Phytophagous insects associated with endemic, macaronesian, and exotic plants in the Azores

AVANCES EN ENTO MOLOGiA IsfRlcA, 1995, págs. 179-188

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L. SIL 'A J. TAVARES

Abstract: A survey of Myrica faya Aiton (Myricaceae) natural enemies, was per­ form.ed fra m. 1991 to 1993, in order to f1nd potential biocontrol agents for that plant, an ibero-macaronesian endemic, considered as a noxious weed in Hawaii. Samples were collected weekly at two sites in São Miguel, and complementary at São Jorge, Faial, Pico and Terceira islands (Azores). Since 1992, the survey was extended to include phytophagous insects associared wi th the other dominant trees at l\1yrica faya stands: Erica scoparia ssp. azo rica (Hochstetrer) (Ericaceae) an endemic, and Pittosporum unduLatum Ventenat (Pinosporaceae) an exotic planr. Only 20 species of phyrophagous inseCLs were found: two Hereroptera, ten Homoprera, one Thysa­ noptera, two Coleoptcra and five Lepidoptera. M. foya and E. scoparia ssp. azorica

support the life-cycle of four endemic insecrs. P. unduLatum is an occasional shelter for some insects. A correspondence analysis c1early separated the rhree plants, on the basis of rheir associared phytophagous insects.

Insectos fitófagos associados a plantas endémicas, macaronésicas e exóú cas, nos Açores.

Resumo: Emre 1991 e 1992, realizou-se a prospecção dos inimigos na rurais de Myrica fo)'a Aiton (Myricaceae), um endemismo ibero-macaronésico, considerado como uma infestante nociva, no Hawaii. A amostragem foi semanal, em dois locais da ilha de São Miguel.. Efectuaram-se amostras complementares nas ilhas de São Jorge, Faial, Pico e Terceira (Açores). A partir de 1992, estudatam-se igualmente os insectos firófagos associados a duas plantas abundantes nos biótopos de M. foya: Erica scoparia ssp. azorica (Hochstetrer) (Ericaceae) um endemismo, e Pittosporum unduúttum Ventenarr (Pittosporaceae) uma exótica. Encontraram-se 20 espécies de insectos fitófagos: dois Hereroptera, dez Homoptera, um Thysanoprera, dois Coleoptera, e cinco Lepidoprera. M. foya e E. scoparia ssp. azorica suportam o ciclo de vida de quarro insectos endémicos. P unduLatum funciona como abrigo ocasional para alguns insectos. Uma análise de correspondências separa as três plantas, com base nos insectos firófagos associados a cada uma.

INTRODUCTION

Myrica faya Aiton (Myricaceae) is a small tree or shrub that is considered an ibero-macaronesian endemic (QUEIRÓS, 1987). The pIant was inrroduced to

180 L. Silva y J Tavares

Hawaii by the end of the last scentury, and in the 1950's it was already considered a noxious weed, invading pastures, rangelands and the natural ecosystems ofHawaii (YAMAYOSHY, 1954; VITOUSEK et aI., 1987). On the other hand, in its natural habitat, namely in the Azores islands, M. foya disrribution is decreasing, as a consequence of human activities and after the inuoduction of

Pittosporum undulatum Vemenat (Pitrosporaceae) (DROUET, 1866; SJOGREN,

1984; QUEIROS, 1987).

A survey for the natural enemies of the piant was initiated in order to nnd potemial, biocontrol agents (KAAuss, 1964; H ODGES & GARDNER, 1985;

GARDNER et aI. 1988; MARKlN, 1990; MARK:rN et ai., in press). ln 1991, a survey was started in the Azores, but since Erica scoparia ssp. azorica (Hochsterrer) ( ricaceae), an endemic, and P undulatum, were also dominating the vegetation

in that area, we decided to extend our sampling program to those planrs.

ln the present work the phytophagous insects associated with each of those

plants are compared, and those foundin Myrica foya are evaluated as potemial biological control agenrs. Consequences of a further spread of the exoric pIam on the community of phytophagous insects are discussed.

METHODS

Sampling was performed weekly, at two places at São Miguel lsland (Azores): Lombadas (550 m) and Pico das Camarinhas (150 m). C omplemen­ tary, sampIes were taken at orher iocarions in São Miguel island and ar the islands of São Jorge, Faial, Pico and Terceira.

Insects were collected by:

bearing in the foliage, and collecring the falling insects with an entomological ner (bearing in 100 branches, per plant species);

cutting terminal shoots with flower, fruit or leaf damage (30 shoors per piam species).

lnsects were moumed or preserved in 75% ethanol, and sem for idemincation. Species were sorted in categories, depending on their total abundance alI arround rhe year, namely: O) absent; 1) log(total number) ~1; 2) log(total number) ~ 2; and 3) log(toral number) >2.

Where possible, insect degree of host specincity was analysed, or checked in the literature.

A correspondence analysis was performed for the three plants at the two si­ tes in São M iguel, using the abundances of the various species as variables.

181 Phytophagous insects associated with endemic, macaronesian ..

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O nly twenty species of phytophagous insects were found (Table 1): two Heteroptera, ten Homoptera (one endemic), one Thysanoptera, two Coleoptera

and five Lepidoptera (three endemic).

Table I

Phytophagous insects associated with an exotic (Pittosporum undulatum), a macaronesian (Myrica foya) and an endemic pJant (Erica scoparia ssp. azorica) at twO sites in São Miguel Island, Azores:

Lombadas (550 m) -L; and Pico das Camarinhas (150 ro) -C. Data was

coUected from Octobcr 1992 until Ocrober 1993. Complementary, sampling was performed at other sites at São Miguel, São Jorge, Faial, Pico and Terceira Islands.

*Breeding population

Host Piam

Erica scoparia Myrica Pittosporum ssp. azo rica foya undulatum Insect L

c

L

c

L

c

HETEROPTERA Miridae Orthops sp. Lygaeidae

KLeydoce ris truncatuLus (Walker) 2* 2 2 2

HOMOPTERA

Cercopidae

Philaenus spumarius Linnaeus C ixiidae

Cixius insularis Lindberg 2 2

F1aridae

Cyphopterum sp. Apbididae

Aphis gossypii Glover

o

o

Pico*

o

o

PsylJidae

Strophingia harteni Hodkinson 1* 2*

o

O O O

Trioza alacris Flor l

Coccidae

Ceroplastes sinensis (Dei Guercio) O O Lagoa* O O

Diaspididae

ChrysomphaLus sp. 2 2 O O

Margarodidae

lcerya purchasy (Maskell) O O

Pseudococcidae

182 L. Silva yj. Tavam

H osr Planr

Erica scoparia Myrica Pittosporum ssp. azo rica faya undufatttm Insect

L C L C L C

THYSANOPTERA

T hripidae

Hefiothrips haemorroicfalis Bouche 2* O O

COLEOPTERA Niridulidae

Afeligethes aeneus (Fabricius) 2 O O

Anaspidae

Anaspis proteus Wollasron

LEPIDOPTERA

Yponomeuridae

Argyresthia atlanticefa Rebel 3* 3* 3* 3' O O Gracillariidae

Calaptilia atlranfiaca (Wollasron) O O O 2 O O Geomerridae

AseatiJ flrtunata azarica Pinker 2* 3* 3* 3* 1

G"ymnoseelis rufifasciata (Hawonh) O O Lagoa* O O

Cyelapha ra azaremis (Prour) 3* 3* O O O O

Spcc:ic-s wcre sorted in c:I[t"gorics. depending of rheir annual abundanc...e, n3nldy: O) abscnr; I} log(tmal number) 5.1; 2) log(lOral numbcr) S 2; and 3) lo)«toral l1umbcr) > 2.

Erica scoparia SSp. azorica supports the complete life-cycle of Kleydoceris

truncatulus (Walker) (HeteIOptera, Lygaeidae), Strophingia harteni Hodkinson

(Homoptera, Psyllidae), Argyresthia atlanticella Rebel (Lepidoptera, Ypono­

meuridae), Ascotis fortunata azorica Pinker (Lepidoptera, Geometridae) and

CjJclophora azorensis (PIOur) (Lepidoptera, Geometridae). Myrica foya supports

the life-cycles of Ceroplastes sinensis (DeI Guercio) (Homoptera, Coccidae),

Heliothrips haemorroidalis Bouche (Thysanoptera, Thripidae), Argyresthia atlan­

ticella, Caloptilia aurantiaca (Wollaston) (Lepidoptera, G racillariidae) and

Ascotis fortunata azorica, but the first (wo insects as well as Gymnoscelis rufifos­

ciata (Haworth) (Lepidoptera, Geometridae), are rarely found on thar plant.

Active populations of Chrysomphalus sp. (H omoptera, Diaspididae) and Pseudo­

coccus sp. (Homoptera, Pseudococcidae) were also found on M. foya. T he other insects were pIObably only using Myrica and Erica as shelter and not as a pri­ mary host.

As regards P undulatum, we have found very reduced feeding damage cau­ sed by insects, and we suspect that this piam, in the Azores lslands, is only an occasional shelter for some insect species.

-1

183

Phytophagous insects associated with endemic, macaronesian..

i

a LI /\Ii Th PI G2 -1

Figure 1. Correspondence ana.lysis. Simwtaneous projeclÍon of the variables (insects abundan­ ce) and objects (differem plants at two differem sites). Data based on the abundances of differem species oE phytophagous insects, over three pIam species at tWO sires in São Miguel Island, Azares.

Pc. Pittosporum unduLatum at Pico das Camarinhas PL. Pittosporum undu/atum at Lombadas

EC. Eriea seoparia ssp. azo rica at Pico das Camarinhas

EL. Eriea seoparia ssp. azorica at Lombadas

MC. M)'riea foya at Pico das Camarinhas ML. Myriea foya at Lombadas

Li -Lidgaeidae, Ci - Cixiidae, Ps -Psyllidae, Ma -Margarodidae, Di - Diaspididae, Ni -Nitidulidae, Th - Thrypidae, Gl & G2 - Geometridae, Yp - Yponomeutidae, Gc ­ G racillari idae.

A correspondence analysis on rhe data collecred ar two sires in São M iguel (Figure 1), clearly separared the rhree planrs, on the basis of rheir associated phy­ tophagous insecrs. The first axis, separares M. faya from E. scoparia ssp. azo rica,

and the second separates rhese two planrs from P undulatum. T he main diffe­ rence bctween M . faya and E. scoparia ssp. azo rica is rheir association with

Caloptilia aurantiaca and Cyclophora azorensis, respectively.

DISCUSSION

Ascotis fortunata azo rica, an endemic defoliator, is a polyphagous species (SILVÂ, 1992), feeding on M. faya and E. scoparia ssp. azo rica, as well as on orher pianr species, namely: Myrsine africana L. (Myrsinaceae), Viburnum tim.is

spp. subcordatum (Trel.) Padre Silva (Caprifoiiaceae) and Ligustrum henryi

Hemsley (O leaceae). First insrars cause only light scarificarion on rhe leaves, but

lasr instars originare large feeding damage during summer monms. Larvae are also abundanr over E. scoparia ssp. azo rica.

184 L. Silva y j. Tavares

(G RDNER et ai., 1988), and green fruits, but aIso of

E.

scoparia ssp. azorica and

Vaccinium cyLindraceum Smathers in Rees (Ericaceae) flowers and leaves.

Starvation tests showed that this insect is polyphagous (SILVA et aI., in prep.). ln multiple choice oviposition tests, the insect prefered

E.

scoparia ssp. azo rica, whi­

le M. faya, Cafluna vulgaris (L.) (Ericaceae) and Vaccinium cyLindraceum, were not so frequently se/ected as oviposition sites, and Juniperus brevifoLia (Seubert) An oine (Cupressaceae), Pofygonum capitatum D. Don (Polygonaceae) and

Myrsine africana were only rarely selected (SILVA, et aI., in prep.). First instar lar­

vae developed tO the adult stage feeding of M. faya flowers and green fruits,

E.

scoparia ssp. azorica flowers and leaves, V cylindraceum flowers and leaves, and P capitatum flowers. First instars search for a flower or a leaf tO mine. Last instars

feed from the oLltside. Larvae are found ali arround the year ove r Erica scoparia

ssp. azo rica, but also during Myrica faya, Vaccinium cy/indraceum and CaLLuna vulgaris flowering periods.

Cycfophora azorensis brst instar larvae were tested (unpublished data) usi ng Erica scoparia spp. azorica, Cafluna vuLgaris, Vaccinium cyLindraceum, Myrica faya, Myrsine africana, Viburnum tinus ssp. subcordatum, Pittosporum unduLatum, Laurus azorica (Seub.) Franco (Lauraceae), and I1ex perado sp. azorica (Loes.)

Tutin (Aquifoliaceae). Larvae only survived and dcveloped on Erica scoparia ssp.

azorica. he ocher tested planrs did not allowed survivaJ beyond three days, and

larvae never reached second instar. Only Erica scoparia spp. azorica (Ericaceae) was a suitable hosc, supporting the !ife cycle of the insecto Larvae feed on flovver buds and leaves, and are abundam ali arround the year. ln oviposition tests, Erica was clearly prefered tO Myrica, with a tOtal of 279 and 13 eggs, respecti­ velly.

CaloptiLia aurantiaca is a leaf-miner that was released in H awaii (MARK.IN,

1990). Ir was brst erroneously identibed as PhyLLonorycter myricae Deschka (Lepidoptera, Gracillariidae). T hi insect was found associated with Myrica faya and Hypericum jofiosum Airon (Hypericaceae). First instars mine M. faya leaves,

but similar mines were found on Hypericum joLiosum in Terceira and São M iguel Island . Last instar larvae leave the mine and roll the tip of the leaf, creating a chamber where they pupate. Two spe ies are known for the Azares (CARVALHO,

1982), CaLoptiLia aurantiacaand Caloptifia bistrigeLLa (Rebel). CaLoptilia schinel/a Walsingham from Madeira (AGUIAR, 1993) is a polyphagous insect that also fe­ eds 011 Myrica faya.

Gymnoscelis rufifasciata feeds on Cynara carduncuLus L. (Asteraceae) flowers

and is considered as a p st in Egypt (SADDIK & EL-MINIAWI, 1978). ln the Azores this species was found on Laurus azo rica and Myrica faya flowers. T his

species was considered as a pest of various crops (HARAKLY & ASSEM, 1978). Kleidocerys truncatuLus was collected at Lombadas and Pico das Camarinhas,

185

Phytophagous imects associated with endemic, macaronesian ..

Palearctic region. ln England it is associated wíeh Eriea sp.. It probably feeds on seeds or mature fruits. ln the Azores many specímens were found ín Eriea seopa­

ria ssp azoriea, but also in Juniperus brevifolia and Pittosporum undulatum.

Kleidoeerys resedae Pam. in France (VILLIERS, 1977) and Kleidoeerys truneatulus

erieae Horvarth in Madeira are found ín Eriea spp. (AGUIAR, 1993) . T his insect

is noe speciflc to Myriea faya.

Cixius insularis Lindberg (Homopeera, Cixiidae) an endemic, was found sin­ ce March mainly in spring and summer, bu( also in Eriea seoparia ssp. azoriea

and Juniperus brevifolia, including where no M. faya exists (Caldeira, Faial). Cixiidae nymphes are found in soil where ehey feed on the roots of the host. Adults feed on various host specíes. Cixius nervosus L. and C. pilosus 0 1. are com­ mon in France where they have several hosts (VI LLIERS, 1977). AGUIAR (1993)

has found Cyxius vertiealis Noualhier in M. faya on M adeira.

T he remaining species (Table 1) are known to be polyphagous or peses.

The azorean encomofauna is relatively poor in number of species and ende­

mics (OROMI, 1982; QUARTAU, 1982; MENDES, 1982; MACHADO, 1982;

ILHARCO, 1982; BAEZ, 1982; BORGES, 1990; VIEIRA & PINTUREAU, 1991).

Argyresthia atlantieella, Aseotis fortunata azoriea and Cyc!ophora azorensis are azo­

rean endemics. O n the other hand, Pittosporum undulatum is not a suitable host for these and other species of insects, present in Myriea-Eriea stands. Myriea­

Eriea stands in che Azores islands are endangered by human activities and by the

spread of exotic species, namely Pittosporum undulatum (DROUET, 1866;

S]OGREN, 1984; Q UEIROS, 1987). Further spread of the exotic plant, an unsui­ table host for several phytophagous insects supported by Myriea faya and Eriea seoparia ssp. azoriea, will affect not only the flora but aIso the entomofauna.

CONCLUSION

O f the lepidoptera found none is specific to Myriea faya. O n the other

hand, we can conclude that lepidoptera are important phytophagous in Myriea­ Eriea stands in lhe Azores Islands. No other species of insects specific to Myriea

faya were found in the Azores, so that, no more species will be sent to Hawaii as

biocontrol agents.

Since Caloptilia aurantiaea is not specifie to Myriea faya no fu nher intro­ ductions of this inseet should be allowed in H awaii.

If we are to preserve the natural eeosystems of the Azores, it does nOt suffi­ ce ro preserve che native flora, but also the associated entomofauna, and the

trophic relationships that characterize those ecosystems. To achieve that goal,

186 L. Silva y j. Tavares

ACKNOWLEDGEMENT

S

T hanks are due to Passos de Carvalho (Estação Agronómica Nacional, O eiras, Portugal), H. Shanderl, A. O nofre, and P. Borges ( niversidade dos

Açores, Portugal), and to the taxonomists of the Imernational Instirute of Emomology (London, UK), for the identification of various insects.

Als

o

to

V Vieira (Universidade dos Açores) for his sciencific and technical suppore.

To Clifford Smith (University of Hawaii) and George Markin (Forest-Service)

for their support and advice. To Fernando Almeida and José Viveiros for their

supporr in field-work. This work was partly supporred by the Coopera tive

National Park Resources Srudies Unit, Botany Deparement, University of

Hawaii.

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