Genetic strategy reverses insecticide resistance

Using CRISPR/Cas9 technology, scientists have genetically engineered a method to reverse insecticide resistance. The gene replacement method offers a new way to fight deadly malaria spread and reduce the use of pesticides that protect valuable food crops.

Insecticides play a central role in efforts to counter global impacts of mosquito-spread malaria and other diseases, which cause an estimated 750,000 deaths each year. These insect-specific chemicals, which cost more than $100 million to develop and bring to market, also are critical to controlling insect-driven crop damage that poses a challenge to food security.

But in recent decades many insects have genetically adapted to become less sensitive to the potency of insecticides. In Africa, where long-lasting insecticide-treated bed nets and indoor spraying are major weapons in the fight against malaria, many species of mosquitoes across the continent have developed insecticide resistance that reduces the efficacy of these key interventions. In certain areas climate change is expected to exacerbate these problems. Continue reading

Common insecticide is harmful to bees in any amount – for the average bee, every little bit counts

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 The dangers of neonicotinoid insecticides likely can’t be watered down. That’s the conclusion of a new study showing an insecticide made for commercial plant nurseries is harmful to a typical bee even when applied well below the label rate and the plant receives high levels of irrigation.

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A new UC Riverside study shows that a type of insecticide made for commercial plant nurseries is harmful to a typical bee even when applied well below the label rate.

The study was published in the journal Proceedings of the Royal Society B: Biological Sciences.

Chemically similar to nicotine, neonicotinoids are insecticides that protect against plant-consuming insects like aphids, but seriously harm beneficial insects, like bees. They are widely used by commercial growers.

Much research has focused on their use in food crops like canola, in which they are typically applied at low doses. However, this study is one of the few to examine neonicotinoid application in potted ornamental plants, which can represent more potent, acute sources of exposure to the toxin for bees. Continue reading

EPA says grounds have been established to reassess neonicotinoids

The Environmental Protection Authority (EPA) has determined there are grounds to reassess approvals of substances containing neonicotinoids used in New Zealand.

Neonicotinoids, a group of insecticides, have been the subject of ongoing concern regarding their effects on bee populations internationally. A reassessment is a formal review of the rules controlling a substance that is already in use in New Zealand.

“Grounds” is a specific term under the Hazardous Substances and New Organisms Act (HSNO). It refers to certain criteria required by HSNO, which must be met before a reassessment can be initiated.

Notification of grounds means an application can be made to reassess a substance. Continue reading

UCSB scientists report on the effects of landscape characteristics on insecticide use

The effects of certain landscape characteristics on insecticide use depend on context and crop type, an American study has found.

The research has been reported (HERE) by the University of California – Santa Barbara.

Over the past half century, food production has intensified to meet the growing demand, the UCSB report says. And as agricultural fields have become ever larger, more pesticides are required to enhance yield.

Among increasingly huge spreads of single crops, insects tend to thrive as the landscape leaves little habitat for natural enemies such as birds or other predators. whether this plays out in reality has been difficult to determine scientifically.

Empirical landscape-scale studies of the drivers of agricultural insecticide use have produced ambiguous results and aggregated statistics make it difficult to tease apart the effects of underlying components.

A new study by UC Santa Barbara scientists has overcome that obstacle. Using detailed data from roughly 13,000 fields observed from 2005 to 2013 in Kern County, California, Ashley Larsen and Frederik Noack parsed the different effects of landscape characteristics such as crop diversity, field size and cropland extent on insecticide use. Their findings appear in the Proceedings of the National Academy of Sciences.

“If we are to minimize the negative effects of insecticides on human and environmental health, it is critical to understand if and how we can leverage landscape features to reduce insecticide use,” said lead author Larsen, an assistant professor in UCSB’s Bren School of Environmental Science & Management.

“Unlocking the different landscape components across multiple crops and spatial scales provides a novel understanding of which characteristics are likely to increase or decrease insecticide use for specific crops.”

The analysis by Larsen and Noack, a post-doctoral researcher at the Bren School, demonstrated potentially valuable benefits to crop diversity and to smaller fields. However, these benefits were highly dependent on crop type.

The research showed that while crop diversity reduced insecticide use, its impact was small in comparison to the differences in insecticide use between different crops.

“The choice of crops we produce or the type of crops we eat has a much larger impact on overall insecticide use than do landscape characteristics such as crop diversity or cropland extent,” Noack said.

As surrounding grape crop diversity increased, for example, insecticide use fell by nearly 8 kilograms per hectare.

“Grapes use about 49 kilograms of insecticide per hectare, so an 8 kg reduction is a fairly substantial fraction,” Larsen explained. “For oranges, the reduction is less than 2 kilograms per hectare, which is not significant, and for carrots there is no effect at all.”

Moreover, the investigators consistently found that larger fields use more insecticide.

A huge swath of single crop may serve to meet growing demand, but it also provides an uninterrupted breeding ground for insects, which in turn may promote increased chemical treatment to control the pests.

While many factors are at play, on the ecological side the paper was a big advance because scientists haven’t had this type of fine-scale understanding before, Larsen said. The researchers had been able to show that landscape drivers of agricultural insecticide use are very crop specific.