Lower reproductive rates of Asian citrus psyllid (Hemiptera: Psyllidae) on 'Tahiti' acid lime than on 'Valencia' sweet orange

The 'Tahiti' acid lime and orange trees are hosts of 'Candidatus Liberibacter asiaticus' (CLas), the pathogen associated with the severe Asian form of huanglongbing (HLB), the most devasting citrus disease. They are also hosts of the vector of CLas, the Asian citrus psyllid (ACP) Diaphorina citri Kuwayama. Relatively small numbers of lime trees occur in gardens and small orchards near large commercial 'Valencia' sweet orange orchards in Brazil. Applications of insecticides to suppress populations of ACP on the lime trees are usually nil or less frequent than in the orange orchards. Abundance of the psyllid on lime trees may therefore increase the risk of CLas spreading to the orchards. Because the abundance of the psyllid is influenced by the suitability of the trees as hosts, we compared reproductive potential of the insect on the two hosts in a controlled environment chamber (CEC) and in a greenhouse (GH). Daily temperature and relative humidity averaged 22°C and 60% inside the CEC and 24°C and 70% inside the GH. Two pairs of adult male and female psyllids were caged for 3 days on new shoots and the fecundity and durations of development and survival of eggs and nymphs evaluated. Overall, acid 'Tahiti' was 3.5 times less suitable to ACP than 'Valencia'. Fecundity and survival of nymphs were 27% and 59% lower, and the life cycle 34% longer on 'Tahiti' than on 'Valencia'. Potential impacts of the results on CLas spread and HLB control are discussed.