Monarch butterfly larvae

Marty, M.A. and Krieger, R.I., Metabolism of uscharidin, a milkweed cardenolide, by tissue homogenates of monarch butterfly larvae, Danaus plexippus L. /. Chem. Ecol., 10,945,1984. 

Ecological concerns are real as we do not know what may occur with the widespread propagation of transgenic plants. There were initial fears that Bt corn was toxic not only to the European corn borer but also to the monarch butterfly larvae that may eat milkweed leaves laced with Bt corn pollen. However, EPA studies dismissed this threat. It is possible that other insects, not intended as targets of bioengineered proteins, may also be affected. It is absolutely essential that these ecological issues be addressed. However, these are not food safety issues. The same concerns occur with the widespread use of organic pesticides relative to runoff and water pollution. Both must be addressed on their own merits. 

When hungry or gravid insects move within centimeters of potential host plants and encounter their volatiles, displacement is often delimited by olfactory responses. Monarch butterfly larvae (Danausplexippus) not able to contact host and non-host foliage but moving on a screen immediately over the plants, turn and double back more frequently to milkweed foliage than to nonhost foliage (Dethier, 1937). In similar tests (de Wilde, 1958), Colorado potato... 

In May of 1999, a note submitted to the editor of Nature from scientists at Cornell University purported to demonstrate that pollen from a Bt com hybrid caused harm to monarch butterfly larvae diat consumed it widi their diet of milkweed leaves This led to the formation of a collaborative group of scientists from Canada and the United States to investigate the nature of pollen from Bt com hybrids and the potential of pollen from these commercial hybrids to intact populations of monarch butterflies in the Com Belt. 

Anderson, P.L., R.L. Hellmich, M.K. Sears, D.V. Sumerford, and L.C. Lewis. 2004. Effects of CrylAb-expressing corn anthers on monarch butterfly larvae. Environ. Entomol. 33 1109-1115. 

Dively, G.P., R. Rose, M.K. Sears, R.L Hellmich, D.E. Stanley-Horn, D.D. Calvin, J.M Russo, and P.L. Anderson. 2004. Effects on monarch butterfly larvae (Lepidoptera Danaidae) after continuous exposure to CrylAb-expressing corn during anthesis. Environ. Entomol. 33 1116-1125... 

Stanley-Horn, D.E., G.P. Dively, R.L. Hellmich, H.R. Manila, M.K. Sears, R. Rose, L.C.H. Jesse, J.E. Losey, J.J. Obrycki, and L. Lewis. 2001. Assessing the impact of Cryl Ab-expressing corn pollen on monarch butterfly larvae in field studies. Proc. Natl. Acad. Sci. (USA) 98 11931-11936. 

Sears, M. and H. Mattila. 2001. Determination of the Toxicity of Corn Pollen Expressing a CrySBbl Variant Protein to First Instar Monarch Butterfly Larvae Danaus plexippus) via Laboratory Bioassay Lab Project Number MSL-17235 01-01-39-26. Unpublished study prepared by University of Guelph. 33 p. 

Butterfly larvae (Monarch, Danaus plexippus Queen, Danaus gillipus Eastern Black Swallowtail, Papilio polyxenes asterius and Atala, Eurnaceus atala florida) were collected in South Florida approximately seven to eight days after hatching. The larvae were carefully dissected to remove the gut to prevent the contamination of the epidermis with the intestinal contents. The epidermis was... 

The yellow coloration in the Monarch as well as the larva of three other species of butterfly from South Florida is exclusively due to the specific accumulation of exceptionally high levels of lutein producing a pigmented epidermis. This active accumulation, reminiscent of the specific accumulation that occurs in the primate macula, indicates that butterfly larva is an excellent animal model for the study of carotenoid transport and binding. As such, elucidation of the mechanism of transport and binding of lutein in the epidermis and other tissues of these butterfly larvae may provide insight into xanthophyll uptake within the human eye (Bhosale et al. 2004). 

The relationship between milkweeds and the monarch butterfly demonstrates a synergistic relationship between a plant and an insect (Harborne, 1993). The larvae of the monarch butterfly feed on milkweeds and accumulate cardenolides. Birds feeding on the caterpillars, pupae, or adults, will vomit and subsequently become averted and thus avoid the monarch butterflies. Interestingly, other butterflies, such as viceroy, which do not feed on milkweed, have evolved with nearly identical color pattern (mimicry), so birds avoid these nontoxic insects as well. 

Cardenolldes appear to be metabolized by a variety of species, possibly as a mechanism for converting these steroids into compounds that can be efficiently sequestered. The milkweed bug, Oncopeltus fasclatus, metabolizes (hydroxylates ) the nonpolar cardenollde dlgltoxln to more polar compounds that are subsequently sequestered In the dorsolateral space fluid (17. 18). Larvae of another cardenolide-adapted Insect, the monarch butterfly, Danaus plexlppus. also convert these steroids Into compounds that are readily sequestered. For example, uscharldln, which contains a carbonyl group at C-3 ( ) of the... 

Monarch butterflies t.g., Danaus plexipus) combine two sets of natural compounds. Larvae feed on plants rich in cardiac glycosides and use them as chemical defense compounds. Adult butterflies visit plants with PAs, where they collect PAs that are converted to pheromones or transferred to their eggs 4,17,31,33,361,515). A similar PA utilization scheme was observed with larvae of the moth Utetheisa ornatrix 367,516), where the compounds were shown to be deterrent for spiders and birds 225, 525). The chrysomelid beetle Oreina feeds on PA-containing plants, such as Adenostyles, and stores the dieUuy PAs in the defense fluid 463,524). 

Concerns over the safety of transgene introduction into environment was sensitized early in the GMO debate with significant focus on the potential toxicity of Bt endotoxins to monarch butterfly [Danaus plexippus) larvae exposed to transgenic pollen. Early data suggested that Bt corn pollen could result in potentially significant reactions in the monarch gut. 

C. procera R.Br and toxicity F. Briischweiler et at., Helv. Chim. Acta 52, 2086 (1969). Revised structure eidem, ibid. 2276. Sequestration by larvae of Monarch butterfly Danaus plexippus L. 1. N. Sieber et al.. J. Chem. Ecol. 6, 321 (1980). Quantitative analysis of cardenolides in latex and leaves of C procera eidem. Phytochemistry 21, 2343 (1982). Biosynthesis of labelled compd M. S. Lee, J. N. Sieber, ibid. 22, 923 (1983). 

Even if the main target of a toxin is an insect which causes considerable damage to the crop, very often other insects can feed on the plant. If they are sensitive to the expressed toxin, they will also be affected which, of course, is advantageous in terms of crop protection. However, some insects could be affected in a nonintended way. An example of this is the monarch butterfly Danaus plexippus), a mythic butterfly of North America. Losey et al. [88] observed a higher mortality rate in butterfly larvae fed milkweed coated with 5t-maize pollen as compared to larvae fed leaves coated with nontransformed maize pollen or with leaves free of pollen. However, it is important to note that this study was performed under artificial laboratory conditions which do not reflect most of the characteristics of the monarch way of life [89]. In a very recent report, the EPA (September 22, 2000), on the basis of further trials, concluded that monarch butterflies were at very little risk from Bt com products, contrary to widely published reports. EPA further found that In fact, some authors are predicting that the widespread cultivation of Bt crops may have huge benefits for monarch butterfly survival. ... 

Some animals, as well, use toxins to defend themselves. Some poisonous toads and frogs can synthesize toxins. Others acquire their chemical defenses from plants they eat. The Monarch butterfly is probably the best example of this. The larvae eat milkweed leaves and the toxins are retained in their bodies. The toxins are still there after metamorphosis from larva to butterfly. Birds that eat Monarch butterflies regurgitate their prey and quickly learn to avoid others of the same species. 

Over its natural range in North America, the female monarch butterfly may lay her eggs on several Asclepias species that differ in the complement and amount of cardenolides present. By TLC analysis of adult butterflies, it is possible to determine the species upon which the larva feed. Depending on the complement and quantity of cardenolides present in the host plant, the larvae are able to adjust their diet to modify the amount of cardenolide sequestered (Harbome, 1991). 

Larvae of the butterfly, Pachlioptera aristolochiae, which feed exclusively on plants of the family Aristolochiaceae, accumulate aristolochic acid (46) (Levinson, 1976). Aristolochic acids have also been isolated from several lepidop-teran caterpillars and are transferred to the pupae. Imagos of the swallowtail butterflies, Battus polydamas and B. phi-lenor, contain aristolochic acid (Nahrstedt, 1982 Urzua et al., 1987), but do not appear able to adjust the levels of toxins, as do monarch butterflies (Harbome, 1986). 

Calotropin (D 6.4.8) Taken up by larvae of the monarch butterfly Danaus plexippus from food source (Asclepias sp.), stored in the body, deterring birds... 

There is some evidence that the monarch butterfly suffers physiological cost as a result of sequestering cardiac glycosides. For example melanic larvae, in addition to other aberrations have been observed in the monarch (L. Brower et al., 1972 L. Brower and Glazier, 1975 Seiberetc/., 1980). Dixon etc/. (1978)... 

Similar experiments, made on monarch butterflies, allow to assume, that small but meaningful quantity of magnetic substance is synthesized at the transition stage from larva to the adult insect [1]. The obtained experimental data indicate that normally imago, pupae and prepupae of working bees have noticeable magnetic moments. 

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