Biological control of the fruit‐spotting bug Amblypelta lutescens using weaver ants Oecophylla smaragdina on African mahoganies in Australia

Abstract

1 African mahogany Khaya senegalensis is a high-value timber tree. Pilot plantings showed that the fruit-spotting bug Amblypelta lutescens causes severe damage of the tree in the wet-dry tropics of northern Australia. The weaver ant Oecophylla smaragdina is an efficient biocontrol agent in some horticulture crops. To investigate whether the ants control this pest, field experiments were conducted from April 2006 to January 2009 at two study sites in the Darwin area, Australia. A laboratory experiment was carried out in March 2007 at Berrimah Farm. 2 During the experimental period, in the weaver ant treatments, the overall percentage of trees damaged by the pest was 0-8% at both sites, and the damaged trees were attacked once only. In the treatments without weaver ants, however, the damage level was > 80% at Berrimah Farm and 31-100% at Howard Springs, and the damaged trees were attacked more than once. 3 The mean percentage of trees damaged per monitoring occasion was 0-2.6% in the weaver ant treatments at both sites, whereas, in the treatments without the ants, the damage percentages were 14.2-27.0% at Howard Springs and 28.2-48.6% at Berrimah Farm. 4 Extrafloral nectar of African mahoganies is attractive to weaver ants. Fruit-spotting bugs only damage the tender parts of flushing shoots and growing tips. Weaver ants live on sugar solution and meat, and they frequently harvest extrafloral nectar on growing shoots, on which they catch nymphs of the pest for their meat supply. The aggressive behaviour of the ants also repels the pest away from flushing shoots. 5 The data suggest that weaver ants were effective biocontrol agents of fruit-spotting bugs, and the ants can be used to manage the pest on African mahoganies. 6 The present study demonstrates that the introduced African mahogany comprises another major host of the fruit-spotting bug.

High invasive ant activity drives predation of a native butterfly larva

“…Although O. smaragdina is displaced by A. gracilipes (Lach & Hoffmann ), it is known for its aggressive defense of plants from herbivores (Peng & Christian , Peng et al . ) and has been used a biological control agent in agricultural systems for centuries (Huang & Yang ). The difference in the attack rate between the two ant species likely stems from the difference in their visitation to, and abundance on, the plants.…”

Oecophylla smaragdinaants provide pest control in Australian cacao

“…together, due to their similar biology (similar size, phloem feeding nature, broader taxonomic grouping, and response to ants in other studies; Peng et al . , , Wielgoss et al . ) and low densities.…”

Using weaver antsOecophylla smaragdinato control two important pests on African mahoganyKhaya senegalensisin the Northern Territory of Australia

“…Alexander). The impacts of fruit-spotting bugs and shoot borers and the control strategies have been reported (Peng et al 2011b(Peng et al , 2012. Although the damage caused by the yellow looper and bush crickets does not kill the trees, the resultant stem deformation reduces the production of timber (Peng et al 2009).…”

“…Wylie 1974;Macfarlane et al 1976;Lim and Kirton 2003;Peng et al 2010aPeng et al , 2011bPeng et al , 2012 and in horticultural crops (e.g. Stapley 1972;Huang and Yang 1987;Van Mele et al 2002;Peng et al 2004Peng et al , 2010bPeng and Christian 2005a).…”