Memórias do Instituto Oswaldo Cruz Fundação Oswaldo Cruz, Fiocruz ISSN: 1678-8060 EISSN: 1678-8060 Vol. 90, Num. 4, 1995, pp. 487-488

Morphology of Abdominal Bristles Determined by Scanning Electron Microscopy in Six Species of Triatominae (Hemiptera, Reduviidae)

Joao Aristeu da Rosa, Jose Maria Soares Barata*, Nilso Barelli**

Faculdade de CiEncias FarmacEuticas, UNESP, Caixa Postal 502, 14801-902 Araraquara, SP, Brasil *Faculdade de Saude Publica, USP, Av. Dr. Arnaldo 715, 01246-904 Sao Paulo, SP, Brasil **Instituto de Quimica, UNESP, R. Prof. Francisco Degne, s/n , 14800-900 Araraquara, SP, Brasil

Code Number: OC95095
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The bristles of Triatominae are taxonomically valuable elements which may vary among species in outer appearance, i.e., shape, density, length, thickness and mode of implantation.

With respect to the systematic value of bristles several reports have been published (Lent, Wygodzinsky 1979 Bull Am Mus Nat Hist 163: 123-520, Mc Iver, Siemicky 1984 J Morphol 180: 19-28, Goncalves et al. 1985 Mem Inst Oswaldo Cruz 80: 263-276).

The present morphological study of the ventral abdominal bristles of six species of Triatominae using 5th instar nymphs and scanning electron microscopy (SEM) confirmed the systematic importance of this structure, since the predominant bristles of each species were different.

The 5th instar nymphs of triatomines used in the present study were obtained from colonies maintained in the insectary of the Department of Epidemiology, Public Health College, University of Sao Paulo, Special Health Service in Araraquara. The species studied were Panstrongylus megistus (Burmeister, 1835); Rhodnius neglectus Lent, 1954; Triatoma brasiliensis Neiva, 1911; Triatoma infestans (Klug, 1834); Triatoma matogrossensis Leite and Barbosa, 1953, and Triatoma tibiamaculata (Pinto, 1926).

The specimens were examined with a SEM JEOL model JSM-P15 and JSM-T330A by the method described by Rosa et al. (1992 Mem Inst Oswaldo Cruz 87: 257-64).

The predominant ventral abdominal bristles of 5th instar nymphs of six species of Triatominae presented differentiated shapes. P. megistus have spiniform bristles implanted into tubercles, each bristle presenting spines at different points in the posterior 2/3 (Fig. 1) and frizzled and barbed bristles implanted in raised tubercles shaped like small volcanoes, located on the connexivum (Fig. 2). R. neglectus have claviform and dentate bristles in the posterior half, implanted in circular alveolo which are inserted in prominent oval tubercles recalling an American football in shape (Fig. 3). T. brasiliensis have frizzled and serrate bristles implanted into alveolar tubercles (Fig. 4). The bristles are frizzled in the beginning and serrate on the posterior end (Fig. 4). T. infestans have frizzled and serrate bristles implanted into alveolar tubercles (Fig. 5). T. matogrossensis have frizzled and serrate curved bristles finer in the initial portion, becoming thicker in the subintermediate portion and ending in a thin point and implanted in alveolo (Fig. 6). T. tibiamaculata have grooved, barbed and curved bristles (Fig. 7).

The six species presented smooth bristles on the central portion of the eighth segment and on connexivum always in small numbers (Figs 1, 2, 7). Similar bristles were also detected by Costa et al. (1991 Mem Inst Oswaldo Cruz 86: 247-263) in the antennal segments of Cavernicola lenti.

The 8th abdominal segment of P. megistus and T. tibiamaculata presented frizzled bristles of similar shape, location and number (2) (Figs 1, 7). Costa et al. (loc. cit.) have detected similar bristles in C. lenti.

P. megistus presented four types of bristles (Figs 1, 2). T. tibiamaculata presented three types of bristles (Fig. 7). R. neglectus, T. brasiliensis, T. infestans and T. matogrossensis presented two types of bristles.

The others caracteristics shared by the six species were the presence of pores and spiniform structures in the 9th segment (Figs 2-8).

Acknowledgements: to Bento Gregorio de Jesus and Joao Luis Molina Gil from Special Health Service in Araraquara. To Aparecida Bernardete Rocateli Jesus and Solange Maria Torres for typing the manuscript.

Figures 1 - 8

Copyright 1995 Fundacao Oswaldo Cruz

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