Biological Control of Insect Pests: Southeast Asian Prospects - EcoPort

Biology
Host plants
4.11
Leucinodes orbonalis
187
The flat, oval eggs are mostly laid at night, either singly or in groups of 2 to 4
(and up to 200 per female), on the lower surface of young shoots, flower
buds and calyces of developing fruits. They hatch in 4 days at an optimum
temperature of 30¡C and relative humidity of 70% to 90%. Larval
development occupies 14 days and pupal development 19 days. With a
preoviposition period of 2 days, this results in a generation time of about one
month. Details from three authors are shown in Table 4.11.1. Up to 9 larvae
have been found in a single fruit and, when mature, pupate within a tough
silken cocoon on the fruit, stem or among ground litter (Tamaki and Miyara
1982; Khoo et al. 1991; Yin 1993). In the absence of fruit, larvae feed on the
growing points of the plant. In the plains of India it occurs throughout the
year but, at higher altitudes, cold weather interrupts its development and it
overwinters as a larva in a silken cocoon, usually 1 to 3 cm below the soil
surface. It is capable of surviving temperatures as low as Ð6.5¡C (Lal 1975).
It thrives best under warm, moist monsoonal conditions. L. orbonalis can be
reared in the laboratory on dried eggplant fruit or on a semi-synthetic diet
(Islam et al. 1978, Patil 1990). Virgin females produce a pheromone that
attracts males (Gunawardena 1992; Yasuda and Kawasaki 1994).
In addition to eggplant, which is its main host, L. orbonalis is reported to
feed on several other Solanum species, e.g. S. tuberosum (potato: shoots
only) (Fletcher 1916; Mehto et al. 1980; Isahaque and Chaudhuri 1983),
S. nigrum (black berry nightshade) (Nair 1967; Das and Patnaik 1970;
Isahaque and Chaudhuri 1983 ), S. indicum,
S. myriacanthum (shoots only)
(Menon 1962; Isahaque and Chaudhuri 1983) and S. xanthocarpum (Menon
1962). It has also been reported from tomato ( Lycopersicon esculentum)
(Hargreaves 1937; Das and Patnaik 1970), potato ( Solanum tuberosum)
and
several unexpected plants, including cape gooseberry (Pillai 1922), green
pea pods (Hussain 1925), mango shoots (Hutson 1930), cucumber, sweet
potato and capsicum (Whittle and Ferguson 1987). Screening egg plant
varieties for resistance to L. orbonalis has revealed several that are relatively
resistant. Thick-skinned varieties appear to be more resistant (Patil and Ajri
1993; Patel et al. 1995).