Distribution and population structure of two phylogroups of the parasitoid Encarsia smithi (Hymenoptera: Aphelinidae) in tea fields infested with the invasive camellia spiny whitefly Aleurocanthus camelliae (Hemiptera: Aleyrodidae) in Shizuoka Prefecture, Japan.
A recent study revealed that two phylogenetic groups of the parasitoid Encarsia smithi (Hymenoptera: Aphelinidae) can attack the camellia spiny whitefly Aleurocanthus camelliae (Hemiptera: Aleyrodidae), an invasive pest of Japanese tea fields. Type I was introduced in 1925 from China to Japanese citrus orchards to control the citrus spiny whitefly A. spiniferus, but it has also recently appeared in several tea fields. Type II, presumably introduced accidentally, was also found in many tea fields. However, little is known about distribution and their relative importance as a biocontrol agent in tea fields. To investigate these aspects, we developed specific PCR for the two groups using a variation in their nuclear ribosomal DNA's ITS region. We then surveyed their distribution in 23 tea fields in Shizuoka Prefecture, Japan, from 2013 to 2015 using this specific PCR. We found that both types were distributed, sometimes coexisting, in many tea fields during 2013-2015, although the population structure of these types varied with the field, year and season. These results suggest that A. camelliae can be controlled unintentionally by accidentally introduced exotic natural enemies (Type II) and/or Type I species originally introduced to control other invasive pests such as A. spiniferus.