Sequestration of host plant carotenoids in the larval tissues of Helicoverpa zea

The host plant as a factor in the synthesis and secretion of salivary glucose oxidase in larval Helicoverpa zea

“…Salivary lysozyme, for instance, follows a very different expression pattern in larvae feeding on these hosts, with the lowest expression found when they ingest tobacco (unpublished data). Other findings in our laboratory indicate that the host plant has a profound effect on non-protein components (e.g., carotenoids) of the labial and mandibular salivary glands (Eichenseer et al, 2002) Preliminary evidence indicates that GOX has the strongest effect of mitigating induced resistance in tobacco (Musser et al, 2002a), which could suggest that this serves an adaptive response to the inducible defenses of tobacco. In tomato, GOX may not be as effective in mitigating induced resistance.…”

“…Surprisingly, the amount of protein in the salivary glands was inversely related to the quality of the host. Larvae grow considerably better on cotton, followed by tomato and tobacco (Eichenseer et al, 2002;unpublished data). It should be noted that not only is there a quantitative effect of host plant on salivary proteins, but also qualitative effects.…”

Crystallization of α- and β-carotene in the foregut of Spodoptera larvae feeding on a toxic food plant

“…They can be found in the gut, fat body, epidermis and hemolymph of lepidopteran larvae (Starnecker, 1997). It has already been noticed that the midgut epithelium and mandibular glands of H. zea became yellow after feeding on plant materials, and the relative ratio of lutein and b-carotene absorbed into the gut is similar to that in plant leaves (Eichenseer et al, 2002). In all the lepidopteran species we tested, the color of their gut wall changed from white to greenish yellow after feeding on plant leaves, due to passive absorption of carotenoids and possibly some chlorophyll degradation products, which are green and lipophilic (Mangos and Berger, 1997).…”

“…Total carotenoids were extracted from Lima bean leaves and the foregut and midgut of 11 caterpillars and analyzed with high pressure liquid chromatography (HPLC) as described by Eichenseer et al (2002). Standard chemicals were purchased from Sigma.…”

“…Carotenoids are hydrophobic molecules, and can therefore be absorbed by the lipid membrane through passive diffusion (Bhosale and Bernstein, 2007;Goodwin, 1986). This appears to be responsible for the yellow color conferred by accumulation of carotenoids by the mandibular glands of Helicoverpa zea larvae feeding on leaves in particular soybean (Eichenseer et al, 2002). Among 38 Lepidoptera species analyzed, the majority tend to store the carotenoids from their food unchanged (Feltwell and Rothschild, 1974).…”