Efficacy of Chlorantraniliprole in Controlling Structural Infestations of the Eastern Subterranean Termite in the USA.

Subterranean termites are the most economically important structural pests in the USA, and the eastern subterranean termite, Reticulitermes flavipes (Kollar) (Dictyoptera: Rhinotermitidae) is the most widely distributed species. Soil treatment with a liquid termiticide is a widely used method for controlling subterranean termites in structures. We assessed the efficacy of a nonrepellent termiticide, Altriset® (active ingredient: chlorantraniliprole), in controlling structural infestations of R. flavipes in Texas, North Carolina, and Ohio and determined the post-treatment fate of termite colonies in and around the structures. In all three states, microsatellite markers indicated that only one R. flavipes colony was infesting each structure. A single chlorantraniliprole treatment provided effective structural protection as there was no further evidence of termite activity in and on the majority of structures from approximately 1 month to 2 years post-treatment when the study concluded. Additionally, the treatment appeared to either severely reduce the infesting colony's footprint at monitors in the landscape or eliminate colony members from these monitors. A supplemental spot-treatment was conducted at one house each in Texas and North Carolina at 5 and 6 months post-treatment, respectively; no termites were observed thereafter in these structures and associated landscaping. The number of colonies found exclusively in the landscape (not attacking the structure) varied among the states, with the largest number of colonies in Texas (0-4) and North Carolina (0-5) as compared to 0-1 in Ohio, the most northern state.

Implementation of an indoxacarb susceptibility monitoring program using field-collected German cockroach isolates from the United States.

Indoxacarb, a sodium channel-blocking insecticide, has been in widespread use for German cockroach control in the United States since 2006. A two-tiered indoxacarb susceptibility monitoring strategy was previously developed as a first step toward determining indoxacarb susceptibility levels in German cockroach field populations. This strategy entails: (tier 1) testing field-collected populations in vial bioassays at two diagnostic concentrations; and (tier 2) testing populations at three diagnostic doses in oral (feeding) bioassays with treated bait matrix. In the current study the two-tiered technique was implemented to evaluate field (n = 14) and susceptible laboratory (n = 2) strains collected from 13 different U.S. locations. Our hypothesis was that at least some of the field-collected populations would display significant survivorship in both bioassays relative to susceptible laboratory populations. In agreement with this hypothesis, significantly reduced susceptibility was detected in 13 and 7 field strains with vial and feeding bioassays, respectively. In general, the lower number of strains displaying reduced susceptibility in feeding bioassays (seven strains) supports previous findings that indoxacarb is more toxic via ingestion. Although these findings suggest a reduced risk for resistance selection via feeding on indoxacarb-containing baits, they also suggest a need for proactive resistance management with respect to both spray and bait products.

Toxicity and horizontal transfer of chlorantraniliprole in the eastern subterranean termite.

Toxicity and horizontal transmission of chlorantraniliprole were measured against field-collected eastern subterranean termites, Reticulitermes flavipes (Kollar). Chlorantraniliprole was highly toxic to termite workers in brief and continuous exposure assays across arange of concentrations from 5 to 100 ppm. All doses tested resulted in 100% mortality in the termites in 14 d. The effect of exposure route (topical, oral, or both) was investigated by exposing termites to treated substrate only, treated food only, or both. Results indicate that exposure route has no significant effect on chlorantraniliprole toxicity and demonstrate that chlorantraniliprole is highly active by feeding and contact. Results of feeding assays (paper consumption tests) demonstrate that as little as 5-ppm chlorantraniliprole applied to sand prevents termites from consuming cellulose that is in contact with the treated sand. Termites on untreated soil consumed 79 +/- 3% of the available paper in 3 d, whereas termites on chlorantraniliprole-treated did not consume any paper before they became symptomatic and died. Results of transfer tests demonstrate that chlorantraniliprole is transferred efficiently among the termites. The rate and the level of secondary mortality in the recipient termites depend on both the concentration of chlorantraniliprole and the duration of exposure in the donors. Little secondary mortality was observed with the lowest dose of 5 ppm, which was effective at killing the donor termites, but insufficient to cause mortality in the recipient termites. In contrast, highly efficient transfer was observed with 25 and 50 ppm chlorantraniliprole. Both doses resulted in 100% mortality in the donors and the recipients at 21 d after exposing the recipients to the treated donors. These data demonstrate that chlorantraniliprole has dose-independent toxicity, delayed toxicity, and is readily transferred in eastern subterranean termites.

Toxicity of seven termiticides on the formosan and eastern subterranean termites.

Using both topical application and substrate (sand) treatments the toxicities of seven new generation soil termiticides were evaluated to determine the LD50 and LC50 against two economically important subterranean termite species, eastern subterranean termite, Reticulitermes flavipes (Kollar), and Formosan subterranean termite, Coptotermes formosanus Shiraki. The lethal dose toxicity (LD50) rankings for R. flavipes from highest to lowest were: fipronil > bifenthrin > chlorantraniliprole > cyantraniliprole > imidacloprid > chlorfenapyr > indoxacarb; the rankings for C. formosanus were fipronil > imidacloprid > chlorantraniliprole > cyanthraniliprole> bifenthrin > chlorfenapyr > indoxacarb. The respective lethal concentration toxicity (LC50) rankings were fipronil > bifenthrin > chlorfenapyr > indoxacarb > cyantraniliprole > chlorantraniliprole > imidacloprid for R. flavipes; and fipronil > chlorfenapyr > bifenthrin >imidacloprid > cyantraniliprole > chlorantraniliprole > indoxacarb for C. formosanus. The study provides an opportunity to directly compare toxicity, action speed, and bioavailability among this group of newer generation soil termiticides.

Horizontal transfer of bait in the German cockroach: indoxacarb causes secondary and tertiary mortality.

Horizontal transfer of indoxacarb in the German cockroach, Blattella germanica (L.), was examined under laboratory conditions. Results show that a single bait-fed adult cockroach (i.e., the donor) transferred indoxacarb to numerous primary recipients (secondary mortality),which then became secondary donors. These recipients subsequently became donors to other cockroaches and caused significant mortality in other members of the aggregation, resulting in tertiary kill. Indoxacarb was effectively transferred among adult cockroaches and resulted in significant secondary mortality. When adult males served as donors and vectored the insecticide to adult males, the donor:recipient ratio affected the mortality of the recipients and the rate of secondary mortality increased with increasing the ratio of donors to recipients. Furthermore, secondary mortality in the untreated cockroaches was significantly affected by the freshness of excretions from the donors, the presence of alternative food, and the duration of contact between the donors and the recipients. Ingested indoxacarb was most effectively translocated when the recipients interacted with freshly symptomatic donors in the absence of alternative food. The transfer of indoxacarb continued beyond secondary mortality and resulted in significant tertiary mortality. Excretions from a single bait-fed adult killed 38/50 (76%) nymphs within 72 h. The dead nymphs then vectored indoxacarb to 20 adult males and killed 16/20 (81%) recipients within 72 h. Behavioral mechanisms involved in the horizontal transfer of indoxacarb may include: contact with excretions, necrophagy, emetophagy, and ingestion of other excretions that originate from the donors.

Transfer of indoxacarb among workers of Coptotermes formosanus (Isoptera: Rhinotermitidae): effects of dose, donor:recipient ratio and post-exposure time.

Horizontal transfer of indoxacarb among workers of the Formosan subterranean termite, Coptotermes formosanus Shiraki, was examined under laboratory conditions. The effects of dose (0, 10, 20, 50, 100 or 200 ng AI per donor), donor:recipient ratio (1:1, 1:4 or 1:9) and post-exposure time (2, 4, 8, 16, 20 and 24 days) on lethal transfer of indoxacarb were investigated using a donor/recipient model in groups of 100 workers. Transfer of lethal doses from donors to recipients was evidenced by significant recipient mortality in 13 out of 15 treatments within 24 days post-exposure. Dosage significantly affected indoxacarb transfer. Higher doses resulted in greater recipient mortality than lower doses. The highest dose tested resulted in 100% death of recipients and donors within 20 days. A dose of 100 ng resulted in recipient mortalities ranging from 68 to 100%, whereas doses < or =50 ng killed <60% of recipients within 24 days. Donor:recipient ratio also had considerable effect on indoxacarb transfer. At 24 days post-exposure, greater recipient mortalities were observed at ratios > or =1:4 at doses > or =20 ng, but only at a ratio 1:1 at dose 10 ng. Recipient mortality increased significantly as post-exposure time increased. The higher the doses applied on donors, the shorter were the times required for the onset of recipient mortality to occur and for recipients to reach maximum mortality. Significantly greater recipient mortalities were not observed at doses 20 and 50 ng until more than 20 days post-exposure, indicating a delayed activity of indoxacarb. Possible transfer mechanisms are discussed.