Biological Control of Insect Pests: Southeast Asian Prospects - EcoPort

Biology
Host plants
4.13
Ophiomyia phaseoli
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The adult O. phaseoli is a small fly (females 2.2 mm and males 1.9 mm in
length), shiny black in colour except for legs, antennae and wing veins,
which are light brown (Abul-Nasser and Assem 1966). Females generally
oviposit in bright sunlight in the upper surface of the cotyledons (soybeans)
or young leaves of its many hosts, laying from 100 to 300 eggs during a
2Ðweek period (Otanes y Quesales 1918). Not all ovipositor punctures
receive an egg, many provide sap which the females ingest (Goot 1930). On
hatching from the egg after 2 to 4 days, the young larva forms a short leaf
mine before tunneling into the nearest vein. Next the petiole is mined and the
larva then moves down the stem (Taylor 1958). In young plants the main
feeding takes place in the lower layers of the stem and the tap root may be
penetrated. When larvae are numerous, some feed more deeply inside the
stem and higher up in the plant.
The larval and pupal stages occupy 7 to 10 days and 9 to 10 days
respectively, resulting in a life cycle of about 3 weeks (Taylor 1958; Ooi
1988). However, the life cycle may be as short as 17 days in the field in
Malaysia (Khoo et al. 1991) and in the laboratory in India at 24¡ to 31¡C as
short as 11 days (Singh et al. 1991). At the other end of the scale, at higher
altitudes in Java, the larval stage can be extended from 17 to 22 days and the
pupal stage from 13 to 20 days (Goot 1930). Pupation occurs head upwards
beneath the epidermis and generally near the base of the stem (Greathead
1969). In older plants, larvae may pupate at the base of the petioles.
Talekar and Lee (1989) have developed a method for mass rearing bean
fly on newly-germinated soybean cotyledons, permitting one person to
produce 2 000 adults per day.
Bean fly is known to attack at least 40 plant species. Most of its important
hosts belong to the legume tribe Phaseoleae and particularly to the genus
Phaseolus.
The very susceptible P. vulgaris (French, kidney, haricot, runner
or snap bean) is of Central American origin as are several other economic
species of Phaseolus.
However, from the point of view of the possible origin
of O. phaseoli in Asia, all of the Asiatic species formerly placed in the genus
Phaseolus have now been placed in the genus Vigna (Verdcourt 1970) and it
is relevant that a number of important Vigna species are believed to have
originated in India or nearby (Purseglove 1968). These include
V. aconitifolia (moth bean), V. aurea (green or golden gram, mung bean)
V. calcarata (rice bean) and V. mungo (black gram, urd bean). Other
important hosts include Cajanus cajan (pigeon pea: origin Africa); Glycine