In Cambodia, farmers construct artificial household bat roosts to collect and sell guano as fertilizer. We investigated farming practices and attendant spillover risks using: 1) surveys on guano production; 2) estimating bat population size and species present using carcasses, visual identification, and audio recordings; 3) surveying guano-producing and neighbor households on water, sanitation, and hygiene practices; and 4) testing guano and household food, water and surfaces for coronaviruses by PCR. Bat roosts are constructed using dried palm leaves with coconut tree and/or steel/concrete supports. Roosting areas ranged from 42-327 m², bat abundance varied from 0-11,187, guano production was 5-120 kg/week, guano yields were 0.15-0.4 kg/m2/week, and farmers earned ~100-200 USD/household/month. Higher guano production in peak (normally wet) season was associated with greater bat abundance (p=0.016). The lesser Asiatic yellow house bat (Scotophilus kuhlii) was the only bat species identified. Roosts were <20 m from guano-producing households. Neighbors and households’ hygiene risks included not having handwashing stations and not covering food in storage/while drying. Alphacoronaviruses or Infectious Bronchitis Virus were found in 14.6%, 17.3%, 2.9%, 1.4%, and 0.0% of guano, urine, surface, food, and water samples, respectively. While guano farming offers economic benefits, spillover risks exist. Safe guano collection and storage, handwashing, and food covering in guano-producing communities are necessary to mitigate spillover risks.

Soil salinity is a major problem that reduces the growth and yield of rice, particularly in coastal rice-growing regions such as certain provinces of Cambodia. This study evaluated salinity tolerance in 60 Cambodian rice varieties at germination and seedling stages and combined physiological analyses with genome-wide association study (GWAS) to identify traits and genomic regions associated with salinity tolerance. The screening at the seedling stage showed CAR 11 was a highly salt-tolerant variety in response to salt stress, suggesting this variety could be used in actual salt-affected fields using the transplanting method and may also serve as a valuable genetic resource for salt-tolerance breeding. K ⁺ concentration and Na ⁺ /K ⁺ ratios in roots and shoots were identified as physiological traits determining salt tolerance of Cambodian rice varieties. Several varieties also exhibited high tolerance during germination under salt stress, suggesting their potential value as genetic resources for salt-tolerance breeding. GWAS identified some marker-trait associations and putative candidate genes associated with salinity tolerance-related traits under salt stress. These findings provide fundamental knowledge regarding salt tolerance and putative genes associated with traits in Cambodian rice varieties, and this knowledge is essential for developing salt-tolerant varieties via breeding programs and extending rice production in salt-affected areas.

In Cambodia, farmers construct artificial household bat roosts to collect and sell guano as fertilizer. We investigated farming practices and attendant spillover risks using (1) surveys on guano production; (2) an estimation of bat population size and species present using carcasses, visual identification, and audio recordings; (3) surveys of guano-producing and neighboring households on water, sanitation, and hygiene practices; and (4) the testing of guano and household food, water, and surfaces for coronaviruses using RT-qPCR. Bat roosts are constructed using dried palm leaves with coconut tree and/or steel/concrete supports. Roosting areas ranged from 42 to 327 m², bat abundance varied from 0 to 11,187, guano production was between 5 and 120 kg/week, guano yields were from 0.15 to 0.4 kg/m²/week, and farmers earned USD ~100–200/household/month. Higher guano production in the peak (normally wet) season was associated with greater bat abundance (p = 0.016). The lesser Asiatic yellow house bat (Scotophilus kuhlii) was the only bat species identified. Roosts were <20 m from guano-producing households. Neighbors and households’ hygiene risks included not having handwashing stations and not covering food in storage/while drying. Coronaviruses (Alphacoronaviruses or Infectious Bronchitis Virus) were detected in 14.6%, 17.3%, 2.9%, 1.4%, and 0.0% of guano, urine, household surface, food, and water samples, respectively. While guano farming offers economic benefits, spillover risks exist. Safe guano collection and storage, handwashing, and food covering in guano-producing communities are necessary to mitigate spillover risks.