Occurrence and unlimited spread of Diaphorina citri Kuwayama (Hemiptera: Liviidae) in Tanzania: A potential economic threat to the citrus industry

Citrus production is a cornerstone of Tanzania's agricultural sector, supporting economic development and food security. However, the industry faces a critical threat from the Asian citrus psyllid (Diaphorina citri Kuwayama), the primary vector of the destructive Huanglongbing (HLB) disease. This study investigates the distribution, abundance, and environmental drivers of D. citri and the African citrus triozid (Trioza erytreae) in major citrus-growing regions of Tanzania. Surveys conducted between March and May 2023 revealed the presence of D. citri in the Tanga and Morogoro regions, including the first documented occurrence in the Tanga region. Conversely, T. erytrae was confined to the Arusha region. Altitude emerged as a significant factor influencing psyllid abundance. D. citri populations decreased with increasing altitude, while T. erytrae exhibited the opposite trend. Temperature also showed correlations with psyllid populations, though additional research is needed to fully elucidate these relationships. Citrus variety significantly influenced D. citri abundance, with Late Valencia (Kitenesi) being the most susceptible. Importantly, several varieties showed no presence of D. citri, offering potential sources of resistance. The intensity of new flush growth was strongly correlated with psyllid abundance. These findings highlight the urgent need for region-specific and altitude-tailored citrus pest management strategies. The identification of potentially HLB-resistant citrus varieties provides a promising avenue for breeding programs. This research offers critical insights to protect Tanzania's citrus industry and ensure the sustainable production of this vital economic crop. Keywords: Citrus, Citrus greening, Diaphorina citri Kuwayama, Huanglongbing, Trioza erytreae, Distribution, Altitude, Tanzania