A. Raga

Population dynamics of phytophagous and predaceous mites on coffee in Brazil, with emphasis on Brevipalpus phoenicis (Acari: Tenuipalpidae)

The objective of this work was to study the population dynamics of Brevipalpus phoenicis (Geijskes) and predaceous mites (Phytoseiidae and Stigmaeidae), as well as the interactions among these mite species, in a coffee plantation in the State of São Paulo, Brazil. Tydeids were also evaluated because of the high frequency of these mites on coffee plants. Samples of leaves, branches and fruits were taken fortnightly, from April 2001 to June 2003, from plants randomly chosen in the coffee plantation. B. phoenicis mites were found on leaves in higher number during the drier periods of the year. Among the predaceous mites, Euseius citrifolius Denmark & Muma and Euseius concordis (Chant) were the most frequent species on the surface of leaves. During the evaluations, 72,534 domatia were cut and opened to remove the mites, from 6,360 leaves examined. Zetzellia malvinae Matioli, Ueckermann & Oliveira was the most frequent predator species found inside domatia. Significant correlations were observed between population dynamics of, among others, E. concordis and B. phoenicis, Z. malvinae and B. phoenicis, and Z. malvinae and E. concordis. Significant correlations were also verified between the number of domatia and the population densities of B. phoenicis, E. concordis, Lorryia sp. and Z. malvinae. Interactions between predator–prey and predator–predator on coffee plants are discussed. The influence of the meteorological factors temperature and precipitation on the most frequent mite species is also discussed.

Seleções para resistência e suscetibilidade, detecção e monitoramento da resistência de Tetranychus urticae ao acaricida clorfenapir

SELECTIONS FOR RESISTANCE AND SUSCEPTIBILITY, DETECTION AND MONITORING OF RESISTANCE TO THE ACARICIDE CHLORFENAPYR IN TETRANYCHUS URTICAE KOCH (ACARI: TETRANYCHIDAE) Problems associated with acaricide resistance in Tetranychus urticae Koch have been recorded in several countries including Brazil. The objective of this study was to characterize the resistance of T. urticae to the acaricide chlorfenapyr and to evaluate the resistance frequency in commercial fields of six crops in the State of Sao Paulo (SP). Selections for resistance and susceptibility to chlorfenapyr were performed in a population of T. urticae collected in 2002 from a commercial chrysanthemum field in Holambra county, SP. After six selections for resistance and five selections for susceptibility, susceptible (S) and resistant (R) strains of T. urticae to chlorfenapyr were obtained. The resistance ratio (R/S) at the LC50 reached values of 571-fold . A discriminating concentration of 37.4 mg L -1 of active ingredient (A.I.) was established for monitoring chorfenapyr resistance in T. urticae . Twenty one mite populations were collected from different crops (papaya, strawberry, bean, tomato, chrysanthemum, rose), in various counties

Effect of Hot-Water Treatment in the Mortality of Fruit Fly Eggs

This work was carried out to verify hot water treatment efficiency on the mortality of Ceratitis capitata eggs. The following combinations of temperatures and immersion times were applied using a bi-factorial design: temperatures of 25°C (control ), 42, 44, 46, 48 and 50°C, and immersion times of 0, 20, 30, 40, 50, 60 and 90 min. Eight replicates were evaluated for each treatment, each one containing 20 eggs, with a maximum age of 24 hours, separated by electron microscope, placed in porcelain crucibles (capacity of 50 ml) containing 10 ml of distilled water. After the treatment, the eggs were removed, transferred to petri dish plates and stored in B.O.D. at 25°C. After 24 hours of the process, the plates were evaluated for the mortality of eggs. According to the results, we concluded that C. capitata eggs were tolerant to hot water up to 44°C for 20 min. Therefore, the use of temperatures equal to or above 46°C for 20 min or more promoted 100% of mortality. The mortality of C. capitata eggs increased with the increase of the temperature and exposition time.