Contents - LAC Biosafety

258 Insect pests in plantations: case studies
specifically recorded in Dehra Dun, Madhya Pradesh, Uttar Pradesh, Maharashtra
and Kerala.
Nature of damage and impact As a result of feeding by the adults and
nymphs, the leaves become spotted and discoloured and wither. Eventually the
shoots die back. In an outbreak in a year-old, 10 ha plantation in Kerala, southern
India in 1978, 67% of the saplings were infested, of which 21% suffered total
defoliation while the remainder suffered varying degrees of leaf fall. Heavy
infestation was concentrated over a patch of about two hectares where there was
total defoliation (Nair and Mathew, 1988). In this patch, most saplings later
showed dieback of shoots and epicormic branching. In Madhya Pradesh, India,
Harsh et al. (1992) found that the insect attack was followed by infection of the
plant by the fungus Hendersonula toruloidea (Nattrassia mangiferae) which was
characterized by black necrotic lesions at leaf bases, followed by defoliation and
drying of young shoots. They found that spraying a mixture of insecticide and
fungicide (0.02% monocrotophos and 0.1% carbendazim) controlled the damage.
Natural enemies No natural enemies are on record.
Control Nair and Mathew (1988) found the systemic insecticide,
dimethoate, ineffective against T. beesoni in field trial, but lindane was effective.
As noted above, Harsh et al. (1992) recommended a combination of insecticide
and fungicide because of the additional infection by a fungus. Meshram and
Tiwari (2003) recommended application of the synthetic pyrethroid, deltamethrin
(0.005%) and the fungicide, carbendazim (0.1%), at 15-days interval.
Knowledge gaps There is little information on the natural control agents
of T. beesoni and on the seasonal population trend of the pest in areas where there
is no well-defined winter season. The circumstances under which outbreaks of
T. beesoni population occur are not understood.
10.10 Leucaena leucocephala (Fabaceae: Mimosoideae)
(Common name: leucaena)
Tree profile
Leucaena leucocephala (Lam.) de Wit is a multipurpose legume native
to Mexico and some parts of Central America, within 16°N to30°Nlatitude. Because it is cultivated throughout region, its true natural distribution is
obscure (CABI, 2005). Two major varieties are recognized – the Hawaiian shrubby
variety that grows up to 8 m tall and the giant or Salvador variety that grows up
to 16 m tall. Due to its several uses – for fodder, green manure, fuel, shade for