Desert Locust Plagues Managed with Insecticides

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Spraying for locusts

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Locust swarm

Since prehistoric times, plagues of desert locusts (a large grasshopper that swarms) have threatened food production in Africa, the Middle East and Asia. The swarms may cover several hundred square kilometers and contain 50 million locusts per square kilometer. A square kilometer of locusts can consume about 100 tons of crops per day. Regular monitoring of locust breeding areas and targeted insecticide sprays as populations increase prevent plagues most years. However, monitoring locust breeding areas can be difficult as many are located in remote areas or are in areas inaccessible due to border disputes and lack of security. When major outbreaks occur, widespread insecticide spraying is necessary.

“When locust upsurges and plagues develop, large scale control campaigns must be mounted on an emergency basis. These campaigns are expensive, use large quantities of insecticide and involve external assistance. During the last plague of 1986-89, some 40 countries were affected and more than 14 million hectares were treated. The total amount of assistance provide by the international community during the plague was about US$ 250 million. The total amount of assistance provided by the international community  during the last major upsurge from 2003-2005 was about 400 million US Dollars where about 13 million litres of pesticides were used to treat 13 million hectare in 11 countries.

Ground and aerial application of chemical pesticides is the only viable method of locust control at present.”

Authors: FAO
Title: Workshop on Spray Equipment Used in Desert Locust Control, 10-14, May. 2009.

An Invasive Fly from Asia Means African Mango Farmers Must Spray to Protect Their Crop

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Ruined Mangoes

In 2003, a new invasive fruit fly from Asia was detected in Africa. The pest has spread across a north-south distance of over 5000 km in West Central Africa. The female fly implants its eggs in young mango. The larvae or maggots develop in the flesh of fruit by digging tunnels (which provide opportunities for secondary infections when the larvae emerge from the fruit).

Bactrocera invadens… is a recently described fruit fly species from Asia that is of major quarantine concern in Africa and elsewhere.

On mango, direct damage owing to B. invadens has been reported to range from 30 to 80% of the crop depending on the cultivar, locality, and season. In addition to direct losses, indirect losses attributed to quarantine restrictions on the pest have been enormous.

The European Union (EU) phytosanitary regulations in relation to non-European Tephritidae are tightening and interception and rejection of African mangoes in the EU, owing to fruit flies, have been on the increase since the arrival of B. invadens. These direct and indirect costs have wide reaching socioeconomic implications for millions of people in rural and urban communities involved in the mango value chain across Africa.

In this study, we evaluated the relative efficacy of six commercially available food-based attractants in trapping male and female B. invadens in mango. Furthermore, we evaluated the efficacy of the most attractive bait, sprayed in conjunction with spinosad for field suppression of B. invadens in mango orchards in Kenya during two fruiting seasons.

At harvest, the proportion of fruit infested was significantly lower in the treated orchards (8%) compared with the control orchards (59%). Estimated mango yield was significantly higher in orchards receiving the bait sprays (12,487 kg/ha) compared with control orchards (3,606 kg/ha). Based on bait spray costs, yield data, and monetary gains, a cost-benefit ratio of 1:9.1 was realized, which is acceptable for growers.”

Authors: Ekesi, S., et al.
Affiliation: International Centre of Insect Physiology and Ecology, Kenya.
Title: Comparison of Food-Based Attractants for Bactrocera invadens (Diptera: Tephritidae) and Evaluation of Mazoferm-Spinosad Bait Spray for Field Suppression in Mango.
Source: Journal of Economic Entomology. 2014. 107[1]:299-309.

Here Comes the Sunn…………..Pest

Sunn Pest

Normal Grain (L) versus Sunn Pest Damage to Grain (R)

The sunn pest are a group of insects representing several genera of the shield bug and stink bug families. The sunn pest lives for one year and produces a single generation per year. About three months are spent feeding in wheat fields. The rest of the year is spent resting and in hibernation on hillsides which are usually about 10-20 km from the wheat fields. In spring, the surviving adults migrate down to the wheat fields in one non-stop flight and, after feeding, mate and lay eggs. The adults of the next generation appear and feed intensively in order to accumulate fat reserves for the hibernation period. They return to the higher elevations following wheat harvest.

Sunn pest feeding on wheat results in yield loss as most of the kernel contents can be sucked out by the insect, resulting in smaller, lighter, and shriveled kernels. In addition, the sunn pest injects digestive enzymes to liquefy the wheat tissues into a nutrient-rich slurry.

In some countries, foliar applications of insecticides to control sunn pest are made by air by governments, while in others, ground sprays, partially supported by the government, are made by farmers. A single spray will often suffice to control populations effectively.

“One of the most significant limiting factors in the production of wheat and barley in many areas of the world is the Sunn pest, Eurygaster integriceps, which causes severe damage to cereal yield. This insect has been observed in >15 million ha of wheat and barley farms, which extend from northern Africa, throughout the Middle East and western Asia, to central Asia and some parts of Russia. The Sunn pest feeds preferentially on wheat. Thus, its damage to wheat is considerably greater than that to barley (i.E., it often causes losses of 20-30% in barley and 50-90% in wheat).

In recent years, considerable efforts have been made to biologically control this pest. However, pesticide application is the main method of Sunn pest control in areas where infestation is high.”

Author: Rahimi, V. and A. R. Bandani.
Affiliation: University of Tehran, Iran.
Title: Comparison of the effects of cereal and legume proteinaceous seed extracts on a-amylase activity and development of the Sunn pest.
Source: Journal of Asia-Pacific Entomology. 2014. 17:7-11.

Sustaining Water Resources in Asia Means Rice Growers Must Use Herbicides

Rice Fields

Rice Fields

Flooding rice fields prevents certain weed species from developing and rice fields in Asia are major users of water resources. However, a looming water shortage in Asia means that rice growers will have to cut back on water use. Herbicides are being tested as a replacement for flooding for weed control in rice fields.

Currently, sustainability of water resources is of major concern, and declining water availability threatens the sustainability of traditional flood-irrigated rice ecosystems. In Asia, it is predicted that 17 million ha of irrigated rice areas may have “physical water scarcity” and 22 million ha areas may be subject to “economic water scarcity” by 2025. It is, therefore, no longer feasible to flood rice fields for better crop establishment and weed control.

“Aerobic rice, growing rice in non-saturated and non-puddled aerobic soil, is a promising water-wise technique of rice cultivation under the context of ever-mounting water scarcity. But weed menace continues to be a severe problem in aerobic rice systems resulting in up to 90% reduction in grain yield. When direct seeded, rice seeds germinate simultaneously with weed seeds without any “head start” over germinating weed seeds, and the initial flush of weeds is not suppressed by flooding. …Therefore, effective weed management in aerobic rice has become a serious challenge for researchers and farmers.

Eight commercial herbicide products were applied singly or as tank-mix or in sequence to evaluate their efficacy, rice selectivity and cost-effectiveness in aerobic rice. …Most of the herbicide treatments provided excellent weed control, and produced much higher net benefit than weedy or weed-free check. …Among the herbicide treatments, sequential application of Cyhalofop-butyl + Bensulfuron at early growth stage followed by Bentazon/MCPA at mid growth stage provided the highest weed control efficiency, productivity and net benefit. …Since manual weeding was not economic, herbicide rotation using the above chemicals may be recommended for effective weed management in aerobic rice.

In the present study, cost of different herbicide treatments ranged from RM 167 to RM 469 ha-1 depending upon the price and rate of application, while manual weed control required a high investment of RM 2500 ha-1 for season-long weed-free checks.

In our study, the net benefit of the herbicidal weed control was two to three times higher than that obtained from manual weed control. Hence, manual weeding is less remunerative than herbicidal control, and keeping aerobic rice field weed-free manually throughout the season is a losing concern, confirmed by many others.”

Authors: Anwar, P., et al.
Affiliation: Institute of Tropical Agriculture, Universiti Putra Malaysia
Title: Efficacy, phytotoxicity and economics of different herbicides in aerobic rice.
Source: Acta Agriculturae Scandinavica Section B – Soil and Plant Science. 2012. 62:604-615.

Fly Eggs in Fruit? Insecticides Are the Only Option

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Serrated Egg Layer Drosophila

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Blueberries: Drosophila Infestation (Right)

The invasive spotted wing drosophila fly came into the US from Asia in 2008 and has spread throughout the US. The fly prefers softer, sweeter ripe fruit- cherries, raspberries, blueberries,blackberries and strawberries. The female flies use saw-like blades on their abdomens to cut through the skin of ripe fruit and lay their eggs inside. The eggs hatch into worms that feed on the flesh of the fruit – ruining the fruit for sale. Insecticides are currently the only option for drosophila control and growers throughout the US are being advised to spray.

“The spotted wing drosophila, a tiny fly that can take a big bite of orchards and gardens, has gradually been making its way across the country from the West Coast and has discovered the summer bounty in the Granite State is much to its liking, according to Dr. Alan Eaton, an entomologist with the University of New Hampshire.

If the flies show up around the time the fruit ripens, the farmers have to immediately spray to kill them off, Eaton said. There are both standard and organic remedies available, he said, but spraying is vital to saving crops. “We’ve had a few growers who weren’t listening to us and their entire crops were wiped out,” said Eaton.”

Author: Nancy Bean Foster
Affiliation: Union Leader Correspondent
Title: Fruit farmers on guard for new pest
Source: Union Leader. August 26, 2013. Available at: http://www.unionleader.com/article/20130827/NEWHAMPSHIRE07/130829419?dm_i=1ANQ,1T79M,6LPYOS,6H5RF,1

Chilean Apple Growers Must Use Insecticides to Control Quarantine Pests

Codling Moth Frass

Codling Moth Frass

Chile is a major exporter of apples to other Latin American and Asian countries. Some of these countries do not have populations of the codling moth and they want to keep the insect out. Codling moth is present in Chilean apple orchards which means that growers must spray insecticides to assure that their export fruit shipments will not be rejected.

“Regular applications of insecticides have been the main management practice against codling moth in Chile. … Pest management in Chilean apple orchards with fruit grown for export is dependent on intensive pesticide use, mainly because of strong quarantine restrictions toward the codling moth from Asian and Latin America countries. In this production scenario, even low levels of fruit damage at harvest (<0.5%) are a major concern for growers. To avoid quarantine rejection of exports, an increase in the frequency of insecticide sprays has been observed.”

Authors: E. Fuentes-Contreras1, M. Reyes2, W. Barros1 and B. Sauphanor2

Affiliation:
1Department de Producción Agrícola, Universidad de Talca, Talca, Chile; 2PSH-Ecologie de la Production Intégrée, INRA Site Agroparc, Avignon Cedex, France
Title: Evaluation of azinphos-methyl resistance and activity of detoxifying enzymes in codling moth (Lepidoptera: Tortricidae) from central Chile.
Publication: Journal of Economic Entomology. 2007. 100(2):551-556.

Fungicides Result in Mangoes Suitable for Export

Mango - Anthracnose

Mango – Anthracnose

Commonly known as the “King of Fruits,” the mango is the most important fruit of Asia. It is grown throughout the tropics and subtropics. Until recently, mango fruit was considered an exotic, specialty item in import markets such as the U.S. and Europe. Today a million tons of mangoes are exported. Among the diseases of mango, anthracnose is the most prevalent in humid growing regions. The incidence of this disease can reach almost 100% in fruit produced under wet or very humid conditions.

“Diseases are primary constraints to production in virtually all areas where mango is grown. … In humid regions, anthracnose is most destructive. … Pesticides are used in most commercial production situations, especially where anthracnose [is] important.”

“…irregular, dark brown to black lesions develop that are somewhat depressed and can crack the fruit surface. Under humid conditions, large areas may be involved and orange to pinkish masses of conidia are formed on the decaying surface. … Lesions on fruit are initially superficial, and penetrate deeper than 5 mm into the flesh only late in development. Anthracnose is caused by three closely related fungi. … Although some mango cultivars are moderately tolerant, none are sufficiently resistant to be produced without fungicides in humid areas.”

“In general, mango production currently has a heavy dependence on chemical disease control measures, especially where disease-conducive environments exist and when export quality fruit are desired.”

Author: R.C. Ploetz
Affiliation:
University of Florida Tropical Research and Education Center, Homestead, FL
Title: The major diseases of mango: strategies and potential for sustainable management.
Publication: Proceedings of the VIIth International Symposium on Mango. 2004. 137-150.