Temporal abundance of African weaver ant, Oecophylla longinoda (Hymenoptera: Formicidae) under unimodal rainfall pattern in Tanzania

ABSTRACT

Weaver ants, Oecophylla spp., provide adequate protection to crops against insect pests when their populations are high and stable. A study was conducted in a cashew field in Tanzania from November 2012 to October 2014 to determine temporal abundance of O. longinoda. We determined (i) the number of shoots with O. longinoda in a tree (established fortnightly) monitored at four cardinal points of a tree, using 1 m² wooden quadrats, (ii) the percentage of branches with ant trails per tree per month and (iii) the number of visible ant nests within the tree canopy per month. Furthermore, we assessed the association of weather and phenology with O. longinoda populations. More weaver ant populations were recorded during reproductive and vegetative phases of cashew. We recorded significant positive associations between rainfall and temperature with the number of shoots with O. longinoda (p < .001), as well as relative humidity with the number of nests (p < .001). The percentage of shoots with O. longinoda was significantly associated with cashew growth phases. Rainfall and temperature negatively affected the number of nests. Consideration of cashew phenology and weather parameters can greatly enhance successful weaver ant augmentation strategies.

KEYWORDS:

• Cashew
• phenology
• Oecophylla longinoda; weather parameters
• Tanzania

Acknowledgements

The authors are grateful to the Director of NARI for allowing the undertaking of this study in Naliendele fields. Frank Thadeo is acknowledged for his assistance on data collection.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This study was funded by the Danish International Development Agency through project [DFC 10-025AU].