Adalécio Kovaleski

Why demographic and modeling approaches should be adopted for estimating the effects of pesticides on biocontrol agents

Recent studies have shown that simplistic measures of toxicity such as the LC50 do not provide enough information about the actual effects that may occur in pesticide-exposed populations over longer time periods than a few days. In this paper we discuss the use of demography and population modeling for estimation of pesticide effects on pest and beneficial species and argue that these new approaches are essential to further our understanding of the potential impacts that pesticides might have on both pest and beneficial species such as biological control agents.

Movement of Anastrepha fraterculus from native breeding sites into apple orchards in Southern Brazil

We report movements exhibited by adults of Anastrepha fraterculus (Wiedemann) (Diptera: Tephritidae) from patches of native forests into apple orchards in Southern Brazil. Two mark‐release‐recapture experiments were conducted using wild flies. Released flies behaved as wild unmarked flies, and periods of peak captures of marked adults coincided with those of unmarked ones. In the first experiment (December 94), out of 2154 released adults, 7.1% were recaptured from day 2 through day 20 after release. Captures peaked from day 7–9 after release. Most marked flies (94.7%) were trapped within 200 m of the release point but eight adults (seven females and one male) were captured in traps placed in an apple orchard, 400–800 m from the release point. The vegetation found between forest and orchard consisted of pastures and annual crops. In the second experiment (January 95), a total of 3284 flies was released in an area where native host plants were abundant and located at ca. 900 m from an apple orchard. In all, 37.1% of marked flies were captured, 99.0% of them at a distance of less than 200 m from the release point. Four adults were captured in an apple orchard, 7 to 24 days after release. They may have reached the orchard through a large and continuous area of native forest. Our results unequivocally demonstrate that A. fraterculus adults are able to disperse from native forests where they originate and invade apple orchards, probably foraging for food and oviposition sites.

Evolution of pre-zygotic and post-zygotic barriers to gene flow among three cryptic species within the Anastrepha fraterculus complex

Tropical tephritids are ideally suited for studies on population divergence and speciation because they include species groups undergoing rapid radiation, in which morphologically cryptic species and sister species are abundant. The fraterculus species group in the Neotropical genus Anastrepha is a case in point, as it is composed of a complex of up to seven A. fraterculus morphotypes proposed to be cryptic species. Here, we document pre‐ and post‐zygotic barriers to gene flow among adults of the Mexican A. fraterculus morphotype and three populations (Argentina, Brazil, and Peru) belonging to two separate morphotypes (Brazilian 1 and Peruvian). We unveiled three forms of pre‐zygotic reproductive isolation resulting in strong assortative mating. In field cages, free‐ranging male and female A. fraterculus displayed a strong tendency to form couples with members of the opposite sex belonging to their own morphotype, suggesting that male pheromone emission, courtship displays, or both intervene in shaping female choice before actual contact and coupling. In addition, males and females of the Peruvian morphotype became receptive and mated significantly later than adults of the Mexican and Brazilian 1 morphotypes. After contact, Mexican females exhibited greater mating discrimination than males when facing adults of the opposite sex belonging to either the Peruvian or the Brazilian 1 morphotype as evidenced by vigorous resistance to penetration once they had been forcefully mounted by heterotypic males. Forced copulations resulted in production of F1 hybrids that were either less viable (and partially fertile) than parental crosses or even sterile. Our results suggest that the Mexican morphotype is a distinct biological entity and that pre‐zygotic reproductive isolation through divergence in courtship or male‐produced pheromone and other mechanisms appear to evolve faster than post‐zygotic isolation in the fraterculus species group.

Dissimilaridade genética de linhagens de Trichogramma Westwood (Hymenoptera: Trichogrammatidae) através de marcadores moleculares ISSR

Demands for sustainable agricultural systems have forested the development of biological control techniques, such as the use of the egg parasitoid Trichogramma Westwood. However, the arduous identification of the parasitoid at the species level, due to the tiny size and the morphological similarities is an obstacle to increasing its use. Molecular markers are useful to reach the specimen genome and avoid environmental effects that could misguide identification. Several molecular markers techniques are available and the ISSR technique has been used to differentiate close individuals, due to its high polymorphism level, reproducibility and low cost. The objective of this study was to measure the level of genetic differentiation among five lines of Trichogramma, using ISSR markers: three belonging to the species T. pretiosum Riley, one to T. atopovirilia Oatman & Platner and one to T. bruni Nagaraja. Morphological identification of the parasitoids was conducted at ESALQ/USP - Piracicaba, SP. After DNA removal and standatization, PCR reactions were performed with 26 ISSR primers; 11 of them were selected because they presented greater polymorphism and consistency. Molecular data were converted into a binary matrix and analyzed (NTSYS v. 2.1). The 11 primers produced 172 polymorphic sections. Genetic similarity ranged from 19% to 96%, showing that the ISSR technique can efficiently identify DNA polymorphism in Trichogramma. Results also indicate important inter and intra-specific variations among the parasitoid lines.

Exigências térmicas e estimativa do número de gerações de Bonagota cranaodes (Meyrick) (Lepidoptera: Tortricidae) em regiões produtoras de maçã do Sul do Brasil

The thermal requirements of the apple leafroller Bonagota cranaodes (Meyrick) (Lepidoptera: Tortricidae) were estimated at four constant temperatures (14, 18, 22 e 26oC) in laboratory (70±10% R.H. and 14:10L:D). Artificial diet was fed to the insects. The low threshold temperature and thermal requirement for eggs, larvae, pupae and biological cycle (egg to adult) were 7,2 e 140; 7,1 e 410; 6,4 e 183 e 6,8oC and 745 GD, respectively. It was estimated that this species complete three to four annual generations. In the three regions, one generation occurs during the winter.

Differences in sperm storage and remating propensity between adult females of two morphotypes of the Anastrepha fraterculus (Diptera: Tephritidae) cryptic species complex.

The South American fruit fly, Anastrepha fraterculus, is a complex of cryptic species composed of at least seven morphotypes. Some of them, such as the Peruvian and Brazilian 1 morphotypes (which include Argentinean populations), exhibit strong pre-copulatory isolation, yet it is possible to obtain heterotypic crosses when forcing copulation of adults under laboratory conditions. The cross involving Peruvian males and Argentinean females produces F1 offspring with reduced viability in terms of egg hatch. This low hatchability could be caused by a reduced amount of sperm transferred to and stored by females mated with heterotypic males, which in turn could affect their post-copulatory behaviour. To test these hypotheses, we investigated sperm transfer and female mating and remating behaviour for homotypic and heterotypic crosses between adults of two morphotypes (Brazilian 1 [Argentina] and Peruvian [Peru]) of the A. fraterculus cryptic species complex. As reported before, Argentinean males and females mated earlier in the day than the other three mating combinations. Peruvian females engaged in shorter copulation times than Argentinean females. Peruvian females tended to store smaller quantities of sperm than Argentinean females, and almost a half of the crosses involving Argentinean males and Peruvian females were unsuccessful (no sperm transfer). However, there was no evidence that the cross between Peruvian males and Argentinean females resulted in storage of a critically small amount of sperm (posing risk of sperm shortage). Argentinean females were more willing to remate than Peruvian females, irrespective of male morphotype, but latency to remating was not affected by male or female morphotype. This study shows that mating behaviour differs between some of the A. fraterculus complex morphotypes, with female but not male morphotype determining female likelihood to remate.

Biologia e exigências térmicas de Trichogramma pretiosum Riley (Hymenoptera: Trichogrammatidae) sobre ovos de Bonagota cranaodes (Meyrick) (Lepidoptera: Tortricidae)

Este trabalho teve como objetivo estudar a biologia de Trichogramma em laboratorio, visando a sua utilizacao em programas de manejo integrado para o controle de Bonagota cranaodes na cultura da macieira. A biologia de Trichogramma bruni Nagaraja e de duas linhagens (L3 e L4) de Trichogramma pretiosum foi realizada sobre ovos de B. cranaodes. Alem disso, suas exigencias termicas e o numero anual de geracoes tambem foram determinados. A linhagem L3 apresentou maior parasitismo (52,3%), no entanto, a viabilidade foi semelhante entre as linhagens estudadas, com ciclo evolutivo de 8,7 dias, longevidade de femeas de 10,65 dias, temperatura base de 11,35°C e constante termica de 128,70GD. O numero de geracoes anuais dessa linhagem em laboratorio foi de 47,22 e de 13,59 geracoes para as condicoes da regiao de Vacaria - RS. O baixo parasitismo de T. bruni e da linhagem L4 de T. pretiosum pode estar ligado a camada de secrecao existente sobre as posturas da praga. Embora este parasitismo seja considerado baixo, a utilizacao destas linhagens nao pode ser descartada dentro do sistema de Producao Integrada da Maca, devendo novos estudos serem realizados em condicoes de campo.

Desenvolvimento e exigências térmicas de Trichogramma pretiosum Riley (Hymenoptera: Trichogrammatidae) em ovos de Bonagota cranaodes (Meyrick) (Lepidoptera: Tortricidae)

The aim of this study was to evaluate the development of Trichogramma pretiosum Riley on eggs of Bonagota cranaodes (Meyrick) under different temperatures. B. cranaodes eggs were maintained under seven constant temperatures (14, 18, 20, 22, 25, 28 and 30oC), 70 ± 10% R.H. and, 14 h L. Forty replicates with 20 parasitized eggs each were kept in glass tubes (8.5 x 2.5 cm) covered with a plastic film. The method of hyperbole was used to calculate the temperature threshold (Tb) and the thermal constant (K). The Tb obtained was 11.9oC and to thermal constant was 153,4 DD. The most favorable temperature range was from 25oC to 30oC, at which the shortest egg-adult development period and the highest survivorship were observed.

Concentração e tempo de liberação do feromônio sexual sintético de Bonagota cranaodes (Meyrick) (Lepidoptera: Tortricidae) na cultura da macieira

The effect of five dosis of the synthetic sex pheromone of Bonagota (=Phtheochroa) cranaodes (Meyrick) (a 9:1 blend of E,Z 3,5 dodecanyl acetate and Z9 hexadecenyl acetate) and the duration of the synthetic pheromone under field conditions were evaluated in a commercial apple orchard in Vacaria, RS, Brazil. No significant differences were observed among concentrations ranging from 0.25 to 3.0 mg per rubber septum. Delta traps baited with two virgin females were ca. four times more attractive than those baited with the synthetic sex pheromone at the dosis of 3 mg per septum. Rubber septa containing this amount of synthetic sex pheromone remained attractive for 120 days. Comparing number of males captured in traps baited with the synthetic pheromone and males captured in traps with virgin females during seven months, a significant and positive correlation is observed, demonstrating that the seasonal variations in B. cranaodes population density are detected using the synthetic sex pheromone in delta traps.

Persistência de agrotóxicos utilizados na produção integrada de maçã a Trichogramma pretiosum

No sistema de Producao Integrada de Maca (PIM) o controle biologico de pragas e uma importante tatica de controle, no entanto, a sua utilizacao pode ser limitada pela utilizacao de agrotoxicos. Nesse contexto, objetivou-se, com este trabalho, avaliar a persistencia (duracao da atividade nociva) de dez agrotoxicos recomendados na PIM sobre o parasitoide de ovos Trichogramma pretiosum. Insetos adultos foram expostos ao contato com residuos de agrotoxicos pulverizados sobre folhas de videira cv. Isabel, sendo avaliado o efeito residual dos agrotoxicos sobre o parasitismo de T. pretiosum, aos 3, 10, 17, 24 e 31 dias apos a pulverizacao, de acordo com a metodologia sugerida pela IOBC. O parâmetro utilizado para classificar os agrotoxicos foi a reducao no parasitismo. Os resultados demonstraram que os produtos comerciais/ingredientes ativos (g ou mL da formulacao comercial.100 L-1): o inseticida Malathion® 1000 CE/malationa (100) e os fungicidas Domark® 100 CE/tetraconazole (50), Manzate® 800/mancozebe (200), Mancozebe Sipcam®/mancozebe (200) e Metiltiofan®/tiofanato metilico (90) foram classificados como de vida curta ( 31 dias de acao nociva) a T. pretiosum.