Josué Sant'Ana

Comparative Electrophysiological Studies of Olfaction in Predaceous Bugs, Podisus maculiventris and P. nigrispinus

Electroantennograms (EAGs) were recorded from both sexes of spined soldier bug (SSB), Podisus maculiventris, and Brazilian SSB (BSSB), P. nigrispinus to determine antennal olfactory responsiveness of 23 compounds in SSB and 14 compounds in BSSB, including the multicomponent male-produced aggregation pheromone and plant volatiles. EAGs of both species were similar. (E)-2-Hexenol and (E)-2-hexenal elicited the greatest EAGs, followed by heptanol, nonanal, hexanal, and the pheromonal compounds, (±)-α-terpineol and benzyl alcohol. Both sexes of SSB and BSSB were more sensitive to components of the male-produced aggregation pheromone [(±)-α-terpineol, (±)-linalool, and benzyl alcohol] and nonanal than either (E)-2-hexenol or (E)-2-hexenal (a component of the aggregation pheromone). BSSB were more sensitive to (±)-α-terpineol, (±)-linalool, benzyl alcohol, and nonanal than were SSB. EAGs to the plant volatile 1-hexanol and the pheromonal components (E)-2-hexenal and (±)-α-terpineol decreased significantly with removal of antennal segments, suggesting that receptors for these compounds are distributed over the distal three segments of the five-segmented antennae.

Morphometry and distribution of sensilla on the antennae of Anastrepha fraterculus (Wiedemann) (Diptera: Tephritidae)

Antennal sensilla of Anastrepha fraterculus (Wied.) were examined using scanning electron microscopy. In the flagellum, there are trichoid, basiconic, clavate type I and II, and styloconic sensilla and microtrichia. Only microtrichiae and chaetica sensilla were observed in the scape and pedicel. The number of sensilla in the flagellum was similar between sexes. At the apex there was a higher density of trichoid and an absence of clavate sensilla, while basiconic sensilla were more abundant in the proximal region.

Aprendizagem e memória de Telenomus podisi (Hymenoptera, Platygastridae)

The egg parasitoid Telenomus podisi Ashmead, 1893 is an important natural control agent of stink bugs. Its success as a parasitoid depends on its host-locating ability, which may be influenced by learning and memory. This study used lemongrass [Cymbopogon citratus (DC.) Stapf. (Poales, Poaceae)] extract to assess the capacity for learning and memory retention time of T. podisi at different developmental stages of the immature phase. Eggs of Euschistus heros (Fabricius, 1798) (Hemiptera, Pentatomidae) parasitized by T. podisi and at different parasitoid juvenile developmental stages were isolated in glass tubes containing filter paper with lemongrass extract or acetone solvent (control). After emergence, T. podisi females were tested in a Y-tube olfactometer containing both scents. Inexperienced females were subjected to the same scents as experienced. To assess memory, females that emerged from eggs that were in contact with lemongrass extract throughout the immature developmental stage were given a choice between lemongrass extract and acetone when they were 24, 48, 72, and 96 hours old. Females that had contact with the lemongrass during the juvenile phase preferred lemongrass, while inexperienced females or those exposed to acetone chose the solvent. The presence of lemongrass all through the immature developmental stage altered the chemotaxic orientation of T. podisi and prompted learning in these organisms that lasted for up to 72 hours.

Percepção química e visual de Anastrepha fraterculus (Diptera, Tephritidae) em laboratório

Chemical and visual perception of Anastrepha fraterculus (Diptera, Tephritidae) in laboratory. The South American fruit fly Anastrepha fraterculus (Wiedemann, 1830) is one of the greatest threats to the fruit growing industry in Brazil. During the feeding process, the larvae build galleries within the fruit, altering the flavor and damaging its production and commercialization. The present work had as its objective to study the factors involved in the choice of the host by A. fraterculus. Electroantennographic responses of the males and females to the ethanolic extracts of the fruits of the peach tree - Prunus persica, cultivar Chimarrita (Rosaceae), Surinam cherry tree - Eugenia uniflora (Myrtaceae), Guabirobeira tree - Campomanesia xanthocarpa (Myrtaceae) and Brazilian guava tree - Psidium cattleianum (Myrtaceae) were considered. Also recorded was the influence of the color (yellow, green and red) and the composition of the substratum of oviposition (pulps of Brazilian guava, Guabiroba, Surinam cherry and peaches) in the fecundity. Electroantennographic responses of the females were distinct to the extracts of the unripe and ripe Guabiroba, ripe Brazilian guava and unripe Surinam cherry. In antennae of the males, the greatest depolarization average was registered in the responses to the extracts of ripe and unripe Guabiroba, ripe and unripe Brazilian guava and unripe Surinam cherry. Electrophysiologic responses did not differ statistically between the sexes for all the treatments. The colors of the substratum of oviposition did not affect the fecundity. The females ovipositioned more on the substratum containing pulp of peaches and of Guabiroba, when compared to the respective controls.

Parasitismo de ovos de Tibraca limbativentris Stål (Hemiptera: Pentatomidae) em lavoura de arroz irrigado, Eldorado do Sul, RS

The rice stem stink bug, Tibraca limbativentris Stal (Hemiptera: Pentatomidae), is an important pest of rice in Brazil. This study aimed to register egg parasitoids of T. limbativentris in irrigated rice crop in Eldorado do Sul (state of Rio Grande do Sul, Brazil). The area (603 m2) was inspected weekly from 01/21/2010 to 03/03/2010 and rice stem stink bug eggs were collected. It was observed only the occurrence of Telenomus podisi (Ashmead) (Hymenoptera: Platygastridae) as egg parasitoid and the parasitism rate was 75%. This is the first record of T. podisi in rice stem stink bug eggs collected in rice fields in the state of Rio Grande do Sul.

Behavioral analysis of learning and memory in Anastrepha fraterculus

We evaluate the influence of prior exposure to artificial substrate for oviposition on learning and memory in the fruit fly Anastrepha fraterculus (Wiedemann) (Diptera: Tephritidae). Some females were previously exposed to artificial fruits made of water, agar, and blackberry [Rubus spec. (Rosaceae)] or guava [Psidium guajava L. (Myrtaceae)] pulp for 48 and 72 h. We also studied adult flies exposed for 72 h to essential oil of lemongrass [Cymbopogon citratus (DC) Stapf, Poaceae] and adult flies from larvae exposed to the oil. Control females were naive with respect to these experimental substrates. Prior experience with blackberry‐based artificial fruits resulted in an increase in the number of punctures and deposited eggs by A. fraterculus, and memory lasted for up to 72 h. On the other hand, fly behavior was independent of exposure to guava‐based substrate. Prior exposure of 1‐ or 15‐day‐old females to artificial substrate with lemongrass oil modified innate substrate selection behavior. The scent of lemongrass oil during the larval stage modified innate oviposition responses of adult A. fraterculus. The study shows that A. fraterculus females are able to learn and retain information through chemical stimuli released by both host (blackberry and guava) and non‐host (lemongrass) species, and they can use olfactory memory obtained during the larval stage to select oviposition sites.

Age and multiple mating effects on reproductive success of Grapholita molesta (Busck) (Lepidoptera, Tortricidae)

Age and multiple mating effects on reproductive success of Grapholita molesta (Busck) (Lepidoptera, Tortricidae). The reproductive success of the oriental peach moth was evaluated in four experiments: 1) assessment of the mating duration, fecundity, fertility and longevity of females paired with virgin and immediately mated males; 2) mating duration, spermatophore size, fecundity, fertility and longevity in females paired with virgin and up to four times mated males; 3) receptivity of females to additional copulations after mating with virgin or mated males, and the effects of this behavior in female fecundity, fertility and longevity; 4) influence of insects age in the reproductive output. Males (33%) could copulate immediately after a previous copula. They were fertile until the fourth mating, but only in the first copula they transferred the longest (1.43 ± 0.10 mm) and widest (0.83 ± 0.11 mm) spermatophore, presenting the fastest mating duration (34.8 ± 2.62 min). A high proportion of females copulated by non-virgin males (84%) was receptive to other copulas, in comparison to those copulated by virgin males (32.4%). However, the fecundity, fertility, and longevity were similar among females that copulate once or more. The age was the most important factor affecting reproductive variables, where one and three day old insects had a significant higher fecundity, fertility and presented a shorter mating duration in comparison with older individuals. Results pointed out that the reproductive capacity of Grapholita molesta changes a little with respect to the analyzed factors, highlighting the elevated biotic potential of the species.

SUSCETIBILIDADE DE GENÓTIPOS DE MACIEIRA A Anastrepha fraterculus (DIPTERA: TEPHRITIDAE) EM DIFERENTES CONDIÇÕES DE INFESTAÇÃO

ABSTRACTThe study aimed to record damages of Anastrepha fraterculus(Diptera: Tephritidae), on two developmental stages of apple fruits genotypes M-11/00 and ‘Catarina’, submitted to three different infestation conditions in the field, during the 2011/2012 crop season. The experiment was carried out in an organic apple orchard management at Epagri Experimental Station in Cacador, SC, Brazil. The average number of fruit flies was weekly recorded with four McPhail traps. Unripe and ripe fruits of the selection M-11/00 and of the Catarina cultivar, were submitted to artificial, controlled and natural infestation conditions. In the beginning of fruiting, after the thinning, in each genotype, 500 fruits were randomly bagged with nontextured fabric (TNT) packing. Fruits submitted to the artificial infestation were involved, individually, in a cage containing two mated females of A. fraterculus that stay for three days for oviposition. In the controlled infestation, in the same day of placing the cages, protected fruits were unbagged to be exposed for three days. No bagged fruits were used to evaluate the natural infestation. In each developmental stage the values of physico-chemical attributes of fruits were recorded. During the crop season, the average number of A. fraterculus was 3.08 fruit flies/trap/week. The average number of larvae and pupae was greater in M-11/00 ripe fruits, in all of the infestation conditions. These numbers, in the Catarina cv., did not differ neither among infestation conditions, nor in developmental stages. Pupae of A. fraterculus were not observed in ‘Catarina’ fruits, in these cultivar was recorded a highest acidity and lowest relationship of soluble solids/acidity.

Efeito da dose e exposição à terra de diatomácea de diferentes insetos em milho armazenado

Sitophilus zeamais and Tribolium castaneum are important insect pests of stored grain and their damage corresponds to approximately 25% of post-harvest losses in Brazil. The methods used for the control of these pests notably include the use of post-harvest inert dusts. Therefore, the objective was to assess the mortality of adult S. zeamais and T. castaneum with the use of diatomaceous earth (DE) at different dosages and durations. The treatments with diatomaceous earth were 1,000 and 2,000 GT-1 and control (no application). Insects (10 each species) were placed in 300-ml plastic containers containing 100 g of corn kernels with different moisture contents (12, 14 and 16% wb). Infestations occurred 1 hour, 10 and 20 days after the application of TD. Mortality was evaluated at 30 and 60 days. There were five replicates per treatment. There was a higher mortality for the species S. zeamais than for T. castaneum, and this morality rate increased in direct relation to insect exposure time. It was concluded that T. castaneum has greater tolerance and that the more time the insects are in contact with treated grain the greater the mortality.

Efeito de fatores endógenos na percepção química de Grapholita molesta(Busck) (Lepidoptera: Tortricidae) ao feromônio sexual

The oriental fruit moth, Grapholita molesta (Busck), stands out as one of the most important pest in Rosaceae orchards in Brazil. During feeding, caterpillars bore into shoots, branches and fruits, impairing the commercial production. This work aimed to study the effect of endogenous factors in the chemical perception and in the species chemotactic behavior, seeking to optimize monitoring and the behavioral control of this pest. We evaluated male electroantennographical (EAG) and chemotactical (olfactometry) responses to the synthetic sex pheromone in different ages, virgins or mated and fed or unfed. The EAG responses of males did not differ for all evaluated factors. Nevertheless, the chemotactical behavior of males seems to decrease with age, not varying as a function of mating or feeding conditions. The knowledge about the interference of these factors in G. molesta may help with the interpretation of field results, allowing the development of suitable and reliable control measures based on infochemicals for behavioral control.