ON THE OCCURENCE OF GIANT MALES IN NANNOTRIGONA (SCAPTOTRIGONA) POSTIÇA LATREILLE (HYMENOPTERA, APIDAE, MELIPONINAE)

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1 Bolm. ZoolUniv. S. Paulo 8:11-16, 19ti4 ON THE OCCURENCE OF GIANT MALES IN NANNOTRIGONA (SCAPTOTRIGONA) POSTIÇA LATREILLE (HYMENOPTERA, APIDAE, MELIPONINAE) LUCI ROLANDI BEGO Departamento de Ecologia Geral, Instituto de Biociências, Universidade de São Paulo, Caixa Postal 11U61, Sio Paulo - SP CONCEIÇÃO APARECIDA DE CAMARGO Faculdade de Farmácia e Odontologia de Ribei rão Preto»Universidade de São P a u l o,ribeirão Preto, São Paulo, (recebido em ) RESUMO - Machos normais e gigantes de Nannotrigona (Scapto - trigona) postiça Latr. foram analisados, através de caracteres morfológicos e m o r f o m é t r i c o s. Os resultados demonstram que não há diferenças entre os mesmos^ exceto em tamanho. A produção de machos gigantes nesta espécie é um fato raro, comparado com outras espécies de Meliponinae. ABSTRACT - Morphological and morphometric characters of n o r mal and giants males of Nannotrigona (Scaptotrigona) postica Latr. were analyzed. The results show that there are no differences between them, except in size. The production of giant males in this species is a rare event compared with other Meliponinae. INTRODUCTION Queens in most Trigonini species are produced when larvae are fed more larval food than workers (C a m a r g o,1972) In Meliponini (M e l i p o n a ) the system of caste determination is a result of an interaction of larval food and genetics (Kerr, 1950, 1966; Kerr & Nielson, 1966; Kerr, Akahira & Camargo, 19 75) Nevertheless, other mechanisms which control the male and queen production by normal colonies are still not un - derstood (suitable conditions of the colonies, ethological factors, and so on) This paper is a by-product of our studies on social regulation in Nannotrigona (Scaptotrigona) postica. In the course of our research we noticed the presence of giant ma - les in normal and orphan colonies.

2 12 L.R. Bego & C.A. de Camavgo The aim is to report this fact based on morphometric and morphological characters, considering that this will be impor an for later studies on the biology of stingless bees, MATERIAL AND METHODS Several colonies of N. (S.) postioa were used for e x periments related to production of giant males "in vitro" The methodology used is reported by Camargo (1972) Other two colonies (normal and orphan) were kept in observation hives (Sakagami & Z u c c h i, 1963; S a k a g a m i, 1966) The morphometric characters were evalueted by some usual measures in Meliponinae bees: Eye length, maximal in - terorbital distance, Lower interorbital distance, Maximum head width, Mesoscutum length and width, length of fore wing partial - (distance between M-Cu bifurcation and basal tip of marginal cell), hind tibia length. The measurements of genitalia are shown in Fig 2 which are: genitalia width (total - a - and partial - b -) maximal length of gonocoxite - c -, lower length of gonocoxi width - f g nosty lus iength (partial) - e maximal valve From the mean of the measurements (x) taken from sampled specimens ( N ), the standart deviation ( S D ), the range of variation (RV), and the coefficient of variation (CV) were calculated, and are given in Table 1. * RESULTS Table 1 and Pigs. i ancj 2 show the comparisons of nor and giant males, stressing only the difference in thei? sizes. There are no distinctions in their external and inter nal morphology. Over two years of intensive observations inside nor - mal colonies and at nest entrances it was possible to detect only one giant male. Another case was found in the course of experiments on social regulation made in an orphan colony. i n * f ^ ng tlm? orphanage the workers built royal cells and laid eggs inside them. The usual behaviour of workers in such circunstance is to destroy the brood cell and start a n e w one. So, to avoid this the royal cell Sas re moved from the colony to an incubator at 28 C until ml ce of the giant male. L untl1 emergen DISCUSSION /c. Based upon the experiences acquired on behaviour N. (S.) poatzaa along many years, it was possible to veni? that the occurence of giant males in this species is a p + mely rare event, compared with some species of M e l i p o n i n J ^ - The production of giant males in stingless bees first reported by Nogueira-Neto (1951) Juliani (1967) shos! ed that colonies of Plebeia julianii were able to produ them. Imperatriz (1970) also observed the emergence of giant

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4 14 L.R. Bego & C.A. de Camargo Figure 1 - General morphology of normal (N) and giant(g) m a les of N. (S.) postiaa. Figure 2 - Genitalia of giant (A,B) and normal (C,D) of N. (S.) postiaa. (Dorsal and Ventral view) 1 - g o n o c o x i f tes; 2 - spatha; 3 - penis; 4 - valve; 5 - gonostylus. a h c, d, e, f = measures used *

5 Giant males in Nannotrigona postica 15 males from atypical brood cells in orphan colonies of Plebeia (Fviesella) sahrottkyi and royal cells in Paratrigona subnuda. In colonies of Geotrigona (Zucchi, personal informa - tion), Nannotrigona (N.) testaoeiaornis (Silva, 1973) and Plebeia remota, Plebeia emerina and Plebeia droryana, giant males are frequently produced (Imperatriz-Fonseca, 1976). Camillo (1971) evidenced the usual presence of giant males in normal colonies of Plebeia (Fviesella) sahrottkyi They appear in high frequencies when high densities of nor - mal males also occur. Imperatriz Fonseca (1976) expressed the possibility that giant males have an important biologycal role in the co lonies, since they can avoid a high production of queens which damage the colonies. Otherwise, Zucchi (personal infor mation) has suggested that giant males are produced as a result of normal males' production. The workers would not be able to distinguish royal from normal cells. As a consequence, giant males would take the place of queens. According to the same author, giant males would not have an important role in colonies of stingless bees. Bego (1977) observed that in N. (S.) post i c a, in spite of colonies always producing royal cells along the year the number of royal cells increases at the same period as that of male production, probably as a result of high popula tional density- The maximal number of royal and normal cells found were respectively 5 and It is possible that in N. (S.) postica giant males are rare, because of a low probability of workers laying eggs inside royal cells; thus they probably do not have any special role in the colony, being produced as an accidental e v e n t. REFERENCES BEGO, L.R Aspectos da regulação social em Nannotrigona (Scaptrigona) postica Latreille (Hynu, A p i d a e, Meliponinae) Tese de doutoramento. Depto.Genética, Fac.Med. R i b.p reto,usp, 180 pp. CAMARGO, C.A Determinação de castas em Scaptotrigona postica Latreille ( H y m., Apidae) Rev.Bras.Biol.,R;*Janei ro, 3 2 ( 1 ) : CAMILLO, C Estudos adicionais sobre zangões de Trigona (Fviesella) sahrottkyi Friese ( H y m., Apidae) Ciên. Cult., São Paulo, 23(Suplemento): 273. IMPERATRIZ, V.L.M Aparecimento de supermachos em Frie_ sella sahrottkyi (Apoidea, Apidae, Meliponinae) Ciên. Cult., S.Paulo, (Suplemento) 22(7):291. IMPERATRIZ- FONSECA, V.L Studies on Paratrigona subnuda (Moure) (Hym., Apidae, Meliponinae) I. Members of the colony. R e v.b r a s.e n t., São Paulo, 20( 2 ): J U L I A N I, L A descrição do ninho e alguns dados biológicos sobre a abelha Plebeia julianii Moure, 1962 (Hym., Apoidea). R e v.b r a s.e n t., S. Paulo, 72: KERR, W.E Genetic determination of castes in the ge - nus Melipona. Genetics 35:

6 16 L.R, Bego & C.A. de Camargo KERR, W.E Determinação de castas no gênero Melipona. Reunião Anual, S.B.G. Piracicaba, S.Paulo, B r a s i l :l- 5 KERR, W.E. & NIELSON, R.A Evidences that genetically determined Melipona queens can become workers. Genetics, Princeton, N.J., 54: KERR,W.E.; AKAHIRA. Y. & Camargo, C.A Sex determina - tion in bees. IV Genetic Control of juvenile Hormone pro duction in Melipona quadri fas d a t a (Apidae) Genetics, Princeton, N.J, 52: NOGUEIRA-NETO, P Stingless bees and their study. Bee World, Benson, 3 2 (10): S A K A G A M I, S.F Techniques for the observation of behaviour and social organization of stingless bees by using a special hive. P a p.a v.d e p t o.zool.s.paulo,b rasil,19: SAKAGAMI, S.F. & Z U C C H I, R Oviposition process in a stingless bee, Trigona (Scaptotrigjona) postica Latreille (Hym.). Studia Entomologica, P e t r õ p o l i s, R.J., 5(1-4) : SILVA, D.L.N Estudos bionômicos em colônias mistas de Meliponinae (Hym., Apoidea) Tese de doutoramento, Pac. F i l.ciên.l e t.rib.preto,s.p aulo, 144 pp.