1. PLANT RESISTANCE
Sublethal Effects of Antibiosis Resistance on the Reproductive Biology
of Two Spittlebug (Hemiptera: Cercopidae) Species Affecting
Brachiaria spp.
PAOLA A. SOTELO, MARI´A F. MILLER, CESAR CARDONA,1
JOHN W. MILES,
GUILLERMO SOTELO, AND JAMES MONTOYA
Centro Internacional de Agricultura Tropical (CIAT), Apartado Ae´reo 6713, Cali, Colombia
J. Econ. Entomol. 101(2): 564Ð568 (2008)
ABSTRACT Several greenhouse experiments were used to measure how high levels of antibiosis
resistance to nymphs in two interspeciÞc Brachiaria (brachiariagrass) hybrids affect life history
parameters of the spittlebugs Aeneolamia varia (F.) and Zulia carbonaria (Lallemand), two of the most
important spittlebug (Hemiptera: Cercopidae) species affecting Brachiaria production in Colombia.
The A. varia-resistant hybrid CIAT 36062, the Z. carbonaria-resistant hybrid SX01NO/0102, and the
susceptible accession CIAT 0654 were used to compare the effect of all possible combinations of food
sources for nymphs and adults. Calculation of growth indexes showed a signiÞcant impact of antibiosis
resistance on the biology of immature stages of both species. Median survival times of adults feeding
on resistant genotypes did not differ from those recorded on the susceptible genotype, suggesting that
factors responsible for high mortality of nymphs in the resistant hybrids did not affect adult survival.
Rearing nymphs of A. varia on CIAT 36062 and of Z. carbonaria on SX01NO/0102 had deleterious
sublethal effects on the reproductive biology of resulting adult females. It is concluded that high
nymphal mortality and subsequent sublethal effects of nymphal antibiosis on adults should have a
major impact on the demography of the two spittlebug species studied.
KEY WORDS Brachiaria, spittlebugs, resistance, antibiosis, sublethal effects
Several genera with numerous species of cercopids
(Hemiptera: Cercopidae), are the most important in-
sect pests affecting productivity of Brachiaria spp.
pastures in tropical America (Vale´rio et al. 2001). Both
nymphs and adults of spittlebugs feed from the xylem,
causing severe damage to the foliage. As a result,
digestibility and quality of forage are reduced, thereby
decreasing stocking rates and milk and meat produc-
tion (Vale´rio et al. 2001). Resistance to spittlebugs in
Brachiaria spp. has been studied mainly in Colombia
and Brazil. Since the last reviews on the subject (Vale´-
rio 1995, Vale´rio et al. 2001), progress has been made
in the development of Brachiaria interspeciÞc hybrids
with high levels of antibiosis resistance to several
spittlebug species (Miles et al. 2006). The different
levels of antibiosis resistance to nymphs of several
spittlebug species have been characterized in several
Brachiaria genotypes (FerruÞno and Lapointe 1989,
Lapointe et al. 1992, Vale´rio 1995, Cardona et al. 1999,
Cardona et al. 2004, Miles et al. 2006). These studies
deal with direct effects of antibiosis on the duration of
the nymphal stage and on survival of nymphs, weight
of nymphs and weight of surviving adults. None of
these studies refers to the effect of antibiosis to
nymphs on the reproductive biology of surviving
adults, which according to Smith (2005) is one of the
most important adverse effects of resistance. As the
current breeding program to develop Brachiaria hy-
bridswithmultipleantibioticresistancestospittlebugs
progresses (Miles et al. 2006), very high levels of
resistance have been achieved, warranting the assess-
ment of the overall impact of this resistance on the
demography of the target species.
The objective of these studies was to quantify the
effect of high levels of antibiosis resistance in two
interspeciÞc Brachiaria hybrids on life history param-
eters of Aeneolamia varia (F.) and Zulia carbonaria
(Lallemand), two of the most important spittlebug
species affecting Brachiaria in Colombia (Peck 2001,
Rodrõ´guez and Peck 2006). The experiments also
sought to assess the effects of nymph-resistant geno-
types on the biology of adults and to detect potential
sublethal effects of antibiosis (e.g., prolonged preovi-
position periods, reduced oviposition rates, reduced
longevity, or reduced egg fertility) on adults emerging
from nymphs reared on antibiotic genotypes.
Materials and Methods
Plant Materials, Insects, and Environmental Con-
ditions. We used three genotypes to conduct the ex-
perimentsreportedhere:1)CIAT0654,aB.ruziziensis1 Corresponding author, e-mail: c.cardona@cgiar.org.
0022-0493/08/0564Ð0568$04.00/0 ᭧ 2008 Entomological Society of America

2. Germain and Evrard accession that is very susceptible
to spittlebugs; 2) CIAT 36062, an apomictic hybrid
highly resistant to nymphs of A. varia (Cardona et al.
2004); and 3) SX01NO/0102, a sexual clone isolated
from the Þfth cycle of a synthetic tetraploid breeding
population undergoing selection for spittlebug resis-
tance (Miles et al. 2006). SX01NO/0102 is highly re-
sistant to nymphs of Z. carbonaria (Miles et al. 2006).
Test plants were multiplied from cuttings by vegeta-
tive propagation. Test insects were A. varia and Z.
carbonaria obtained from colonies maintained at
CIAT.Allexperimentswereconductedinaglasshouse
at a mean temperature of 24ЊC (range, 19Ð27ЊC) and
mean relative humidity of 75% (range, 70Ð90%).
These studies were carried out in 2004 and 2005.
Biological Parameters. To measure the full impact
of resistance on the biology of the test species and to
identify possible antibiotic effects of nymph-resistant
genotypes on adults, we set up four treatment com-
binations: 1) nymphs reared on susceptible genotype,
resulting adults feeding on susceptible genotype; 2)
nymphs reared on susceptible genotype, resulting
adults feeding on resistant genotype; 3) nymphs
reared on resistant genotype, resulting adults feeding
on susceptible genotype; and 4) nymphs reared on
resistant genotype, resulting adults feeding on resis-
tant genotype.
Spittlebugs were reared on the respective suscep-
tible or resistant genotype using the technology de-
veloped by Lapointe et al. (1989). For mass-rearing
purposes, variable numbers of individual host plants,
each grown in 30-cm-diameter pots, were infested
with 100 mature eggs of the respective spittlebug spe-
cies. Eggs not eclosed 24 h after infestation were re-
placed. Each plant was taken as an observation. In-
festation was then allowed to proceed without
interference until adult emergence occurred. Adult
emergence was recorded daily. Percentage of
nymphal survival and mean days to adult emergence
were recorded on each plant. These values were used
to calculate growth indexes (Se´tamou et al. 1999) as the
ratio between percentage of nymphal survival and days
to adult emergence. Adult sex ratios were recorded.
Groups of 30 newly emerged adults (15 females, 15
males) were conÞned to individual muslin cages (36
cm in width, 62 cm in length, 70 cm in height) to feed
on Þve, 30-d0-old plants of the respective genotype
according to the different treatment combinations
cited above. Each cage constituted a replication.
Given the size of the experiments, we used seven
replications in time for A. varia and six replications in
time for Z. carbonaria. Thus, in total, 105 pairs of A.
varia and 90 pairs of Z. carbonaria were studied per
treatment combination. Cages (replications) were
placed in a completely randomized design on green-
house tables. Adult mortality and mean number of
eggs per female were recorded daily until all females
died. Data on duration of the preoviposition and ovi-
position periods, and adult dry weight were taken. Egg
viability, calculated as percentage of nymphs hatching
from the eggs, was determined by incubating all of the
eggs obtained in petri dishes. Host plants were re-
placed daily to avoid food depletion effects.
Statistical Analysis. All statistical analyses were con-
ducted using the Statistix 8 package (Analytical Soft-
ware 2003). To compare adult survival on the different
treatments, median survival times were calculated us-
ing the KaplanÐMeier test (Lee 1992). The CoxÐ
Mantel survival test (Lee 1992) was used to compare
survival distributions (survival patterns). Data on
adult dry weight, duration of preoviposition and ovi-
position periods, total eggs per female, and percentage
of egg viability (transformed to arcsine square root of
proportion) were tested for normality by means of the
ShapiroÐWilk normality test (Analytical Software,
Tallahassee, FL) and then submitted to one-way anal-
ysis of variance (ANOVA). When the F-test for treat-
ment differences was signiÞcant, means were com-
pared by least signiÞcant difference (LSD) at the ␣ ϭ
0.01 level of conÞdence. Means and standard errors of
retransformed percentage of egg viability data are
presented.
Results and Discussion
Effects on Nymphal Survival and Duration of
Nymphal Period. A. varia was mass-reared three times
on each of the susceptible (CIAT 0654) or resistant
(CIAT 36062) genotypes. Mean nymphal survival on
CIAT 0654 was 82.0% (n ϭ 7,000; range, 77Ð86%).
Mean duration of the nymphal stage was 44.7 d (range,
43.5Ð45.5). In contrast, mean nymphal survival on
CIAT 36062 was 7.7% (n ϭ 20,000; range, 3Ð17%).
Mean duration of the nymphal stage on this genotype
was 56.8 d (range, 55.5Ð57.5). These results point to a
major impact of antibiosis resistance on the biology of
A. varia nymphs and are consistent with those ob-
tained by Cardona et al. (2004) who found very low
survival and prolonged duration of surviving nymphs
feeding on CIAT 36062. Resistance did not affect sex
ratios. The mean proportion of females obtained with
the susceptible genotype (CIAT 0654) was 0.505; the
mean proportion of females obtained with the resistant
genotype (CIAT 36062) was 0.490. Analysis showed that
sex ratios did not differ from 1:1 (P Ͻ 0.01).
Z. carbonaria was mass-reared two times on each of
the susceptible (CIAT 0654) or resistant (SX01NO/
0102) genotypes. Mean nymphal survival of this spe-
cies reared on CIAT 0654 was 77.1% (n ϭ 1,860; range,
75.0Ð79.1). Mean duration of nymphs from egg hatch-
ing to adult emergence was 40.5 d (range, 40.4Ð40.8).
This value is similar to that obtained by Rodrõ´guez et
al. (2002) who calculated a nymphal duration of 42.4 d
when Z. carbonaria was reared on B. decumbens Stapf.
The mean survival of Z. carbonaria on the resistant
hybrid SX01NO/0102 was 7.8% (n ϭ 15,500; range,
4.2Ð11.4), and the mean duration of surviving nymphs
was 49.8 d (range, 47.0Ð52.5). These results are very
similar to those of Miles et al. (2006) and indicate a
major impact of antibiosis on survival and duration of
nymphs feeding on the resistant hybrid. As with A.
varia, sex ratios of Z. carbonaria were not distorted
from 1:1 by resistance (P Ͻ 0.01). The proportion of
April 2008 SOTELO ET AL.: REPRODUCTIVE BIOLOGY OF SPITTLEBUGS 565

3. females obtained with the susceptible genotype
(CIAT 0654) was 0.509; that obtained with the resis-
tant genotype (SX01NO/0102) was 0.521. Calculation
of growth indexes (Se´tamou et al. 1999) clearly illus-
trates the impact of antibiosis resistance on immature
biology of the two spittlebug species studied (Fig. 1).
Effects on Adult Survival. Median survival times of
both sexes of A. varia and Z. carbonaria are shown in
Table 1. On the basis of ␹2
values, the KaplanÐMeier
survival test (Lee 1992) revealed the occurrence of
signiÞcant differences among treatments (nonover-
lapping conÞdence limits). Further analysis using the
two-sample CoxÐMantel test was performed to make
pairwise comparisons between median survival times
on the absolute check (nymphs reared on the suscep-
tible genotype, adults feeding on the susceptible ge-
notype) and those recorded on the other treatment
combinations. For A. varia, this analysis showed that,
surprisingly, male and female adults from nymphs
reared on the susceptible genotype and subsequently
fed the resistant one (susceptibleÐresistant combina-
tion) lived signiÞcantly longer than those in the ab-
solute check (susceptibleÐsusceptible combination).
This effect may have been due to better food quality
provided to the adults by the nymph-resistant, some-
what adult-tolerant genotype CIAT 36062. Most im-
portantly, the median survival time of adults reared on
the resistant genotype (resistantÐsusceptible and re-
sistantÐresistant combinations) did not differ from
that registered on the absolute check (Table 1), sug-
gesting that whatever factor or factors responsible for
high mortality of nymphs in CIAT 36062 did not affect
adult survival. This absence of direct antibiosis resis-
tance to adults coincides with recent results (CIAT
0
1
2
Aeneolamia varia Zulia carbonaria
Growthindex
CIAT 0654 (S) CIAT 36062 (R) SX01NO/0102 (R)
0
1
2
Fig. 1. Growth indexes of two spittlebug species as affected by rearing nymphs on susceptible (S) or resistant (R)
Brachiaria genotypes. Growth indexes were computed as the ratio between the percentage of survival of nymphs to adults
and the duration of the immature (nymphal) period (Se´tamou et al. 1999).
Table 1. Median survival time of adults of two spittlebug species as affected by different combinations of rearing nymphs and feeding
resulting adults on susceptible (S) or resistant (R) Brachiaria genotypes
Treatment combination Median survival time (d)a
Nymphs
reared on
Adults
feeding on
Femaleb
Malec
A. varia
CIAT 0654 (S) CIAT 0654 (S) 7.0 (6Ð9) 6.0 (5Ð7)
CIAT 0654 (S) CIAT 36062 (R) 10.0 (9Ð11)** 8.0 (7Ð8)**
CIAT 36062 (R) CIAT 0654 (S) 6.4 (5Ð7) 5.0 (4Ð7)
CIAT 36062 (R) CIAT 36062 (R) 7.0 (6Ð8) 5.0 (4Ð7)
␹2
72.4 35.3
df 3 3
P Ͻ0.001 Ͻ0.001
Z. carbonaria
CIAT 0654 (S) CIAT 0654 (S) 27.0 (23Ð29) 29.0 (26Ð31)
CIAT 0654 (S) SX01NO/0102 (R) 35.7 (27Ð42)** 27.1 (20Ð29)
SX01NO/0102 (R) CIAT 0654 (S) 26.0 (23Ð30) 16.5 (14Ð22)**
SX01NO/0102 (R) SX01NO/0102 (R) 21.0 (17Ð25) 16.0 (14Ð17)**
␹2
16.6 27.2
df 3 3
P Ͻ0.001 Ͻ0.001
** Within species, signiÞcant at the 1% level with respect to the absolute check (SÐS combination). Pairwise comparison using the two-sample
CoxÐMantel survival test.
a
Median (95% CI) calculated for each species according to the KaplanÐMeier survival test (Lee 1992).
b
n ϭ 105 A. varia, 90 Z. carbonaria per treatment.
c
n ϭ 105 A. varia, 90 Z. carbonaria per treatment.
566 JOURNAL OF ECONOMIC ENTOMOLOGY Vol. 101, no. 2

4. 2006) on mechanisms of resistance to adults, which
suggestthattolerance,notantibiosis,isthemechanism
responsible for moderate levels of resistance to adult
feeding damage in some of the few genotypes that
have been studied. For example, when 164 apomictic
hybrids selected for high levels of antibiosis resistance
to A. varia were tested for resistance to adults, none
of the hybrids affected survival of adults. A handful
(16.2%) showed tolerance to adult damage. The rest
were classiÞed as susceptible to adult feeding damage
(CIAT, unpublished data). The lack of correspon-
dence between mechanisms of resistance to nymphs
and adults is one of the subjects of current research at
CIAT.
Results with Z. carbonaria were similar: females
reared on the susceptible genotype and fed the resis-
tant one lived signiÞcantly longer (Table 1). As with
A.varia,feedingofadultsontheresistantgenotypedid
not affect their survival, suggesting that antibiosis fac-
tors responsible for high nymph mortality on
SX01NO/0102 do not seem to have an effect on adults.
Interestingly, males of Z. carbonaria were less Þt than
females, living signiÞcantly fewer days than males
reared on the susceptible genotype (Table 1). We do
not have a plausible explanation for this sex difference
in this species.
Sublethal Effects on Reproductive Biology and
Weight. Rearing nymphs of A. varia on CIAT 36062
and of Z. carbonaria on SX01NO/0102 had a delete-
rious effect on the reproductive biology of the test
insects (Table 2). Independent of the food substrate
used to feed them, female adults of both spittlebug
species emerging from nymphs reared on the respec-
tive resistant genotype had signiÞcantly longer pre-
oviposition periods, and laid fewer, less viable eggs, for
a shorter period, than those female adults from the
nymphs reared on the susceptible genotype. This can
be interpreted as a sublethal effect of antibiosis on the
reproductive capacity of both insect species. The im-
pact of antibiosis on the reproductive capacity of both
insects (eggs per female in the case of A. varia, eggs
per female and percentage of viable eggs in the case
of Z. carbonaria) was more evident in the resistant-
resistant combination than in the resistant-susceptible
combination. Sublethal effects also were detected
when the weight of adult females was analyzed (data
not shown): Females of A. varia reared on nymph-
resistant CIAT 36062 and fed on susceptible CIAT
0654 weighted 13.0% less than those reared and fed on
CIAT 0654 (P Ͻ 0.01). Those of Z. carbonaria reared
on nymph-resistant SX01NO/0102 and fed CIAT 0654
weighed 3.4% less than those reared and fed on CIAT
0654 (P Ͻ 0.01).
We conclude that high nymphal mortality and sub-
lethal effects of antibiosis on adults have a major im-
pact on the demography of the two spittlebug species
studied. We expect that the information generated in
this study provides an insight on the possible fate of
spittlebugpopulationsinareaswithhighratesofadop-
tion of Brachiaria-resistant hybrids.
Acknowledgments
We thank Juan Miguel Bueno, Gilberto Co´rdoba, and
Reinaldo Pareja for technical support. CIAT core funds sup-
ported this work.
References Cited
Analytical Software. 2003. Statistix 8. UserÕs manual. Ana-
lytical Software, Tallahassee, FL.
Cardona, C., J. W. Miles, and G. Sotelo. 1999. An improved
methodology for massive screening of Brachiaria spp.
genotypes for resistance to Aeneolamia varia (Ho-
moptera: Cercopidae). J. Econ. Entomol. 92: 490Ð496.
Cardona, C., P. Fory, G. Sotelo, A. Pabo´n, G. Diaz, and J. W.
Miles. 2004. Antibiosis and tolerance to Þve species of
Table 2. Reproductive biology of females of two spittlebug species as affected by different combinations of rearing nymphs and feeding
resulting adults on susceptible (S) or resistant (R) Brachiaria genotypes
Treatment combination
Preoviposition
period (d)
Oviposition
period (d)
Eggs per
female
% of viable
eggsNymphs
reared on
Adults
feeding on
A. varia
CIAT 0654 (S) CIAT 0654 (S) 3.1 Ϯ 0.34ab 8.4 Ϯ 0.52ab 137.7 Ϯ 8.02a 92.4 Ϯ 1.41a
CIAT 0654 (S) CIAT 36062 (R) 2.6 Ϯ 0.29b 10.6 Ϯ 0.68a 147.8 Ϯ 8.73a 92.6 Ϯ 0.94a
CIAT 36062 (R) CIAT 0654 (S) 3.8 Ϯ 0.50a 7.6 Ϯ 0.84b 108.0 Ϯ 9.05b 80.6 Ϯ 1.94b
CIAT 36062 (R) CIAT 36062 (R) 3.8 Ϯ 0.50a 8.1 Ϯ 0.88b 85.4 Ϯ 3.77c 80.5 Ϯ 2.48b
F 2.1 3.1 12.1 15.6
df 3, 24 3, 24 3, 24 3, 24
P Ͻ0.05 Ͻ0.05 Ͻ0.001 Ͻ0.001
Z. carbonaria
CIAT 0654 (S) CIAT 0654 (S) 4.3 Ϯ 0.21b 33.7 Ϯ 1.68b 451.4 Ϯ 13.11a 97.4 Ϯ 0.20a
CIAT 0654 (S) SX01NO/0102 (R) 4.5 Ϯ 0.22b 44.2 Ϯ 1.58a 440.0 Ϯ 16.12a 96.8 Ϯ 0.09a
SX01NO/0102 (R) CIAT 0654 (S) 6.2 Ϯ 0.30a 31.2 Ϯ 0.98bc 353.7 Ϯ 17.02b 88.1 Ϯ 0.77b
SX01NO/0102 (R) SX01NO/0102 (R) 5.7 Ϯ 0.33a 28.2 Ϯ 1.01c 286.9 Ϯ 19.73c 85.2 Ϯ 0.55c
F 8.0 26.4 5.6 217.0
df 3, 20 3, 20 3, 20 3, 20
P Ͻ0.001 Ͻ0.001 Ͻ0.001 Ͻ0.001
Means Ϯ SEM of seven replications (A. varia) and six replications (Z. carbonaria) per treatment, 15 females and 15 males per replication;
within species, means within a column followed by the same letter are not signiÞcantly different at the 1% level by LSD.
April 2008 SOTELO ET AL.: REPRODUCTIVE BIOLOGY OF SPITTLEBUGS 567

5. spittlebug (Homoptera: Cercopidae) in Brachiaria spp.:
implicationsforbreedingforresistance.J.Econ.Entomol.
97: 635Ð645.
[CIAT] Centro Internacional de Agricultura Tropical.
2006. Studies on tolerance to adult feeding damage as a
component of resistance to spittlebug, pp. 36Ð38. In An-
nual Report 2005, Tropical Grasses and Legumes: Opti-
mizing Genetic Diversity for Multipurpose Use. Centro
Internacional de Agricultura Tropical, Cali, Colombia.
Ferrufino, A., and S. L. Lapointe. 1989. Host plant resis-
tance in Brachiaria grasses to the spittlebug Zulia colom-
biana. Entomol. Exp. Appl. 51: 155Ð162.
Lapointe, S. L., G. Sotelo, and G. L. Arango. 1989. Improved
technique for rearing spittlebugs (Homoptera: Cercopi-
dae). J. Econ. Entomol. 82: 1764Ð1766.
Lapointe, S. L., M. S. Serrano, G. L. Arango, G. Sotelo, and
F. Co´rdoba. 1992. Antibiosis to spittlebugs (Homoptera:
Cercopidae) in accessions of Brachiaria spp. J. Econ.
Entomol. 85: 1485Ð1490.
Lee,E.T. 1992. Statisticalmethodsforsurvivaldataanalysis.
Wiley, New York.
Miles, J. W., C. Cardona, and G. Sotelo. 2006. Recurrent
selection in a synthetic brachiariagrass population im-
proves resistance to three spittlebug species. Crop Sci. 46:
1088Ð1093.
Peck, D. C. 2001. Diversidad y distribucio´n geogra´Þca del
salivazo (Homoptera: Cercopidae) asociado con gramõ´n-
eas en Colombia y Ecuador. Rev. Colomb. Entomol. 27:
129Ð136.
Rodrı´guez, J., and D. C. Peck. 2006. Para´metros poblaciona-
les de Zulia carbonaria sobre Brachiaria decumbens. Rev.
Colomb. Entomol. 32:145Ð150.
Rodrı´guez, J., D. C. Peck, N. A. Canal. 2002. Biologõ´a com-
parada de tres especies de salivazo de los pastos del
ge´nero Zulia (Homoptera: Cercopidae). Rev. Colomb.
Entomol. 28: 17Ð25.
Se´tamou, M., F. Schulthness, N. A. Bosque-Pe´rez, H. M.
Poehling, and C. Borgemeister. 1999. Bionomics of Mus-
sidia nigrivenella (Lepidoptera: Pyralidae) on three host
plants. Bull. Entomol. Res. 89: 465Ð471.
Smith,C.M. 2005. Plantresistancetoarthropods.Molecular
and conventional approaches. Springer, Dordrecht, The
Netherlands.
Vale´rio, J. R. 1995. About the evaluation of forage grasses
aiming resistance to spittlebugs (Homoptera: Cercopi-
dae), Abstract 1058. In Proceedings of the 13th Interna-
tional Plant Protection Congress, 5Ð7 July 1995, The
Hague, The Netherlands. European Journal of Plant Pa-
thology, Dordrecht, The Netherlands.
Vale´rio, J. R., C. Cardona, D. C. Peck, and G. Sotelo. 2001.
Spittlebugs: bioecology, host plant resistance and ad-
vances in IPM, pp. 217Ð221. In Proceedings 19th Inter-
national Grassland Congress, 11Ð21 February 2001, Sa˜o
Pedro, Sa˜o Paulo, Brazil. Brazilian Society of Animal Hus-
bandry, Sa˜o Paulo, Brazil.
Received 6 June 2007; accepted 23 October 2007.
568 JOURNAL OF ECONOMIC ENTOMOLOGY Vol. 101, no. 2