California State University Fresno Fresno, California
The Californian almond and pistachio industry is valued at an estimated value of $8.1 billion. Post-harvest, almonds and pistachios are stored for several weeks outdoors under tarps, or in shipping containers in open facilities. Under these conditions the crops are highly susceptible to several storage pests including Indian meal moth, red flour beetle, raisin moth and navel orangeworm amongst others. Phosphine fumigation is the industry standard for management of post-harvest pests of tree nuts. However, increasing rates of phosphine resistance in storage pests has called phosphine’s sustainability into question. Here we present research investigating the use of Synthetic Amorphous Silica (SAS) to manage lepidopteran and coleopteran post-harvest pests of almonds and pistachios. SAS is an industrial silicon dioxide product, which is widely used as a post-harvest insecticide in grains in Southeastern Asia and Australia. Growth chamber experiments were used to assess the efficacy of SAS in controlling two common post-harvest pests of tree nuts, the coleopteran Tribolium castaneum and the lepidopteran Plodia interpunctella. Unmodified SAS was applied to both almonds and pistachios as a surface treatment. SAS significantly reduced populations of both P. interpunctella and T. castaneum at all doses tested, as low as 200g/ton. SAS also inflicted significantly higher mortality against both pests than the industry standard diatomaceous earth. This initial data suggests that SAS could effectively manage coleopteran and lepidopteran post-harvest pests of tree nuts. Refinement of application techniques and investment in field treatments of harvested nuts may further increase the product’s efficacy.
