Temperature, humidity, and substrate: keys to red palm mite survival in the environment

Bioclimatic variables are ecologically sensitive indicators that help define the physiological tolerance limits of animals. Mites, being minute organisms, often face constraints due to their limited mobility, restricting them to narrow environmental ranges. Nonetheless, certain species, such as the red palm mite (RPM), Raoiella indica Hirst, exhibit efficient dispersal capacities. This phytophagous invasive mite commonly disperses via wind currents, especially during dry periods. However, abandoning the host plant carries risks, as individuals may become exposed to adverse environmental conditions. In this study, we examined how temperature and relative humidity, combined with different substrates-host plants (Cocos nucifera), non-host plants (Canavalia ensiformis), and inert material (plastic pots-Bio-Serv incorporation cells)-affect the survival of R. indica. Our findings were: (1) elevated temperatures and low humidity significantly decreased R. indica survival when away from the host plant; (2) under tropical-like conditions (27 °C and 75% RH), mites survived for an average of 3.5 days; and (3) in greenhouse settings, R. indica longevity was 53 days on the host plant, 1 day on the non-host plant, and 3 days on inert material. These results indicate that both climatic conditions and substrate type critically influence R. indica survival following dispersal events.