Contents - LAC Biosafety

10.16 Swietenia species (Meliaceae) 305
the egg-laying female. Studies on S. macrophylla in West Java, Indonesia, showed
that the degree of infestation of H. robusta decreased with the increasing age and
height of the tree. Infestation was about 90% for trees aged 3 years or 2.5 m high,
decreasing to less than 5% for trees older than 14 years or taller than 13 m
(Morgan and Suratmo, 1976; Suratmo, 1977). Seedlings in nurseries are also
often attacked (Beeson, 1941; Ambika-Varma et al., 1996). In exceptional cases,
infestation has been found in the crowns of 50-year-old plantation trees, 45 m in
height, in north Queensland, Australia (Nair, 2001a). According to Wagner et al.
(1991), on Khaya species in Africa H. robusta feeds extensively on the soft, living
bark of the terminal stem of saplings, causing heavy sap exudation. But recent
morphological and molecular studies indicate that the so-called African
H. robusta is a separate species and that two different Hypsipyla species are
present on Khaya in Ghana (Marianne Horak, unpublished report, 2000).
In young mahogany plantations, incidence of Hypsipyla attack is usually
heavy. In plantations in Kerala, in southern India, about 70% of plants in three to
four-year-old plantations were attacked, with less damage in younger and older
plantations (Mohanadas, 2000). In some plantations in India, 100% infestation
has been recorded by the second year (Beeson, 1941).
Retardation of growth in the early years of establishment of a plantation is a
serious disadvantage, but more damaging is the formation of forked, crooked or
branchy boles. Consequently, many mahogany plantations have been abandoned
on account of Hypsipyla damage in Asia-Pacific, Latin America and Africa (Beeson,
1941; Newton et al., 1993; Wagner et al., 1991). Nevertheless, since shoot borer
incidence is usually confined to the sapling stage, many abandoned plantations
have survived and fared well later.
Host range and geographical distribution Hypsipyla species are polyphagous on
tree species of the subfamily Swietenioideae of Meliaceae. Recorded hosts
include Carapa guianensis, C. grandiflora, C. procera, Cedrela odorata, C. lilloi,
Chukrasia tabularis, Entandophragma angolense, E. candollei, E. cylindricum, E. utile,
Khaya anthotheca, K. grandifolia, K. ivorensis, K. nyasica, K. senegalensis, Lovoa
trichilioides, Pseudocedrela kotshyi, Soymida febrifuga, Swietenia macrophylla,
S. mahagoni, Toona ciliata, T. sinensis, T. sureni and Xylocarpus moluccensis (Beeson,
1941; Wagner et al., 1991; Speight and Wylie, 2001). Either H. grandella or
H. robusta is present wherever the host trees are grown in the tropical,
subtropical and temperate regions, with the exception of Fiji and some smaller
islands in the Pacific, which the insect has not reached due to geographic
isolation. It was found in the Pacific island of Vanuatu only in the year 2000.
H. grandella occurs in Latin America and southern Florida and H. robusta in
South and Southeast Asia, Australia and West and East Africa. A third species,