ABSTRACT Interspecific competitions are important mechanisms in structuring ecological communities, including agroecosystems, in which different species may share the same food resource. In melons, two major pests coexist in time and space, Liriomyza sativae Blanchard (Diptera: Agromyzidae) and Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae). The former feeds on the leaf mesophyll, while the latter on the phloem sap. Therefore, the same niche exploitation can trigger interactive processes between both populations. The present research aimed to determine if there are positive or negative interactions between whiteflies and leafminers under field conditions. The experiment was conducted in four commercial melon fields in northeast Brazil in two planting seasons. Thirty random plants were weekly selected for detection of whitefly nymphs and leafminer larvae throughout the entire crop cycle. The data was organized and analyzed considering the species abundance of L. sativae (larvae) and B. tabaci (nymphs and adults) in the same plant. Thus, the coabundance of species was investigated by using regressions with Poisson errors. The results suggest different fractions of negative, positive and neutral (not significant relationships) coabundance between the two species. Among 34 significant interactions, 56% were negative, suggesting that more than half of significant interactions are due to interspecific competition with negative coabundance.

RESUMO:Os estudos foram conduzidos em pomares de goiaba, em dois municípios do estado de Sáo Paulo. Em Monte Alegre do Sul, o levantamento foi realizado em uma estação experimental da Agência Paulista de Tecnologia dos Agronegócios, na qual foram cole tadas 13 espécies de Anastrepha, desde janeiro de 2002 a dezembro de 2003. Em Monte Alto, em pomar comercial, foram coletadas oito espécies, desde janeiro a dezembro de 2004. Anastrepha fraterculus foi a espécie mais frequente nos dois municípios. Os parâmetros cli máticos exerceram baixa influência sobre a flutuação populacional das espécies de Anastrepha, nos dois pomares. Os picos populacio nais das espécies de Anastrepha mais abundantes variaram entre os pomares. A disponibilidade de frutos no pomar e nos entornos é o fator que determina o tamanho das populações de moscas-das-frutas.

ABSTRACT:Studies were carried out in guava orchards, in two municipalities of the State of Sâo Paulo, Brazil. In Monte Alegre do Sul, the survey was done in an experimental station of Agência Paulista de Tecnologia dos Agronegócios, in which 13 Anastrepha species were collected from January 2002 to December 2003. In Monte Alto, in a commercial orchard, eight species were captured, from January to December 2004. Anastrepha fraterculus was the most frequent species in both municipalities. The climatic parameters had low influence on the population fluctuation of the Anastrepha species in both orchards. The most common population peaks of Anastrephaspecies varied between the orchards. The availability of fruits in the orchard and nearby them is the factor that determines the size of the fruit fly populations.

O objetivo desse trabalho foi descrever os aspectos biológicos e morfométricos da lagarta desfolhadora do paricá, Syssphinx molina (Cramer), e fazer recomendações para a criação do inseto. O ciclo de vida foi de 62,9 dias com períodos médios para as fases de ovo, lagarta, pré-pupa e pupa de 5,6; 31,1; 2,2 e 16,6 dias, respectivamente. A viabilidade das pupas foi de 60,5% para fêmeas e 48,6% nos machos. A razão sexual foi de 0,5 e a produção média de 182,3 ± 2,2 ovos por fêmea com viabilidade de ovos de 24,3%. A longevidade média foi de 7,9 ± 2 e 8,1 ± 3 dias para fêmeas e machos, respectivamente. Outros parâmetros foram igualmente observados e comparados com a descrição de outras espécies de Saturniidae.

The objective of this research was to describe the biological and morphometric aspects of the parica tree defoliator, Syssphinx molina (Cramer), and make recommendations about the insect rearing. The life cycle was 62.9 days with mean periods for the egg, larval, pre-pupal and pupal stages of 5.6, 31.1, 2.2 and 16.6 days respectively. The pupal viability was 60.5% for females and 48.6% for males. The sexual ratio was 0.5 with mean production of 182.3 ± 2.2 eggs per female and egg viability of 24.3%. The mean longevity was 7.9 ± 2 and 8.1 ± 3 days for females and males respectively. Other parameters were also observed and compared with description of other Saturniidae species.