Temperature-dependent development of Asian citrus psyllid on various hosts, and mortality by two strains of Isaria

The Asian citrus psyllid (ACP), Diaphorina citri Kuwayama (Hemiptera: Psyllidae) is a devastating pest of Citrus spp. The aim of present study was to investigate the development and mortality of ACP on citrus (Citrus sinensis) (healthy and Huánglóngbìng- (HLB) diseased) and jasmine (Murraya paniculata) plants at various temperatures. Two new Isaria strains were collected from citrus orchards of Fuzhou (China), and HLB-diseased plants were verified by running PCR for 16S gene of Candidatus Liberibacter asiaticus (CLas). Development observations were recorded for egg, nymph and adult stages on all plants and three different temperatures (20, 25 and 30 °C) whereas mortality observations were recorded for the nymph (fifth instar) and adults on all plants at 25 °C. Field collected Isaria strains were belonged to previously reported Chinese strains under Maximum Parsimony (MP) and Maximum Likelihood methods, as well as, CLas isolates were belonged to previously reported Chinese isolates under MP and Neighbor-Joining methods. The fastest development and mortality was observed on HLB-diseased plants whereas longest time was taken by development and mortality completion on jasmine plants at all temperatures. The fastest developmental times of egg, nymph (first to fourth and fifth instar) and adult stages were ranged from 3.02 to 3.72 d, to 7.63-9.3 d, 5.35-5.65 d and 24.46-28.47 d on HLB-diseased plants at 30-20 °C, respectively. On the other hand, I. javanica caused the fastest mortality of nymphs and adults (32.21 ± 4.47% and 19.33 ± 4.51%) on HLB-diseased plants with the concentration of 1 × 10⁸ conidia.mL^-1 after 3 d and 7 d, respectively. It is concluded that there is a need for extensive molecular work to understand the extra-development and mortality of ACP on diseased plants, because, CLas bacterium can be supportive to uptake more sap from plant phloem.