particular, the DBM poscs a serious limiting factor in the production of
crucifcrs. For example,Quebral and Carainancion (1972) reported that farmers in
the Philippines experienced extcnsivc yield losses, sometimes up to 100% if no
insecticidal control was instituted. SimilJar situations have also been encountered
elsewhere in Ilndonc:ia (Sudarwohadi 1975), Malaysia (Ho 1965), Singapore
(CInto 1973), and Thailand (Rushl.pakornchai & Vattanatangum 1986).
Among the cruciferous vegetables in cultivation, cabbage ranks highest both
in quantity and area (Lirm 1982, Magallona 1986, Rush tapakornchai &
Vattanatangum 1986). A recent mail survey revealed that the extent ranges from
beLwecn 1,000 and 10,000 ha in countries like Thailand and Malaysia to more
than 30,000 ha in Indonesia. For the Philippines, the estimated annual
production in 1972 was more than 49,500 tons with a value of $5.4 million
(Magallona 1986). In Malaysia the crop value for 1964-74 averaged $6.1
million (Lira 1972). Cabbage cultivation, therefore, contributes a sizeable
soutrce of income towards the livelihood of many vegetable fanning households.
Since DBM can be so destructive, its control during the production of
cabbage (and other crucifers) has commanded top priority among the farmers
concerned. In nearly every situation a unilateral approach, which relies solely on
chemical insecticides that are used indiscriminately, has been the practice. I-low
this has come about shall be examined in this paper, as well as the associated
problems and their implications. A critical appraisal will also be attempted with
the aim of determining necessary direction for future action.
FARMERS' PERCE.PTIONS OF DINI AND THEIR CONTROL
PRAC TI CES
Inall the Southeast Asian counlries where crucifers are cultivated, DBM has
been perceived by farmers to be a very serious, if not the most important, insect
pest. An attitude of desperation exists in most situations, leading farmers to
resort to rampant insecticide use. To the farmers, cultivation of crucifers
(especially cabbage) is not possib!c %vilhoutextensive use of insecticides. Not