Barro Colorado Island: growth of caterpillars

Are plant traits correlated with herbivore defenses against natural enemies?

http://www.blackwell-synergy.com/doi/abs/10.1111/j.2006.0030-1299.14928.x

Oikos Volume 115 Page 219 - 228 November 2006
doi:10.1111/j.2006.0030-1299.14928.x

Volume 115 Issue 2
The effects of plant quality on caterpillar growth and defense against natural enemies
P. D. Coley, M. L. Bateman and T. A. Kursar,

"A survey of 85 species of Lepidoptera feeding on 40 hosts on Barro Colorado Island, Panama showed that growth and defensive traits of caterpillars were correlated with the nutritional and defensive traits of their hosts. Growth rates were faster on young than mature leaves, reflecting the higher nitrogen and water content of the former. Growth was also positively correlated with leaf expansion rate, partially because of higher nitrogen and water contents of fast-expanding young leaves. Specialists grew faster than generalists, but both responded positively to nutritional quality. There was no effect of lepidopteran family on growth. In analyses where the effects of nitrogen and water were removed, the residuals for growth rate were greater for young than for mature leaves and were positively correlated with expansion rates of young leaves. This suggests that traits other than nutrition were also important. As young, expanding leaves cannot use toughness as a defense, one possible explanation for the differences in growth is differences in chemical defenses.

"Growth rate residuals for both specialists and generalists were higher for the more poorly defended fast-expanders, but the effect was greatest for generalists, perhaps because generalists were more sensitive to secondary metabolites. We predicted that slow growth for caterpillars would increase their risk to natural enemies and would select for higher defenses. Generalists had more defensive traits than specialists and were less preferred in feeding trials with ants. Similarly, species feeding on mature leaves were the most defended and those feeding on fast-expanding young leaves were the least defended and most preferred by ants. Thus the effects of plant secondary metabolites and nutrients dictate herbivore growth rates, which in turn influence their susceptibility to the third trophic level and the importance of defenses.

"While we noted that some specialist caterpillars had aposomatic coloring or spines, suggesting effective defense, we also found 14 species of specialists in 11 families that were green and constructed shelters."

See also
D. Janzen (1984) Two ways to be a tropical big moth ... Oxford Surv. Evol. Biol.1:85-140.

Architecture on Rainham Marshes

"Rainham Marshes is a wonderful haven for birds, common, rare, summer and winter visitors alike. No fewer than 250 species are likely to perch, feed and breed here in the course of a year. And out on this mosquito-ridden stretch of boggy terrain - between a housing estate and the elevated A13 - is one of the best new buildings in the Thames Gateway. Designed by Van Heyningen and Haward Architects, the RSPB's new Purfleet Environment and Education Centre is, despite its clumsy name, a delightful surprise."

http://arts.guardian.co.uk/critic/feature/0,,1946412,00.html

"Its walls are lined with sheep's wool, its toilets flush with rainwater, and its funnels glow at sunset. Jonathan Glancey is captivated by a striking new hide for nature lovers "

Monday November 13, 2006
The Guardian (c)

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http://www.rspb.org.uk/england/southeast/reserves/rainham_opens.asp

"The RSPB hopes it new 353-hectare reserve will provide a foundation for the sustainable development of the Gateway, making it a healthy and attractive place to live in and to visit.
Both the reserve and the centre have been designed to allow genuine access for all. The centre's unique design combines uninterrupted views across the marshes with a range of cutting edge energy- and water-saving features.

"In time, thousands should be able to enjoy the peace and tranquillity the new reserve offers and to see the wealth of wildlife that can be found there.

"Graham Wynne, RSPB Chief Executive said, 'The Thames Gateway is a fantastic area for wildlife. It is vital that the people, who live and work in the area, and those who visit, have access to its magnificent open spaces. If they do not, there is a real risk that the regeneration will fail to realise its full potential.

"'The RSPB is working across the whole Gateway to deliver publicly accessible green spaces that bring benefits both to the wildlife that depend on these sites and to the communities that surround them.

"'RSPB Rainham Marshes is the furthest advanced of our projects and we look forward to working with our partners on both sides of the river to help deliver a sustainable Thames Gateway that we can all be proud of.'"