Nutritional Ecology of Heliconia Herbivores: Experiments with Plant Fertilization and Alternative Hosts

Abstract

Efficiencies of food use, growth rates, and consumption rates were measured for larvae of eight tropical insect species, reared upon normal and fertilized Heliconia species (Zingiberales: Heliconiaceae) and Musa sp. (Zingiberales: Musaceae) in Costa Rica. Cephaloleia consanguinea and Chelobasis perplexa (Coleoptera: Chrysomelidae, Hispinae) feed only on Heliconia. Caligo memnon and Opsiphanes tamarindi (Lepidoptera: Brassolidae) are oligophagous, with known hosts in two families of Zingiberales. Sibine apicalis, Sibine sp., and Metraga sp. (Lepidoptera: Limacodidae) and Megalopyge sp. (Lepidoptera: Megalopygidae) are polyphagous, with dicot and monocot hosts.Foliar nitrogen content of natural Heliconia imbricata (x = 1.76%) was lower than that of H. latispatha (x = 3.01%) and Musa sp. (.X = 3.30%). The oligophagous brassolids generally had lower growth rates, lower efficiencies of food use, and lower nitrogen accumulation rates on H. imbricata than on Musa sp.The hispines had lower relative consumption and growth rates than any of the lepidopterans examined on any host or treatment. Growth rates and nitrogen accumulation rates for the hispine species were not affected by host plant fertilization. Efficiencies of nitrogen use declined with increasing foliar nitrogen content for the hispines.Several parameters of food use efficiency were correlated with larval feeding specialization. The specialized hispines and oligophagous brassolids had higher efficiencies of food assimilation and nitrogen use on H. imbricata than did the polyphagous limacodids and megalopygid. Other efficiency indices, such as net growth efficiency, were not correlated with feeding specialization.The hispine Ch. perplexa has one of the longest larval developmental times known for a nondiapausing chrysomelid ( =200 d). Its slow growth is correlated with a low metabolic rate, which we interpret as a physiological adaptation for starvation resistance. Larvae feed only on rolled Heliconia leaves, which are produced infrequently by host plants, and long fasts are a predictable feature of development. Ch. perplexa's eight larval instars are about equal in duration, and closely match the duration of a rolled leafs suitability as food for these larvae. After a rolled leaf unfurls, the larvae must either wait for another on the same plant, or search haphazardly for one on nearby plants. The feeding of Ce. consanguinea larvae is apparently moisture limited in this tropical rain forest, and these larvae also have a high resistance to starvation.The oligophagous brassolids have become pests of banana, which is introduced into the Americas. These species increase growth rates with increased nitrogen content of host tissue. They are infrequent on H. imbricata, which has few chemical defenses against herbivores. Thus, the low nitrogen content of H. imbricata may protect it from some herbivory.

Testing Pollen of Single and Stacked Insect-Resistant Bt-Maize on In vitro Reared Honey Bee Larvae

“…The Heliconia family is known to have chemical defenses against herbivores [27] and anecdotal brood mortality is known for Heliconia foraging honey bee colonies. The pollen of the flowers was collected in a 1.5 ml tube by shaking and scraping pollen from the anthers with a scalpel (45 mg pollen from 41 flowers).…”

Direct and Indirect Effects of Host‐Plant Fertilization on an Insect Community

“…Elevated nitrogen levels in plant tissues may increase herbivore growth rates (Fox and Macauley 1977, Scriber 1979, Scriber and Slansky 1981, final adult weight Feeny 1977, Morrow andFox 1980), fecundity (Vince et al 1981, Prestidge 1982, and/ or overall survivorship (White 1969, McNeill and Southwood 1978, Morrow and Fox 1980. However, since phytophagous insects encompass many orders of arthropods that feed in markedly different ways, it is unrealistic to expect that such a diverse array of herbivores will respond similarly to changes in host quality (Stark 1965, Jones 1976, Auerbach and Strong 1981, Faeth et al 1981, Vince et al 1981, Brodbeck and Strong 1987.…”

Abundance and temporal distribution of Gonioterma exquisita Duckworth (Lepidoptera, Elachistidae, Stenomatinae) on Byrsonima pachyphylla Griseb. (Malpighiaceae) in the Brazilian Cerrado

“…Larcher (2000) suggested that the decrease of nitrogen content may be related to water stress. Plant tissues generally contain low concentrations of nitrogen with an average of 2.14 % (n = 400 plant species) (Auebach & Strong 1981). In Cerrado plants, this percentage is even lower (Marquis et al 2001).…”