Angelo Pallini

Potencial de defensivos alternativos para o controle do ácaro-branco em pimenta "Malagueta"

Lethal and sublethal effects of alternative pesticides on the broad mite Polyphagotarsonemus latus were evaluated. Chilli pepper plants (6 cm high) were sprayed with one of the following treatments: biofertilizer Supermagro, Vicosa mixture (a nutrient amended Bordeaux mixture), lime sulfur, abamectin and water. After spraying, 10 females of P. latus were transferred to each plant. Six days after, the number of mites per plant was counted and the instantaneous rate of increase (ri) was evaluated for each treatment. The population of P. latus on plants treated with lime sulfur, Vicosa mixture and abamectin was significantly lower than on plants treated with biofertilizer and water. Negative values of the instantaneous rate of increase (ri), were obtained for P. latus on plants treated with lime sulfur (ri = -0.2922) and with Vicosa mixture (ri = -0.0301). Positive values were obtained for mites on plants treated with biofertilizer (ri = 0.2373) and water (ri = 0.1971), which indicate increase of P. latus population on these plants. It was not possible to calculate ri for mites on abamectin treated plants, because all females died at the beginning of the experiment. Lime sulfur and Vicosa mixture showed potential for controlling broad mite P. latus on chilli pepper Malagueta.

Inibidores de proteases de hospedeiros nativos e exóticos e sua ação em intestinos de lagartas de Thyrinteina leucoceraea

Insects may cause considerable losses to plants, but some insects inhabit plants without causing any damages. For example, Thyrinteina leucoceraea, found in the guava plants, and a native Myrtaceae family host, does not cause any serious damage. However, Eucalyptus ssp., novel hosts (also Myrtaceae) in Brazil and introduced from Australia, suffer attacks by T. leucoceraea, which became a severe pest of this plant. Plants can defend themselves against herbivores using proteinase inhibitors which reduce insect development and lead them to death. Thus, based on studies on the development of T. leucoceraea caterpillars on these two hosts and plant defense, this work aimed to verify the production of proteinase inhibitors by guava and eucalyptus plants upon T. leucoceraea attack, and to observe the biochemical response of the midgut of the caterpillars to these inhibitors. Eucalyptus plants produced more proteinase inhibitors than guava plants. The good development of T. leucoceraea in eucalyptus plants despite the high concentration of proteinase inhibitors may be due to an increase of enzyme activity in the caterpillars midgut. Our data suggest that T. leucoceraea developed an adaptation to the proteinase inhhibitor produced by eucalyptus plants, by increasing serine-proteinase and cys-proteinase activities.

Aspectos biológicos de Thyrinteina arnobia (Lep.: Geometriadae) provenientes de lagartas criadas em folhas de Eucalyptus cloeziana ou de Psidium guajava sob condições de campo

Eucalyptus plantations in Brazil may be damaged by native insects of many orders including Orthoptera, Coleoptera and Lepidoptera. These insects feed on Brazilian tree species of the family Myrtaceae to which the genus Eucalyptus belongs. The Lepidoptera Thyrinteina arnobia Stoll (Lepidoptera: Geometridae) is the most harmful defoliator of Eucalyptus in Brazil. The objective of this work was to evaluate biological aspects of T. arnobia adults originated from caterpillars fed on guava or eucalyptus plants. Adults of T. arnobia originated from caterpillars reared with eucalyptus or guava leaves presented significant differences for most biological aspects evaluated, except for duration of preoviposition and oviposition periods and sex ratio. This shows that species feeding on host plants related to eucalyptus can cause considerable damage in reforestation with species of this genus. T. arnobia insects are still undergoing an imposed adaptation process to eucalyptus plants and likely feed on these plants to escape from pressure by physical and chemical barriers of Brazilian native Myrtaceae.