Toxicity of Abamectin to Cockroaches (Dictyoptera: Blattellidae, Blattidae)
University of Florida, Gainesville, Florida 32611
Abamectin was fed to German cockroaches, Blattella germanica
choice tests. LT005and LC,oS were estimated
by probit analysis. The L T005for the German
ranged from 4.4 to 1.7 d for males, from 9.0 to 2.4 d for females, and from 4.4
to 1.6 d for nymphs for bait concentrations
were 0.0110 and 0.0040% from males, 0.0240 and 0.0090% for females,
and 0.0200 and 0.0080% for nymphs at 3 and 6 d, respectively.
bait were 3.4, 3.4, 2.4, 7.5, 2.9, and 4.5 d for Periplaneta
(Serville), P. brunnea Burmeister,
P. australasiae (F.), Blatta orientalis L., and
species, time to death for the larger species was longer than for the German cockroach.
abamectin bait, all died within 5 d of exposure to abamectin bait. Abamectin bait consumptionwas not significantly
control being achieved by treating harborages
INSECTICIDALBAITShave become one of the most
1984, Miller et al. 1986, Rousch & Wright
and yellowjackets (Chang 1988). Strong & Brown
(1987) reviewed the mode of action of avermectins
and their effect on target and nontarget species of
Abamectin cockroach bait (Avert, Whitmire Re-
ents used in baits can include compounds like hy-
search Laboratories, St. Louis, Mo.) is a slow acting
toxicant for control of German cockroaches, Blat-
contact activity but are very active as stomach poi-
sons (Rust 1986). Because baits can be placed in
containers, insecticides that stain (e.g., hydrameth-
control of the German cockroach (Ballard & Gold
ylnon has a yellow color) can be applied indoors
1983, Wright & Dupree 1985). Rates of 76.5 ppm
(1985) also found that low concentrations
ermectin caused failure of leg muscles of American
mectin BIb) is effective as a stomach poison against
cockroach, Periplaneta americana (L.), to respond
(Glancey et al. 1982, Baker et al. 1985), lice (Barth
The objective of our study was to evaluate the
& Preston 1985), clothes moths (Bry 1989), gypsy
moth (Deecher et al. 1987), flies (Langley & Roe
a stomach poison and causes delayed toxicity, tox-icity at various concentrations
Thisarticlereportsthe resultsof researchonly.Mentionof a
proprietaryproductdoesnotconstitutean endorsementor a rec-
Speed of kill for a 0.0550% bait was determined
I Currentaddress:Departmentof Entomology,
'Insects AffectingMan and AnimalsResearchLaboratory, suppress populations of German cockroaches were
finely ground laboratory rodent chow, were placed
in each glass utility jar (4.25 liter). Nylon screen
germanica; Oriental cockroaches, Blatta orientalis
(6.6 threads per cm) was placed on top of the pow-
L.; brown banded cockroaches, Supella longipalpa
dered abamectin bait and rodent chow to prevent
(Serville); American cockroaches, P. americana;
spillage. Water and harborage were provided as
Australian cockroaches, P. australasiae (F.); brown
described earlier. Preference tests were conducted
in a room held at 50% RH and 25°C with a pho-
lightly anesthetized with CO. and removed from
Before cockroaches were released, all experi-
colonies maintained at the USDA-ARS Insects Af-
mental jars were placed in the laboratory for 48 h
fecting Man and Animals Laboratory, Gainesville,
to allow the moisture content of the baits and ro-
Fla. "Orlando normal" German cockroaches were
dent chow to equilibrate with the laboratory en-
used in our study. This strain is susceptible to in-
vironment. Twenty male German cockroaches were
secticides (Koehler & Patterson 1986). Adults that
then placed in each jar (lightly greased with a 2:3
had eclosed 3 d before testing and fourth- and fifth-
stage nymphs were used. Males of the other species
To check moisture changes in the baits, control jars
were removed from laboratory colonies and were
with bait and rodent chow were set up without
cockroaches. To check cockroach mortality, other
Whitmire Research Laboratories (St. Louis, Mo.).
with laboratory rodent chow for food.
Seven concentrations of baits ranging from 0.0025
to 0.1000% (wt/wt) were formulated on a standard
laboratory rodent chow, and the number of dead
bait base. Laboratory rat chow (Purina, St. Louis,
Mo.) was finely ground and used as a control diet.
cockroaches were released and daily for 7 dafter
After the initial dose studies with German cock-
release. Five jars for the treatment, three humidity
roaches, a 0.0550% (wt/wt) bait was used for all
control jars, and three untreated control jars were
used. Daily consumption of food and bait by the
Mortality Tests. Thirty German cockroaches (10
cockroaches was corrected using the following for-
male, 10 female, and 10 late-stage nymphs) were
placed in glass utility jars (4.25 liter) that were
lightly greased with a 2:3 (petrolatum/mineral
film to prevent escape. A souffle cup containing
where CC is the corrected consumption, WI is
g of bait was placed in each jar. Water was
weight on day 1, W. is weight on day 2, HCI is
provided with a cotton-stoppered, water-filled plas-
the average weights appropriate hUliJliditychecks
tic vial (20 ml; 5.5 by 2.5 cm inner diameter);
(3 reps) on previous day, and HC. is the average
harborage was a rolled corrugated cardboard strip
weights humidity checks on current day. Adjusted
(6 by 15 cm). Cloth covers were placed over each
food and bait consumption were analyzed by t tests
German cockroaches were exposed to seven con-
Arena Tests. The inside walls of 11 aluminum
arenas (120 by 120 by 30 em, three per treatment)
were greased lightly with a 2:3 (petrolatum/min-
control (finely ground laboratory rat chow). Three
eral oil) film to prevent cockroach escape. Four
jars were set up for each treatment.
cardboard harborages (4.5 by 8.5 cm inner diam-
were nonchoice and done at 50% RH and 25°C
eter; Fonda, Union, N.J.) with holes (2 cm inner
with a photoperiod of 12:12 (L:D). Numbers of
diameter) cut in the side were placed midway along
dead cockroaches were recorded for each jar at 1,
the edge of each arena. German cockroaches (50
2, 3, 6, 8, 10, 12, and 14 d of treatment.
males, 50 females, and 280 nymphs) were placed
The arenas were treated with 1.65% hydrameth-
were placed in glass utility jars (4.25 liter) that were
ylnon bait trays (Combat, American Cyanamid,
Clifton, N.J.), abamectin bait stations (20-30 g of
cockroaches were recorded for each jar at 1, 2, 3,
0.0550% [AI] abamectin) placed in a cardboard dish
(2 by 8.5 cm inner diameter; Fonda), or 5 g of
Data were analyzed by probit analysis (Finney
abamectin bait dusted into each cockroach har-
1971) to estimate LCw values for each day of treat-
borage. Dishes that contained the abamectin or the
ment and LTso values for each concentration
bait. Significant differences in LT50 and LC50 values
each other and an equal distance from a centrally
were determined by failure of 95% confidence in-
placed chicken waterer (1 liter) in each arena.
Dishes that contained laboratory rat chow were
placed in a similar manner, but at a 90° orientation
to the dishes containing the treated bait. Control
0.0550% abamectin bait and the other containing
arenas just received laboratory rodent chow. Are-
LCso values (%) of German cockroaches fed
fed abamectin at various bait concentrations
Abamectin is a slow-acting toxicant that provides
higher doses killing cockroaches faster. The speed
of action for males (L Tso = 1.68 d) is slower than
faster than that of sulfluramid (2.14 d at 1,000 ppm;
Reid et al. 1990) and boric acid (5.06-7.63 d; Appel
1990). Both Reid et al. (1990) and Milio et al. (1986)
non provide delayed mortality of cockroaches thatis dose-related.
licated three and two times, respectively.
than 6 d (Table 2). The LCsoS of abamectin
males, females, and nymphs of the German cock-
were generally significantly higher for females and
0.05) (SAS Institute 1988). This procedure was used
2.8, and 4.5 d, respectively (Table 3). These valueswere significantly
man cockroach. Differences in bait preferences and
The L TsoSfor males, females, and nymphs of the
body size of these other species may account for
bait (Table 1). Generally, LTsoSdecreased with in-creasing
0.0500%. No significant decrease in LTsoSwas found
bait was used in additional studies. At 0.0500%, the
males, females, and nymphs, respectively. Cochran
high mortality at 10 d, and survivors failed to re-
produce. The faster mortality times reported in ourstudy are probably attributable
Data were analyzed by probit analysis (Finney
(> 10 times) of abamectin bait used.
abamectin bails and laboratory rat chow by male German cockroaches in choice
group means in the same column followed by the same letter are not significantly different (P = 0.05; Student's t test
used to suppress populations of peridomestic cock-
important in bait performance for slow-acting oral
roaches, even though the time required to kill the
toxicants. Over a 7-d period, male cockroach (groups
larger cockroaches was> 16 d (Milio et al. 1986).
of 20) consumption of abamectin bait (7.16 mg)
was not significantly less than consumption of rat
er species of cockroaches and is a potentially useful
chow (9.61 mg). The total consumption (16.77 mg)
product for suppression of peridomestic cockroach-
of food in utility jars containing abamectin was less
than consumption (110.59 mg) in the control jars
Preference tests of German cockroaches for the
over the same period. Reduced consumption in the
abamectin bait compared with laboratory rat chow
treated groups was probably attributable to toxicity
resulted in 100% mortality by the fifth day (Table
of abamectin. Similarly, Cochran (1985) reported
4). There was no control mortality. These mortality
reduced consumption of baits by female German
results compare favorably with mortality obtained
cockroaches at bait concentrations >0.3 ppm; but
using formulated baits that contain hydramethyl-
he attributed the reduced consumption to toxicity
non and sulfluramid with this strain of cockroach
rather than unpalatability or repellency.
Arena tests with 0.0500% abamectin and 1.65%
unpublished data). The LT50 of abamectin bait in
choice tests was 2.85 d (n = 100; 95% confidence
tality of German cockroaches after 1-3 d (Table
interval, 2.722-2.981; slope ± SE, 9.122 ± 0.084).
5). Abamectin placed in bait dishes resulted in sig-
This LToowas significantly greater than the LT50
nificantly lower mortality after 9d than abamectin
of a similar concentration of bait fed in non choice
placed in the harborage with the cockroaches. Aba-
tests (1.68 d), but was not significantly different
mectin provided faster mortality than the hydra-
from the L T50 of a bait that was half the concen-
methylnon standard from 1 to 3 d of treatment.
tration (2.68 d for 0.0250% bait). This result would
After 5 d, the abamectin treatment placed in the
be expected if the bait was approximately the pal-
harborage and the hyramethylnon bait stations re-
atability of rat chow (rat chow is not highly pal-
sulted in significantly higher mortality than the
abamectin placed in the bait station or the controls.
After 9 d, abamectin placed in the harborage pro-
affected (Reierson & Rust 1984) if palatability is
vided 75% mortality of German cockroaches, hy-
reduced. Therefore, relative palatability with re-
spect to dietary alternatives is likely to be extremely
mectin placed in the bait station provided 31%
Percent mortality of cockroaches in arena tests treated with 0.0550%
Means within a row followed by the same letter are not significantly different (P = 0.05; Tukey's Studentized range test [SAS Institute
larvae and eggs. J. Econ. Entomo!. 80: 1284-1287.
Glancey, B. M., C. S. Lofgren & D. F. Williams.
possible control agent for the tsetse fly, Glossina mor-sitans. Entomo!. Exp. App!. 36: 137-143.
Miller, J. A., D. D. Oehler & A. J. Siebenaler.
horn flies and stable flies. J. Econ. Entomo!. 79: 1564-
We thank Troy Whitfield, Eurypides Mena, and Susan
Ard for their technical assistance. We also thank Whit-
cockroach suppression with hydramethylnon
support of this project. This is Florida Agricultural
B1attellidae) control. J. Econ. Entomo!.
T. C., S. E. Van Vorhis Key & L. K. Gaston. 386. In G. W. Bennett J. M. Owens [eds.l Advances
contro!. Bull. Entomo!. Res. 77: 357-389.
10 degrees, 15.5 degrees, and 27 degrees C for control
mectin B on the leg muscles and the nervous system
trans (L.) (Diptera: Muscidae). J. Kans. Entomo!. Soc.
of the American cockroach. Pestic. Biochem. Physio!.
RASMUSSON V. SMITHKLINE BEECHAM CORP.: ENABLEMENT UNDER 35 U.S.C. § 112, FIRST PARAGRAPH In an important pharmaceutical related case looking at the enablement requirement under 35 U.S.C. §112, first paragraph, the United States Court of Appeals for the Federal Circuit (“CAFC”) in Rasmusson v. SmithKline Beecham Corp. , 04-1191 (Interference No. 104,646), held that a patent specifi
The Transition of Appalachia and the Transformation of Prosperity in the United States I. Overview Nearly two centuries ago, English economist David Ricardo put forth the “Theory of Comparative Advantage” to guide trade policy between nations. The theory posited that nations should specialize in the production of a small number of goods which they could manufacture efficiently,