Durability of a novel durable bait for control of subterranean termites (Isoptera: Rhinotermitidae): results of five-year field aging studies.

A durable termite bait containing 0.5% noviflumuron was evaluated for physical durability, retention of active ingredient, consumption by termites, and toxicity to termites over 5 yr in field studies at locations in Indiana, Mississippi, and South Carolina. Plots in Indiana and Mississippi included both natural rainfall and irrigated plots, while plots in South Carolina received only natural rainfall. Samples collected every 3 mo for the first 4 yr were evaluated for consumption with a 7 d no-choice bioassay using Reticulitermes flavipes (Kollar). Consumption and toxicity of 5 yr samples were evaluated in similar bioassays conducted for 42 d. Durable baits received from field sites had some cracking, and a small amount of external flaking, but no major deterioration based on visual observation. There were no significant differences in noviflumuron concentration over the 5-yr period and no trend toward reduced concentrations of noviflumuron over time. Consumption of aged durable baits over 4 yr was variable, but termites usually consumed more aged durable bait than fresh durable bait and the differences were frequently significant. There were some exceptions, but termites consumed significantly more fresh durable bait than aged durable bait in only 4% of observations. When 5 yr samples were evaluated, consumption was lowest for fresh durable bait and termites consumed significantly more aged durable bait from irrigated plots in Indiana and from both natural and irrigated plots in Mississippi than fresh durable bait. Survival of termites fed blank durable bait was significantly higher than that for termites fed any of the baits containing noviflumuron and there were no significant differences in survival among the noviflumuron durable baits. Our results suggest that the bait would be durable for at least 5 yr and possibly longer under most environmental conditions.

Elimination of subterranean termite (Isoptera: Rhinotermitidae) colonies using a refined cellulose bait matrix containing noviflumuron when monitored and replenished quarterly.

Using a quarterly (3-mo) monitoring and bait-replenishment interval, 122 subterranean termite colonies throughout the United States were baited with a refined cellulose bait matrix containing 0.5% noviflumuron. All colonies were eliminated in less than 1 yr after initiation of baiting as determined by long-term monitoring and genetic markers. Sixty-three percent of the colonies were eliminated during the first quarter after the initiation of baiting and 77% of colonies were eliminated after consuming two bait tubes or less. This suggests that a single baiting cycle and bait installed in response to a single active monitoring device were sufficient to eliminate the majority of colonies. Although termites temporarily abandoned stations after depleting bait, workers resumed feeding when baits were replenished. Colonies that consumed large amounts of bait before elimination foraged into multiple stations, thus allowing adequate amounts of bait to sustain feeding. The time to eliminate termite colonies with bait replenished quarterly was similar to that previously reported for laminated cellulose bait replenished monthly. Our data support the conclusion that extending the bait replenishment interval from monthly to quarterly for bait tubes with refined cellulose containing 0.5% noviflumuron did not adversely impact colony elimination.

Ovicidal activity of chitin synthesis inhibitors when fed to adult German cockroaches (Dictyoptera: Blattellidae).

Ovicidal activity was observed in four adult groups (virgin males; virgin females; newly gravid females; and inseminated, reproducing females) of the German cockroach, Blattella germanica (L.), fed the chitin synthesis inhibitors triflumuron, chlorfluazuron, hexafluron, and UC 84572 (structure not disclosed) at the LC50's and LC95's determined from fifth-stage nymphs. All compounds were active only when fed to reproducing females (including the feeding period in which the ootheca is developing). Hexafluron and triflumuron at the LC50 caused 100% inhibition of hatch in reproducing females. Chlorfluazuron and UC 84572 at the LC50 had similar ovicidal activity (45.8 and 50.0% hatch, respectively). Female German cockroaches fed the chitin synthesis inhibitors before mating and after the ootheca had protruded from the abdomen were not affected. Reproductive capabilities of males were not affected, and males did not effectively transfer the compounds to untreated females during mating.

Adult German cockroach (Dictyoptera: Blattellidae) movement patterns and resource consumption in a laboratory arena.

Computerized moving-image analysis was used to determine movement behavior of adult German cockroaches among food, water, and harborage resource sites. Adults at different stages in the female reproductive cycle (nonmated females, mated nongravid females, and gravid females) and males were examined continually for 5 d under a photoperiod of 12:12 (L:D) h. Corresponding food and water consumption rates for these adult classes were also determined. Differences were evident among the female reproductive classes and males. Mated nongravid females were the most active overall, and consumed the most resources. Nonmated females were second to the mated nongravid females in consumption and were less active. Gravid females were the most inactive, spending the greatest time in the harborage and consuming the fewest resources. Males were second to females in the mated nongravid class regarding activity, but consumed significantly fewer resources than females in both the mated nongravid and nongravid females. Implications of these findings relating to the biology of these adult classes are discussed.

Diel activity cycles in nymphal stadia of the German cockroach (Dictyoptera: Blattellidae).

Computerized moving-image analysis was used to determine movement behavior of individual German cockroach, Blattella germanica (L.), nymphs (second and fifth instars) between food, water, and harborage resource sites. Both second and fifth instars (n = 10) were examined for the entire nymphal stadium, during which a 12:12 (L:D) photoperiod was maintained. In addition, corresponding resource consumption rates for these nymphal stages also were determined. Both nymphal stages exhibited a pattern of high activity for the first half of the nymphal stadium, especially during each scotophase. For the last third of the stadium, the nymphs remained continuously in the harborage, moved very little, and consumed little or no resources. We discuss implications of these findings regarding control, future research, and possible hormonal behavior regulation.

Efficacy of chitin synthesis inhibitors on nymphal German cockroaches (Dictyoptera: Blattellidae).

Second- and fifth-instar Blattella germanica (L.), fed the chitin synthesis inhibitors triflumuron, chlorfluazuron, hexafluron, and UC 84572 (structure not disclosed) were examined for mortality and developmental abnormalities. All compounds were active against B. germanica (L.), with lower diet concentrations being required to kill second instars compared with fifth instars. Chlorfluazuron was significantly more active against second and fifth instars (LC50 = 0.000191 and 0.000363% AI, respectively for the second and fifth instars). UC 84572 also killed nymphs at extremely low concentrations (LC50 = 0.000508 and 0.000754% AI, respectively, for second and fifth instars). LC50's for hexafluron and triflumuron against fifth instars were more than 1,000 times higher than that for chlorfluazuron. Sensitive periods of exposure were determined by comparing effects when four different age classes of fifth instars (1-, 4-, 7-, and 10-d old) fed on the compounds for 3 d. Triflumuron was most effective when ingested during the first three age classes and hexafluron was most effective during the last three age classes. Chlorfluazuron and UC 84572 were most effective when ingested during the second age class (days 4-6). Adults surviving exposure during the fifth instar were often deformed and weak; they died at a greater rate than the controls. However, most surviving adults were able to reproduce normally.

Oral toxicity, formulation effects, and field performance of flufenoxuron against the German cockroach (Dictyoptera: Blattellidae).

Laboratory and field studies on the benzoylphenyl urea (BPU) chitin synthetase inhibitor flufenoxuron (DPX EY-059) showed great potential for its use in suppressing infestations of German cockroach, Blattella germanica (L.). When fed continuously to fifth (last) instars, the LC50 of flufenoxuron was estimated at 0.82 ppm (95% FL, 0.76-0.87 ppm). A rating scale specific for BPU effects was developed and shown to be positively correlated with the insect's exposure to concentration of flufenoxuron. Manipulating the particle size of wettable powder formulations of flufenoxuron significantly altered their activity in contact bioassays. Larger particles (volume mean diameter, 12.2 mu; range, 10-20 mu) were more active. Field trials in multifamily housing with this wettable powder formulation at 0.033 and 0.066% (AI) achieved high level (greater than 80%) population suppression within 8 wk of treatment. The potential for the use of flufenoxuron in B. germanica management programs is discussed.