Alice Kalisz de Oliveira

THE EFFECTS OF CONSTANT AND ALTERNATING TEMPERATURES ON THE REPRODUCTIVE POTENTIAL, LIFE SPAN, AND LIFE EXPECTANCY OF Anastrepha fraterculus (WIEDEMANN) (DIPTERA: TEPHRITIDAE)

Ovarian development, oviposition, larval eclosion, ornithine decarboxylase (ODC) activity, ovarian, testis and ejaculatory apodeme measurements (length, width, and area), and the number of spermatozoa of Anastrepha fraterculus (Wiedemann) were analyzed at alternating (20 degrees/6 degrees C and 20 degrees/13 degrees C) and constant (6 degrees C; 25 degrees C) temperatures. Life span and life expectancy were also analyzed for both genders. All the results suggest that temperature, especially alternating temperatures, increase not only male and female reproductive potential but also their life span and life expectancy. These changes can be a powerful strategy triggered by A. fraterculus as a means to survive the stressful temperature conditions found in winter in the apple production region in Brazil, enabling this species to increase its population density and cause apple damage when spring begins.

Efeito da temperatura na maturação ovariana e longevidade de Anastrepha fraterculus (Wied.) (Diptera: Tephritidae)

Anastrepha fraterculus (Wied.) shows a populational fluctuation related to the year season in Southern Brazil. Adults cannot be colected by means of conventional methods of capture in the winter. Even with the use of special traps, a very low number of adults is caught. Two hypothesis are pointed out to explain the increase of the population at spring: a) adults migrate from neighbouring areas with temperature more favourable during winter, and b) some individuals that can survive the critical period develop a differential metabolic regulation. In this paper the second hypothesis was tested by studying the effect of four temperatures (9, 13, 20 and 25oC) on ovarian maturation and longevity of the females. Only at 25 and 20oC ovarian maturation has occurred. The life expectancy was larger in the intermediate temperatures (20 and 13oC) than in the extreme temperatures (25 and 9oC). The relation between ovarian maturation and longevity was observed at 25 and 20oC, although at 25oC the ovarian maturation was faster, but the life expectancy was lower. Therefore, the hypothesis of developmental regulation cannot be discarded as a populational mechanism in A. fraterculus for its populational increase in the months subsequent to the winter.

Chromosome studies in southern Brazilian wheat pest aphids Sitobion avenae, Schizaphis graminum, and Methopolophium dirhodum (Homoptera: Aphididae)

We examined the chromosome set of the aphid species Sitobion avenae, Schizaphis graminum and Methopolophium dirhodum by means of conventional staining and C, NOR, AluI and HaeIII banding methods. These species are considered important pests to several plants of economic interest in Brazil. No variation was observed in the number of chromosomes of S. avenae, whereas there was intraspecific variation in the other two species. Interspecific differences in the response to the banding treatments were observed. Whereas these techniques allowed the identification of several S. graminum chromosome pairs, only the AluI treatment was capable of inducing differential staining in the M. dirhodum chromosomes and no clear patterns emerged when the S. avenae preparations were treated

Genetic components affecting embryonic developmental time of Drosophila melanogaster

The developmental time of the embryonic stage of Drosophila melanogaster was 21.66% faster and 14.75% slower than controls in populations selected for fast and slow developmental speed, respectively. The genetic model with two main loci with dominant and additive effect added to maternal effect and their relevant interactions can explain 96% of the phenotypic variability in the embryonic developmental time according to 14 crossing progenies involving fast and slow flies.

Toxicity of fenthion to Anastrepha fraterculus (Wied.) (Diptera:Tephritidae): dose response analysis

Three toxicological bioassays were performed in two F1 south Brazilian field populations of Anastrepha fraterculus (Wied.). Lethal doses of fenthion (50% and 90%) were estimated in two bioassays, with oral administration, and with residual contact bioassay. Results of topical bioassays using fenthion diluted in alcohol, acetone or water were inconsistent. Samples treated with acetone or alcohol diluents presented high mortality (>10%), while the samples treated with water diluent showed a non linear response between dose and mortality. The residual contact bioassay was significatively more toxic when compared to a feeding bioassay, occurring equal slopes in males and females in the populations analysed. Additional test showed that insects did not discriminate between diets with and without fenthion.

Morphometric observations on three populations of Schizaphis graminum (Rondani), a main wheat aphid pest in Brazil

The green aphid Schizaphis graminum (Rondani) is an important pest of Graminae. Samples of this aphid were collected at three environmentally distinct Brazilian localities, Passo Fundo (RS), Jaguariuna (SP) and Dourados (MS). Alatae and apterous viviparous forms were reared on the BR-35 wheat (Triticum aestivum) strain under controlled laboratory conditions and studied as to their variability in measures of body size and production of progeny. Univariate (ANOVA) and multivariate (canonical discriminant functions) techniques were used to evaluate differences among the three populations. Conspicuous differences between populations were observed in the length of five structures of the alatae and eight of the apterous forms, as well as in offspring production. The greatest dispersion in the length of general structures of the individuals obtained by the canonical discriminant function was for Passo Fundo, where climatic conditions are more severe and where aphids cause the most serious damage to wheat crop.

Age and time exposure-related toxicity of fenthion to male and female Anastrepha fraterculus (Wied.) (Diptera: Tephritidae)

O efeito da idade, sexo e tempo de exposicao de machos e femeas de Anastrepha fraterculus (Wied.) a toxicidade do fentiom foi avaliado. A idade das moscas mostrou ser importante para o aparecimento dos primeiros sintomas de intoxicacao; machos e femeas no pico reprodutivo (30 e 60 dias de idade, respectivamente) sao menos susceptiveis ao inseticida que moscas nas demais idades (quatro e 120 dias). Nao foram detectadas diferencas de toxicidade relacionadas com o peso corporal dos insetos. O TL50, que variou de 3-7 min, mostrou serem os machos menos sensiveis que as femeas em todas as idades testadas. Adultos de ambos os sexos, com 30 dias de idade, submetidos a uma exposicao continua e descontinua ao fentiom, nao apresentaram efeito toxicologico cumulativo do inseticida. Analises estatisticas sugerem a possivel ocorrencia de um mecanismo geral de desintoxicacao (quantitativo e/ou qualitativo) relacionado com o sexo, a idade e o tempo de exposicao ao fentiom. Como a especie apresenta alta mobilidade na natureza sugere-se que estas caracteristicas biologicas e comportamentais sejam consideradas para a obtencao de resultados mais realistas.

Ontogenetic development of Anastrepha fraterculus (Diptera: Tephritidae): Isoenzyme patterns of isocitrate and alcohol dehydrogenases

Abstract Anastrepha fraterculus was analysed by electrophoresis during the whole development period. Two Isocitrate dehydrogenase (IDH) loci were found, one of them expressed from first-stage to 100-day-old adults with varied intensity of staining; the other one was detected only from third-stage larvae until 216-hr pupae. Three presumptive Alcohol dehydrogenase (ADH) loci and 14 electromorphs were detected. Isopropanol was the best ADH substrate for adults and both isopropanol and ethanol were similar as good substrates for third-stage larvae. The ADH-1 locus presented two to four electromorphs and its product was better visualized in starch gel; ADH-2 showed three electromorphs and ADH-3 seven electromorphs; polyacrylamide gel was better for the latter isoenzymes. The three loci were activated in third-stage larvae, pupal stage, and adult period; ADH-1 and ADH-3 were present in the second-stage larvae, and no ADH activity was detected during the embryonic period and first-stage larvae. Males and females (more than 30 days old) showed higher ADH activity; the ADH of females was more active in 100-day-old flies. A specific locus for Octanol dehydrogenase was not detected. Third-stage larvae reared in papaya, guava, and banana show identical ADH patterns. No activity of this enzyme was detected when larvae were grown in kiwi.

Effect of α-difluormethylornithine on Anastrepha fraterculus (Diptera, Tephritidae) ovary size

Ovarian sizes (length and width) were measured in young females of Anastrepha fraterculus (Wiedemann) (Diptera, Tephritidae) subjected or not to the inhibitor alpha-difluormethylornithine (alpha-DFMO). The most effective concentration of alpha-DMFO used was 50 mM and the ovarian measurements (length and width) of the treated females were smaller than those of females not treated with alpha-DMFO. These data may suggest some relationship between ornithine decarboxylase (ODC) and sexual maturation in A. fraterculus.