Paul B. Baker

Parasitism of Subterranean Termites (Isoptera: Rhinotermitidae: Termitidae) by Entomopathogenic Nematodes (Rhabditida: Steinernematidae; Heterorhabditidae)

In laboratory bioassays, Steinernema riobrave Cabanillas, Poinar and Raulston (355 strain), Steinernema carpocapsae (Weiser) (Mexican 33 strain), Steinernemafeltiae (Filipjev) (UK76 strain), and Heterorhabditis bacteriophora Poinar (HP88 strain) were all capable of infecting and killing three termite species, Heterotermes aureus (Snyder), Gnathamitermes perplexus (Banks), and Reticulitermes flavipes (Kollar) in laboratory sand assays. S. riobrave and S. feltiae caused low levels of Reticulitermes virginicus (Banks) mortality under the same conditions. At 22 degrees C, significant mortality (> or = 80%) of worker H. aureus and G. perplexus was caused by S. riobrave, in sand assays, indicating the need for further study. Because of the short assay time (3 d maximum), reproduction of the nematodes in the target host species was not recorded. All nematode species were observed to develop to fourth-stage juveniles, preadult stages, or adults in all termite species with the exception of R. virginicus. Only S. riobrave developed in R. virginicus. Nematode concentration and incubation time had significant effects on the mortality of worker H. aureus. S. riobrave consistently generated the highest infection levels and mortality of H. aureus in sand assays.

Foraging Populations and Distances of the Desert Subterranean Termite, Heterotermes aureus (Isoptera: Rhinotermitidae), Associated with Structures in Southern Arizona

Abstract Mark-release-recapture studies were conducted on foraging populations of Heterotermes aureus (Snyder) (Isoptera: Rhinotermitidae) associated with three structures in Tucson, AZ. Foraging population estimates ranged from 64,913 to 307,284 termites by using the Lincoln Index and from 75,501 to 313,251 termites using the weighted mean model. The maximum distance between monitors ranged from 26 to 65 m, with minimum total foraging distance ranging between 297 and 2,427 m. Characterizations of the cuticular hydrocarbons of foraging groups were qualitatively identical. Quantitative similarities within sites and differences among sites suggested that each site was occupied by a single colony during the sampling period. The colony at each site had a proportion of soldiers (0.135, 0.069, and 0.040) that was significantly different from the colonies at each of the other sites. From this study, we question the assumption of equal mixing of marked H. aureus foragers throughout the occupied collars around structures.

Field and laboratory evaluation of persistence and bioavailability of soil termiticides to desert subterranean termite Heterotermes aureus (Isoptera: Rhinotermitidae).

Control information for the desert subterranean termite Heterotermes aureus (Snyder) (Isoptera: Rhinotermitidae) is limited, despite being one of three major termite pests in the United States. Annual control information comes from field evaluations by the USDA-Forest Service. This partial assessment of termiticide efficacy is likely deficient without concurrent residual analysis and laboratory bioassays of termiticides. In this study, six termiticides were evaluated using exposed and covered field plots in Tucson, AZ, over a 5-yr period for persistence and efficacy by using both residue analysis and laboratory bioassays. All the termiticides degraded significantly during the study. Termiticide degradation seemed to be consistently slower in covered plots than in exposed plots, although this trend was not statistically supported. A comparison of yearly degradation rates showed the three classes of termiticides degraded at different rates. Chlorpyrifos, the organophosphate, degraded quickest at a rate of 68.9% for each doubling of time, whereas chloronicotinyls and pyrethroids degraded at much slower rates (50.4 and 48.4% for each doubling of time, respectively). Bioassays showed termites tunneled 1.26 +/- 0.61 cm deeper in uncovered plots than in those that were covered. Mortality rates in bioassays from covered treatments were 16.13 +/- 9.87% higher than in uncovered treatments. Our study demonstrated that the termiticides evaluated could remain effective against H. aureus for at least 4 yr after application, particularly under covered conditions. Additionally, it is anticipated that retreatments may be necessary before the 5-yr warranty expires when using final grade applications to stem walls in warmer parts of Arizona.

Field and Laboratory Evaluations of Chlorantraniliprole as a Termiticide in Southern Arizona

ABSTRACT The desert subterranean termite, Heterotermes aureus (Snyder), is the predominant termite of economic importance in the arid southwest. Chlorantraniliprole, a relatively new nonrepellent, slow acting termiticide has been shown to be capable of being transferred among colony members through social interactions, and thus may be effective beyond its original site of application. Using field grids, we evaluated the colony-level effects of chlorantraniliprole on H. aureus foraging activity. Repeated laboratory soil bioassays at 3, 15, 27 and 39 mo postapplication were performed to determine the effects of chlorantraniliprole on termite mortality and tunneling activity. Additionally, field tests of chlorantraniliprole were completed on 10 structures infested with H. aureus. In the experimental grids, the zone surrounded by a chlorantraniliprole perimeter was the only section in which a significant decrease in the number of termites collected occurred, but this was observed in both treatment and controls plots. Overall, no significant colony-level effects of chlorantraniliprole application were observed within the grids. Laboratory bioassays resulted in high mortality and significantly lower tunneling activity of exposed termites at all time points. In structures, the initial application of chlorantraniliprole was sufficient to control infestations in 6 out of 10 cases without supplemental applications. Additional treatments were confined to areas that had not been treated previously. Results show that chlorantraniliprole is capable of achieving control of desert subterranean termites under most conditions. This is likely a result of its high toxicity instead of colony-level effects resulting from termiticide transfer.

Effectiveness of Commercial and Experimental Termite Monitors for the Desert Subterranean Termite Heterotermes aureus (Isoptera: Rhinotermitidae) in Southern Arizona

ABSTRACT In Arizona, the subterranean termite Heterotermes aureus (Snyder) (Isoptera: Rhinotermitidae) is the most economically important termite pest. We report here the evaluation of several commercial and experimental monitoring stations to capture and monitor H. aureus. In total, 12 monitoring stations were evaluated over two study periods. In 2001–2002, the commercial monitors Firstline and Termicon did not capture any H. aureus, whereas Termitrol did not capture significantly more termites than these two monitors. In contrast, three experimental Arizona Research Monitoring Stations (ARMS)—ARMS-PINE, ARMS-ASH, and ARMS-BBT— captured significantly more termites than Firstline and Termicon, and ARMS-BBT captured termites significantly more frequently than the commercial monitors. Similarly in 2003, the commercial monitors Firstline and Defender did not capture any H. aureus, whereas Extera did not capture significantly more termites than these two monitors. However, four monitor designs including the three most successful ARMS in 2001–2002 captured significantly more termites than Firstline and Defender, and ARMS-ASH captured termites significantly more often than the commercial monitors. On-ground ARMS monitors in general captured significantly more termites than commercial in-ground stations.

Evaluation of Liquid and Bait Insecticides against the Dark Rover Ant (Brachymyrmex patagonicus)

Dark rover ants (Brachymyrmex patagonicus, Mayr) are an exotic ant species native to South America that has recently spread through the southern US. We evaluated the residual activity of three liquid insecticides (indoxacarb, fipronil and lambda-cyhalothrin) as potential barrier treatments against these ants. The factors we considered include the use of a porous or non-porous surface, a short or long exposure time and the changes in insecticide activity after treatment during a 90 day period. We also tested the effect of baits containing three different active ingredients (imidacloprid, sodium tetraborate and indoxacarb) on colony fragments of this species for a 15 day period. Both lambda-cyhalothrin® and indoxacarb® resulted in high levels of ant mortality up to 90 days after application. The results of exposure to fipronil® resembled those from the control treatment. Application of insecticides on a porous surface and the shorter exposure time generally resulted in greater ant survival. Of the baits tested, only the imidacloprid based one decreased ant survival significantly during the evaluation period. Within three days, the imidacloprid bait produced over 50% mortality which increased to over 95% by the end of the experiment. Results from the other two bait treatments were not significantly different from the control.