Uncovering microbiota profiles and traditional Māori host plants of Wiseana spp. in New Zealand

Abstract

The genus Wiseana, commonly known as porina, is a complex of endemic moths that are foliar pests in agricultural pastures across New Zealand. The current control strategies for porina rely on synthetic pesticides and growth regulators. Currently, there is a global interest in identifying and environmentally friendly and sustainable pest management practices to decrease the use of harmful chemicals in the environment. To find effective alternatives for porina control a thorough understanding of the biology of the pest complex, including interactions with the environment and natural enemies, is required. To address some of these knowledge gaps, this work investigated porina species distribution, their bacterial microbiota, and the feeding of porina on kūmara, a crop traditionally grown by Māori. A total of 169 porina larvae were collected from five pasture sites across New Zealand (Ohakune, Taihape, Owaka, Te Anau and Waipori) and from native habitats for the three South Island sites (Owaka, Te Anau and Waipori). A newly developed molecular species identification method was used to identify the species of porina larvae. Five species were identified, and one larva was unidentifiable due to a 20 bp substitutions over the mitochondrial COI sequence. The distribution of porina larvae indicated that W. copularis was predominant in pasture habitats, whereas W. umbraculata was predominant in native habitats. The digestive tracts of the 169 field collected porina were dissected, DNA extracted and the V4 region of the 16S rRNA gene sequenced with Illumina MiSeq. The bacterial sequences were taxonomically assigned. The porina microbiota showed high bacterial diversity at low abundances, with the most abundant genera being Serratia, Acinetobacter, Carnobacterium, and Pseudomonas. Comparisons of the microbiota between porina species, sites and habitats revealed slight differences in the presence and abundance of bacterial genera, including genera known to comprise entomopathogenic species. Laboratory reared porina larvae were subjected to either a 6-week no-choice or a 2-week choice test bioassays with Owairaka Red kūmara (stem, leaf and tuber) and white clover (Trifolium repens). The bioassay results indicated that porina larvae can feed and sustain growth on all kūmara plant organs. There was no statistical difference in preference of porina larvae towards kūmara or white clover. This research has increased the understanding of porina biology and ecology thereby underpinning future management strategies of porina in pastures and has demonstrated potential of porina to act as a pest on a non-pasture plant species. Lastly, this research enhances the connection between mātauranga Māori and scientific investigation to bring forward a holistic view for protecting the earth for future generations.