Soybean Thrips (Thysanoptera: Thripidae) Harbor Highly Diverse Populations of Arthropod, Fungal and Plant Viruses

Soybean thrips (Neohydatothrips variabilis) are one of the most efficient vectors of soybean vein necrosis virus, which can cause severe necrotic symptoms in sensitive soybean plants. To determine which other viruses are associated with soybean thrips, the metatranscriptome of soybean thrips, collected by the Midwest Suction Trap Network during 2018, was analyzed. Contigs assembled from the data revealed a remarkable diversity of virus-like sequences. Of the 181 virus-like sequences identified, 155 were novel and associated primarily with taxa of arthropod-infecting viruses, but sequences similar to plant and fungus-infecting viruses were also identified. The novel viruses were predicted to have positive-sense RNA, negative-stranded RNA, double-stranded RNA, and single-stranded DNA genomes. The assembled sequences included 100 contigs that represented at least 95% coverage of a virus genome or genome segment. Sequences represented 12 previously described arthropod viruses including eight viruses reported from Hubei Province in China, and 12 plant virus sequences of which six have been previously described. The presence of diverse populations of plant viruses within soybean thrips suggests they feed on and acquire viruses from multiple host plant species that could be transmitted to soybean. Assessment of the virome of soybean thrips provides, for the first time, information on the diversity of viruses present in thrips.

Inferring Invasion Paths Into Cotton by Creontiades dilutus (Hemiptera: Miridae) From Arid Zone and Agricultural Sources

Managing agricultural pests that use multiple host plant species is a challenge when individuals move between host plants in natural vegetation and agricultural environments. The green mirid (Creontiades dilutus) Stål (Hemiptera: Miridae) is endemic to Australia and routinely invades cotton from local uncultivated vegetation, but may also originate from remote locations in the arid continental interior. This bug is polyphagous and highly mobile, which contributes to its pest status in cotton L. (Malvaceae) systems as well as its persistence in arid environments with sparsely distributed ephemeral host plants. The aim of this study was to evaluate how C. dilutus individuals use a variety of host species across remote arid regions and highly managed agricultural landscapes. Structured field surveys spanning vast areas across the Simpson Desert in the arid heart of Australia, as well as subcoastal cotton production systems, were designed to evaluate host use across environments that share few plant species. High numbers of C. dilutus were collected from Cullen australasicum (Schltdl.) J.W.Grimes (Fabaceae) (perennial hosts) and Goodenia cycloptera R.Br. (Goodeniaceae) (ephemeral hosts) in the desert following rain. In agricultural environments, C. dilutus bugs were mostly found on irrigated Medicago sativa L. (Fabaceae) (lucerne), and to a lesser extent Melilotus indicus (L.) All. (Fabaceae) near rivers. Significantly, bugs were on these plants prior to the planting of cotton across all environments surveyed. These data allow inferences relating host use, host abundance, and insect migration to one another to understand the connection that C. dilutus bugs have between arid and agricultural environments.