Hypsipyla Shoot Borers of Meliaceae in Sri Lanka - Australian ...

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successful open plantings was a coastal site originally carrying wet sclerophyll forest (ING442) that produced height MAI of 1.2 m over 8.8 years. Steady growth continued to produce height and DBH MAIs of 1.0 m and 1.24 cm by 20.8 years (Cameron and Jermyn 1991). Swietenia macrophylla trees survived well in the hot, dry, conditions of Weipa (ATH399), resulting in trees with MAI of 1.7 m and 0.47 cm at 4.5 years for height and diameter respectively. Unfortunately, form was generally poor with problems including crown breaks at an early age, multiple leaders, heavy lateral branching, and crooked boles. The success of some plantings in north Queensland led to the establishment of further trials investigating provenance differences (ATH559, ATH691). One trial demonstrated differences in survival and growth rates of young trees from two families from Puerto Rico. Overall, the results were disappointing, possibly due to site degradation following clearing and burning (Cameron and Jermyn 1991). A second trial (ATH691) used seed collected from Bolivia, but results have not been recorded. Failure of most plantings was attributed to the combined effects of H. robusta feeding, cattle browsing and severe competition from grass. Trees were damaged by H. robusta in all trials, but damage levels were often low to negligible during the first few years of growth. When planted with T. ciliata, damage levels were lower on S. macrophylla than on T. ciliata and S. macrophylla showed better recovery following attack. Species not adequately assessed (Table 6) Cedrela augustifolia Sesse & Moc. An open planting of C. augustifolia was established in North Queensland (ATH726). The area was badly affected by frost in the first year, resulting in 53% mortality. The surviving trees showed good growth, with mean height of 2.08 m after 1.5 years. Cedrela lilloi C. DC. Experimental plantings of C. lilloi were established in subtropical forests of New South Wales between 1952 and 1958 (Wyatt 1984). The species generally grew best in enrichment plantings with height MAI of up to 1.1 m for the first few years. Trees grew less well when under-planted to Araucaria cunninghamii. Chukrasia tabularis Chukrasia tabularis showed good survival (>90%) and early growth in plantings in North Queensland, achieving MAI in height of 0.8 m to 1.0 m in the first 5 years. However, tree form was poor with heavy 50 branching as a result of repeated damage by H. robusta. This species merits further genetic resource trials since some individual trees grew well (Shea 1992). Khaya ivorensis A. Chev. The best growth of K. ivorensis occurred in an enrichment planting on logged and treated rainforest in North Queensland. After 10 years, MAI of 0.67 m for height and 0.75 cm for DBH were recorded (ATH166). Under these conditions, K. ivorensis outperformed K. senegalensis and S. macrophylla. Open plantings have been less successful, due to high mortality, slow growth and poor form caused in part by frost damage. Swietenia mahagoni (L.) Jacq. The growth rate and form of this species was poorer than that of S. macrophylla. Damage from H. robusta was not recorded. Species in terminated trials (Table 7) Entandrophragma utile (Dawe & Sprague) Sprague An open planting of E. utile was established in north Queensland in 1982; however, results of this trial have not been reported. Khaya anthotheca (Welw.) C. DC. A single trial of K. anthotheca was established in 1982 as an open planting on a silty clay loam cleared of open forest in north Queensland. Very poor survival and growth was reported after 8 years. Swietenia macrophylla × mahagoni Swietenia macrophylla × S. mahagoni hybrids have been planted in North Queensland (ING536). Hybrid trees grew at comparable rates to S. macrophylla achieving MAI of 1.1 m in height and 1.4 cm in DBH and after 14 years (Cameron and Jermyn 1991). Despite showing good early growth, the hybrid has not been planted since the early 1970s. Cedrela microcarpa C. DC. A single planting of this species near Imbil in southeast Queensland was a failure but the reason for failure was not recorded. Hypsipyla Research in Australia Many areas of H. robusta biology and control have received some attention in Australia (Table 8).
Table 8. Summary of current and past research effort on various aspects of Hypsipyla robusta biology and control. o – none; * minor; ** major. Area of study Current research Biology Past research Biology Taxonomy * o Life history ** * Ecology in natural stands * * Ecology in plantations * * Population dynamics * * Natural enemies * * Other o o Control Biological control o o Chemical control o * Silvicultural control * ** Host resistance * o Pheromones * o Genetic engineering o o Other o o There have been few attempts to investigate directly the biology, ecology or taxonomy of H. robusta in Australia. This is despite the recognition of the critical role of the species in limiting the commercial planting of T. ciliata. Early biological observations were made by Froggatt (1923, 1927) and staff of the Queensland and New South Wales forestry services, much of which is contained in unpublished reports. More recent work has been undertaken by Griffiths (1997) and Mo (1996). These studies confirmed that the shoots, fruits and the flowers of T. ciliata and the fruit of the closely related Xylocarpus mangrove species are fed upon by H. robusta in Australia. Infestation of young T. ciliata trees was positively correlated with rainfall and, to a lesser extent, temperature. Infestations were concentrated on opengrown trees, trees greater than 1.5 m high, and shoots in the upper canopy. The percentage of shoots attacked per tree decreased as tree size increased. More than 75% of eggs were laid on leaves. When ovipositing on young trees, H. robusta preferred the upper leaf surface to the lower leaf surface, and was least inclined to choose the stem and petiole. When laid on fruits, eggs were often deposited among or close to the frass and borings of previous damage. Losses of both eggs and early instar larvae were high on young T. ciliata trees. Initial feeding was concentrated in the terminal foliage with larvae wandering extensively before and in the few days following their first feeding. Feeding bioassays confirmed the existence of feeding stimulants in the ethanol extracts of young shoots. 51 The number of larval instars ranged from five to seven under laboratory conditions. This developmental polymorphism is also likely to be a characteristic of natural populations. Success of matings was increased by exposure to light and wind. Observations on the patterns of female calling, mating and flight activity indicated that mated females are responsible for host finding. There are considerable differences in the biology and behaviour of the species in Australia when compared with other regions. For example, Australia and northern India share a similar climate and have the same species of host trees, however, Australian populations lack a distinct sequence of larval generations feeding on different plant parts, have a very low incidence of flower feeding, and have other behavioural and physiological differences in larvae feeding on fruit. These differences call into question the assumption that H. robusta is one species. Biological control Although there has been some reference to the possibility of obtaining control of H. robusta in Australia through utilising natural enemies (Jolly 1914; Queensland Forest Service 1921; K.G. Campbell, formerly of the Forestry Commission of New South Wales, pers. comm.) this possibility has never been addressed. A number of reports have identified insect parasitoids and insect, bird and mammal predators associated with H. robusta in Australia (Queensland Forest Service 1921; Girault 1938; Campbell pers. comm.). However, most of these are generalist species and offer little potential as biological control agents (Sands and Murphy these Proceedings). Chemical control Chemical control of H. robusta has been investigated in Australia since the early 1920s with the initiation of at least 13 insecticide trials utilising 12 different compounds. Most trials failed or were terminated after only one season. The insect has proved difficult to control due to its concealed feeding habit, long period of activity, the tropical climate in which it occurs, low damage threshold of the host, and long protection period required. Many trials have been hampered by logistical problems including a lack of moth attack, severe damage from other insects, equipment failure, and loss of trees to frost, cyclones and hormone spray. In addition, the scheduled spray regimes were frequently disrupted by rain and flooding. Contact poisons such as DDT and endrin provided reasonable to good control in some trials. However, the required frequency of application, particularly in the tropical north where the period of heaviest
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Page 9 and 10: 26° 21° WEST BENGAL (INDIA) PACHA
Page 11 and 12: The only harvesting of Swietenioide
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Page 21 and 22: T. ciliata grows in dry deciduous f
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Page 25 and 26: S. macrophylla and Swietenia mahago
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Page 41 and 42: of these species, plantings have be
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Page 53 and 54: Mr David Spolc (University of Queen
Page 55 and 56: Haley, C. 1954. Forestry in Tropica
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