Formosan Subterranean Termites Re-Found in Southern California – PCT

Editor’s note: Jason and Lowell Boone, Better Off Dead Services (BODS), Riverside, Calif., Discovered an underground termite infestation from Formosan in a house on Canyon Lake, Riverside County, Calif. In June 2020.read the PCT article). The infestation was confirmed by Professor of Entomology at the University of California on the River Dr. Chow-Yang Lee. Lee, along with co-authors Shu-Ping Tseng and Dong-Hwan Choe recently published these results in the Journal of Economic Entomology. Here is a summary of their findings.

The underground termite Formosan, Coptotermes formosanus, is one of the most invasive termite pest species in the world (Rust and Su 2012, Global Invasive Species Database 2021). This species is believed to originate from southern China and Taiwan and to have spread to other parts of the world, including the United States. Some of the earliest records of the underground termite Formosan in the United States were in Oahu, Hawaii, in 1907, in Charleston (SC) in 1957, and in New Orleans (LA) in 1966. It has since been established in at least 11 states, including Hawaii, Texas, Florida, North Carolina, Georgia, and Mississippi.

The subterranean termite Formosan was first discovered in 1992 in California in La Mesa, San Diego County (Atkinson et al. 1993). The original colony was baited (Haagsma et al. 1995), but newer infections were found and also baited, fumigated or corrected soil treatment (Rust et al. 1998). However, the program was discontinued in 1997 due to funding constraints. In 2018, a pest control specialist found another infestation of the underground termite Formosan in La Mesa, about 0.5 km from the site, and treated the termite colony in 1992.

In June 2020, BODS Pest Control found an active C. formosanus infestation in a house in Canyon Lake. This place is about 65 miles north of the La Mesa site (illustration 1). Swarming termites were found indoors and significant damage was found to the wall panels, exterior walls and bathroom floor on the 2nd floor.

The termites were collected from the infested site, soldier termites were examined under the microscope, and they were identified as C. formosanus (Figure 2). In addition, they were compared to the La Mesa samples (previously collected by Dr. Michael Rust, University of California Riverside). DNA techniques were used to determine the genetic differences between the three colonies collected. The genetic sequences of 3 colonies were also compared with the genetic sequences of the Formosan underground termite samples from other parts of the world, which are available in GenBank.

The results showed that both La Mesa colonies (1992 and 2018) were identical but different from the Canyon Lake colony. The La Mesa colonies were genetically similar to those found in Asia, while the Canyon Lake Colony resembled samples previously collected in Mississippi, Hawaii, Louisiana, Florida, and Georgia. In short, the La Mesa colonies were not related to the Canyon Lake colony, suggesting the latter was from a separate introduction.

How widespread the infestation is in Canyon Lake is currently unknown. Judging by the indoor swarms in late May and early June over the past eight years, it is possible that C. formosanus has settled near the infested area. The abundance of trees and plants coupled with abundant irrigation in Canyon Lake could aid its potential expansion and spread. Further sampling of the surrounding properties is required to determine the presence of the underground termite formosan in Canyon Lake.

Shu-Ping Tseng, Dong-Hwan Choe, and Chow-Yang Lee are postdocs, Associate Cooperative Extension Specialist, and Professor and Endowed Professorship in Urban Entomology at the University of California, Riverside. Siavash Taravati is Urban IPM Advisor at UCANR (Los Angeles Office).

References

Atkinson, TH, MK Rust, and JL Smith. 1993. The subterranean termite Formosan, Coptotermes formosanus Shiraki (Isoptera: Rhinotermitidae), was established in California. Pan-Pac. Entomol. 69: 111-113.

Global database on invasive species (2021) Species profile: Coptotermes formosanus. Downloaded from http://www.iucngisd.org/gisd/species.php?sc=61 on 26-04-2021.

Haagsma, K., TH Atkinson, MK Rust, D. Kellum, and DA Reierson. 1995. Formosan underground termite established in California. Calif. Agric. 49: 30-33.

Rust, MK and NY Su. 2012. Dealing with social insects of urban importance. Annu. Rev. Entomol. 57: 355-375.

Rust, MK, DA Reierson, E. Paine, D. Kellum, and K. Haagsma. 1998. Ravenous Formosan termites persist in California. Calif. Agric. 52: 34-37.