Makasih banyak Mas Harry. Tetapi masalah baru keluar. Maaf, saya kurang
ngerti bahasanya. Selain
bidangnya bukan bidang saya, juga bahasanya susah. Kalaupun dipaksakan,
bisa-bisa saya baru memahaminya setelah diskusi ini selesai. Maksud saya,
alangkah sangat baiknya kalau ada orang yang mau meringkaskan (tanpa merubah
substansi) di dalam bahasa Indonesia populer. Jadi saya yang cuma
penggembira (gembira dengan maraknya pemerhati lingkungan sekarang), jadi
tambah gumbira. Pahala lo menggembirakan saya he.. he.. he.. Mudah2an
bukan saya saja yang "bermasalah".
Ada yang mau nolongin?
Salam,
ic.
----- Original Message -----
From: "Harry Surjadi" <[EMAIL PROTECTED]>
To: <[EMAIL PROTECTED]>
Sent: 12 September 2000 18:27
Subject: [lingkungan] artikel (V) transgenik Bt
> Pollen from Bt maize Can Kill Monarch Butterflies
> Maize engineered to produce the Bacillus thuringiensis bacterial toxin to
> protect against pests, has an unwanted side effect: its pollen kills
monarch
> butterfly (Danaus plexippus) larvae in laboratory tests, according to a
> report by Cornell University researchers.
> Writing in Nature, the researchers note that Bt maize has been shown to
have
> no effect on many "nontarget" organisms -- pollinators such as honeybees
or
> beneficial predators of pests such as ladybirds. But the Bt maize corn
> produces pollen containing crystalline endotoxin from the bacterium genes.
> When this corn pollen is dispersed by the wind, it lands on other plants,
> including milkweed (Asclepias sp.), the exclusive food of monarch
> caterpillars and commonly found around maize fields.
> In the laboratory tests, monarchs fed milkweed leaves dusted with
so-called
> transformed pollen from a Bt-corn hybrid ate less, grew more slowly and
> suffered a higher mortality rate, the researchers report. Nearly half of
> these larvae died, while all of the monarch caterpillars fed leaves dusted
> with non-transformed corn pollen or fed leaves without maize pollen
survived
> the study.
> The toxin in the transformed pollen, goes into the gut of the caterpillar,
> where it binds to specific sites. When the toxin binds, the gut wall
changes
> from a protective layer to an open sieve so that pathogens usually kept
> within the gut and excreted are released into the insect's body. As a
> result, the caterpillar quickly sickens and dies.
> Says John E. Losey, Cornell assistant professor of entomology and the
> primary investigator on the study: "We need to look at the big picture
here.
> Pollen from Bt-corn could represent a serious risk to populations of
> monarchs and other butterflies, but we can't predict how serious the risk
is
> until we have a lot more data. And we can't forget that Bt-corn and other
> transgenic crops have a huge potential for reducing pesticide use and
> increasing yields. This study is just the first step, we need to do more
> research and then objectively weigh the risks versus the benefits of this
> new technology."
> Other researchers on the study were Linda S. Rayor, Cornell instructor in
> entomology, and Maureen E. Carter, Cornell research aide.
> "Monarchs are considered to be a flagship species for conservation. This
is
> a warning bell," says Rayor. "Monarchs themselves are not an endangered
> species right now, but as their habitat is disrupted or destroyed, their
> migratory phenomena is becoming endangered."
> Bt-engineered maize is among the first major commercial successes for
> agricultural biotechnology. Last year, more than 7 million acres of the
> hybrid crop were planted by US farmers primarily to control the European
> corn borer. Before the advent of Bt-corn, this pest was extremely
difficult
> to control because it bores into the stalk, where it is protected from
> pesticides. It produces several generations a year. Because it was so
> difficult to control effectively with pesticides, annual losses averaged
> $1.2 billion. In contrast, Bt-maize provides essentially total season-long
> control at a reasonable cost without the use of pesticides. At least 18
> different Bt-engineered crops have been approved for field testing in the
> USA. Several factors make monarch caterpillars particularly likely to make
> contact with maize pollen, Losey says. Monarch larvae feed exclusively on
> milkweed because it provides protection against predators. The plant
> contains cardenolides, which are toxic, bitter chemicals that the monarch
> caterpillar incorporates into its body tissues, rendering it unpalatable
to
> predators. Milkweed grows best in "disturbed" habitats, like the edges of
> maize fields, Losey notes.
> The butterflies overwinter in Mexico and by the spring begin migrating
> north. The first generation of the year crosses into Texas, other Gulf
Coast
> states and Florida, seeking milkweed on which to lay their eggs and feed.
By
> late May or early June, the second generation of adults has emerged and
> heads north to areas including the Midwest Corn Belt. Monarch caterpillars
> are feeding on milkweed during the period when corn is shedding pollen,
> Losey says. Thus "they may be in the right place at the right time to be
> exposed to Bt-corn pollen."
> Field studies presented by Iowa State University scientists at a recent
> conference also suggest that Bt maize pollen is harming monarch
butterflies
> Laura Hansen, graduate research assistant, and John Obrycki, professor of
> entomology determined the amount of pollen deposited on milkweed leaves at
> various distances from a Bt maize field. Leaf samples taken from within
and
> at the edge of the field were used to assess mortality of first instar
> butterflies exposed to Bt and non-Bt maize pollen. Within 48 hours, they
> found 19% mortality in the Bt corn pollen treatment compared to 0% on
non-Bt
> corn pollen exposed plants and 3% in the no pollen controls.
> The Cornell study "proves without doubt that genetically modified crops
pose
> a potentially lethal threat to wildlife," say Friends of the Earth. "FoE
has
> been saying for years that Bt plants are not an ecological solution to
pest
> control. They can produce toxin in all parts of the plant, including
pollen
> which can be spread over a wide area, and therefore adversely affect
benign
> and beneficial insects, as this research demonstrates only too clearly"
said
> Gill Lacroix of FoE Europe's Biotechnology Programme.
> Environmentalists in Mexico urged the government to ban imports and use of
> GM maize. Homero Aridjis, head of the Group of 100 artists group said that
> Mexico, the USA and Canada are obliged to protect the monarch butterfly
> under ecological preservation provisions of the North American Free Trade
> Agreement. The Mexican government has approved the experimental
cultivation
> of GM maize in certain regions.
> "This new research confirms the views put forward by English Nature last
> year that there are serious concerns about the commercial introduction of
GM
> crops before research has been done on their potential effects on
> biodiversity," it says.
> Responding to the Nature article, Monsanto highlighted the reduction in
> spraying with insecticides that had resulted from Bt maize "as a result,
the
> effects on beneficial and other non-target insects also are dramatically
> reduced or
> eliminated." In a statement, the company said "We take very seriously
> research on Monarch butterflies and other non-target species, as well as
> beneficial insects that help control pests in fields. Considered in total,
> research conducted in the field supports the safety of Bt crops for
> beneficial and other non-target insects. The laboratory study in Nature
> provides interesting information, but reflects a situation very different
> than that actually prevalent in the natural environment.
> Monarch larvae feed almost exclusively on milkweed. The natural habitat
for
> milkweed is prairies, fields and roadsides, not the middle of full grown
and
> pollinating corn fields. In real life situations, the exposure
> of milkweed to corn pollen is very low because only a very small portion
of
> milkweed grows in close enough proximity to corn fields for exposure to
corn
> pollen. This information supports the conclusion of a very low likelihood
of
> effect of Bt pollen on non-target insects like the Monarch butterfly in
> their natural habitats.
> Monsanto also said that it was participating in an industry effort to
> support additional field research to reaffirm the lack of impact of Bt
crops
> for non-target and beneficial insects in their natural environment.
> Val Giddings of the BioIndustry Organization argued that "Even if the
> reported results are validated, there are strong reasons to believe they
are
> not relevant to Monarch caterpillars in the wild".
> "Monarch migration and egg laying patterns ensure that the primary period
of
> larval feeding and growth throughout nearly all the Monarch range takes
> place well before any nearby corn produces pollen. Ongoing monitoring of
Bt
> corn fields by companies since their introduction further shows that very
> little pollen lands on adjacent milkweed leaves. It is thus highly likely
> that in the natural setting, outside the laboratory, most Monarch larvae
> would never encounter any significant amounts of corn pollen. This means
the
> real potential for any negative impact is negligible.
> "Ongoing monitoring by companies of Bt corn fields since their
introduction
> also shows that insect biodiversity and population densities in Bt corn
> fields is significantly higher than in fields treated with chemical
> pesticide sprays. Bt corn thus helps enhance beneficial insect populations
> that would otherwise be threatened by the use of pesticidal sprays. This
> further leads to significant improvements to water quality and
environmental
> conservation for insect eating birds, small mammals and other life."
> "Reports of the potential for effects from these Bt corn hybrids on
Monarch
> butterflies or other lepidoptera are not new. They have been reported in
the
> scientific literature and regulatory review documents since at least 1986.
> Both the Environmental Protection Agency and the US Department of
> Agriculture have been provided data on the potential for impacts on
> non-target species from Bt pollen for years. Their analyses indicated
that,
> when compared with the numerous other relevant factors, the impacts from
> such pollen were likely to be negligible. "
> "The key issue is how large an impact is likely, and how significant would
> such an impact be when compared with the numerous other significant
factors
> known to have impacts on Monarch ranges and numbers."
> "BIO members have long been working with groups concerned with Monarch
> butterfly conservation to address the threats they face. It is widely
> recognized that the principal threat facing the Monarch butterfly relates
to
> loss of vital winter habitat in southern California and the highlands of
> central Mexico."
> Novartis, the first company to market Bt maize said that the study does
not
> give any basis for a change in its marketing of Bt maize.
> The paper, Transgenic pollen harms monarch larvae appears by John E.
Losey,
> Linda, S. Rayor and Maureen E. Carter, appears in Nature (1999) 399, 214.
> Contact: John E. Losey, Entomology Dept, 4126 Comstock Hall, Cornell
> University, Ithaca, NY 14853, USA
> Tel: +1 (607) 255 7376
> Fax:+1 (607) 255 0939
> Email [EMAIL PROTECTED]
> L. Hansen, Iowa State University, Ames , IA 50011 and J. Obrycki, Iowa
State
> University, Ames, IA 50011
> Email [EMAIL PROTECTED]
> http://www.pme.iastate.edu/info/monarch.htm
> May 1999
>
>
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