*2.1. Location*

This study was undertaken at the Honiara municipal market and five road-side markets in the Honiara district, Guadalcanal Island and Solomon Islands (Figure 1A,B). The location of the road-side markets assessed: Henderson, Fishing village, Lungga, King George VI and the White river, is shown in Figure 1B,C.

**Figure 1.** Map of the Solomon Islands. (**A**) Location of Guadalcanal Island (indicated in red) within the Solomon Islands archipelago (Map source: CartoGIS Services, College of Asia and the Pacific, The Australian National University, Australia, 2018); (**B**) map of Guadalcanal Island (red square indicates the study site); (**C**) location of the Honiara municipal market and the five road-side markets, Guadalcanal Island (Map source: Popgis@spc.int Solomon Islands National Statistics Office, Solomon Islands, 2018).

#### *2.2. Survey Design and Ethics Approval*

Vendor surveys were undertaken in November 2017 and March 2018. Markets were concurrently surveyed, and involved a series of enumerators from the Solomon Islands National University (SINU) to support this study. The selection of vendors to be surveyed was randomised, but excluded those vendors unable to identify where fruits and vegetables were grown (i.e., farm location) and therefore likely to be involved in inter-market trade, those vendors selling value-added or non-perishable products, and those vendors unwilling to participate in the survey. The survey design was based on semi-structured interview questions on harvesting and packaging practice, transport, market vendor practice, and postharvest loss. Enumerators received prior training in the survey methodology and ethics compliance.

A total of 198 vendors were assessed across all of the key Guadalcanal fruit and vegetable markets. This included 104 professional market vendors at the Honiara municipal market (42 vendors surveyed in November 2017 and an additional 62 vendors surveyed in March 2018). A further 94 road-side market vendors (occasional traders) were also surveyed (42 road-side vendors surveyed in November 2017 and 52 road-side vendors surveyed in March 2018). The survey was replicated across two sampling dates to partially account for potential differences in supply chain demographics and postharvest handling practice due to crop seasonality.

Surveys involved a short semi-structured interview lasting 5–10 min, commonly undertaken in the local language. All interviews were completed in compliance with the University of the Sunshine Coast Human Research Ethics Approval (A16814).
