Assessment of an integrated cashew improvement program, using weaver ants as a major component, in cashew production in Vietnam

  • Nguyen Thanh Binh

    Student thesis: Doctor of Philosophy (PhD) - CDU


    Cashew (Anacardium occidentale L. [Sapindales: Anacardiaceae]) is an important industrial crop in Vietnam, and it has contributed to more than 200,000 farmers’ household incomes in rural areas. Pest damage is one of the constraints on the farmers’ income, and overuse of insecticides has caused environmental and health problems. The integrated cashew improvement (ICI) program using weaver ants (Oecophylla smaragdina (Fabricius) [Hymenoptera: Formicidae]) as a key element developed for Vietnamese cashew farmers has been fully assessed. Weaver ants effectively controlled the main insect pests on cashew, including the tea mosquito bug, the brown shoot borer, leaf rollers and the leafminer. Weaver ants reduced the pest damage to an acceptable level compared to the insecticide treatment, or to levels under the control threshold. Damage caused by sternorrhynchan pests was either negligible or well below the control thresholds. This is because the ICI program enhanced the population of natural enemies, which, in turn, suppressed sternorrhynchan pests. The implementation of the ICI program enhanced arthropod diversity and natural enemy populations in comparison to the farmers’ conventional farming method (FCF), which heavily used insecticides.

    Compared to the farmers’ conventional farming method, the ICI program generally produced similar nut yield, but with a reduction of expenses by 10.3% and an increase of net profits by 13.3%. In addition, the ICI program also produced higher quality nuts than the FCF.

    The competition between weaver ants and other ant species was identified as an important factor in implementation of the ICI program. To resolve this, orchard understorey and boundary tree management, focussing on improving food sources of other ants, was proposed. Continuation of the ICI program implementation on a large scale is highly recommended for the Vietnam cashew industry.
    Date of AwardMar 2010
    Original languageEnglish
    SupervisorKeith Christian (Supervisor), Renkang Peng (Supervisor) & Karen Gibb (Supervisor)

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