Effects of piperonyl butoxide on the toxicity of the organophosphate temephos and the role of esterases in the insecticide resistance of Aedes aegypti

IntroductionThe effects of piperonyl butoxide (PBO) on the toxicity of the organophosphate temephos (TE) and the role of esterases in the resistance of Aedes aegypti to this insecticide were evaluated.MethodsA. aegypti L4 larvae susceptible and resistant to TE were pre-treated with PBO solutions in acetone at concentrations of 0.125, 0.25, 0.5, 1, and 2% for 24h and subsequently exposed to a diagnostic concentration of 0.02mg/L aqueous TE solution. The esterase activity of the larvae extracts pre-treated with varying PBO concentrations and exposed to TE for three time periods was determined.ResultsAt concentrations of 0.25, 0.5, 1, and 2%, PBO showed a significant synergistic effect with TE toxicity. High levels of esterase activity were associated with the survival of A. aegypti L4 larvae exposed to TE only.ConclusionsThe results of the biochemical assays suggest that PBO has a significant inhibitory effect on the total esterase activity in A. aegypti larvae.

Biology of amazonian mosquitoes. III. Esterase isozymes in Anopheles darlingi.

Six esterase isozymes were studied during the development of Anopheles darlingi by using polyacrylamide gel electrophoresis and two different substrates, a-naphthylcelate and a-naphthylpropionate. Esterases 5 and 6'were detected in all developmental stages esterases 1 and 2 were more intensively stained if larvae, while esterases 3 and 4 were better visualized in pupae and adults. Strong differences in intensity of some of the isozymes were observed during the pupal stage.Four out of the six isozymes showed variation in the electrophoretic mobility. Esterase-2 was choosed for genetic studies, because was the best stained isozyme in the gels. Two codominant alleles {Est2*S and Est2*F) code for this polymorphic system, with the Est*S frequency equal to 0.521. Phenotypic distribution is in agreement with hardy-Weinberg expectations.

Junça (Cyperus esculentus Linné), bulbilho consumido no Maranhão e que possui bom valor nutritivo.

Junça (Cyperus esculentus Linné), edible bulb of Maranhão that has good nutritional value. F. Marx, and W. E. Kerr.Bulbs of junça one sold in the streets oF Sao Luis, Ma, Brazil, as a delicacy. It has good nutritional value like: 6-10% protein, 6.95 to 9,32mg/lOOg of alpha-tocoferol, 1.20 to 2.52mg/100 of gama-tocoferol, 424.4mg/100g of K and 3,5mg/100g of Zn.Our samples had 1.4% glicose and 16.0% of saccharose. Literature is revised and this bulb is recommended for human consumption.

Espécies nectaríferas e poliníferas utilizadas pela abelha Melipona compressipes fasciculata (MELIPONINAE, APIDAE), no Maranhão

Este trabalho apresenta 79 espécies de plantas que fornecem néctar e/ou pólen para operárias de Melipona compressipes fasciculata, que é a abelha mais comum do Maranhão. A maioria dessas plantas s��o também visitadas por Apis mellifera. Sugere-se, com isso, o plantio de algumas espécies em estradas, cercas, ruas, avenidas e praças, a fim de melhorar a pasto apícola.

Enzimas e vitaminas do embrião e da amêndoa do babaçu

Analisou-se separadamente amêndoas e embriões de cocos de babaçu, (Orbignya martiana) para estudar algumas de suas enzimas e vitaminas tendo em vista seu maior consumo na alimentação. Detetou-se sistematicamente duas frações protéicas fortemente coradas e uma que aparece em algumas amostras e não aparece em outras. Das enzimas constatou-se três leucino-aminoptidase málicas (MDH1, MDH2, MDH3) e duas deidrogenase do glicerol -3-fosfato (GPD). Quanto às vitaminas constatou-se existir em 100 gramas de material: no embrião 0.100mg de riboflovina, 3,4 de vit. C e 30 de alfa-tocoferol; a amêndoa tem pouco menos da metade das vitaminas B1 e C.

Fenologia e produtividade do Abacate (Persea americana Mill.) na Amazônia Central1

O abacateiro (Persea americana Mill., Lauraceae) é nativo da Mesoamérica e chegou à Amazônia antes dos europeus. Acredita-se que a raça aqui introduzida foi a antilhana, similar a da maioria dos abacateiros pé-franco da Amazônia de hoje. Estudos de sua fenologia podem ajudar o planejamento de seu manejo e comercialização. A floração iniciou-se na segunda metade da estação chuvosa (março/abril) e durou até meados da estação de estiagem (agosto/setembro). As árvores produziram 25±15 mil flores em 1980 e 38±28 mil flores em 1981. A frutificação iniciou-se no final da estação chuvosa (maio/junho) e a safra ocorreu em plena estação de estiagem (agosto/outubro). As árvores produziram 634±299 frutos em 1980 e 1.054±456 frutos em 1981. O vingamento foi de 2,6±1,8%, menor que os valores na literatura. Os frutos pesaram 177,7±41,2 g na safra de 1980, com 51,1±4,5% de polpa. A produtividade, estimado em 112 kg/árvore em 1980 e 187 kg/árvore em 1981, foi abaixo da média de uma árvore bem manejada no sul do Brasil. As flores foram visitadas por oito espécies de abelhas, destacando-se Trigona branneri Ckll, Frieseomelitta sp. e Partamona pseudomusarum Camargo.

Mel Amargo de Breu (Protium sp., Burseraceae)

Foi analisada uma amostra de mel amargo procedente do Município de Mucajaí (Roraima, Brasil), Floresta de Apiaú. A análise polínica constatou a dominância de pólen de breu (Protium sp.) compreendendo 60,9% do total de grãos de pólen.

Substituição natural de rainhas fisogástricas e distância de vôo dos machos em Tiuba (Melipona compressipes fasciculata Smith, 1854) e Uruçu (Melipona scutellaris Latreille, 1811) (Apidae, Meliponini)

Este trabalho relata detalhes da vida reprodutiva de duas espécies de abelhas sem ferrão. Rainhas velhas de Melipona compressipes fasciculata, no Maranhão, morrem e s��o substituídas com sucesso em todos os meses. Rainhas de Melipona scutellaris, trazidas de Lençóis (BA - nordeste do Brasil) para Uberlândia (MG, centro-sudeste do Brasil) morreram durante todos os meses e não mostraram a existência de trimestre preferencial para as novas rainhas iniciarem postura. Quarenta machos de M. scutellaris, após serem marcados no tórax e libertados em grupos de 10 a 100, 400, 800 e 1000 metros do meliponário, tiveram seus retornos observados. Todos os machos libertados a 100 e 400 metros regressaram ao meliponário, 7 de 10 machos e 2 de 10 machos retornaram de 800 e 1000 metros, respectivamente. Os machos esperam constantemente pela saída de uma rainha virgem, próximos às colônias órfãs, o que indica que a maioria das rainhas é inseminada próximo aos seus ninhos, portanto, a dispers��o dos genes depende do vôo dos machos e da distância de enxameagem para ocupação de uma cavidade para o novo ninho.

Formação das castas no gênero Melípona (Illiger, 1806)

The present work is destinated to prove that the castes : workers and queens, in Melipona bees are due to genetic factors and not to differences in food. 2) Material used: Hives of Melipona quadri-fasciata anthidioides (Lep. 1836), M. schenki schenki (Gribodo, 1893), M. fasciata rufiventris (Lep. 1836), M. quadri-fasciata vicina (Lep. 1836), M. marginata marginata (Lep. 1836), Apis mellifera (L. 1758). 3) It should be pointed out that in Melipona bees there are no royal cells for the queens, but all the cells are of the same size independently of being destinated for workers, queens or drones. The numerous queens which are born are killed soon after emerging from their cells. 4) Changes of feeding in quality and in quantity caused no variation of castes. The only variable factor is the size, which becomes bigger when the bee is well nourished. 5) The offsprings of 5 hives were examined : 3 of M. quadri-fasciata anthidioides (n.o 1, n.o 2 and n.o 3), 1 of M. quadri-fasciata vicina (n.o 4) and 1 of M. marginata marginata (n.o 5). Combs of about 40 cells were taken into laboratory and the type of bee registered immediately after emerging. The results of the counts were: BOX COMB WORKER QUEEN PERCENTAGE Σ X2 to 12,5% Nº 1 1th 69 8 10,4% 0, 3139 " 1 2nd 144 18 11,1% 0, 2856 " 2 1th 52 8 13,3% 0, 0384 " 3 1th 45 10 18,2% 1, 6736 " 4 1th 56 4 6,7% 1, 8686 " 4 2nd 29 4 12,1% 0,00432 Σ X2 to 25% " 5 1th 34 14 29,2% 0,44444 "5 2nd 83 27 24,5% 0, 0121 In the 4 first boxes there is a percentage of 11,63% queens and in the last there is a percentage of 25,95%. 6) These percentages are very near two genetical ratios: 12,5% or 7:1, and 25% or 3:1, which correspond to a trifactorial and a bifactorial back-cross. Carrying out a X² test no significant deviations were found ( X² to 12,5% and to 25% and table 1 to 4). 7) We suppose that the formula for the queen in the first case (11,65%) is: AaBbCc. Since the Melipona bees are arrhenotokous hymenopteres, the drones are haploid and may have any one of the following eight formulas, corresponding to the gonic segregation of the queem : ABC, ABc, Abc, Abc, AbC, aBC, aBc, abC, abc. Anyone combination of these males with the queen will give a segregation of 7 workers to 1 queen, since there is always only one triple heterozygote among the eight possible segregates (table 5). 8) In order to explain the second case, it is suffient to assume that in this species there are only two pairs of factors, the queen being the double heterozygote : AaBb, while the drones may have any one of the following constitutions: AB, Ab, aB and ab. Workers are again all diploids which are homozygous for one or both factors, for instance: AABB, AABb, AaBB, aaBb, AAbb, etc. (table 6). 9) It is suggested that the genus Melipona is an intermediary type between the solitary bees, where all females are fertile independently of their feeding, and the genera Apis and Trigona, where without special feeding all females are born sterile, while only specially fed females develop into fertile queens. 10) No speculations are put forward with regards to the evolutionary mechanism which may have been responsible for the development of the genetical determination of castes in Melipona, since it seems advisable point to extend the studies to other insects with complicated caste systems.

Estudos sobre o gênero Melipona

1° - Cita-s�� a evolução das abelhas segundo MICÍÍENÉR" (1944). 2.° - A evolução dos Melíponíneos é estudada sob o ponto de vista da sua biologia, estabelecendo-se o tipo do meliponíneo primitivo. 3.° - S��o feitas considerações sobre a distribuição geográfica dos meliponíneos, entrando-se em detalhes sobre os seus fosseis, sobre a influência dos deslocamentos geológicos do cenozoico sobre sua distribuição, com particular referência ao seu estabelecimento na América do Sul. Considera-se também o e$eito das glaciações e a descontinuidade por ela provocada na distribuição dos meliponíneos. 4.° - S��o feitas hipóteses sobre a época em que se formaram as Meliponas, sobre o processo de determinação das castas e sua influência na evolução das mesmas. O tipo M. marginata é considerado o mais primitivo dos existentes atualmente. É dada uma hipótese, baseada na biologia e genética das Meliponas, para explicar sua evolução a partir de uma Trígona primitiva. 5.° - Sugere-se que a M. fascisrfta (excluidas a M. punc-ticollis e M. concinnula, que necessitam de estudos) seja do tipo da Meliponatrifatorial primitiva, tomando-se por base a sua proximidade a M. marginata, sua distribuição e sua variação. 6.° - Sugere-se como centro de origem das Meliponas a Bacia Amazônica, por ser esse lugar a zona onde há maior variação e por ser o centro geográfico da área habitada pelas Meliponas.

Sobre o comportamento mitótico e meiótico de cromossomas policêntricos ou com ponto de inserção difuso

Material: Studies were made mainly with Ascaris megalocephála Cloq. univalens and bivalens, and also with Tityus bahiensis Perty. 1) Somatic pairing of heterochromatic regions. The heterochromatic ends of the somatic chromosomes in Ascaris show a very strong tendency for unspecifical somatic pairing which may occur between parts of different chromosomes (Figs. 1, 2, 3, 7, 10, 11, 12, 13, 14, 16, 18,), between the two ends of the same chromosome either directly (Figs. 4, 5, 7, 8, 11, 12, 13, 15, 16, 17, 18) or inversely (Fig. 8, in the arrow) and also within a same chromosomal arm (Fig. 6). 2) During the early first cleavage division the chomosomes are an isodiametric cylinder (Figs. 6, 9, 11, 13, 14). But in later metaphase the ends become club shaped (Figs. 1, 2, 3, 4, 5, 7, 10) which is interpreted as the beginning of migration of chromatic substance from the central euchromatic region towards the heterochromatic regions. This migration becomes more and accentuated in anaphase (Figs. 19, 22, 23) and in the vegetative cells where euchromatic region looses more and more staing power, especially in the intersititial zones between the individual small spherical chromosomes into which the euchromatic region desintegrates. The emigrated chromatin material is finally eliminated with the heterochromatic chromosome ends (Fig. 23 and 24). 3) It seems a general rule that during mitotic anaphase all chromosomes with diffuse or multiple spindle fiber attachement (Ascaris, Tityus, Luzula, Steatococcus, Homoptera and Heteroptera in general) move to the poles in the form of an U with precedence of the chromosomal ends. In Ascaris, the heterocromatic regions are pulled passively towards the poles and only the euchromatic central portion may be U-shaped (Fig. 19, 22, 25). While in the other species this U-shape is perfect since the beginning of anaphase, giving the impression that movement towards the poles begins at both ends of a chromosome simultaneously, this is not the case in Ascaris. There the euchromatic region is at first U-shaped, passing then to form a straight or zig-zag line and becoming again U-shaped during late anaphase. This is explained by the fact that the ends of the euchromatic regions have to pull the weight of the passive heterochromatic portions. 4) While it is generally accepted that, during first meio-tic division untill second anaphase, all attachement regions remain either undivided or at least united closely, this is not the case in chromosomes with diffused or multiple attachment. Here one clearly sees in all cases so far studied four parallel chromatids at first metaphase. In Luzula and Tityus (for Tityus all figs. 26 to 31) this division is allready quite clear in paraphase (pro-metaphase) and it cannot be said wether in other species the division in sister chromatids is allready present, but not visible at this stage. During first anaphase the sister chromatids of Titbits remain more or less in contact, while in Luzula and especially in Ascaris they are quite separated. Thus one can count in late anaphase or telophase of Ascaris megalocephala bivalens, nearly allways, four separate chromosomes near each pole, or a total of eight chromatids per division figure (Figs. 35, 36, 37, 38, 39, 40, 41).

Bases para o estudo da genética de populações dos Hymenoptera em geral e dos Apinae sociais em particular

This paper deals with problems on population genetics in Hymenoptera and particularly in social Apidae. 1) The studies on populations of Hymenoptera were made according to the two basic types of reproduction: endogamy and panmixia. The populations of social Apinae have a mixed method of reproduction with higher percentage of panmixia and a lower of endogamy. This is shown by the following a) males can enter any hive in swarming time; b) males of Meliponini are expelled from hives which does not need them, and thus, are forced to look for some other place; c) Meliponini males were seen powdering themselves with pollen, thus becoming more acceptable in any other hive. The panmixia is not complete owing to the fact that the density of the breeding population as very low, even in the more frequent species as low as about 2 females and 160 males per reproductive area. We adopted as selection values (or survival indices) the expressions according to Brieger (1948,1950) which may be summarised as follows; a population: p2AA + ²pq Aa + q2aa became after selection: x p2AA + 2pq Aa + z q²aa. For alge-braics facilities Brieger divided the three selective values by y giving thus: x/y p2 AA + y/y 2 pq Aa + z/y q²aa. He called x/y of RA and z/y of Ra, that are survival or selective index, calculated in relation to the heterozygote. In our case all index were calculated in relation to the heterozygote, including the ones for haploid males; thus we have: RA surveval index of genotype AA Ra surveval index of genotype aa R'A surveval index of genotype A R'a surveval index of genotype a 1 surveval index of genotype Aa The index R'A ande R'a were equalized to RA and Ra, respectively, for facilities in the conclusions. 2) Panmitic populations of Hymenoptera, barring mutations, migrations and selection, should follow the Hardy-Weinberg law, thus all gens will be present in the population in the inicial frequency (see Graphifc 1). 3) Heterotic genes: If mutation for heterotic gene ( 1 > RA > Ra) occurs, an equilibrium will be reached in a population when: P = R A + Ra - 2R²a _____________ (9) 2(R A + Ra - R²A - R²a q = R A + Ra - 2R²A _____________ (10) 2(R A + Ra - R²A - R²a A heterotic gene in an hymenopteran population may be maintained without the aid of new mutation only if the survival index of the most viable mutant (RA) does not exced the limiting value given by the formula: R A = 1 + √1+Ra _________ 4 If RA has a value higher thah the one permitted by the formula, then only the more viable gene will remain present in the population (see Graphic 10). The only direct proof for heterotic genes in Hymenoptera was given by Mackensen and Roberts, who obtained offspring from Apis mellefera L. queens fertilized by their own sons. Such inbreeding resulted in a rapid loss of vigor the colony; inbred lines intercrossed gave a high hybrid vigor. Other fats correlated with the "heterosis" problem are; a) In a colony M. quadrifasciata Lep., which suffered severely from heat, the percentage of deths omong males was greater .than among females; b) Casteel and Phillips had shown that in their samples (Apis melifera L). the males had 7 times more abnormalities tian the workers (see Quadros IV to VIII); c) just after emerging the males have great variation, but the older ones show a variation equal to that of workers; d) The tongue lenght of males of Apis mellifera L., of Bombus rubicundus Smith (Quadro X), of Melipona marginata Lep. (Quadro XI), and of Melipona quadrifasciata Lep. Quadro IX, show greater variationthan that of workers of the respective species. If such variation were only caused by subviables genes a rapid increasse of homozigoty for the most viable alleles should be expected; then, these .wild populations, supposed to be in equilibrium, could .not show such variability among males. Thus we conclude that heterotic genes have a grat importance in these cases. 4) By means of mathematical models, we came to the conclusion tht isolating genes (Ra ^ Ra > 1), even in the case of mutations with more adaptability, have only the opor-tunity of survival when the population number is very low (thus the frequency of the gene in the breeding population will be large just after its appearence). A pair of such alleles can only remain present in a population when in border regions of two races or subspecies. For more details see Graphics 5 to 8. 5) Sex-limited genes affecting only females, are of great importance toHymenoptera, being subject to the same limits and formulas as diploid panmitic populations (see formulas 12 and 13). The following examples of these genes were given: a) caste-determining genes in the genus Melipona; b) genes permiting an easy response of females to differences in feeding in almost all social Hymenoptera; c) two genes, found in wild populations, one in Trigona (Plebéia) mosquito F. SMITH (quadro XII) and other in Melipona marginata marginata LEP. (Quadro XIII, colonies 76 and 56) showing sex-limited effects. Sex-limited genes affecting only males do not contribute to the plasticity or genie reserve in hymenopteran populations (see formula 14). 6) The factor time (life span) in Hymenoptera has a particular importance for heterotic genes. Supposing one year to be the time unit and a pair of heterotic genes with respective survival indice equal to RA = 0, 90 and Ra = 0,70 to be present; then if the life time of a population is either one or two years, only the more viable gene will remain present (see formula 11). If the species has a life time of three years, then both alleles will be maintained. Thus we conclude that in specis with long lif-time, the heterotic genes have more importance, and should be found more easily. 7) The colonies of social Hymenoptera behave as units in competition, thus in the studies of populations one must determine the survival index, of these units which may be subdivided in indice for egg-laying, for adaptive value of the queen, for working capacity of workers, etc. 8) A study of endogamic hymenopteran populations, reproduced by sister x brother mating (fig. 2), lead us to the following conclusions: a) without selection, a population, heterozygous for one pair of alleles, will consist after some generations (theoretically after an infinite number of generation) of females AA fecundated with males A and females aa fecundated with males a (see Quadro I). b) Even in endogamic population there is the theoretical possibility of the presence of heterotic genes, at equilibrium without the aid of new mutations (see Graphics 11 and 12), but the following! conditions must be satisfied: I - surveval index of both homozygotes (RA e Ra) should be below 0,75 (see Graphic 13); II - The most viable allele must riot exced the less viable one by more than is permited by the following formula (Pimentel Gomes 1950) (see Gra-fic 14) : 4 R5A + 8 Ra R4A - 4 Ra R³A (Ra - 1) R²A - - R²a (4 R²a + 4 Ra - 1) R A + 2 R³a < o Considering these two conditions, the existance of heterotic genes in endogamic populations of Hymenoptera \>ecames very improbable though not - impossible. 9) Genie mutation offects more hymenopteran than diploid populations. Thus we have for lethal genes in diploid populations: u = q2, and in Hymenoptera: u = s, being u the mutation ratio and s the frequency of the mutant in the male population. 10) Three factors, important to competition among species of Meliponini were analysed: flying capacity of workers, food gathering capacity of workers, egg-laying of the queen. In this connection we refer to the variability of the tongue lenght observed in colonies from several localites, to the method of transporting the pollen in the stomach, from some pots (Melliponi-ni storage alveolus) to others (e. g. in cases of pillage), and to the observation that the species with the most populous hives are almost always the most frequent ones also. 11) Several defensive ways used for Meliponini to avoid predation are cited, but special references are made upon the camouflage of both hive (fig. 5) and hive entrance (fig. 4) and on the mimetism (see list in page ). Also under the same heading we described the method of Lestrimelitta for pillage. 12) As mechanisms important for promoting genetic plasticity of hymenopteran species we cited: a) cytological variations and b) genie reserve. As to the former, duplications and numerical variations of chromosomes were studied. Diprion simile ATC was cited as example for polyploidy. Apis mellife-ra L. (n •= 16) also sugests polyploid origen since: a) The genus Melipona, which belongs to a" related tribe, presents in all species so far studied n = 9 chromosomes and b) there occurs formation of dyads in the firt spermatocyte division. It is su-gested that the origin of the sex-chromosome of Apis mellifera It. may be related to the possible origin of diplo-tetraploidy in this species. With regards to the genie reserve, several possible types of mutants were discussed. They were classified according to their survival indices; the heterotic and neutral mutants must be considered as more important for the genie reserve. 13) The mean radius from a mother to a daghter colony was estimated as 100 meters. Since the Meliponini hives swarm only once a year we may take 100 meters a year as the average dispersion of female Meliponini in ocordance to data obtained from Trigona (tetragonisca) jaty F. SMITH and Melipona marginata LEP., while other species may give different values. For males the flying distance was roughly estimated to be 10 times that for females. A review of the bibliography on Meliponini swarm was made (pg. 43 to 47) and new facts added. The population desity (breeding population) corresponds in may species of Meliponini to one male and one female per 10.000 square meters. Apparently the males are more frequent than the females, because there are sometimes many thousands, of males in a swarm; but for the genie frequency the individuals which have descendants are the ones computed. In the case of Apini and Meliponini, only one queen per hive and the males represented by. the spermatozoos in its spermateca are computed. In Meliponini only one male mate with the queen, while queens of Apis mellijera L. are fecundated by an average of about 1, 5 males. (Roberts, 1944). From the date cited, one clearly sees that, on the whole, populations of wild social bees (Meliponini) are so small that the Sewall Wright effect may become of great importance. In fact applying the Wright's formula: f = ( 1/aN♂ + 1/aN♀) (1 - 1/aN♂ + 1/aN♀) which measures the fixation and loss of genes per generation, we see that the fixation or loss of genes is of about 7% in the more frequent species, and rarer species about 11%. The variation in size, tergite color, background color, etc, of Melipona marginata Lep. is atributed to this genetic drift. A detail, important to the survival of Meliponini species, is the Constance of their breeding population. This Constance is due to the social organization, i. e., to the care given to the reproductive individuals (the queen with its sperm pack), to the way of swarming, to the food storage intended to control variations of feeding supply, etc. 14) Some species of the Meliponini are adapted to various ecological conditions and inhabit large geographical areas (e. g. T. (Tetragonisca jaty F. SMITH), and Trigona (Nanno-trigona testaceicornis LEP.) while others are limited to narrow regions with special ecological conditions (e. g. M. fuscata me-lanoventer SCHWARZ). Other species still, within the same geographical region, profit different ecological conditions, as do M. marginata LEP. and M. quadrifasciata LEP. The geographical distribution of Melipona quadrifasciata LEP. is different according to the subspecies: a) subsp anthidio-des LEP. (represented in Fig. 7 by black squares) inhabits a region fron the North of the S. Paulo State to Northeastern Brazil, ,b) subspecies quadrifasciata LEP., (marked in Fig. 7 with black triangles) accurs from the South of S. Paulo State to the middle of the State of Rio Grande do Sul (South Brazil). In the margined region between these two areas of distribution, hi-brid colonies were found (Fig. 7, white circles); they are shown with more details in fig. 8, while the zone of hybridization is roughly indicated in fig. 9 (gray zone). The subspecies quadrifasciata LEP., has 4 complete yellow bands on the abdominal tergites while anthidioides LEP. has interrupted ones. This character is determined by one or two genes and gives different adaptative properties to the subspecies. Figs. 10 shows certains meteorological isoclines which have aproximately the same configuration as the limits of the hybrid zone, suggesting different climatic adaptabilities for both genotypes. The exis-tance of a border zone between the areas of both subspecies, where were found a high frequency of hybrids, is explained as follows: being each subspecies adapted to a special climatic zone, we may suppose a poor adaptation of either one in the border region, which is also a region of intermediate climatic conditions. Thus, the hybrids, having a combination of the parent qualities, will be best adapted to the transition zone. Thus, the hybrids will become heterotic and an equilibrium will be reached with all genotypes present in the population in the border region.

A amostragem na avaliação das lixas-do-coqueiro

A avaliação das doenças foliares do coqueiro (Cocos nucifera L.), conhecidas como lixa-grande e lixa-pequena (verrugoses), causadas por Sphaeredothis acrocomiae e Phyllachora torrendiella, respectivamente, depara-se com o problema do método de amostragem, uma vez que não existe um método consensual em uso. Este trabalho foi realizado com o objetivo de comparar dois métodos de coleta de amostras mais utilizados na avaliação dessas doenças: método A: coleta de seis folíolos/planta, em uma única folha; método B: coleta de seis folíolos/planta, um em cada folha. O estudo foi desenvolvido a partir de três amostras de 300 folíolos (dez plantas x cinco folhas x seis folíolos), coletados em três genótipos de coqueiro, nos quais foi determinado o número de estromas da lixa-grande e da lixa-pequena. Com base nesses dados, estimaram-se as variâncias de folhas dentro de plantas e folíolos dentro de folhas e plantas, necessárias para os cálculos das estimativas das médias amostrais nos dois métodos em comparação, além de outras alternativas formuladas. Em ambas as lixas, em todos os genótipos, as estimativas da variância da média amostral calculadas pelo método A foram superiores às calculadas pelo método B, o que comprova que este último é mais eficaz que o primeiro. Outros tamanhos de amostra também foram avaliados e comparados ao método B, e constatou-se que amostras de seis folhas/planta, coletando-se, em cada uma, dois ou três folíolos, reduzem a variância amostral em 20% ou 30%, respectivamente, podendo, portanto, ser utilizadas com mais eficiência.

DIVERGÊNCIA GENÉTICA ENTRE DOZE GENÓTIPOS DE ABACAXIZEIRO (Ananas comosus L, Merril.) ESTIMADA POR ANÁLISE DE MARCADORES RAPD

Por meio de estudos moleculares, este trabalho determinou a distância genética entre 12 genótipos de A. comosus por marcadores RAPD (Random Amplified Polymorphic DNA), utilizando 11 "primers" decâmeros da OPERON Technologies Inc. Dos 12 genótipos , 1 foi proveniente da Jamaica, 2 do Estado do Acre (Quinari e RBR-1), 2 do Estado do Maranhão (Turiaçu e S��o Domingos), 3 do Estado do Piauí (Cefas, Floriano-1 e Floriano-2), 2 do Estado da Bahia (Monte Alegre-1 e Monte Alegre-2) e 2 de Minas Gerais (Pérola e Smouth Cayenne). Pela análise de "cluster", utilizando o método de UPGMA, foi constatada uma grande divergência entre os genótipos de A. comosus estudados com a separação destes em dois grupos a uma distância genética de 31,1%.