Why are they a threat to Australia?
Australia is a major producer and exporter of agricultural products. For example, in the 2013–2014 financial year, Australian farmers produced over A$7 billion worth of fruit, nuts and vegetables (ABARES 2015). The Brown marmorated stink bug has an extremely wide host range and poses a significant threat to the crops of primary producers.
The Brown marmorated stink bug feeds on a wide range of crops including fruit, vegetables, field crops, ornamental plants and native vegetation (Leskey et al. 2012). Since the introduction of Brown marmorated stink bug in the USA, several mid-Atlantic States have suffered severe economic losses due to high population levels of Brown marmorated stink bugs in field crops, vineyards, orchards and ornamental nurseries (Leskey et al. 2012). For example, in 2010, stone fruit growers lost 90–100% of their crop, while apple growers suffered US$37 million in losses (Leskey et al. 2012). The impact of the Brown marmorated stink bug on apples can be seen in Figure 8.
The Brown marmorated stink bug feeds on a wide range of crops including fruit, vegetables, field crops, ornamental plants and native vegetation (Leskey et al. 2012). Since the introduction of Brown marmorated stink bug in the USA, several mid-Atlantic States have suffered severe economic losses due to high population levels of Brown marmorated stink bugs in field crops, vineyards, orchards and ornamental nurseries (Leskey et al. 2012). For example, in 2010, stone fruit growers lost 90–100% of their crop, while apple growers suffered US$37 million in losses (Leskey et al. 2012). The impact of the Brown marmorated stink bug on apples can be seen in Figure 8.
Figure 8: Brown marmorated stink bug damage to an apple (Pennsylvania State University 2010).
The impact of Brown marmorated stink bug on grape vines has only recently been investigated. Brown marmorated stink bugs have been reported to cause changes in grape cluster quality, crop yield and berry damage from progressive necrosis and fruit collapse from feeding on ripening berries (Leskey et al. 2012). Sweet corn (Zea mays) is a strongly preferred crop for Brown marmorated stink bugs and, in the USA, sweet corn crop losses of up to 100% have been observed (Leskey et al. 2012). Brown marmorated stink bugs are able to pierce through the husk and feed on the kernels, which may cause them to discolour or collapse (Figure 9; Leskey et al. 2012). Feeding on bean crops causes the bean pods to be scarred or deformed pods (Leskey et al. 2012). Brown marmorated stink bug has also been found feeding on soybean, wheat crops and field corn crops (Leskey et al. 2012).
Figure 9: Brown marmorated stink bugs on an ear of sweet corn (Virginia Cooperative Extension 2011) and the resulting internal damage (Pennsylvania State University 2010).
An incursion of Brown marmorated stink bugs into Australia would severely impact many agricultural industries. For example, in the 2013–2014 financial year, Australian apple growers produced 267,000 tonnes with an estimated value of A$434 million and Australian grape growers produced 1,438,000 tonnes of wine grapes and 119,000 tonnes of dry and table grapes (ABARES 2015). (ABARES 2015). In the 2014–2015 financial year, Australian vegetable farmers produced 389, 000 tonnes of corn worth an estimated A$122 million (ABARES 2015), while Australian wheat growers produced 23 billion tonnes of wheat (ABS 2015). Therefore, an incursion of Brown marmorated stink bug would cause significant damage to Australia’s agricultural sector and would have a significant impact on the lives of the Australian people.