Impacts on Reticulitermes flavipes (Infraorder Isoptera: Rhinotermitidae) by Chlorantraniliprole Applied to Soil Surrounding Established Tunnels.

Soil-applied liquid termiticides are the most common control measure for subterranean termites. Characteristics unique to insecticidal chemistries such as repellency, toxicity, and time between contact and mortality, influence the interaction of termites with treated soil and overall treatment success. Two different treated-tunnel bioassays were used to evaluate the behavioral impacts and mortality of termites from treatment with chlorantraniliprole (the active ingredient in Altriset® termiticide) to existing, mature tunnels. Termites that were provided constant access to a 10-cm-long mature tunnel within soil treated with 5 or 50 ppm chlorantraniliprole were not repelled by the treatment and began exhibiting slower, uncoordinated movement, and cessation of tunneling and feeding in as little as 1 h after access. Termites provided access for 7, 14, or 21 d to previously constructed tunnels recently treated with 50 ppm chlorantraniliprole exhibited complete or near complete mortality by 28 d. The second bioassay design resembled a more typical field situation with a 40-cm-long mature tunnel and termites allowed access for a maximum of 5 min. Termites collected after just 5 min of access to the previously constructed tunnels recently treated with 50 ppm chlorantraniliprole exhibited similar symptomology within an hour followed by complete mortality at 18 d after exposure. These test designs simulate what occurs in the soil around an infested structure at the time of treatment. Results from these evaluations suggest that termites readily crawl through chlorantraniliprole-treated mature tunnels, rapidly lose ability to feed, and acquire a lethal dose from brief exposures.

Termite colony ontogeny: supplemental data in the long-term assessment of reproductive lifespan, female neotenic production and colony size in Reticulitermes flavipes (Isoptera: Rhinotermitidae).

Reticulitermes flavipes (Kollar) colonies established by field-collected alates were reared in the laboratory for 11 years. Weights of members of each caste and full-colony censuses were performed regularly; the most recent 2003-2004 data are reported. Colonies averaged 11623.5 +/- 910 individuals, and with the exception of primary queens from one genetic lineage, mean weights for all castes had increased since 2001. Female replacement reproductives, or neotenics, developed to replace dead queens in clusters of either few, large individuals or many, small individuals. Regardless of cluster size, female neotenics comprised more reproductive biomass per colony than primary queens. The number and size of female neotenics was independent of colony size or time elapsed since a founding queen's death.

Termite colony ontogeny: a long-term assessment of reproductive lifespan, caste ratios and colony size in Reticulitermes flavipes (Isoptera: Rhinotermitidae).

Thirty Reticulitermes flavipes (Kollar) colonies established by alates collected from two separate field sites were raised in the laboratory for eight years. Twenty-one of the colonies were founded by alates from one field source and nine from another, providing demographic data from two unrelated parental lineages. Colony totals ranged from 3620 to 11641 individuals, with no significant difference in size between lineages. Soldier caste proportion of the colony total and mean wet weights for workers, soldiers and kings were significantly different between the two lineages. This suggests that at least a portion of the variability observed in caste ratios and body size may be heritable. One founding reproductive had died in five of the colonies (17%); none lost both parents. The queenless colonies contained exclusively female replacement reproductives (neotenics); the kingless colony contained a female-skewed mixture of male and female neotenics. All the nests that lost a founding parent contained significantly more pre-alate nymphs than the nests with both a king and a queen. Comparisons with published reports of ontogenetic patterns in other termites and social insects are discussed.

Effects of sublethal exposure to imidacloprid on subsequent behavior of subterranean termite Reticulitermes virginicus (Isoptera: Rhinotermitidae).

Experiments were conducted to determine whether subterranean termites, Reticuliternes virginicus (Banks), previously exposed to sublethal doses of imidacloprid (Premise), and allowed to recover for 1 wk, demonstrated behavioral aversion to a subsequent exposure. Worker termites experiencing a previous sublethal but debilitating exposure to imidacloprid-treated sand (either 10 or 100 ppm for 4 h) showed no apparent aversion to a second encounter with imidacloprid-treated sand under conditions of this experiment. If these laboratory results hold in the field and termites traveling through a zone of soil treated with imidacloprid are impaired but subsequently recover, they will be just as likely as their naive nestmates to reenter the treated area if their travels take them through the nonrepellent application a second time. Our results also indicate that a sublethal exposure to imidacloprid can affect termite tunneling behavior. Many worker termites that received an initial 4-h exposure to 100 ppm imidacloprid-treated sand died, but those that survived tunneled significantly less than did their naive nestmates, as did some termites exposed to 10 ppm imidacloprid.

Increasing density and Borrelia burgdorferi infection of deer-infesting Ixodes dammini (Acari: Ixodidae) in Maryland.

A statewide survey of Ixodes dammini Spielman was done in November 1991 as a follow-up to a study in 1989. In total, 3,434 adult ticks were collected from 922 hunter-killed white-tailed deer processed at 22 check stations (1 per county in 22 of 23 counties in the state). Significantly more male than female ticks were collected. Tick infestation was significantly heavier on male than female deer. The pattern of tick distribution was similar to that in 1989, with low prevalence (percentage tick-infested deer) and abundance (mean ticks per deer) in the Appalachian region, moderate values in the Piedmont, and high values in the western and eastern Coastal Plains regions. The pattern of tick infection with Borrelia burgdorferi spirochetes (determined by polyclonal immunofluorescence assay) was similar to the tick distributional pattern. Overall, tick prevalence and abundance were higher in 1991 than in 1989, as was the spirochete infection rate in ticks. Multiple regression analysis of tick prevalence against six selected physical and biotic parameters (elevation, rainfall, summer and winter temperature, percentage of forest land, deer density) showed a significant relationship with rainfall and elevation in 1989 and elevation alone in 1991. A more extensive study in Caroline and Dorchester counties in the eastern Coastal Plains region (which showed exceptionally low tick density indices in a generally tick-abundant region in 1989) demonstrated that I. dammini was well established in Caroline but not in Dorchester County.

Distribution, density, and Lyme disease spirochete infection in Ixodes dammini (Acari: Ixodidae) on white-tailed deer in Maryland.

A Statewide survey of ticks parasitizing white-tailed deer was carried out in Maryland during November 1989 to assess the status of the deer tick, Ixodes dammini Spielman, Clifford, Piesman & Corwin, the major vector of Lyme disease in the northeastern United States. Ticks were collected from deer carcasses brought in by hunters at 23 check stations (one per county). A total of 3,437 I. dammini were collected from 538 of 1,281 deer (42%), together with 2,013 Dermacentor albipictus (Packard) and 23 Amblyomma americanum (L.) from 34 and 0.5% of deer respectively. I. dammini prevalence ranged from 0 to 79% of deer and mean abundance from 0 to 7.3 ticks per deer at different check stations. Lyme spirochete, Borrelia burgdorferi Johnson, Schmid, Hyde, Steigerwalt & Brenner, infection rates in ticks ranged from 0 to 21%, with a mean of 8%. Deer-tick density and spirochete infection rates varied with physiographic region and were low in the Appalachian, intermediate in the Piedmont, and high in the Western and Eastern Coastal Plains regions. County-based human case rates correlated positively with I. dammini abundance. We concluded that I. dammini was well established except in the mountainous western region of Maryland and was involved in Lyme disease transmission.