Use of grafting to prevent Hypsipyla grandella (Zeller) (Lepidoptera: Pyralidae) damage to new world Meliaceae species

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Use of grafting to prevent Hypsipyla grandella (Zeller) (Lepidoptera: Pyralidae) damage to new world Meliaceae species

Julian Perez^I; Sanford D Eigenbrode^II; Luko Hilje^III; Robert R Tripepi^II; Maria E Aguilar^III; Francisco Mesen^IV

^IColegio de Postgraduados - Campus Tabasco, Periférico Carlos A Molina s/n km 3.5, 86500 H. Cárdenas, Tabasco, México; [e-mail]

^IIUniv of Idaho, Dept of Plant, Soil and Entomological Sciences, 83844-2339 Moscow, ID, USA; [e-mail]; [e-mail]

^IIICATIE, Dept of Agriculture and Agroforestry, 7170, Turrialba, Costa Rica; [e-mail]; [e-mail]

^IVInternational Consultant Forestry, Cartago 7050, Costa Rica; [e-mail]

ABSTRACT

The susceptible species Cedrela odorata and Swietenia macrophylla to attack by Hypsipyla grandella (Zeller) larvae were grafted onto the resistant species Khaya senegalensis and Toona ciliata. Six-month-old grafted plants were then compared to their reciprocal grafts and to both intact (non-grafted) and autografted plants for damage due to H. grandella larvae and for their effects on larval performance. Two experiments were conducted: one in which the apical bud of the main plant shoot was inoculated with H. grandella eggs, and the other in which the bud was inoculated with third instars. Damage in each experiment was assessed by the number of frass piles, number and length of tunnels, number of damaged leaves, and damage to the apical bud. Larval performance was evaluated in terms of time to reach pupation and pupal weight and length. In both experiments, plant damage differed significantly among treatments (P < 0.03). Resistant rootstocks conferred resistance to susceptible scions. In both experiments, grafting by itself, regardless of the rootstock and scion combination, also reduced damage caused by H. grandella larvae. Scions of autografted susceptible species had similar resistance to susceptible scions grafted on resistant rootstocks. Few larvae reached pupation, and their pupal weight and length were similar.

Key words:Cedrela, Swietenia, Khaya, Toona, graft, mahogany shootborer

High-quality timber from Spanish cedar, Cedrela odorata, and mahogany Swietenia macrophylla (Meliaceae) are important for the economy of many neotropical countries (Newton et al 1993). Unfortunately, natural populations of these species are being reduced quickly due to selective harvest (Albert et al 1995). In addition, the mahogany shootborer, Hypsipyla grandella (Zeller), has limited their establishment in commercial plantations in Latin America, as its larva mainly feeds on apical shoots, inducing branching on the trees and rendering the timber unmarketable (Grijpma 1971).

Exotic Meliaceae species are less susceptible than indigenous ones to attacks by native Hypsipyla spp. (Cunningham et al 2005). For example, Australian red cedar Toona ciliata (Meliaceae), closely related to Cedrela spp., is heavily attacked by H. robusta Moore when growing in its Old World native habitats (Bygrave & Bygrave 1998), but is not attacked by H. grandella when planted in Central America (Grijpma 1976). Conversely, imported Cedrela spp. are not attacked by H. robusta in Australia (Bygrave & Bygrave 2001). Moreover, S. macrophylla and the African mahogany Khaya senegalensis (Meliaceae) have been reported to suffer less damage from either H. robusta or H. grandella, respectively.

This reduced susceptibility of exotic Meliaceae to native Hypsipyla species (Manso 1974, Grijpma 1976, Agostinho et al 1994) may allow production of resistant native Meliaceae trees to H. grandella by grafting susceptible scions onto resistant, exotic rootstocks. For instance, in Costa Rica, C. odorata shoots grafted onto T. ciliata were shown to be resistant, although this resistance was lower than that for Toona trees themselves (Grijpma 1976). Also in New South Wales, C. odorata and C. fissilis (Meliaceae) scions grafted onto T. ciliata differed in susceptibility to attack by H. robusta, with C. odorata scions being more susceptible than C. fissilis scions (Bygrave & Bygrave 2001). Resistance of Cedrela scions grafted to Toona rootstock scions strongly suggests that some defensive substances are translocated from root to grafted shoot (Grijpma & Roberts 1975). Translocation was later confirmed by Silva et al (1999) who found catechin (a phenolic compound synthesized by T. ciliata) in scions of C. odorata grafted onto T. ciliata rootstocks.

Autografting (a scion of a plant onto another part of the same plant or species) (Hartmann et al 2002) could potentially improve insect resistance of susceptible plant species by inducing production of secondary defensive compounds in response to the wounding from making the graft union. The phenomenon of inducible resistance after wounding is widely demonstrated (Schoonhoven et al 2005), but the implications for grafting have not been examined. In addition, the effect of grafting per se, regardless of the combinations of species has not been taken into account in prior grafting studies involving Hypsipyla spp. In this study, autografts were included as additional controls to consider potential grafting effects. So far, grafting effects on H. grandella resistance have been examined only in combinations of Cedrela spp. and T. ciliata, neglecting other resistant and susceptible timber species within Meliaceae. In addition, the effects of reciprocal grafting and autografting are unknown, so that the basis for changes in scion resistance is unclear.

The objective of this study was to determine the effect of grafting different combinations of susceptible and resistant Meliaceae species in precluding damage by H. grandella. The hypotheses tested were: 1) exotic species (K. senegalensis and T. ciliata) are resistant to H. grandella attack, 2) resistant rootstocks confer resistance to susceptible scions, 3) susceptible rootstocks do not affect the resistance of exotic resistant scions, and 4) autografting confers resistance.

Material and Methods

Research was conducted at the Cabiria Experimental Station, on the premises of the Tropical Agricultural Research and Higher Education Center (CATIE), in Turrialba, Costa Rica. CATIE is located in the Caribbean watershed of this country, at 602 m altitude, within the premontane wet forest life zone (Tosi 1969). Average annual values for climatic variables are 2600 mm rainfall, 22ºC, 88% RH, and 17 MJ m² of solar radiation (Salas 2000).

All four species selected for study belong to the subfamily Swietenioideae (Pennington & Styles 1975). Seeds of the susceptible species C. odorata and S. macrophylla from Pococí, Costa Rica, as well as the resistant K. senegalensis from Burkina Faso, and T. ciliata from Australia, were provided by the Forest Seed Bank at CATIE.

Seeds were sown at CATIE's nursery, and the plants were kept inside a screenhouse used to acclimatize coffee plants. The wedge grafting technique (Bygrave & Bygrave 1998) was used to produce the various grafted combinations when the plants were 12 months old. The grafting union was 20-30 cm above the soil surface. Rootstocks were less than 1 cm in diameter at the grafting union, whereas the scions were slightly thinner. Grafted plants were maintained in the screenhouse until the scions developed at least 10 leaves (ca. six months).

Plant species susceptible to H. grandella were grafted onto resistant ones. Also, reciprocal combinations (i.e., resistant scion onto susceptible rootstock) and autografts (scion and rootstock from the same species) were completed. Intact (i.e., non-grafted) and autografted plants were used as controls (Table 1). The aim was to have a full set of 12 combinations, but grafts of C. odorata onto K. senegalensis and K. senegalensis onto C. odorata, for experiment I, or S. macrophylla onto T. ciliata, for experiment II, were unsuccessful due to incompatibility or were not ready when experiments were completed.

Two experiments were completed with the main plant shoot inoculated either with eggs or third instars (8-16 mm long) of H. grandella. In this way, early instars emerging from eggs and the later instars were tested.

Eggs and larvae for experiments were taken from a colony maintained at the Entomology Laboratory at CATIE. The colony was established in 1998, and yearly renewed from field-collected larvae feeding on C. odorata. Larvae in the colony were normally fed with tender C. odorata leaves from first to third instars, and then placed onto an artificial diet (Vargas et al 2001) until pupation. The combination of leaves and artificial diet ease the management of the colony. Eggs hardly hatch on diet but easily on leaves. Feeding larvae only with leaves is hard since they are so voracious that they become cannibalistic if short in food. On another hand, tender leaves are scarce during the dry season. Pupae were moved to a metal framed cage covered with fine mesh, kept at a greenhouse for adult emergence, mate and oviposition. Eggs were collected and taken to the laboratory to sustain the colony.

Thirteen and fifteen treatments for experiment I (eggs) and II (third instars), respectively, were arranged in a completely randomized design with six replicates. Each replicate consisted of an individual plant with three eggs or two H. grandella larvae. Three eggs were used to ensure the presence of at least one larva per plant.

Experiment I: Hypsipyla grandella eggs. This experiment was conducted from 23 April to 15 June 2004. Plants were carefully inspected to preclude predation by ants, wasps or spiders. Bird predation was prevented by closing the sides of the greenhouse with a plastic shade net (50-60% of full sunlight), whereas ants were avoided by smearing a sticky substance, Tanglefoot (The Tanglefoot Co., Grand Rapids, MI), around tree stems 10-15 cm above the ground.

Four-day-old H. grandella eggs were placed on the main shoot by using a thin paintbrush between 16:30h and 17:00h, which is the natural time for oviposition (Ramírez-Sánchez 1964). Age of H. grandella eggs was based on coloration; they were white just after oviposition and turned red before hatching on the fifth day (Taveras et al 2004).

Damage was appraised daily from day 2 to 15 after initiation by counting the number of frass piles (mounds of feces, 'sawdust' and silk), number and length of tunnels in the main or lateral buds and in shoots, number of damaged leaves due to larval feeding (whether on petioles or leaflets) and damage to the apical bud (scored at 0 for intact or 1 for either partially or fully consumed bud). Buds or shoots were then dissected and the length of all tunnels made by the larvae was measured; an average tunnel length per plant was calculated afterwards.

On day 15, the number of surviving larvae was recorded and individual larvae were transferred to vials with artificial diet (Vargas et al 2001). Vials were kept inside an environmental chamber (Percival I-35L, Boone, Iowa) at 25ºC, 80-90% RH, and 12:12 L:D, and the time to reach the pupal stage (days from oviposition to pupation), pupal length (mm) and weight (mg) were recorded. Pupation was considered completed when pupae turned dark brown, so that they could be weighed and measured without stress or injury.

Experiment II: Hypsipyla grandella third-instar larvae. This experiment was conducted from 25 November 2004 through 18 January 2005. Plants were 18 months old, including the period prior to grafting. Larvae were placed on the main plant shoot with a fine paintbrush. Variables examined and methods used were the same as those in experiment I.

Statistical analysis. Since the number of eggs or larvae was higher than required by H. grandella to cause damage, the number of surviving larvae was considered as a covariate for all the other variables. Data were examined for compliance of assumptions required for analysis of covariance (ANCOVA). If necessary, data were transformed by Y = sqrt(Y + 0.5) to meet these assumptions.

Analysis of covariance was completed using the GLM procedure (SAS 2001). Orthogonal contrasts (P < 0.05) were used to test the species and graft combination effects on plant damage and larval performance. The contrasts were as follows: 1) intact susceptible vs. intact resistant species (C, S vs. K, T); 2) autografted susceptible vs. autografted resistant species (C/C, S/S vs. K/K, T/T); 3) autografted susceptible vs. susceptible grafted on resistant species (C/C, S/S vs. C/K, C/T, S/K); 4) autografted resistant vs. resistant grafted onto susceptible rootstock species (K/K, T/T vs. K/S, T/C, T/S). Apical bud damage was analyzed by a Chi-square test to examine the hypothesis that damage was similar among the species tested.

Results

Damage on plants. In both experiments, plant species, whether grafted or intact, significantly affected the number of frass piles, tunnel length and number of damaged leaves, whereas tunnel number differed only in experiment I (Table 2).

The number of frass piles was lower in both experiments for resistant species compared to susceptible ones (Table 2, Fig 1). The same result was obtained for autografted plants, but the effect was reduced for resistant species (Table 2, Fig 1). None of the other contrasts for treatment effects on frass piles was significant for either experiment (Table 2). In the first experiment, autografting susceptible species reduced the number of frass piles to a level as low as that of the susceptible species grafted onto the resistant ones (Fig 1a). In the second experiment, the number of frass piles was almost nil for both autografted resistant species and resistant species grafted onto susceptible ones. Even though the number of frass piles was almost nil on the resistant species, larvae occasionally attacked them, especially K. senegalensis. Also, although not significant, the number of frass piles tended to be consistently lower on S. macrophylla plants compared to C. odorata (Fig 1b).

The number of tunnels made in the various intact and graft combination plants was significantly affected (P < 0.0384) by only hatched larvae in experiment I (Table 2). Numbers tended to be lower in resistant plants compared to susceptible ones (both intact and autografted) (Fig 2), but contrasts revealed that the numbers were not statistically different (Table 2). In experiment I, however, intact and autografted resistant species completely lacked tunnels (Fig 2a).

Tunnel length differed significantly between susceptible and resistant intact plants in both experiments (Table 1, Fig 3), with C. odorata having much longer tunnels than S. macrophylla. The trend was similar among autografted plants, but was significant only in experiment II. None of the other contrasts for tunnel length was significant.

The number of damaged leaves differed substantially and significantly between susceptible and resistant plants for both experiments (Table 2, Fig 4), with C. odorata having more damaged foliage than S. macrophylla plants. Autografted susceptible plants had more damaged leaves than autografted resistant ones only in experiment II. None of the other contrasts for the number of damaged leaves was significant. In experiment I, autografted and intact K. senegalensis and T. ciliata plants lacked leaf damage (Fig 4a), although in experiment II some minor damage on T. ciliata leaves was observed (Fig 4a).

Apical bud damage differed among treatments (X² = 41.13, 39.29; P < 0.0001, 0.0003; d.f. = 13, 14) for experiments I and II, respectively. Both intact and autografted K. senegalensis and T. ciliata plants completely lacked apical bud damage (Fig 5), whereas intact C. odorata and S. macrophylla plants suffered 90% and 100% and 40% and 80% damage in experiments I (Fig 5a) and II (Fig 5b), respectively.

In experiment I, apical bud damage on autografted C. odorata was reduced by 78%, but autografting failed to reduce bud damage of S. macrophylla. When the latter was grafted onto K. senegalensis, damage was reduced by 50% with respect to intact S. macrophylla plants. Moreover, apical bud damage was absent from C. odorata scions grafted on T. ciliata with respect to damage on intact C. odorata (Fig 5a). In experiment II, apical bud damage was reduced by 50% and 16% on the respective autografts of C. odorata and S. macrophylla with respect to intact plants. Moreover, C. odorata grafted onto T. ciliata and T. ciliata grafted onto C. odorata, reduced the apical damage by up to 80% as compared with intact C. odorata. Cedrela odorata grafted onto K. senegalensis and K. senegalensis grafted onto C. odorata reduced the apical damage by 67% and 100%, respectively, compared to intact C. odorata (Fig 5b).

Larval performance. In experiment I, only larvae on intact C. odorata plants developed to the pupal stage (e.g., 29%, seven out of 24 surviving larvae), which required 32 days. In experiment II, 67% (i.e., six out of nine) surviving larvae on intact and autografted C. odorata, as well as on C. odorata or S. macrophylla grafted onto K. senegalensis plants developed to pupa requiring 30 days to do so. Therefore, the statistical analysis was completed only for pupal weight and length in experiment II, and these variables were similar among plant species (F = 0.26, 0.39; d.f. = 4, 1; P > F = 0.88, 0.81, respectively). Orthogonal comparisons were not completed due to high larval mortality mainly on T. ciliata plants.

Discussion

Although grafting has proven to be a successful propagation technique for a number of Meliaceae species (Bygrave & Bygrave 2005), some grafts failed. Grafts of S. macrophylla onto T. ciliata seemed to be incompatible under Turrialba, C. R. conditions. Intergeneric grafts such as these typically have low success rates (Hartmann et al 2002), as noticed by Bygrave & Bygrave (1998) trying to graft T. ciliata onto C. odorata. Fortunately, enough combinations of susceptible and resistant grafted species were produced to test the hypotheses regarding plant damage and larval performance.

In both experiments, the exotic species (K. senegalensis and T. ciliata) were clearly resistant to attack by H. grandella larvae, whereas the native species (C. odorata and S. macrophylla) were susceptible. These results possibly reflect the lack of coevolution between this New World insect species and Old World Meliaceae species, as was also demonstrated for neem Azadirachta indica (Meliaceae), whose metabolites showed either direct insecticidal or growth-disrupting effects on H. grandella (Mancebo et al 2002). Also, longer-term toxicity (Cornell et al 1998) apparently contributed to H. grandella mortality on resistant plants (based on the lower pupation observed in experiment I, since only intact C. odorata plants allowed development to pupation, whereas in experiment II more grafted plant combinations allowed pupation).

Cedrela odorata and S. macrophylla appeared to respond differently to grafting, as shown by their respective autografts. In both experiments, the number of frass piles was reduced by 66% by autografting C. odorata, whereas the reduction was only 51% for S. macrophylla. Autografting also diminished tunnel length in C. odorata stems but not in S. macrophylla stems. Intact S. macrophylla plants are less susceptible than intact C. odorata (Speight & Wylie 2001), probably making the autografting effect to attack by H. grandella larvae more difficult to detect.

Intact susceptible plants had the most damaged apical buds in both experiments. In agreement with Speight & Wylie (2001), damage by H. grandella larvae was more severe on C. odorata than on S. macrophylla plants. An autografting effect was detectable based on the amount of apical damage, and this effect was most evident in experiment I for C. odorata. This finding is important since apical bud damage is the type of injury that leads to loss of apical dominance and causes branching of the main trunk, which results in a noncommercial tree (Grijpma 1976). The reduction of apical shoot damage on either autografted or any rootstock/scion combination plants is encouraging since it indicated that even attacked autografted trees could overcome shootborer damage and still grow into economically useful trees in commercial plantations.

Plant damage by H. grandella was noticeably influenced by larval age (neonates responses differed from those of third instars). For example, susceptible plant species had more damage as indicated by the number of frass piles and tunnels made by younger larvae than by older ones, whereas resistant species were free from damage indicated by both tunnel number and length in experiment I. In this experiment, resistant intact plants, and grafted plants using T. ciliata either as rootstock or scion had only shallow perforations, which were soon sealed by the plant. These patterns were consistent with expectations based on prior studies showing that H. grandella neonates first feed on petiole and leaf surface or shoot surface, and then on the apical bud (Grijpma 1971). Therefore, the 21.7% and 30.8% of apical damage for experiment I and II, respectively, were expected.

Hypsipyla grandella has limited the establishment of commercial plantations of C. odorata and S. macrophylla species in Neotropics. Due to the damage threshold of one larva per plant and the susceptibility of native species (Hilje & Cornelius 2001), losses from H. grandella infestations approach 100% in many plantations (Cornelius et al 2004). Therefore, the resistance detected in exotic species and in C. odorata grafted onto T. ciliata, or S. macrophylla grafted onto K. senegalensis, as well as on the autografted susceptible species, could be economically important and exploit internal defenses of the trees against H. grandella.

Our results indicate that resistance from K. senegalensis and T. ciliata can be transferred to scions of native species by grafting. This resistance may have been due to toxins or feeding deterrents translocated from rootstocks across the graft union. Candidate bioactive compounds include alkaloids (Smolenski et al 1974), limonoids (Koul & Isman 1992, Maia et al 2000), or phenolics (Newton et al 1999, Silva et al 1999), all of which are produced in these species and have been implicated as defensive compounds (Schoonhoven et al 2005).

After contact with T. ciliata main shoots, third instars ballooned to lower leaves and tried to feed on them instead of the main shoot, but this response resulted in the death of the larvae. If they bit a lateral bud, an exudate was produced, in which larvae became entrapped. Both susceptible species grafted onto resistant rootstocks, autografted susceptible species, and resistant K. senegalensis plants lacked an exudate on lateral buds that could trap larvae. The exudates produced by T. ciliata were apparently part of the defenses of this species, as are resinous exudates in other plant species (Lewinshon 1991, Phillips & Croteau 1999), but fail to be transmitted in the grafting procedure.

In addition to the expected resistance to H. grandella by intact (Bygrave & Bygrave 2001) and autografted resistant plants, grafting alone provided some degree of resistance even for the susceptible species. This improved resistance could be attributed to plant-induced defenses resulting from the mechanical damage (wounding to make the graft). Plants respond to mechanical wounding by the induction of numerous genes (Reymond et al 2000) and may prevent insect feeding by decreasing nutritional value or increasing concentrations of defensive secondary compounds in new foliage (Schoonhoven et al 2005) which could be toxic for insects. This result seems to diminish the potential importance of defensive substances unique to the resistant plant species and also may explain the high mortality of larvae in both experiments including the susceptible species. Mortality was higher for later H. grandella instars (experiment II) than for neonates (experiment I). Although neonates may be more susceptible to specific resistance factors in the plants involved in this study, neonate lepidopterans can detect diets that could be toxic to them, whereas later instars seem to lack that ability (Zalucki et al 2002), so behavioral effects could contribute more to the results in experiment I than those from experiment II.

Whatever the mechanisms, resistant trees could be deployed in two ways. First, entire plantations of C. odorata grafted onto T. ciliata plants could be established. This approach has been successful for T. ciliata grafted onto C. fissilis in Australia, where the trees maintained their resistance against H. robusta after eight years (Bygrave & Bygrave 2005). Taking into account that, depending on the site, five to eight years are required by C. odorata and S. macrophylla plants to achieve a commercially valuable bole (Cibrián et al 1995), long-term evaluation of the grafted plants should be completed to determine if resistance is maintained and if they are adapted to field conditions.

Second, autografted C. odorata and S. macrophylla providing some level of resistance could lead to simple methods for enhancing tree resistance based only on wounding. This avenue needs to be explored more thoroughly, with additional studies to test the effects of wounding on insect resistance. One question that must be investigated is the duration of the wounding effect on elevating the plant's resistance to H. grandella larvae. Wounding trees may have a positive effect on their growth, since T. ciliata trees damaged by H. robusta (Cunningham & Floyd 2006) or S. macrophylla and C. odorata damaged by H. grandella (Pers. obs.) grow more quickly and produce more biomass than non-damaged trees.

Acknowledgments

Mr Carlos Castro is thanked for his help in the grafting procedure and care of the plants, Arturo Ramírez for kindly provide H. grandella larvae and Gustavo López for his assistance in the statistical analysis. Financial support for this research came from CONACYT, México, and the Plant, Soil, and Entomological Sciences Department of the University of Idaho, USA.

Received 12/I/09.

Accepted 15/V/10.

Edited by José Salvadori EMBRAPA

• Agostinho S M, Silva M F G F, Fernandes J B, Vieira P C, Pinheiro A L, Vilela A (1994) Limonoids from Toona ciliata and speculations on their chemosystematic and ecological significance. Biochem Syst Ecol 22: 323-328.
• Albert P D, López A A, Rodríguez T M, Duarte R M (1995) Recursos fitogenéticos forestales, I. Familia Meliaceae. Fontqueria 42: 329-351.
• Bygrave F L, Bygrave P L (1998) Cedrela species are attacked by the tipmoth Hypsipyla robusta when grafted on to red cedar Toona ciliata Aust For 61: 45-47.
• Bygrave F L, Bygrave P L (2001) Host preference of the Meliaceae shootborer Hypsipyla: further information from grafting Cedrela odorata and Cedrela fissilis on Toona ciliata (Australian red cedar). Aust For 64: 216-219.
• Bygrave F L, Bygrave P L (2005) Growing Australian red cedar and other Meliaceae species in plantation. RIRDC Publicaction no. 04/135, Camberra, 59p.
• Cibrián D, Méndez J T, Campos R, Yates III H O, Flores J E (1995) Insectos forestales de México. Universidad Autónoma Chapingo - Comisión Forestal de América del Norte (COFAN). Publ. n. 6, 453p.
• Cornelius J P, Wightman K E, Grogan J E, Ward S E (2004) Swietenia (American Mahogany), p.1720-1726. In Burley J, Evans J, Youngquist J A (eds) Encyclopedia of forest sciences. Academic Press, Amsterdam, 2400p.
• Cornell H V, Hawkins B A, Hochberg M E (1998) Towards an empirically-based theory of herbivore demography. Ecol Entomol 23: 340-349.
• Cunningham S A, Floyd R B (2006) Toona ciliata that suffer frequent height-reducing herbivore damage by a shoot-boring moth (Hypsipyla robusta) are taller. For Ecol Manag 225: 400-403.
• Cunningham S A, Floyd R B, Griffiths M W, Wylie F R (2005) Patterns of host use by the shoot-borer Hypsipyla robusta (Lepidoptera: Pyralidae) comparing five Meliaceae tree species in Asia and Australia. For Ecol Manag 205: 351-357.
• Grijpma P (1971) Studies on the shoot-borer Hypsipyla grandella (Zeller) (Lepidoptera, Pyralidae). V. Observation on rearing technique and on host selection behavior of adults in captivity. Turrialba 21: 202-213.
• Grijpma P (1976) Resistance of Meliaceae against the shootborer Hypsipyla with particular reference to Toona ciliata Roem M J var. australis (F & M) C. D. C., p.69-79. In Burley J, Styles B T (eds) Tropical trees. Variation breeding and conservation. London England, Academic Press, 258p.
• Grijpma P, Roberts S C (1975) Biological and chemical screening for the basis of resistance of Toona ciliata Roem M J var. australis (F & M) C. D. C. Turrialba 25: 152-159.
• Hartmann H T, Kester D E, Davies F T, Geneve R L (2002) Hartmann and Kester's Plant propagation. Principles and practices. New Jersey, Prentice-Hall, Englewood Cliffs, 880p.
• Hilje L, Cornelius J (2001) ¿Es inmanejable Hypsipyla grandella como plaga forestal? Hoja Técnica n. 38, Man Integr Plagas 61: i-iv.
• Koul O, Isman M B (1992) Toxicity of the limonoid allelochemical cedrelone to noctuid larvae. Entomol Exp Appl 64: 281-287.
• Lewinshon T M (1991) The geographical distribution of plant latex. Chemoecology 2: 64-68.
• Maia B H L N S, Paula J R de, Sant'Ana J, Silva M F G F, Fernandes J B, Vieira P C, Costa M do S S, Ohashi O S, Silva J N M (2000) Essential oils of Toona and Cedrela species (Meliaceae): taxonomic and ecological implications. J Braz Chem Soc 11: 629-639.
• Mancebo F, Hilje L, Mora G A, Salazar R (2002) Biological activity of two neem (Azadirachta indica A. Juss., Meliaceae) products on Hypsipyla grandella (Lepidoptera: Pyralidae) larvae. Crop Prot 21: 107-112.
• Manso D M (1974) Observaciones sobre el comportamiento y control de Hypsipyla grandella (Zeller) en Cuba. Baracoa 4: 3-4.
• Newton A C, Baker P, Ramnarine S, Mesén J F, Leakey R R B (1993) The mahogany shoot borer: prospects for control. For Ecol Manag 57: 301-328.
• Newton A C, Watt A D, López F, Cornelius J F, Mesén J F, Corea E A (1999) Genetic variation in host susceptibility to attack by the mahogany shoot borer, Hypsipyla grandella (Zeller). Agric For Entomol 1: 11-18.
• Pennington T D, Styles B T (1975) A generic monograph of the Meliaceae. Blumea 22: 419-540.
• Phillips M A, Croteau R B (1999) Resin-based defenses in conifers. Trends Plant Sci Rev 4: 184-190.
• Ramírez-Sánchez J (1964) Investigación preliminar sobre biología, ecología y control de Hypsipyla grandella (Zeller). Bol Inst For Latino-Amer 16: 54-77.
• Reymond P, Weber H, Damond M, Farmer E E (2000) Differential gene expression in response to mechanical wounding and insect feeding in Arabidopsis Plant Cell 12: 707-719.
• Salas S A (2000) Resumen acumulado de datos agroclimáticos. CATIE, Turrialba, Costa Rica.
• SAS Institute (2001) SAS/STAT User´s guide, version 8.2, SAS Institute, Cary, USA.
• Schoonhoven L M, van Loon J J A, Dicke M (2005) Insect-plant biology. London, Chapman and Hall, 421p.
• Silva M F G F, Agostinho S M M, Paula J Rde, Neto J O, Castro-Gamboa I, Filho R E, Fernandes J B, Vieira P C (1999) Chemistry of Toona ciliata and Cedrela odorata graft (Meliaceae): chemosystematic and ecological significance. Pure Appl Chem 71: 1083-1087.
• Smolenski S, Silinis H, Farnworth M (1974) Alkaloid screening IV. Lloydia 37: 30-61.
• Speight M R, Wylie F R (2001) Insect pests in tropical forestry. New York, CABI Publishing, 350p.
• Taveras R, Hilje L, Carballo M (2004) Development of Hypsipyla grandella (Zeller) (Lepidoptera: Pyralidae) in response to constant temperatures. Neotrop Entomol 33: 1-6.
• Tosi J (1969) Mapa ecológico de la República de Costa Rica, según la clasificación de zonas de vida de Holdridge L R. Centro Científico Tropical, San José, Costa Rica.
• Vargas C, Shannon P J, Taveras R, Soto F, Hilje L (2001) Un nuevo método para la cría masiva de Hypsipyla grandella Hoja Técnica n. 39. Man Integr Plagas 62: i-iv.
• Zalucki M P, Clarke A R, Malcolm E B (2002) Ecology and behavior of first instar larval Lepidoptera. Ann Rev Entomol 47: 361-393.

Publication Dates

• Publication in this collection
  14 Sept 2010
• Date of issue
  Aug 2010

History

• Accepted
  15 May 2010
• Received
  12 Jan 2009