Rapid and Efficient Detection of 16SrI Group Areca Palm Yellow Leaf Phytoplasma in China by Loop-Mediated Isothermal Amplification.

Areca palm yellow leaf (AYL) disease caused by the 16SrI group phytoplasma is a serious threat to the development of the Areca palm industry in China. The 16S rRNA gene sequence was utilized to establish a rapid and efficient detection system efficient for the 16SrI-B subgroup AYL phytoplasma in China by loop-mediated isothermal amplification (LAMP). The results showed that two sets of LAMP detection primers, 16SrDNA-2 and 16SrDNA-3, were efficient for 16SrIB subgroup AYL phytoplasma in China, with positive results appearing under reaction conditions of 64oC for 40 min. The lowest detection limit for the two LAMP detection assays was the same at 200 ag/µl, namely approximately 53 copies/µl of the target fragments. Phytoplasma was detected in all AYL disease samples from Baoting, Tunchang, and Wanning counties in Hainan province using the two sets of LAMP primers 16SrDNA-2 and 16SrDNA-3, whereas no phytoplasma was detected in the negative control. The LAMP method established in this study with comparatively high sensitivity and stability, provides reliable results that could be visually detected, making it suitable for application and research in rapid diagnosis of AYL disease, detection of seedlings with the pathogen and breeding of disease-resistant Areca palm varieties.

Effect of temperature on the population growth of Rhynchophorus ferrugineus (Coleoptera: Curculionidae) on sugarcane.

The effect of temperature on the developmental time, survival, and reproduction of Rhynchophorus ferrugineus (Olivier) reared on sugarcane was studied at seven constant temperatures (16, 20, 24, 28, 32, 36, and 40 degrees C). The developmental threshold temperatures and effective accumulated temperatures for the whole generation were 17.41 degrees C and 1,590.72 DD, respectively. One generation had the highest survival rate (26.67%) at 28 degrees C. The egg failed to survive at 16 and 40 degrees C. The population trend index (I = 38.22) and net reproductive rate (R(o) = 38.3) were highest at 28 degrees C. The net reproductive rate (R(o) = 3.36), intrinsic rate of increase (r(m) = 0.0028), and finite capacity of increase (lambda = 1.0028) were lowest at 20 degrees C. The mean generation time (T(o) = 85.82) was shortest at 36 degrees C. The population double time (PDT = 27.08) was shortest at 32 degrees C. Based on these studies, we concluded that the temperatures from 28 to 32 degrees C were the most suitable temperatures for the development of R. ferrugineus.