ECOLOGY AND BEHAVIOR

Foraging Activity and Seasonal Food Preference of Linepithema micans
(Hymenoptera: Formicidae), a Species Associated With the Spread of

Eurhizococcus brasiliensis (Hemiptera: Margarodidae)

ALINE NONDILLO,1,2 LEONARDO FERRARI,3 SABRINA LERIN,3 ODAIR CORREA BUENO,1

AND MARCOS BOTTON3

J. Econ. Entomol. 107(4): 1385Ð1391 (2014); DOI: http://dx.doi.org/10.1603/EC13392

ABSTRACT Linepithema micans (Forel) (Hymenoptera: Formicidae) is the main ant species re-
sponsible for the spread of Eurhizococcus brasiliensis (Wille) (Hemiptera: Margarodidae), a soil scale
that damages vine plants in southern Brazil. The daily foraging activity of L. micans and its seasonal
preference for protein- and carbohydrate-based foods were evaluated. The study was carried out in
a greenhouse using seedlings of the Paulsen 1103 rootstock (Vitis berlandieri � Vitis rupestris) planted
individually in pots and infested with colonies of L. micans. To determine the daily foraging activity
and seasonal preference, a cricket (Gryllus sp.) and a 70% solution of inverted sugar and water were
offered once a month for 12 mo. The ants foraging on each food source were counted hourly for 24 h.
L. micans foraged from dusk until the end of the next morning, with higher intensity in the spring and
summer. Workers of L. micans showed changes in food preference during the year, with a predom-
inance of protein-based food during winter and spring and carbohydrate-based food during autumn.
The implications of this behavior for control of the species with the use of toxic baits are discussed.

KEY WORDS grapevine, soil scale, daily foraging, seasonal preference

Linepithema micans (Forel) (Hymenoptera: Formi-
cidae) is the main ant species responsible for the
spread of Eurhizococcus brasiliensis (Wille) (Hemi-
ptera: Margarodidae), the main pest of vineyards in
Brazil (Martins and Bueno 2009, Sacchett et al. 2009,
Nondillo et al. 2013). One strategy to reduce infesta-
tion by E. brasiliensis in vineyards is to control L.
micans through the use of toxic baits (Nondillo 2013),
as with Linepithema humile (Mayr) (Hymenoptera:
Formicidae) in South Africa and California (Addison
and Samways 2000; Daane et al. 2006, 2007; Cooper et
al. 2008; Nyamukondiwa 2008). A basic requirement
for success in the use of toxic baits is knowledge of the
foraging period and seasonal food preferences, which
will guide the choice of attractive ingredients for bait
(Markin 1970, Abril et al. 2007).

L. humile forages only during the coolest hours of
the day; during spring and summer, the ants forage
mainly at night when temperatures are lower. Work-
ers of L. humile change their food preference depend-
ing on the stage of the colony reproductive cycle
(Abril et al. 2007). Protein foods are preferred during
the spring and autumn to feed queens and larvae, and
carbohydrate-based foods during the periodwhen the

density of males and workers in the colony is higher
(Markin 1970, Rust et al. 2000, Abril et al. 2007).

Because of the lack of information on the foraging
behavior and food preference of L. micans, this study
evaluated the daily and seasonal foraging activity of
the species and its seasonal preference for protein-
and carbohydrate-based foods.

Materials and Methods

The experiment was carried out from June 2011
throughMay 2012 in a greenhouse located at Embrapa
Uva e Vinho, Bento Gonçalves, Rio Grande do Sul,
Brazil. Ten seedlings rooted in Paulsen 1103 vine root-
stocks (Vitis berlandieri � Vitis rupestris) were
planted in individual 5-liter pots.

After the planting, the vine seedlings remained in
the pots for �2 mo, after which they were infested
with nests of ants. Nests of L. micans of similar size,
with approximately 10queens and1,500workers,were
transferred to each pot. All the nests contained eggs,
larvae, and pupae. The ants were collected from vine-
yards infested with E. brasiliensis and L. micans. The
ant nests, together with soil, were removed and trans-
ported to the laboratory in plastic bags and later trans-
ferred toplastic trays.Tocapture theants, two tiles (10
by 10 cm) were placed in each tray, with the abrasive
faces toward each other and with wooden sticks (2
mm in width) between them. The sticks were placed
with a space between their tips, for the ants to enter.

1 A. Nondillo, O.C. Bueno, Instituto de Biociências, UNESP Ð Uni-
versidade Estadual Paulista, Campus de Rio Claro, SP, Brazil. Depar-
tamento de Biologia, C.E.I.S. - Centro de Estudos de Insetos Sociais.

2 Corresponding author, e-mail: alinondillo@yahoo.com.br.
3 L. Ferrari, S. Lerin, M. Botton, Laboratório de Entomologia, Em-

brapa Uva e Vinho, Bento Gonçalves, RS, Brazil.

0022-0493/14/1385Ð1391$04.00/0 � 2014 Entomological Society of America



Cotton moistened with a 25% sugar solution was
placed between the tiles to stimulate the ants to enter
the set of tiles (Nondillo et al. 2012, 2013).

After the colonies established themselves between
the tiles, a pair of tiles were placed on the surface of
each pot, thus enabling the ants to transfer the colony
themselves (Nondillo et al. 2012).

After the infestation, the ants were fed three times
per week with larvae of Tenebrio molitor L., adults of
Gryllus sp., an aqueous solution of inverted sugar
(25%), and water ad libitum. The pots were placed in
trays Þlled with talcum powder, with the edges cov-
ered with Teßon-30 (DuPont, Wilmington, DE), to
prevent the ants from escaping.

To determine the daily and seasonal foraging activ-
ity and food preference during the year of workers of
L. micans, the number of ants foraging on two food
sources was counted during each month of the year.
The food resources were arranged on a formic plate,
allowing the foragers to choose between foods (Fig.
1). The food sources evaluated were crickets (Gryllus
sp.) and a solution of 70% inverted sugar inwater (Fig.
1A and B). The foods selected are preferred by work-
ers of L. micans, based on prior food-preference ex-
periments (Nondillo 2013).

After the food was offered, we counted the number
of ants around the food source (Fig. 1C). This pro-
cedure was repeated each hour for 24 h; in other
words, all hours of the day, once a month, for 1 yr. The
temperature and air relative humidity were also mea-
sured in these intervals.

Each treatment was repeated 10 times in a fully
randomized experimental design.

Statistical Analysis. The data were evaluated for
normality by the ShapiroÐWilk test, and for variance
homogeneity by the Levene test. Non-normal data
were square root-transformed.

The numbers of ants foraging at the different times
of day (morning, afternoon, night, and dawn) were
analyzed using analysis of variance, followed by the
comparison of means using the Tukey test at the 5%
signiÞcance level.

The environmental factors of temperature and hu-
midity, and the daily and seasonal foraging activity
were analyzed using PearsonÕs correlation coefÞcient.

For analysis of the food preference throughout the
year, thedatawere arcsine-transformedandevaluated

by StudentÕs t-test. The software Statistica 10 (StatSoft
Inc., Tulsa, OK) was used in all analyses.

Results and Discussion

The ant foraging activity on the vine rootstocks was
continuous throughout the year (Fig. 2). The workers
foraged most actively at dusk, with peaks in the morn-
ing, andwere least active during thewarmest and least
humid hours of the day (Fig. 2).

Although activity was low in the months of lower
temperatures (June, July, and August), foraging ac-
tivity was more intense at night (June: F � 21.064; P �
0.001; July: F � 10.911; P � 0.001; August: F � 35.359;
P � 0.001). This pattern continued in September (F �
67.152; P � 0.001) and October (F � 7.580; P � 0.001)
with peaks during the Þrst hours of the night (Fig.
2AÐE).

In November (F � 76.907; P � 0.001), December
(F � 55.242; P � 0.001), February (F � 39.526; P �
0.001), March (F � 49.079; P � 0.001), April (F �
17.251; P � 0.001), and May (F � 2.772; P � 0.042),
activity increased in the Þrst hours of dusk and con-
tinueduntil themorning,with a signiÞcant decrease in
the afternoon (Fig. 2, FÐL). In January, a signiÞcantly
higher peak of foraging was recorded in the morning
(F � 17.777; P � �0.001; Fig. 2H).

The daily foraging activity of the colonies of L.
micans was negatively correlated with temperature
and positively correlated with air relative humidity in
most months (Fig. 2; Table 1).

The foraging activity pattern is one of the most
distinct characteristics of ant species (Hölldobler and
Wilson 1990). InterspeciÞc divergences in the forag-
ing activity pattern arise from morphological, physi-
ological, and behavioral characteristics that deÞne the
ecological tolerance of a species (Bernstein 1974).
This temporal dimension in the foraging behavior de-
pends on abiotic factors that vary seasonally, such as
temperature, relative humidity, luminosity, and rain-
fall, and also on biotic factors such as food and intras-
peciÞc competition among others (Carrol and Janzen
1973, Bernstein 1974, Traniello 1989).

The variation in daily foraging activity observed in
this study indicates that the temperature and relative
humidity strongly affected the foraging pattern, with

Fig. 1. Formic plate of double pick with two food sources: (A) Gryllus sp. and (B) an aqueous solution of invert sugar
(70%). (C) Detail of ants feeding on food resource during the evaluation period. (Online Þgure in color.)

1386 JOURNAL OF ECONOMIC ENTOMOLOGY Vol. 107, no. 4



a signiÞcant correlation between these variables and
the number of ants foraging.

The strategy to reduce the period of exposure to
high temperatures was evident, as in all months, the
foraging intensity decreased in the Þrst hours of the
afternoon when the temperatures are higher and air

relative humidity is lower. Similar patterns were ob-
served for L. humile by Markin (1970) and Abril et al.
(2007) in thewarmer seasonsof theyear, and forother
ant species such as Anoplolepis tenella Santschi (For-
micinae) (Kuate et al. 2008), Odontomachus chelifer
(Latreille) (Ponerinae) (Raimundo et al. 2009), and

Fig. 2. Mean number of workers of L. micans foraging per hour (bars), temperature (Ñ), and air relative humidity (. . . . . .)
in greenhouse. In 2011: (A) June, (B) July, (C) August, (D) September, (E) October, (F) November, and (G) December.
In 2012: (H) January, (I) February, (J) March, (K) April, and (L) May. *: Same lowercase letters do not differ by TukeyÕs
test (P � 0.05).

August 2014 NONDILLO ET AL.: FORAGING OF Linepithema micans 1387



Tapinoma indicum Forel (Dolichoderinae) (Cerdá et
al. 1998).

According to Abrams (1991), obtaining food gen-
erally involvesphysiological costs. Thehighest cost for
ants foraging at high temperatures is desiccation,
which can be lethal, and represents a high risk for the
entire colony (Cerdà et al. 1998). Comparisons with
native North American species showed that L. humile
is sensitive to desiccation, given its small size (Schil-
man et al. 2005). Because workers of L. micans are also
small and morphologically similar to L. humile, it can
be assumed that they use the samebehavior pattern to
avoid high temperatures.

The seasonal foraging activity of L. micans varied
through the year, with a reduction in the activity
rhythm from July through September and a higher
frequency ofworkers searching for food fromNovem-
ber through February (Fig. 3). A positive correlation
was found between the temperature and the monthly
foraging patterns (r � 0.646; P � 0.017) with a larger
number of ants searching for food in the warmest
months. The monthly analysis showed no signiÞcant
correlation with relative humidity (r � �0.153; P �
0.617).

The increase in foraging activity in the warmest
seasons was also reported for Tetramorium semilaeve
André (Myrmicinae), Camponotus foreli Emery (For-
micinae) (Cerdà et al. 1998), A. tenella (Formicinae)
(Kuate et al. 2008), and O. chelifer (Ponerinae)
(Raimundoetal. 2009)amongothers. Similarbehavior
was observed in species of Dolichoderinae, such as
Tapinoma nigerrimum (Nylander) (Cerdà et al. 1998)
and L. humile (Markin 1968, Abril et al. 2007).

A possible explanation for the seasonal change in
foraging activity may be associated with the repro-
ductive phase of the colony. With the increase in
temperature and the beginning of the reproductive
cycle, the queen must ingest larger amounts of food to
support oviposition. Thus, during the reproductive
cycle, the workers increase their own activity to carry
out several tasks such as caring for the brood and
feeding the queens (Carrol and Janzen 1973, Benois
1973, Keller 1988, Abril et al. 2007), and consequently
intensify their search for food. According to Nondillo

Fig. 2. (Continued).

Table 1. Correlation coefficients (r) between the foraging ac-
tivity of L. micans, with temperature, air relative humidity, and
associated probabilities (P) in each month

Month
Temp. Rel. humidity

r P r P

June �0.488 0.013* 0.754 �0.001*
July �0.412 0.046* 0.776 0.001*
Aug. �0.811 �0.001* 0.807 �0.001*
Sept. �0.656 0.001* 0.628 0.001*
Oct. �0.447 0.029* 0.222 0.298
Nov. �0.452 0.027* 0.778 �0.001*
Dec. �0.709 �0.001* 0.622 0.001*
Jan. 0.528 0.008* �0.498 0.013*
Feb. �0.531 0.008* 0.588 0.033*
Mar. �0.242 0.255 0.253 0.232
April �0.490 0.015* 0.550 0.005*
May �0.405 0.049* 0.514 0.010*

* SigniÞcant correlation at the 0.05% level.

1388 JOURNAL OF ECONOMIC ENTOMOLOGY Vol. 107, no. 4



(2013), the period of highest oviposition of L. micans
queens occurs from November to February, coincid-
ing with the months of higher foraging activity.

L.micansworkers collectedmore high-protein food
in June(t� �6.114; df�46;P�0.001), July(t�3.259;
df � 35.259; P � 0.001), September (t � �6.704; df �
46; P � 0.001), October (t � 0.003; df � 46; P � 0.001),
November (t � �4.554; df � 46; P � 0.001), and
December (t � �4.354; df � 46; P � 0.001; Fig. 3). In
February (t � 12.647; df � 37.302; P � 0.001), March
(t�7.278; df�46;P�0.001), andMay(t�4.174; df�
46; P � 0.001) they preferred carbohydrate-based
foods (Fig. 4).

This preference for different food sources during
the year is probably owing to the nutritional require-
ments of the colony. According to Fowler et al. (1991)
and Parra (1991), the standard food of ants basically
consists of proteins, carbohydrates, and lipids. Pro-
teins are acquired frompredation on other insects and
small invertebrates, carbohydrates from the ingestion
of sugars andpolysaccharides fromthenectarofplants
and the excretions of other insects, and lipids from the
ingestion of different types of oil.

Carbohydrate-rich foods are an important source of
energy for workers (Markin 1970, Abbott 1978, Stra-
dling 1978, Grover et al. 2007), and acquisition of this

type of food is indispensable for the maintenance of
the entire colony (Glancey et al. 1981, Tobin 1994,
Helms and Vinson 2008). A protein-rich diet is essen-
tial for the development of the larvae and higher egg
production by the queen (Markin 1970, Abbott 1978,
Stradling 1978, Rust et al. 2000). Consequently, high-
protein food is gathered in higher proportions in the
period when the colony needs to increase egg pro-
duction, thus increasing the population size of the
colony (Dussutour and Simpson 2009).

Nondillo (2013) found that larvae in L. micans col-
onies are produced mainly from April through Octo-
ber, corresponding to the period when the collection
of protein food increased. These results concord with
those foundbyRust et al. (2000)andAbril et al. (2007)
for L. humile colonies.

The development of efÞcient baits to control ants is
a challenging task (Hooper-Bui and Rust et al. 2000,
Silverman and Brightwell 2008). In the case of L.
micans, better results would be obtained by the use of
protein matrices during the winter, when the colony
needs protein-rich foods to feed the large numbers of
larvae(Nondillo 2013).With increasing temperatures,
the number of ants in the population increases and
oviposition begins (Nondillo 2013), as a consequence

Fig. 3. Monthly mean foraging activity of L. micans (bars), temperature (continuous line), and air relative humidity
(dotted line) in a greenhouse.

Fig. 4. Ratio of workers of L. micans feeding on inverted sugar and Gryllus sp. *, signiÞcant at 5% probability by the
t-test.

August 2014 NONDILLO ET AL.: FORAGING OF Linepithema micans 1389



the, workers require more food, and carbohydrate-
based foods could be offered in the warmer seasons.

Acknowledgments

The authors thank the Conselho Nacional de Desenvol-
vimento CientṍÞco e Tecnológico (CNPq) for Þnancial sup-
port and the award of a scholarship, and FAPERGS (Funda-
ção de Amparo à Pesquisa do Estado do Rio Grande do Sul).

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Received 10 September 2013; accepted 18 April 2014.

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