THE PREY AND PREDATORS OF LOXOSCELES INTERMEDIA MELLO-LEITÃO 1934 (ARANEAE, SICARIIDAE)

2006·3.9 MB·English

by  Marta L Fischer

2006. The Journal of Arachnology 34:485-488
SHORT COMMUNICATION
THE PREY AND PREDATORS OF LOXOSCELES INTERMEDIA
MELLO-LEITAO 1934 (ARANEAE, SICARHDAE)
Marta L. Fischer: Departamento de Biologia, Centro de Ciencias Biologicas e da
Saude, Pontificia Universidade Catolica do Parana, Nucleo de Estudos do
Comportamento Animal, Av. Silva Jardim, 1664/1101, CEP 80250-200, Curitiba,
Parana, Brazil. E-mail: [email protected]
Joao Vasconcellos-Neto: Departamento de Zoologia, Instituto de Biologia-
Universidade Estadual de Campinas, UNICAMP, C.R 6109, Campinas, Sao Paulo,
Brazil. CEP 13083-970, Brazil.
Lms Gonzaga dos Santos Neto: Departamento de Zoologia-Curso de Pos-Graduagao
em Entomologia-Universidade Federal do Parana, Brazil.
ABSTRACT. We examined the prey caught in L. intermedia webs in one fragment offorest and in the
garage of an urban house in Curitiba, Brazil. A total of 693 prey items was recorded in 131 webs. The
prey richness was greater in the forest. The results show that L. intermedia is a dietary generalist. We
found remains ofL. intermedia in the feces of a frog and a bat in the forest.
Keywords: Diet, brown spider, synanthropic fauna, loxoscelism, Brazil, frog, bat
The sedentary species of the genus Loxosceles same microhabitat in one fragment offorest and in
are hunting and weaving spiders active mostly at a house in Curitiba.
night. The webs of some species in this genus are We made weekly visits from December 1993 to
durable, large, irregular and sticky, with the spiders March 1995 to a forest located in the Santa Monica
constantly adding silk threads to the web, which field club, in the district ofColombo (25°23'22.9"S,
serves as a retreat and a snare. The webs are built 49°09'01.3"W). The area is up to 950 meters above
in a great variety of habitats, including around sea level and the climate is humid subtropical me-
buildings that provide many ideal microhabitats sothermic, with fresh summers and with severe and
(Bucherl 1961; Hite et al. 1966; Galiano 1967). frequentfrosts (Maack 1981). The native vegetation
Loxosceles spiders can capture prey in their web or was transitional between forest with Araucaria and
when walking around at night (Gorham 1968). Atlantic forest, now replaced in some areas with
Q((uNLaiulccioatlsaett1i8v13e943)l2i)s(tDs(eLolefgvaitdho&e1Sp9rp6ei6y)e,lcmLaa.pntrue1rc9el6ud4s)ab,yGLe.Lr.trsulcfaihepte&as Eoaruneceaa.loyfIpnttithuiesa.lflryT,ahgwemeenptsrseesa(ern1ct6h.e2ds4tfuhodary)Lwcoalxosossecceatlroreiasecdianomaupltlinoigfn
Mulaik 1940 (Hite et al. 1966) and L. gaucho
the trees (native and exotic) present in the fragment
Gertsch 1967 (Rinaldi et al. 1997) have been pub-
but spiders were present only in five of 20 Euca-
lished.
In Curitiba, capital ofthe southern Brazilianstate lyptus trees planted at the border ofthe forest frag-
of Parana, hundreds of bites caused by Loxosceles ment. The vegetation around the Eucalyptus was
species are registered each year. Two species occur essentially grass and small herbaceous plants.
in the city: L. intermedia Mello-Leitao 1934 (with Webs containing the remains of prey present in
90% of records) and L. laeta with 10% (Fischer holes, hollows and bark peels from five Eucalyptus
m
1994). Among the conditions favoring the growth (up to 7 above ground level) and the fauna pres-
ofLoxosceles populations in and around urban cen- ent in the same places, were sampled. Loxosceles
ters are the abundance and richness ofprey and the intermedia webs consist of a central area with a
absence of potential predators. In this study, we larger concentration of silk from which radiate ir-
documented the range of prey captured in L. inter- regular sticky threads of varying thickness. The
media webs and recorded the fauna present in the webs cover the surface where the spiders live. The
485
486 THE JOURNAL OF ARACHNOLOGY
form and size ofthe webs depend on the substratum cidae), as well as chemically noxious taxa such as
on which the web is built. Chrysomelidae, Pentatomidae, Opiliones, Heterop-
Abandoned webs with remains offood were col- teraand Staphylinidae. Thecaptureofheavily scler-
lected and prey items were removed with forceps otized or dangerous prey has been recordedforoth-
from webs with the spider present. We did not dis- er species of Loxosceles (L. laeta: Levi &
tinguish webs of adults and juveniles, nor if the Spielmann 1964; L. reclusa: Hite et al. 1966). Ac-
spider present in the web was the same in succes- cording to Riechert & Harp (1987), the degree to
sive samples. We considered as associatedfaunathe which potentially injurious or large prey are taken
animals present in the same microhabitat as L. in- varies with local prey abundance and the relative
termedia webs; these animals were collected availability of different prey types. In the present
through visual search and with the use of forceps study, Corinnidae, Salticidae and Opiliones were
and fixed in 70% alcohol. The identity of animals captured in a period of low resource availability,
that we could not collect was recorded. The mate- i.e. at a time when no other prey were found in the
rial is deposited in the Arachnological collection of webs.
Dra. Vera Regina von Eicksted in the section of Cannibalism was recorded once in the forest for
poisonous arthropods ofthe Imunologic Production a female spider that ate a juvenile. We also found
and Research Center (SESA-PR), Piraquara, Para- a dead female without an abdomen in an L. inter-
na, Brazil. media web. This spiderappearedtohavebeeneaten
In the urban building, visits were undertaken ev- by a conspecific. No cannibalism or dead spiders
ery 15 days to the garage of a masonry house lo- occurred in L. intermedia webs in the building.
cated within the urban perimeter of Curitiba Ofthe 36 invertebrate groups {n = 1427 animals)
(25°23'28.3"S, 49°17'28.2"W). The spiders were collected alive near the webs of L. intermedia, 22
present in a pile of lumber of 100 cm height, 200 were exclusive to theforest, 14werepresentinboth
cm width and 40 cm depth, placed against a wall. habitats, and none was exclusive to the building.
The method of collection of the prey and of the Pholcidae, Salticidae, Selenopidae and Theridiidae
associated fauna was the same as that used in the were the most frequent Araneae families. Even so,
trees. only Corinnidae and Salticidae occurred as prey in
During the study period we sampled 91 webs in the webs. When the amountoffood was high (iden-
the forest and 40 in the garage. The webs of Lox- tified by the presence of many prey in the webs),
osceles species capture a wide range ofinvertebrate L. intermedia shared the microhabitat with other
prey, with the range ofpotential prey groups in the Arachnidabutdid notusethem as prey. The spiders
forest being greater than in the building. Ofthe 55 Selenopidae and Eusparassidae, although frequent
prey groups sampled, 27 (49%) were exclusive to in the trees, were not found in L. intermedia webs
the forest, 3 (5.4%) were exclusive to the building, (Table 1). The fauna associated with the wood
and 25 (45%) occurred in both habitats (Table 1). dumps in the garage was less diversified than that
The greater prey richness in the forest (x^d) = 6.2, in the trees. Of the invertebrate groups recorded
P < 0.01) reflected the larger variety of microhab- alive, only lepidopteran larvae were not found in
itats, and the greaterdiversity, abundance and prox- the webs. As in the forest, the Araneaefamilies Sal-
imity of vegetation, although the Sorensen similar- ticidae, Pholcidae and Araneidae were abundant
ity index of the prey captured in the building and (Table 1).
in the forest was rather high (0.64). Thus, spiders In the forest, two vertebrates were confirmed as
that colonized the building did not have access to predators of L. intermedia: Sinax gr. rubra (Am-
the same prey richness, but more than 50% of the phibia, Hylidae) and the bat Eptesicus brasiliensis
prey was similar to the prey in the forest. (Mammalia, Vespertilionidae). The identification
The 693 prey items found in L. intermedia webs was based on analysis of fecal pellets, which con-
represented five invertebrate groups, Insecta being tained fragments of exoskeleton. The presence of
the dominant group in both habitats (Table 1). Levi amphibians (Leptodactylinae), lizards (Squamata)
& Spielmann (1964) reported that virtually all Ar- and six nests of a bird (insect predator) found in
thropoda that occurred in a basement site were rep- the hollows of Eucalyptus, suggested that these
resented in the webs of L. laeta. Likewise, for L. could also be potential predators (Table 1). Foelix
intermedia, only nine higher taxa in the forest and (1996) considered amphibians andreptiles tobeim-
one in the building were not recorded in the webs portant spider predators. Delgado (1966) recorded
(Table 1). This demonstrates a low selectivity ofthe the gecko Tapidurusperuvianus as a predator ofL.
L. intermedia web. rufipes in Peru. There arefew mammalian predators
The diet ofL. intermedia often contains taxa re- ofspiders, e.g., shrews and bats, although the South
jected by other spiders. For L. intermedia, we re- American woolly monkey Lagothrix apparently
corded the capture of groups considered to be an- prey on a poisonous Loxosceles with no adverse
tagonist enemies of spiders, including wasps effects (Foelix 1996). Two L. intermedia were ob-
(Pompilidae and Ichneumonidae) and ants (Formi- servedbeing eaten by ants (subfamily Myrmicinae).
FISCHER ET AL.~PREY OF LOXOSCELES INTERMEDIA 487
— —
Table 1. Number of prey items collected in L. Table 1. Continued.
intermedia webs and the associated fauna (AF, fau-
na collected in the same microhabitat as L. inter- Forest Building
media webs) in urban forest and in a building. Taxon Prey AF Prey AF
Numbers indicated at order level are the sums of — —
catches given at family level. Various Fragments 12 5
Diptera 39 —0 11 —0
Forest Building Acalyptradae 1 — 2 —
Taxon Prey AF Prey AF Anosopodidae 1 — —1 —
Asilidae 1 — — —
PLATYHELMINTHES — — — Bibionidae 7 — —
Turbelaria 6 Culicidae 1 — 1 —
ANNELIDA — — — Muscidae 3 — —2 —
Oligochaeta 1 Mycetophilidae 1 — — —
MOLLUSCA — — — Phoridae 3 — — —
Gastropoda 2 Phsychodidae 3 — — —
CRUSTACEA Sciaridae 3 — —
Isopoda 84 315 40 60 Stratiomydae 12 — —1 —
INSECTA — — — Tabanidae 1 — —
Thysanura —3 — — Tipulidae —2 — 2 —
Collembola I Various Fragments 2
Blattariae 7 —3 10 —2 MYRIAPODA — — —
Isoptera —3 1 Diplopoda —1 — —
Orthoptera — 2 5 4 Chilopoda 4
Gryllidae 2 5 4 ARACHNIDA — —
Hemiptera 7 —11 —2 —0 Opiliones 6 184 — —
Aradidae —2 — — — Pseudoescorpiones 1 24
Corimelaenidae — — — Araneae —4 438 —0 81
Cydnidae — —1 — Araneidae — 49 — —6
Miridae 1 — — Ctenidae — 14 —
Pentatomidae 1 1 — — Lycosidae — 10 — 1
Reduviidae 2 —10 — — Pholcidae — 46 — —27
Scutelleridae —1 — — Theridiidae 67 — —
Nymph —1 — Corinidae —2 3 — —
Homoptera 1 5 — — Eusparassidae 7 —
Cicadidae —1 5 — — Salticidae —1 156 — —47
Psocoptera 4 Selenopidae — 86 — —
Coleoptera —51 8 28 —1 Thomisidae 1
Carabidae —2 2 — CHORDATA — —
Cerambycidae 4 1 — Amphibia —2 6 — —
Chrysomelidae 12 —1 3 — Leptodactylidae — 2 — —
Curculionidae 1 — 1 Hylidae — 4 — —
Elateridae 3 — 5 —1 Reptilia — 1 — —
Lampyridae 1 Mammalia — 4 — —
Passalidae 3 — Vespertionidae 4
Scarabaeidae 1 —3 1 —
Scolytidae 3 — 1 —
Staphylinidae 3 —2 —
Tenebrionidae 1 —02 — However, it was not possible to determine whether
Various Fragments 20 11 the ants had killed these spiders or if the spiders
Hymenoptera 145 1—17 77 —52 had died from other causes. We have not detected
Apidae (Meliponinae) 6 — 1 — any potential predators (occasional or common) of
Braconidae 13 2 L. intermedia in residential areas of Curitiba.
Formicidae 93 —97 —69 —52 The results of this study indicate that L. inter-
Ichneumonidae 1 — — — media is a generalistfeeder that uses alow-cost sit-
Monomachidae 16 — — — and-wait predation strategy. The urban habitat pro-
Pompilidae 3 — — vides more than 50% ofthe prey types found in the
Vespidae 1 20 natural habitat, it has a lower density of other spi-
ders (Table 1) and a possible lack of natural ene-
488 THE JOURNAL OF ARACHNOLOGY
mies. All these factors probably contribute to the tion. Oxford University Press, New York. 330
persistence ofL. intermedia in urban areas. PP-
The authors thank Prof. Dr. Luis Amilton Foers- Galiano, M.E. 1967. Ciclo biologico y desarollo de
ter, Prof. Dr. Emygdio Monteiro and Dr. S0ren Toft Loxosceles laeta (Nicoltet, 1849). Acta Zoolo-
for their comments and help in preparing this man- gica Liloana 23:431-464.
uscript. To Prof. Msc. Joao Carlos Jascerski and to Gorham, R. 1968. The brown recluse spider. Jour-
biologists Iris Trochimczuk, Sergio A. Morato, nal of Environmental Health 31:138-143.
Moises B. de Sousa, Eloisa M. Wistuba, Teresa Hite, M.J., W.J Gladney, J.L Lancaster, Jr. & W.H.
CristinaC. Margarito, Ricardo PintodaRocha. This Witcomb. 1966. Biology of the brown recluse
paper was suported by Curso de Pos-Graduagao em spider. Arkansas Agriculture Experimental Sta-
Zwoaoslosguipap,orUtFedPRbyanadgCraAnPtEfSr.omJ.CVoanssceolnhcoelNlaocsi-oNneatlo Levtii,onH.BWul.le&tinA.71S:p2i-e2l6m.an. 1964. The biology and
de Desenvolvimento Cientifico e Tecnologico control of the South American brown spider,
(CNPq, grantn° 300539/94=0) andBIOTA/FAPESR Loxosceles laeta (Nicolet), in a North American
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