, Volume 72, Issue 1, pp 65–68 | Cite as

Treefall gaps versus forest understory as environments for a defoliating moth on a tropical forest shrub

  • S. Harrison
Original Papers


The moth Zunacetha annulata (Dioptidae) is a specialist on the understory shrub Hybanthus prunifolius (Violaceae) in the forest of Barro Colorado Island (BCI), Panama. The larvae, which are capable of defoliating entire shrubs, concentrate their attack upon the small minority of H. prunifolius individuals that grow in treefall gaps. Field experiments demonstrated that larval growth rates were 37% higher, and weights at pupation 25% higher, on shrubs in gaps than on shrubs in the understory. In a common environment in the laboratory, growth rates of larvae were 23% higher on foliage taken from shrubs in gaps than on foliage from shrubs in the understory.

However, larvae grown in a temperature regime simulating that of gaps did not grow faster than larvae in an understory regime, when the two groups were reared in growth chambers on foliage taken from the same shrubs. In the field, predation appeared higher in gaps: experimental groups of larvae survived at rates of 65% per day in gaps and 78% per day in the understory. Quality of foliage, and not direct effects of the environment, appears to be responsible for the observed pattern of defoliation by this moth.

Key words

Treetell gaps Zunacetha (Dioptidae, Lepidoptera) Food quality Hybanthus (Violaceae) 


Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.


  1. Augspurger CK (1979) Irregular rain cues and the germination and seedling survival of a Panamanian shrub (Hybanthus prunifolius). Oecologia (Berlin) 44:53–59Google Scholar
  2. Augspurger CK (1980) Mass flowering of a tropical shrub (Hybanthus prunifolius): influence on pollinator attraction and movement. Evolution 34:475–488Google Scholar
  3. Augspurger CK (1981) Reproductive synchrony of a tropical shrub: experimental studies on effects of pollinators and seed predators on Hybanthus prunifolius (Violaceae) Ecology 62:775–788Google Scholar
  4. Boardman NK (1977) Comparative photosynthesis of sun and shade plants. Ann Rev Plant Phys 28:355–377CrossRefGoogle Scholar
  5. Brokaw NVL (1982) Treefalls: frequency, timing and conse-quences. In: Leigh EG, Rand AS, Windsor DM (eds) The ecology of a tropical forest, Seasonal rhythms and long-term changes. Washington, DC: Smithsonian InstitutionGoogle Scholar
  6. Coley PD (1983) Herbivory and defensive characteristics of tree species in a lowland tropical forest. Ecol Monogr 53:209–233Google Scholar
  7. Hartshorn GS (1978) Treefalls and tropical forest dynamics. In: Tropical forests as living systems. Tomlinson PB, Zimmerman MH (eds) Cambridge: Cambridge University PressGoogle Scholar
  8. Hubbell SP, Foster RB (1986) Commonness and rarity in a Neotropical forest: implications for tropical tree conservation. In: Conservation biology: the science of scarcity and diversity. Soule ME (ed) Sinauer Associates, Sunderland, MAGoogle Scholar
  9. Janzen DH (1985) A host plant is more than its chemistry. Ill Nat Hist Surv Bull 33:141–174Google Scholar
  10. Knapp R, Casey TM (1986) Thermal ecology, behavior and growth of gypsy moth and castern tent caterpillars. Ecology 67:598–608Google Scholar
  11. Langenheim JH, Arrhenius SP, Nascimento JC (1981) Relationship of light intensity to leaf resin composition and yield in the tropical leguminous genera Hymenaea and Copaifera. Biochem Syst Ecol 9:27–37CrossRefGoogle Scholar
  12. Scriber JM, Slansky F Jr (1981) The nutritional ecology of immature insects. Ann Rev Ent 26:183–211CrossRefGoogle Scholar
  13. Sokal RR, Rohlf JF (1981) Biometry (Second edition). WH Freeman, New YorkGoogle Scholar
  14. Tingey WM, Singh SR (1980) Environmental factors influencing the magnitude and expression of resistance. In: Maxwell FG, Jennings PR (eds) Breeding plants resistant to insects. Wiley, New YorkGoogle Scholar
  15. White TCR (1978) The importance of a relative shortage of food in animal ecology. Oecologia (Berlin) 33:71–86Google Scholar
  16. White TCR (1984) The abundance of invertebrate herbivores in relation to the availability of nitrogen in stressed food plants. Oecologia (Berlin) 63:90–105Google Scholar
  17. Windsor DM (ed) (1985) Environmental monitoring and baseline data, Smithsonian Environmental Sciences Program. Smithsonian Institution, Washington DCGoogle Scholar
  18. Wolda H, Foster R (1978) Zunacetha annulata (Lepidoptera; Dioptidae), an outbreak insect in a neotropical forest. Geo-Eco-Trop 2:443–454Google Scholar

Copyright information

© Springer-Verlag 1987

Authors and Affiliations

  • S. Harrison
    • 1
  1. 1.Department of Biological SciencesStanford UniversityStanfordUSA

Personalised recommendations