New findings give body blow to anti-GM campaign

Scientists on Wednesday reported that the monarch butterfly population dwindled in north America much before the introduction of the genetically modified crops as popularly claimed by the anti-GM activists.

The discovery – reported in the Proceedings of the National Academy of Sciences (PNAS) – has the potential to provide a strong counter to the agitations against GM crops.

Since the introduction of Bt cotton in 2002, the Indian government didn't allow marketing of any other GM crop seeds partly due to a strident anti-GM campaign with the activists influencing the policymakers and approaching the courts with their plea.

The monarch butterfly studies lie at the core of the scientific arguments put forward by the anti-GM lobby groups. They cite multiple scientific research to suggest that the main cause of the monarch butterfly's decline is the loss of milkweed — its food — in breeding grounds due to the adoption of genetically modified crops.

Scientists from the College of William and Mary now challenge the notion. They report that monarch butterfly and milkweed declines began around 1950, well before the introduction of genetically modified crops.

The role of genetically modified crops in milkweed and monarch declines is unclear, partly because previous monarch population data sets only extend back to 1993.

Now Joshua Puzey and colleagues gathered digitized museum and herbaria records for 1,191 monarch specimens and 39,510 milkweed specimens collected from 1900 to 2016.

Analysis of long-term trends revealed that both monarchs and milkweeds suffered a two-fold decline between approximately 1950 and 2016.

Moreover, the decline in the abundance of the common milkweed, the primary host plant of monarchs, was linked to the consolidation of smaller farms in the same period. The findings suggest that a decrease in the number of farms may predict common milkweed trends more strongly than herbicide-resistant crops, which were not introduced until 1996.

According to the authors, while the findings do not exclude a role for changes in agricultural practices, such as agrochemical use, factors other than genetically modified crops may influence the abundance of monarchs and milkweeds.

“The recent decline of the monarch butterfly has attracted a great deal of attention. One of the leading hypotheses blames GM crops, ostensibly because of the impact of GM-related herbicide use on the monarch’s food plants, milkweeds. We use museum specimen records to chart monarch and milkweed occurrence over the past century (1900 to 2016), dating well before previous data sets begin (in 1993) and show that monarch and milkweed declines begin around 1950 and continue until the present day,” the scientists reported in the PNAS.

“Whatever factors caused milkweed and monarch declines prior to the introduction of GM crops may still be at play, and, hence, laying the blame so heavily on GM crops is neither parsimonious nor well supported by data,” they added.

After Bt-cotton, two other genetically engineered crops – eggplant and mustard - were deemed fit for commercial release by Indian regulators. However, in both cases the Union Ministry for Environment and Forest didn't finally take the plunge.