Archive for the ‘Pest control’ Category

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.

Landcare team looks into fighting wasps with wasps

Landcare Research scientists are exploring possible biocontrol agents, including a mite, to help control German and common wasps which cost the country’s primary industries around $130 million each year.

The most recent addition to the line-up is Sphecophaga, a species of parasitic wasp whose larvae feed off their host, eventually killing it.

The species was tried as a biocontrol agent against wasps in New Zealand starting in the 1980s, but so far has been established only in a few locations.

Recent research suggests this could have happened because the parasitic wasps were from the wrong region – sourced from Switzerland, Israel and the United States. Victoria University recently discovered New Zealand’s dominate wasp species originate from the UK.

Landcare Research biocontrol scientist Dr Ronny Groenteman said this information was “a key piece of the puzzle”.

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Combined seed treatment to help protect NZ crops is given approval

A new version of an insecticide used to help protect corn, wheat grass and brassica crops has been approved by the Environmental Protection Authority (EPA).

Bayer New Zealand’s Poncho Votivo is a seed treatment that will help control pests that can attack these crops.such as Argentine stem weevil, black beetle, greasy cutworm and parasitic nematodes.

It’s a reformulation of an already approved insecticide called Poncho and is applied to seeds at a treatment plant before they’re sown.

“What’s different about Poncho Votivo is that it contains a lower concentration of the neonicotinoid clothianidin, alongside a soil-dwelling micro-organism called Bacillus firmus. This is found naturally in New Zealand soil but has not been used before as an active ingredient in an insecticide,” says Ray McMillan, EPA’s Acting General Manager of Hazardous Substances and New Organisms.

After weighing the risks and benefits of Poncho Votivo following a public hearing in December 2015, the EPA’s decision-making committee approved its use and set specific controls to manage risks to people and our environment. It means those applying the insecticide must wear protective clothing and adhere to specific restrictions related to the rate, method and timing of application.

Mr McMillan said the combined insecticide had benefits for the New Zealand environment because it treats two types of pest at once and farmers are less likely to need a separate soil treatment.

View decision details and information



Wasp approved to lead fight against tomato and potato pest

The Environmental Protection Authority has approved a type of parasitic wasp as a biological control agent to combat the tomato potato psyllid (a plant louse), which attacks tomatoes, potatoes, capsicums and tamarillos in New Zealand. Biological control agents are natural enemies of a plant or insect pests, and are released to reduce, control or supress those pests.

The wasp (Tamarixia triozae) will be introduced and released to kill the tomato potato psyllid (Bactericera cockerelli).

The psyllid was first found in New Zealand in 2006 and is known as a pest in several countries, creating a significant impact on plants and crops. The psyllid has three life stages – egg, nymph and adult. Adult females lay eggs on the upper and lower surface of potato, tomato, capsicum and tamarillo plant leaves.

The psyllid nymphs and adults feed on the underside of leaves, leaving the plant stunted and discoloured, with poor or little fruit growth. The psyllid also spreads a bacteria that causes Zebra Chip disease in some crops, like potatoes, which affects crop yields.

The wasp is a psyllid parasitoid which means it attaches to or within a single host, eventually killing it. It is a black, winged red-eyed wasp normally found in North America and Mexico. The wasp lays its eggs on the surface of the psyllid nymphs. The eggs develop into larvae that feed on the nymphs, killing them.

The parasitic wasp will be introduced as part of a pest management programme, in combination with other beneficial insects and chemical control strategies.

The application to introduce the wasp was made by Horticulture New Zealand Inc on behalf of a number of growers’ industry groups under the Hazardous Substances and New Organisms Act 1996.

The EPA received 36 submissions on the application, 32 of them in support, two neither supporting nor opposing, and two opposed.

Chemicals that make plants defend themselves could replace pesticides

New research published in Bioorganic & Medicinal Chemistry Letters identifies five chemicals that trigger rice plants to fend off a common pest – the white-backed planthopper, Sogatella furcifera.

This paves the way for  pesticides being replaced by chemical triggers that make plants defend themselves against insects.

The widespread use of pesticides to control insects that destroy crops has raised environmental concerns because of the detrimental effect on ecosystems. One problem is that many pesticides kill indiscriminately.

Plants have natural self-defence mechanisms that kick in when they are infested with pests like the white-backed planthopper, Sogatella furcifera, that is a pest for rice crops. This mechanism can be switched on using chemicals that do not harm the environment and are not toxic to the insects or their natural enemies.

In the new study, researchers from Zhejiang University 
in China developed a new way of identifying these chemicals. Using a specially designed screening system, they determined to what extent different chemicals switched on the plants’ defence mechanism.

The team designed and synthesized 29 phenoxyalkanoic acid derivatives. Of these, they identified five that could be effective at triggering the rice plants to defend themselves.

The researchers used bioassays to show that these chemicals could trigger the plant defense mechanism and repel the white-backed planthopper. This suggests that these chemicals have the potential to be used in insect pest management.

“We demonstrate for the first time that some phenoxyalkanoic acid derivatives have the potential to become such plant protection agents against the rice white-backed planthopper,” said Dr. Yonggen Lou, one of the authors of the study and professor at Zhejiang University 
in China.

“This new approach to pest management could help protect the ecosystem while defending important crops against attack.”

The next step for the research will be to explore how effective the chemicals are at boosting the plants’ defenses and controlling planthoppers in the field.

Submissions sought on fungicide for onion mildew

The Environmental Protection Authority is calling for submissions on an application for release of DuPont Zorvec Enicade Fungicide. This fungicide contains the active ingredient oxathiapiprolin and is intended to be used for the control of downy mildew in onions. This active ingredient has not previously been approved under the Hazardous Substances and New Organisms Act and is not a component in any approved formulation.

DuPont Zorvec Enicade Fungicide is an oil dispersion formulation to be applied to onion foliage by boom spray methods. It is intended to be applied up to two times per crop cycle, with a minimum of 10 days between applications. The intended maximum application rate is equivalent to 35 g of oxathiapiprolin per hectare.

Application details and decision documents can be viewed here.

The public are invited to make submissions on the application to the EPA. The submissions period for this application opened on 23 July and closes at 5pm on 3 September.

Submissions are an opportunity to provide further information and raise issues about an application. They will inform a decision-making committee that will decide whether to approve or decline the application.

A public hearing may be held before a decision is made. The EPA will provide at least 10 working days’ notice of the hearing date, time and place. We’ll provide this information to all submitters and the applicant.

Find more information on submissions and the hearing process here.

Landcare reports mite-y development in potential wasp biocontrol

A tiny mite found on wasps continues to look a promising biocontrol agent against the winged pest.

New Zealand’s wasp problem is considered the worst in the world. The pest is estimated to sting the country’s primary industries around $130 million a year. But wasps also pose a hazard to people and harm native bird populations by competing with them for food resources including honeydew and insects.

Landcare Research scientist Dr Bob Brown, who discovered the unnamed mite in 2011, has been researching if they could be a suitable solution. His latest findings suggest they could be.

He has found wasp nests where the mites are present are “significantly smaller”.

“Wasp nests infested with the mites are 50 to 70 percent smaller than uninfested nests,” Brown said.

Another encouraging discovery has been immature mites in wasp nests.

“It’s a good indication that the wasps could be a host for the mites – that the mites presence in the nests is not coincidental,” Brown said.

“Before we started surveying systematically, we only knew that adult mites were found in wasp nests, and we couldn’t say if mites were spending their entire life-cycle in association with wasps or not. Now that we found immature mites in wasp nests we are more confident that the mites are spending a significant part of their life in the nest.

“The relationship between the wasps and the mite is slowly beginning to reveal itself,” he said.

Brown’s earlier research found the mites on sick wasps and those wasps infested with mites did not display normal aggressiveness. Mites were also found on wasp queens hibernating over winter strongly suggesting there was a link between the two organisms from year-to-year.

Landcare Research biocontrol scientist Dr Ronny Groenteman said the new findings were a “great step forward”.

“There is still some way to go though. We still don’t know for certain that the mites adversely affect wasps, that they are safe to other organisms, or that they can be effective – this could take years,” she said.

Brown is currently collecting more information about the mites’ presence on queens over winter and is seeking help from the public. He is after wasp queens from around the country to see how many are infested with the mite.

“At this time of year, the queen leaves the colony to hibernate for the winter. They go in search of somewhere dry and dark. They can often come into people’s garages, sheds or wood piles.

“The queens are distinguishable as they are much larger than workers and, when they are hibernating, can be found sitting quietly with their wings tucked underneath their abdomen.”

Brown said wasp queens were “very docile” when hibernating, but still advised people take care when approaching one. Once captured, he recommended placing the wasp in the freezer overnight to kill it before posting.

Anyone who finds a wasp queen and wants to send it to Brown is asked to post it to PO Box 69040, Lincoln 7640. He recommends putting the dead wasp with tissue paper inside a pill jar. Senders are also asked to include a brief description of where they found the wasp (for example: wood pile), the geographic location and contact details.

Landcare Research has been contracted by the Vespula Biocontrol Action Group to investigate the mite’s potential as a biocontrol agent against wasps.

“We’re delighted with the progress being made by Landcare Research in assessing the impact of the mite on wasp colonies. This could provide enormous benefits to the primary producers and to natural ecosystems. Biocontrol agents are the best long-term solution to dealing with pests on a landscape scale,” Vespula Biocontrol Action Group chairman Bryce Buckland said.

The research is funded by the Ministry of Primary Industries’ Sustainable Farming Fund.