Emergence and Infestation Level of Hypothenemus hampei (Coleoptera: Curculionidae) on Coffee Berries on the Plant or on the Ground During the Post-harvest Period in Brazil

The coffee berry borer (CBB), Hypothenemus hampei Ferrari (Coleoptera: Curculionidae), is the most important coffee pest in most of the coffee growing countries. CBB females leave old dry berries after harvest and search for dry noninfested berries on the plant or on the ground to lay eggs or to use as refuge until new berries are available on the coffee trees in the following season. The CBB infestation level and emergence from berries on the ground or on the plants were evaluated in two fields post-harvest in the Spring in Brazil over two seasons. Twenty infested or noninfested berries in separate cages (250 ml plastic cups) were placed on the plants or on the ground under the tree canopy, in each field. The number of infested berries and CBB females that emerged from the infested berries were recorded weekly. CBB emergence was higher from berries on the ground than those on the coffee trees in both seasons, whereas CBB infestation was higher on coffee berries on the plants than those on the ground in season I. Insolation (hours of sunlight) and temperature were the main covariates that affected emergence and infestation by this insect. The results are discussed for monitoring CBB during the time of dispersal with implications on integrated management of this pest.

Age Influence on Sexual Behavior of the Lesser Cornstalk Borer, Elasmopalpus lignosellus (Zeller) (Lepidoptera: Pyralidae)

The objective of this work was to evaluate the reproductive behavior and response of Elasmopalpus lignosellus (Zeller) males to calling females. Frequency of mating was recorded in couples during the first 7 days of the adult stage. Calling behavior of females was observed during the first 4 days of the adult stage and responses of males, in the same age intervals, to calling females were recorded in wind tunnel bioassays. The maximum number of matings occurred when the couple was between 24 and 48 h old. The scotophase period significantly influenced mating behavior, which peaked between 6 and 8 h of darkness and the mean mating duration was 93.9 ± 4.2 min. Calling females, when evaluated in a wind tunnel, attracted significantly more males than in bioassays with clean air (control). The number of individuals in calling behavior was significantly lower for females that were between 0 to 24 h old compared to the other females evaluated, but this did not influence male response. A lower proportion of males between 48 to 72 h old responded to calling females and these responses were delayed in comparison with males of other ages (0 to 24, 24 to 48, and 72 to 96 h old). These results indicate that the age of E. lignosellus males influences the response to conspecific calling females.

How much is a pheromone worth?

Pheromone-baited traps have been widely used in integrated pest management programs, but their economic value for growers has never been reported.  We analyzed the economic benefits of long-term use of traps baited with the citrus fruit borer Gymnandrosoma aurantianum sex pheromone in Central-Southern Brazil. Our analysis show that from 2001 to 2013 citrus growers avoided accumulated pest losses of 132.7 million to 1.32 billion USD in gross revenues, considering potential crop losses in the range of 5 to 50%. The area analyzed, 56,600 to 79,100 hectares of citrus (20.4 to 29.4 million trees), corresponds to 9.7 to 13.5% of the total area planted with citrus in the state of São Paulo. The data show a benefit-to-cost ratio of US$ 2,655 to US$ 26,548 per dollar spent on research with estimated yield loss prevented in the range of 5-50%, respectively. This study demonstrates that, in addition to the priceless benefits for the environment, sex pheromones are invaluable tools for growers as their use for monitoring populations allows rational and reduced use of insecticides, a win-win situation.

A multifaceted trophic cascade in a detritus-based system: density-, trait-, or processing-chain-mediated effects?

We investigated three pathways by which predators on an intermediate trophic level may produce a trophic cascade in detritus-based systems. Predators may increase lower trophic levels (bacteria) by reducing density of bacteriovores, by altering behavior of bacteriovores, and by processing living bacteriovores into carcasses, feces, and dissolved nutrients that are substrates for bacteria. We tested these pathways in laboratory experiments with mosquitoes in water-filled containers. Larval Toxorhynchites rutilus prey on larval Aedes triseriatus, which feed on bacteria. Using containers stocked with oak leaf infusion as a bacterial substrate, we compared bacterial productivity at 7 and 14 days for: prey alone; prey with a predator; and prey with predation cues but no predator. Controls contained no larvae, either with predation cues or without cues. Predation cues in the control treatment increased bacterial abundance at 7 days, but this effect waned by 14 days. Aedes triseriatus larvae reduced bacterial abundance significantly at 14 days. Predator cues and real predation both eliminated the negative effect of A. triseriatus on bacterial abundance. Predation cues reduced survivorship of A. triseriatus larvae at 14 days, however this effect was smaller than the effect of real predation. We further tested effects of residues from predation as cues or as detritus in a second experiment in which A. triseriatus were killed at similar rates by: real predators; mechanical damage without the predator and carcasses left as detritus; or mechanical damage and carcasses removed. No prey larvae were killed in controls. Bacterial productivity was greater with real predation than in all other treatments and greater when prey larvae were killed or killed and removed, than in controls. Thus we find evidence that all three pathways contribute to the trophic cascade from T. rutilus to bacteria in tree hole systems.

Sex Pheromone of the Brazilian Apple Leafroller, Bonagota cranaodes Meyrick (Lepidoptera, Tortricidae)

The female sex pheromone of Bonagota (=Phthteochroa) cranaodes (Meyrick) is a blend of (E,Z)-3,5-dodecadienyl ajcetate (E3,Z5-12:Ac) and (Z)-9-hexadecenyl acetate (Z9-16:Ac) according to analysis of pheromone - gland extracts and field trapping in apple orchards. This is the first time that E3,Z5-12:Ac has been identified as a lepidopteran sex pheromone. Traps baited with 100 μg E3,Z5-12:Ac were attractive over 15 weeks in the field and were as effective as traps baited with virgin females. Addition of Z9-16:Ac to E3,Z5-12:Ac at ratio of 1:10 had a significantly increase of male moths. The addition of the Z,E and Z,Z isomers to rubber septa baited with E3,Z5-12:Ac did not modify B. cranaodes male attraction, but 10% of EE enhanced trap catch.

Attracted to the enemy: Aedes aegypti prefers oviposition sites with predator-killed conspecifics

Oviposition habitat choices of species with aquatic larvae are expected to be influenced by both offspring risk of mortality due to predation, and offspring growth potential. Aquatic predators may indirectly influence growth potential for prey by reducing prey density and, for filter-feeding prey, by increasing bacterial food for prey via added organic matter (feces, partially eaten victims), creating the potential for interactive effects on oviposition choices. We tested the hypothesis that the mosquito Aedes aegypti preferentially oviposits in habitats with predatory Toxorhynchites larvae because of indirect effects of predation on chemical cues indicating bacterial abundance. We predicted that A. aegypti would avoid oviposition in sites with Toxorhynchites, but prefer to oviposit where bacterial food for larvae is abundant, and that predation by Toxorhynchites would increase bacterial abundances. Gravid A. aegypti were offered paired oviposition sites representing choices among: predator presence; the act of predation; conspecific density; dead conspecific larvae; and bacterial activity. A. aegypti preferentially oviposited in sites with Toxorhynchites theobaldi predation, and with killed conspecific larvae, but failed to detect preferences for other treatments. The antibiotic tetracycline eliminated the strongest oviposition preference. Both predation by Toxorhynchites and killed larvae increased bacterial abundances, suggesting that oviposition attraction is cued by bacteria. Our results show the potential for indirect effects, like trophic cascades, to influence oviposition choices and community composition in aquatic systems. Our results suggest that predators like Toxorhynchites may be doubly beneficial as biocontrol agents because of the attraction of ovipositing mosquitoes to bacterial by-products of Toxorhynchites feeding.

Changes in the fat body during the post-embryonic development of the predator Toxorhynchites theobaldi (Dyar & Knab) (Diptera: Culicidae)

Several studies have focused on understanding the biochemistry and morphology of the fat body of the hematophagous mosquito Aedes aegypti (L.) (Diptera: Culicidae). In contrast, few studies, if any, have focused on morphological characters of the fat body in other mosquitoes, especially non-hematophagous taxa such as the culicid Toxorhynchites. Larvae of Toxorhynchites prey upon the larvae of other mosquito species and are used in vector mosquito control. We investigated aspects of the fat body trophocytes, including the morphometric analyses of the lipid droplets, protein granules and nuclei, during Toxorhynchites theobaldi (Dyar & Knab) post-embryonic development. Following the body weight increase from larval stage L2 to L4, the size of lipid droplets within the trophocytes also increase, and are likely the result of lipogenesis. Lipid droplets decrease in size during L4 to the female pupal stage and increase once again during the period from newly-emerged to mature adult females. Protein granules are observed for the first time in female pupae, and their appearance might be related to protein storage during metamorphosis. The size of the nucleus of trophocytes also increases during larval development, followed by a decrease during metamorphosis and an additional increase as adult female ages. In conclusion, the morphology of the fat body of T. theobaldi changes according to the developmental stage. Our study provides for the first time important insights into T. theobaldi fat body development and contributes to understand this species biology.

Multiple queens in founding colonies of the neotropical ant Pachycondyla striata Smith (Formicidae: Ponerinae)

In social insects, the typical mode of colony foundation occurs when a single queen is inseminated by a male and establishes a new colony, although we can find interspecific and intraspecific variations in queen number and queen-mating frequencies in a single colony. This study aimed to verify the queen number in Pachycondyla striata (Smith) colonies and to evaluate the level of aggressiveness among workers. We collected 14 colonies of P. striata. The behaviors of individuals from five multiple-queen colonies maintained in laboratory were studied by the method of scan sampling. In order to evaluate aggressiveness, dyadic encounters among heterocolonial and homocolonial workers were performed. The results showed that colonies of P. striata can have two or more mated queens (polygynous colonies) besides to monogynous ones (colony containing one queen). Because in polygynous colonies the number of workers was relatively low, such colonies could represent colonies in the foundation phase that characterize a pleometrosis state. In fact, ovarian development analysis from queens showed that the number of queens in the colonies seemed to be unstable. Despite a few cases of oophagy (egg cannibalism), social hierarchy among queens is unclear in comparison to other Pachycondyla species. In addition, aggressiveness increased with distance among nests. Nearby colonies (less than 1 m apart) showed a low level of aggressiveness, suggesting the presence of polydomy, that is, a unique colony can occupy multiple nests. Polygyny associated to polydomy in founding colonies may confer benefits on growth and dispersion of colonies in the studied environments.

Response of the predatory mite Phytoseiulus macropilis (Banks) to volatiles produced by strawberry plants in response to attack by Tetranychid mites (Acari: Phytoseiidae: Tetranychidae)

The attack of phytophagous mites may induce plants to produce volatiles, which in turn may attract predators. The occurrence of multiple phytophagous infestations on plants may influence predator response. In this paper, we investigated whether the attraction of the predatory mite Phytoseiulus macropilis (Banks) to phytophagous-infested plants would change with the simultaneous presence of two tetranichid mites Oligonychus ilicis (McGregor) and Tetranychus urticae Koch. While the former species is rarely found on strawberry plants and is only occasionally found in association with P. macropilis, the latter is commonly found on strawberry plants and is frequently found in association with P. macropilis. Y-tube olfactometer test assays demonstrated that the predator preferred plants infested with T. urticae, avoided plants infested with O. ilicis, and had no preference for plants infested with both phytophagous mite species. These results indicated that the presence of a non-prey species (O. ilicis) on a given plant can alter the response of the predator to one of its prey (T. urticae). The consequences of the predatory behavior determined in this study on the predator ability to control T. urticae population on strawberry plants are discussed.

[Spatial distribution of phytophagous mites (Acari: Tetranychidae) on strawberry plants]

Many phytophagous mites can attack strawberry plants, Fragaria x ananassa, among them the southern red mite, Oligonychus ilicis McGregor, and the two-spotted spider mite, Tetranychus urticae Koch. They are found together feeding on the same plant on the upper and underside of the leaves, respectively. Here we studied the choice for feeding sites of O. ilicis and T. urticae on strawberry plants. The first hypothesis tested whether the feeding site choice would be related to the fitness of the species. The second hypothesis dealt whether the feeding site would be determined by the presence of a heterospecific mite. We evaluated the preference, biology and reproductive success of O. ilicis and T. urticae on the under and upper side surface of strawberry leaves infested or not by the heterospecific. O. ilicis preferred to stay on the upper side surface while T. urticae preferred the underside. The preference for the leaf surface correlated with the reproductive success of the species (measured by the intrinsic growth rate). The choice pattern of feeding sites did not alter when the choice test was applied using sites previously infested by heterospecific. Although O. ilicis and T. urticae, apparently, do not interact directly for feeding sites, there is a chance that the first species induces defenses in strawberry plant enabling to reduce the fitness of the second species. The possibility of those species stay together on strawberry plant increases the damage capacity to the culture.

[Mating behavior of the coffee leaf-miner Leucoptera coffeella (Guérin-Mèneville) (Lepidoptera: Lyonetiidae)]

Despite the importance of Leucoptera coffeella (Guérin-Mèneville) in coffee production worldwide, there is a lack of information on its reproductive biology. This knowledge will help in mass rearing, as well as support the development of behavioral control techniques for this insect. The purpose of the study was to determine the periodicity of mating and male capture and describe the mating behavior L. coffeella. In laboratory, we observed the periodicity of mating with virgin couples of different ages, zero to five days after emergence. Male activity was studied in a 0.7 ha coffee plantation, cv. Catuaí, where Delta traps were installed at 0.5 m above ground, using either virgin females or rubber septa lured with the synthetic sex pheromone. The sequence of mating behavior was studied by making visual observations and recorded of pairs placed on individual plastic tubes. Mating occurred between 4h and 6h of photophase, when the highest frequencies involved pairs with ages of one and three days after emergence, with peak of mating occurring in 5th hour of photophase. The young or old pairs showed significantly copulation frequency and the peak of matings advance in 1h. The highest male capture occurred at 12p.m. and 13 p.m. by traps with virgin females or traps with synthetic sex pheromone lures, respectively. L. coffeella is one insect with diurnal mating and the mating behavior was not different from what is know for other Lepidoptera species.

Identification, synthesis, and field evaluation of the sex pheromone from the citrus leafminer, Phyllocnistis citrella

Using male antenna as the sensing element, three electroantennographic detection (EAD)-active peaks were detected from pheromone gland extracts of the citrus leafminer, Phyllocnistis citrella. Based on gas chromatography (GC)-mass spectrometry and GC-infrared data, the semiochemicals were tentatively identified as a novel pheromone, (Z,Z,E)-7,11,13-hexadecatrienal, a previously identified attractant, (Z,Z)-7,11-hexadecadienal, and (Z)-7-hexadecenal in a ratio of 30:10:1, respectively. Identification was confirmed with synthetic compounds, which gave retention times identical to those of the natural products on three capillary columns with polar and nonpolar phases. While traps baited only with the previously identified attractant alone did not catch any males in Brazil, binary and tertiary mixtures with the major constituents caught significantly more male moths than traps baited with five virgin females.

Towards the identification and synthesis of the sex pheromone of the citrus leafminer, Phyllocnistis citrella Stainton (Lepidoptera: Gracillariidae)

The objective of this work was to characterize the sexual behavior of the citrus leafminer, Phyllocnistis citrella Stainton, as the foundation for the isolation, identification, and synthesis of the complete sex pheromone of this species. Mating occurred in a time window of 2h, starting 1h before the onset of photophase. The large majority of tested insects mated in the first two days after emergence, with no significant difference between mating at day 1 and day 2. A stereotypical courtship and copulation behavior were described for this species. When mating was successful, the copulation was recorded in average for 49.6 min. In Y-olfactometer tests conducted at the time of mating activity, males were strongly attracted to caged virgin females as well as to extracts from putative pheromone glands.

Field evaluation of potential of alarm pheromone compounds to enhance baits for control of grass-cutting ants (Hymenoptera: Formicidae)

Leaf-cutting ants are important economic pests of the Neotropics, and the most common method of control involves the use of insecticidal baits. Baits that are currently available exhibit low attractiveness to grass-cutting species, thus there is a need to develop improved baits. The potential for using alarm pheromone compounds to enhance the attractiveness and subsequent harvest of baits was examined for two economically important species of grass-cutting ant, Atta bisphaerica (Forel) and Atta capiguara (Goncalves). Compounds of the alarm pheromone were applied to rubber septa that were then sealed inside plastic sachets together with citrus pulp-based bait. The best candidate compound for bait enhancement was 4-methyl-3-heptanone. This compound significantly increased the attractiveness of bait sachets to both species. It also appeared to improve the discovery of nearby unenhanced sachets. However, 4-methyl-3-heptanone resulted in only a slight and non-significant improvement in bait harvest. Enhanced and unenhanced bait sachets were applied at a number of positions to obtain an improvement in harvest, but without success. The possible reasons for the lack of an enhancement of harvest and the potential for using alarm pheromone compounds as leaf-cutting ant bait enhancers are discussed.

Identification, synthesis, and field evaluation of the sex pheromone of the citrus fruit borer Ecdytolopha aurantiana

The sex pheromone of the citrus fruit borer Ecdytolopha aurantiana has been identified by gas chromatography coupled to an electroantennographic detector (GC-EAD). The electron impact mass spectral (EI-MS) fragmentation of the major EAD-active peak gave identifying features for a monounsaturated acetate. Further analyses by chemical ionization mass spectrometry (CI-MS), vapor-phase infrared spectroscopy (GC-IR), along with chemical derivatization (DMDS reaction), led to full characterization of the major component as (E)-8-dodecenyl acetate (E8-12 : Ac). The second constituent was identified as the related alcohol, (E)-8-dodecenol (E8-12 : OH). The two compounds were indistinguishable from the authentic synthetic standards in chemical and EAD analyses. Samples of the two compounds were obtained by a facile synthesis utilizing lithium chemistry. Field tests showed that captures in traps baited with a mixture of E8-12 : Ac and E8-12 : OH at 100 : 1 and 10 : 1 ratios were not significantly different from the catches in traps having two virgin females. Dosage tests showed better performance of traps baited with 1 mg than those with 0.1 mg of the pheromone blend, either in 100 : 1 or 10 : 1 ratio.

Sexual behavior and diel activity of citrus fruit borer Ecdytolopha aurantiana

Males and virgin females of the citrus fruit borer Ecdytolopha aurantiana Lima, displayed two flight peaks during a 24-hr period, one at dawn and the other at dusk in an orange grove near Gavião Peixoto, São Paulo, Brazil. During the day, when temperatures were highest and relative humidity lowest, most individuals rested on leaves in the lower and middle crown. Moths rapidly moved higher in the crown after sunset, and many were observed flying above the tree canopy. This behavior was mainly associated with mating. Males and virgin females marked with fluorescent powder of different colors were observed in the dark with the aid of a black light. Mating was observed only in the upper crown of citrus trees from 6:00 to 9:00 PM, with a peak (64%) between 7:00 and 8:00 PM. Males of E. aurantiana were captured in traps baited either with virgin females or female extracts, suggesting the use of a long-range sex pheromone. At close distance (1-2 cm), males and females displayed a short-range communication behavior, with males exposing hairpencils and vibrating their wings. Females were frequently stimulated to contact the body of a male before copulation. The mean duration of copulation was 1 hr 40 min.

Identification of a four-component sex pheromone blend in Bonagota cranaodes (Lepidoptera: Tortricidae)

Analysis of sex pheromone glands of the apple leafroller Bonagota cranaodes Meyrick by gas chromatography coupled with mass spectrometry or electroantennographic detection showed the presence of 14 structurally related acetates and alcohols of the chain length 10-18, including the main pheromone component (E,Z)-3,5-dodecadienyl acetate (E3,Z5-12Ac). Male antennae responded to the main compound, its Z,Z isomer, (E,Z) -3,5-tetradecadienyl acetate (E3,Z5-14Ac), and the monoenes (Z)-5-dodecenyl acetate (Z5-12Ac) and (Z)-9-hexadecenyl acetate (Z9-16Ac). Traps baited with a four-component blend of E3,Z5-12Ac, Z5-12Ac, E3,Z5-14Ac, and Z9-16Ac in a 100:5:5:100 ratio were significantly more attractive than the main compound alone. This improved trap lure is more suitable for monitoring population densities of B. cranaodes, and for detection of the onset of the seasonal flight period. A more complete pheromone blend is of importance also with respect to current attempts to develop mating disruption for control of this major pest of apple in Brazil.

Evaluation of the synthetic major component of the sex pheromone of Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae)

In wind-tunnel bioassays, dispensers loaded with 1 microg of the synthetic major component (3E,8Z, 11Z)-3,8,11-tetradecatrienyl acetate (TDTA) of the sex pheromone emitted by Tuta absoluta (Meyrick) females were found to be highly attractive to conspecific males. Field experiments were conducted to evaluate the efficacy of five trap designs. The best trap, baited with 100 microg of the synthetic sex pheromone caught on average 1,200 males per trap per night, while those baited with virgin females caught only 201 males. The male response to this pheromone is restricted to the same early-morning time window during which females exhibit calling behavior. The high biological activity of the synthetic pheromone suggests that it could be useful for pest monitoring and in mating disruption.

Method for maintenance of coffee leaves in vitro for mass rearing of Leucoptera coffeellum (Guérin-Méneville) (Lepidoptera: Lyonetiidae)

To accomplish systematic studies with coffee leafminer, it is necessary to establish a mass rearing system under artificial conditions. It is possible to rear this species, from egg to adult, under laboratory conditions, without using coffee seedlings but detached leaves maintained in vitro. Synthetic cytokinins are routinely used for maintenance of plant cell and plant tissues in vitro. Two plant growth regulators, benzyladenin and kinetin, in concentrations 10-6 and 10-7 M were used to mantain the leaves. Green leaves collected in the field were maintained in the solution to be tested. Distilled water served as control. The experiment lasted 30 days, a period longer than the necessary for the complete development of the insect. Both artificial cytokinines indeed increased the lifetime of the coffee leaves, maintaining them green and healthy. Leaves placed in the cages for oviposition were attractive to the insect, with significant number of eggs per leaf. In most cases, eggs resulted in individuals that completed the whole developmental cycle. Tests with regulator in different concentrations with healthy leaves showed efficiency. However, we believe that hormone concentrations to be used with mined leaves should be larger, because these when maintained at 10-7 M leaves did not present a satisfactory lifetime. Therefore, tests with mined leaves with different hormone concentrations should be made to find out the ideal concentration for leaf survival. In our laboratory we are successfully using 10-6 M benzyladenin for the maintenance of mined leaves.

Predators impairing the natural biological control of parasitoids

A well known case of ineffective natural biological control: the puzzling coexistence of the coffee leaf miner, Leucoptera coffeellum (Guérin-Mèneville), and its natural enemies was analyzed. Despite being a suitable prey to eight parasitoid species and three wasp species, all occurring simultaneously, the coffee leaf miner too often presents populations far above the damaging level for the coffee plantation. It is demonstrated that predatory wasps and parasitoids interact negatively, possibly because predatory wasps kill parasitized miner's larvae. In doing so, predatory wasps indirectly kill parasitoids, thereby impairing the efficacy of the natural biological control. It is warned that biological control programs should be based on knowledge of food web interactions, rather than simply on strategies involving introduction of exotic natural enemies.

Efeito da densidade e do tamanho de sauveiros sobre a produção de madeira em eucaliptais

Foram coletados os dados sobre a produção volumétrica de madeira de eucalipto dos talhões reflorestados da Mannesmann Florestal Ltda., em João Pinheiro, MG, entre 1991 e 1996. Esses dados foram associados aos de densidade de sauveiros por classe de tamanho, obtidos pelo sistema de monitoramento de formigas cortadeiras da empresa (SIMFOR), no mesmo local e período. Além disso, determinaram-se, para cada talhão, o tipo de vegetação circundante, a distância desses à vegetação nativa e a presença ou não da faixa de vegetação nativa à sua margem. Esses dados foram ordenados numa planilha, tendo o talhão como unidade amostral, e então analisados. A densidade total média de sauveiros encontrada nas áreas de estudo foi suficiente para afetar negativamente o volu -me de madeira produzida. As espécies Eucalyptus camaldulensis Dehnh, E. citriodora Hook e E. tereticornis Smith tiveram sua produção volumétrica mais afetada pelo desfolhamento provocado pelas formigas cortadeiras do que E. cloeziana F. Muell. e E. urophylla S.T. Blake.

Localização e aceitação de dieta artificial contendo feromônio sexual pelo predador Podisus nigrispinus (Dallas) (Heteroptera: Pentatomidae)

Estudou-se o efeito da adição do feromônio sexual sintético de Podisus nigrispinus (Dallas) (Heteroptera: Pentatomidae) na localização e aceitação da dieta artificial utilizada para criação do inseto em laboratório. Avaliou-se o efeito do feromônio sexual completo, dos três componentes que ocorrem em maior proporção no feromônio [a-terpineol, fenilmetanol e (E)-2-hexenal] e de um dos componentes que ocorrem em menor proporção no feromônio (trans-piperitol) sobre a dieta, comparados à dieta pura e a larvas de Musca domestica L. (Diptera: Muscidae). A atração de ninfas de segundo ínstar de P. nigrispinus à dieta artificial foi facilitada pela presença do feromônio sexual adicionado à mesma, sendo que a dieta com feromônio completo mostrou maior atratividade que a dieta pura após cinco ou 120 min do oferecimento da dieta. Porém, larvas de M. domestica foram, na maioria das vezes, mais atrativas que os demais tratamentos. O ganho de peso foi significativamente maior para ninfas alimentadas com dieta com os três componentes majoritários, dieta com trans-piperitol e larvas de M. domestica, apresentando peso médio de 1,4 mg, 1,35 mg e 1,3 mg, respectivamente. P. nigrispinus apresentou menor ganho de peso com dieta pura e dieta com feromônio completo, com ninfas pesando 0,37 mg e 0,6 mg, respectivamente. Os resultados demonstraram que os componentes do feromônio utilizados causaram efeito fagoestimulante sobre o predador P. nigrispinus, e que podem atuar auxiliando estes insetos no processo de localização do alimento.

Biologia reprodutiva de Euschistus heros (F.) (Heteroptera: Pentatomidae)

Estudou-se a biologia de Euschistus heros (F.) (Heteroptera: Pentatomidae) em laboratório sob 24±0,5ºC, 70±10% UR e fotofase de 14 h. O tempo médio de desenvolvimento até adulto foi de 38,6 d, sendo o 2º estádio ninfal, o de maior índice de mortalidade (10,4%). A longevidade de E. heros variou de acordo com o sexo e atividade sexual. Machos e fêmeas atingiram a maturidade sexual com 11,4 e 11,2 d, respectivamente. O tempo médio para a colocação de posturas, após o primeiro acasalamento, variou de 9,1 d para fêmeas, que acasalaram uma única vez, até 13,9 dias para fêmeas que acasalaram várias vezes durante o período de sobrevivência. O número médio de ovos por fêmea variou de 108,5 até 130,5, dependendo do número de acasalamento das fêmeas estudadas. Juntamente com a deposição das massas de ovos, foi observada a colocação de posturas isoladas com percentagens de 71,7 e 77,8 respectivamente, também dependendo do número de acasalamentos.

Fenologia e dinâmica populacional da broca do café Hypothenemus hampei (Ferr.) relacionadas às fases de desenvolvimento do fruto

A dinâmica populacional da broca do café, Hypothenemus hampei Ferrari foi estudada em Paula Cândido, MG, Brasil (20º S; 660 m altitude, 1391 mm precipitação anual média, 18º C temperatura média anual). Semanalmente, de novembro de 1992 a maio de 1993, acompanhou-se: os estádios de desenvolvimento fenológico dos frutos de café (chumbinho, verde, início de maturação, cereja e seco); os números de frutos brocados em cada estádio fenológico; e o número de indivíduos da broca em cada estádio de desenvolvimento, presentes nos frutos brocados. Verificou-se que existem no mínimo três gerações completas da broca desenvolvendo-se durante o período de formação dos frutos. A preferência da broca para atacar frutos em diferentes estagios de maturação é descrita por uma equação logistica em função da idade dos frutos. Depois de infestarem o fruto as fêmeas aguardam até o início da maturação dos frutos para iniciar a oviposição. Os resultados indicam que medidas de controle devem ser dirigidas ao período compreendido entre o final da safra e o início da maturação dos frutos na safra seguinte, atingindo os adultos antes do início da oviposição.

Avaliação do comportamento reprodutivo e do feromônio sexual sintético de Mocis latipes (Guenée) (Lepidoptera: Noctuidae)

Durante a escotofase, fêmeas de Mocis latipes (Guenée) pousaram em superfícies verticais e iniciaram o comportamento de chamamento aos machos, abaixando levemente as asas, levantando o final do abdômen e protraindo o ovipositor. As fêmeas começaram a chamar a partir do 2º dia de idade, sendo o pico de chamamento no 4º dia. O início do chamamento aconteceu na 2ª hora da escotofase e o máximo de indivíduos chamando aconteceu na 3ªhora. As proporções entre os componentes (Z,Z,Z)-3,6,9-heneicosatrieno e o (Z,Z)-6,9-heneicosadieno de 70:30 e 60:40 mostraram ser as mais atrativas aos machos de M. latipes em túnel-de-vento. Os machos iniciaram a resposta às fêmeas 24 h após a emergência, na 3ª hora da escotofase. São descritas as seqüências de corte e cópula e apresentada uma análise comparativa do comportamento reprodutivo de M. latipes e Anticarsia gemmatalis (Hübner).

Field tests of predaceous pentatomid pheromones and semiochemistry of Podisus and Supputius species (Heteroptera: Pentatomidae: Asopinae)

Traps baited with synthetic pheromones for either Podisus nigrispinus (Dallas) or Supputius cincticeps (Stäl) were field tested at the Universidade Federal de Viçosa, Minas Gerais, Brazil, beginning September 7, 1995. No P. nigrispinus were caught but, in September and October, several adult males and females of P. distinctus (Stäl) were caught along with a few adults of S. cincticeps and two females of a tachinid fly parasitoid, Cylindromyia atra Roeder. Chemical analysis of the pheromone gland extract of P. distinctus males indicated that this species produces a pheromone containing the major compounds of P. nigrispinus and S. cincticeps. Therefore, on November 6 a set of traps was baited with the pheromones of both P. nigrispinus and S. cincticeps, and monitored in the field until February 6, 1996. During this second phase of the study, six times more P. distinctus were caught in the combined pheromone treatment than in traps baited only with the P. nigrispinus pheromone. The phenology of these neotropical asopines is like that for P. maculiventris (Say) in temperate North América, although fewer predators and host-seeking parasitoids were caught. Suspected pheromones were also identified for P. rostralis (Stäl) from Goiás, Brazil, and P. sagitta (Fabricius) from Honduras. In addition, the chemistry of other exocrine secretions from these neotropical species was investigated.

(3E,8Z,11Z)-3,8,11-tetradecatrienyl acetate, major sex pheromone component of the tomato pest Scrobipalpuloides absoluta (Lepidoptera: Gelechiidae)

The major sex attractant emitted by Scrobipalpuloides absoluta females is shown to be (3E,8Z,11Z)-3,8,11-tetradecatrien-1-yl acetate by a novel strategy involving the random reduction of double bonds, followed by methylthiolation of the reduced products. Each female sex gland contains ca. 1-5 ng of this pheromone. This triene ester, synthesized by a stereospecific procedure, shows spectral and gas chromatographic properties identical to those of the natural substance. In field tests and wind tunnel bioassays, the synthetic ester was found to be highly attractive to conspecific males. The male response to this pheromone, however, is restricted to the same early-morning time window during which females exhibit calling behavior.