Vector surveillance was conducted at Narita International Airport in 2021. A total of 8,120 adult mosquitoes were collected. The most abundant species was Culex tritaeniorhynchus (7,821 adults, 96% of the total). The second was Cx. pipiens complex (184 adults) and the third was Aedes albopictus (84 adults). Among them, 8,097 female adults were tested for pathogen genes of flavi virus (8,085 adults, 377 pools), chikungunya virus (83 adults, 18 pools), and plasmodium parasites (12 adults, 10 pools). Japanese encephalitis virus (JEV) genotype I was detected from 2 pools (30 females) of Cx. tritaeniorhynchus. All other tests were negative. In response to the collection of JEV positive mosquitoes, we put up posters reminding passengers to avoid mosquito bites. Furthermore, people working outdoors at the airport at night were warned to avoid mosquito bites and to prevent mosquitoes from entering the cabin of aircraft parked at Narita International Airport. After the detection of JEV gene, we increased the frequency of survey and intensified surveillance until no more adult female Cx. tritaeniorhynchus were collected. Based on this survey, no risk of Japanese encephalitis infection at Narita International Airport was announced to the public on October 29, 2021.
Growth-inhibiting sheets containing pyriproxyfen have recently been developed to control the cigarette beetle Lasioderma serricorne. In this study, we evaluated effective use of a commercially available sheet through a rearing experiment in which the distribution of whole-wheat flour as a food and the shape of the sheet were manipulated. The results based on three replications indicated that the sheet effectiveness decreased by 0.51 times with each 1 cm increase in the flour depth on average, and that the effect was weakened by 0.58 times under conditions where the sheet shape did not match with the coverage of the flour. We also detected a 4.06-fold greater risk of allowing the individuals to develop from larvae into adults when the sheet shape was not matched compared to when it was matched. These findings suggest that an application covering the targeted area by the sheet without any gaps is essential to qualitatively and quantitatively prevent any development of the larvae.
Several adults of the alien millipede Chamberlinius hualienensis Wang, 1956, a pest introduced from Taiwan, were discovered on October 16, 2021 at the Tama Zoological Park, Tama Area, Tokyo, Japan. This is the first known record of C. hualienensis from mainland Tokyo. Species identification was primarily conducted by examining morphological diagnostic characters of the species within the genus Chamberlinius and subsequently confirmed by DNA barcode based on standard COI gene fragment.
Ixodid ticks were recovered from various animals in the northern area of Okinawajima Island, Japan, in the period 2016–2021. The ixodid tick species Rhipicephalus sanguineus (n=39), Haemaphysalis hystricis (n=20), and Amblyomma testudinarium (n=1) were recovered from dogs. Similar tick species, namely H. hystricis, Haemaphysalis formosensis, and A. testudinarium, were recovered from cats, Ryukyu long-furred rats, and rabbits. Our results suggested that these three species are the dominant ticks that feed on small and medium-sized mammals in this area. Furthermore, A. testudinarium and H. hystricis were detected on human clothes, and A. geoemydae was recovered from Protobothrops mucrosquamatus.