Chemical prevention of colony foundation by Cryptotermes brevis (Isoptera: Kalotermitidae) in attic modules.

Disodium octaborate tetrahydrate (DOT) dust, DOT aqueous solution, imidacloprid dust, and amorphous silica gel dust with synergized 1% pyrethrins were applied on wood surfaces to simulated attic modules. Modules (30 by 30 cm) with and without fiberglass insulation were exposed to dispersal flights of Cryptotermes brevis (Walker) in May and June of 1998 and 1999. Six months after flights, modules were disassembled and inspected for nuptial chamber location and contents. During both years, air and water control treatments contained 22.2+/-9.94 (mean +/- SD) nuptial chambers, 7.5+/-5.7 live imagos, and 2.0+/-1.4 chambers with brood. This survivorship indicated that the attic modules performed well as a colonizing platform for C. brevis. C. brevis dealates preferred constructing nuptial chambers in the crevices at the bases or tops of the modules instead of internal crevices. Modules treated in 1998 and 1999 with DOT or silica dusts contained no live termites, whereas zero of five modules treated with imidacloprid dust in 1998 and two of 20 modules treated with imidacloprid dust in 1999 contained single live incipient colonies. In 1998, 15% DOT solution, applied as a postconstruction treatment, yielded significantly fewer chambers and live termites than controls, but was not as effective as dusts in preventing successful colonization. In 1999, the DOT solution, applied as a construction-phase treatment, was equally as effective in preventing colonization as the dust treatments during that year. Results indicate that dust formulations of DOT, silica gel, and imidacloprid can be used to prevent drywood termite colonization in existing building voids and attics. Where the entire wood framing is exposed to treatment, such as during building construction, aqueous DOT solution can be equally effective as dusts in preventing colonization by C. brevis.

Dynamics of Belonolaimus longicaudatus Parasitism on a Susceptible St. Augustinegrass Host.

St. Augustinegrass (Stenotaphrum secundatum) cv FX-313 was used as a model laboratory host for monitoring population growth of the sting nematode, Belonolaimus longicaudatus, and for quantifying the effects of sting nematode parasitism on host performance in two samples of autoclaved native Margate fine sand with contrasting amounts of organic matter (OM = 7.9% and 3.8%). Following inoculation with 50 Belonolaimus longicaudatus per pot, nematodes peaked at a mean of 2,139 nematodes per pot 84 days after inoculation, remained stable through 168 days at 2,064 nematodes per pot, and declined at 210 days. The relative numbers of juveniles and adults demonstrated senescence after 84 days. Root dry weight of nematode-inoculated plants increased briefly to an apparent equilibrium 84 days after inoculation, whereas root weights of uninoculated controls continued to increase, exceeding those of inoculated plants from 84 to 210 days (P < 0.01). At 210 days, uninoculated plants had 227% the root dry weight of inoculated plants. Transpiration of FX-313 was reduced by nematodes (P < 0.0001) at 84 and 126 days after inoculation; reduction was first observed at 42 days and last observed 168 days after inoculation (P < 0.05). OM content affected all plant performance variables at multiple dates, and generally there were no inoculation x OM content interactions. OM content had no effect on nematode numbers per pot, although there was a slight (P < 0.05) increase in the number of nematodes per gram root dry weight in the low-OM soil compared with the high-OM soil.

Parasitism of Hoplolaimus galeatus on Diploid and Polyploid St. Augustine grasses.

'Floratam' and 'FX-313' St. Augusfinegrasses (Stenotaphrum secundatum) were compared in a time-course experiment for host suitability and susceptibility to the lance nematode, Hoplolaimus galeatus. Nematode densities were determined in the soil and acid-fuchsin stained roots 42, 84, 126, 168, and 210 days after pots containing 230 cm(3) of autoclaved native Margate fine sand/pot were infested with 104 +/- 9 nematodes and maintained at 25 +/- 2 C in the laboratory. 'FX-313' was a more suitable host for H. galeatus. Numbers of H. galeatus reached a maximum at 210 days after inoculation, with 5,550 and 4,120 nematodes (adults plus juveniles)/pot for 'FX-313' and 'Floratam,' respectively. Root and shoot dry weights of both grasses were not affected by H. galeatus throughout the experiment. Three polyploid, 2n = 30 to 32 ('Floratam,' 'FX-10,' and 'Bitterblue') and three diploid, 2n = 18 ('FX-313,' 'Florida Common,' and 'Seville') S. secundatum genotypes were inoculated with H. galeatus (99 +/- 9/pot) and compared with uninoculated controls 210 days after inoculation. St. Augustinegrass genotypes differed as hosts of H. galeatus. 'FX-313' and 'Florida Common' represented the high and low extremes, respectively, for nematode reproduction (9,750 and 5,490 nematodes/pot or 4,239 and 2,387 nematodes/100 cm(3) of soil). However, differences in root and shoot growth were not detected 210 days after inoculation with H. galeatus.

Susceptibility of Diploid St. Augustinegrasses to Belonolaimus longicaudatus.

A fine-textured, dwarf St. Augustinegrass (Stenotaphrum secundatum (Walt.) Kuntze) genotype, FX-313, was severely damaged in plots in the third year of evaluation in sandy soil in southern Florida. Damage was associated with numerous (> 40/100-cm(3) soil) sting nematodes, Belonolaimus longicaudatus Rau. Damage was ameliorated (P < 0.05) by fenamiphos applied broadcast at 2.2 g a.i./m(2), and B. longicaudatus numbers were reduced (P < 0.01), compared with untreated plots. Root dry weights of four diploid (2n = 18) St. Augustinegrasses--FX-261, FX-299, FX-313, and Seville--were reduced (P < 0.001) by B. longicaudatus in a temperature- and light-controlled experiment. Estimated daily transpiration, an indicator of plant health, was reduced (P < 0.001) after 112 days to 3.32 g/pot for inoculated plants, compared with 5.10 g /pot for uninoculated plants. Genotypes did not differ in nematode number per pot (mean 551/215 cm(2) soil) 128 days after inoculation, but differed (P < 0.05) in nematode numbers on a root dry weight basis, with FX-313 and Seville representing the extremes, 12,300 and 4,000 B. longicaudatus/g root dry weight, respectively. The diploid St. Augustinegrasses evaluated were good hosts for B. longicaudatus, but field data and controlled inoculation demonstrate genetic variation in susceptibility.