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Improvement of IPM of Brassica vegetable crops in China and Australia

Overview of Project

The project aimed to develop and implement sustainable management strategies that would effectively control insect pests in brassica vegetables and be acceptable to growers, thus reducing pesticide hazards.

Brassica crops account for about half the total vegetable production and consumption in the Changjiang River Valley in China. In Australia, the brassica industry is centred in Queensland’s Lockyer Valley and Eastern Darling Downs. Growers in both countries face similar problems from insect pests, particularly the diamondback moth (DBM).

In China the control of pest insects has relied heavily on chemical insecticides, which are often overused or misused. Problems encountered include pest resistance, expense, increases in insecticide residues in the harvested vegetables, and hazards to the health of spray operators. The brassica group and its pests presented a good case for the use of integrated pest management (IPM) to reduce the level of insecticide applied to the plants. IPM uses other means - especially beneficial species, such as parasites and predators - along with judicious use of environmentally acceptable pesticides to control pest insects."

Key Outcomes of Project

In both China and Australia the scientists completed investigations of major quantitative factors affecting the numerical changes of pest abundance in brassica crops in the field, and particularly the role that benefical organisms (parsitoid, predators and pathogens) played in suppressing pest populations. In China, 112 species of parasitoids were recorded for four major insect pests - six species recorded as native species for the first time from China. In Australia, two egg parasitoids and one larval pupal parasitoids of DBM were recorded for the first time from this geographic region.

To determine the impact of the main pests on yield and quality loss in major brassica crops and varieties under field conditions the scientists undertook an evaluation of DBM populations in southeast Queensland from 2000 to 2002. They demonstrated that mortality of DBM larvae caused by predators and parasitoids on farms using IPM practices was usually 70-80%, significantly higher than for farms that practised calendar chemical sprays, where the mortality of DBM larvae was usually around 20%.

IPM trials were conducted for four different crops at six sites in east China from 1999 to 2002. Significantly higher numbers of beneficial arthropods and higher rates of parasitism of insect pests were regularly observed in IPM plots than in chemical spray plots. In both Australia and China, the scale of the studies and the consistency of the results across farms, years and different crop production systems provided convincing field evidence that where natural enemies are properly protected and promoted they can dramatically suppress pest populations.

Laboratory bioassays, semi-field tests and field trials were conducted to screen for biological and ‘soft’ insecticides, leading to recommendations of a number of selective insecticides for field use. Strategies to improve insecticide application were tested, focusing on options that promoted ‘soft’ insecticides and reduced total insecticide use.

The IPM trials and field assessments demonstrated that, compared to conventional practice, pest monitoring and use of simple action thresholds helped to reduce the number of sprays and insecticide input substantially and yet achieved similar, or better, control of insect pests at all sites studied.

The scientists established resistance levels to major insecticides used in the brassica production system. They improved their methods for promoting implementation of IPM in brassica vegetable production and applied them widely in the project areas.

There are now a large number of Chinese institutions involved in the implementation of integrated pest management with farmers. The rates of uptake of project outputs by farmers are encouraging. Interest in integrated pest management has grown in the Lockyer Valley in Queensland. Growers interested in IPM have established the Brassica Improvement Group (known as the BIG Boys). A second offshoot has developed of people who are going beyond IPM into full, certified organic culture of broccoli (still using the results of the ACIAR research as the basis of their IPM)."

Project Dates

01 Jul 1999 - 30 Jun 2003

Partners

Queensland Department of Primary Industries - Australia
Zhejiang Department of Agriculture - China
Shanghai Academy of Agricultural Science - China
Zhejiang University - China
Zhejiang Academy of Agricultural Sciences - China

Leaders

Professor Myron Zalucki

Email

M.Zalucki@uq.edu.au

Phone

61 7 33651747

Website
Launch Website