Ailton R. Monteiro

Effect of population densities of Pratylenchus brachyurus on the growth of cotton plants

The effect of different population densities of Pratylenchus brachyurus on the growth of cotton (Gossypium hirsutum) plants was studied in three greenhouse experiments, using cultivars IAC 20 and IAC 22. Both cultivars proved to be good hosts to the nematode, which however did not affect plant height and affected only slightly fresh root weight and dry top weight of both cultivars, even at the highest population density (over 9,000 nematodes/plant).

Molecular and morphometric analyses of Xiphidorus species (Nematoda: Longidoridae)

Xiphidorus nematodes are indigenous to Latin America and have a restricted geographical distribution compared to Xiphinema. A principal component analysis (PCA) based on eight morphometric characters from 39 South American populations clearly separated populations previously identified as X. achalae, X. amazonensis, X. minor, X. saladillensis and X. uruguayensis and three undescribed Xiphidorus species. However, populations identified as X. balcarceanus, X. parthenus and X. yepesara did not form similar discrete groupings and exhibited either considerable morphological variability or were incorrectly identified. Maximum likelihood phylogenetic trees derived from both 18S rDNA and ITS-1 sequences discriminated six Xiphidorus species (X. balcarceanus, X. minor, X. parthenus, X. yepesara, and two undescribed Xiphidorus species) from Brazil. Also, restriction analysis of PCR products derived from the ITS-1 region using three restriction enzymes (Taq I, Rsa I and Hin f I) yielded repeatable patterns that clearly discriminated these six Xiphidorus species. Sequence divergence was noted between X. parthenus and X. yepesara. Our morphometric and molecular data suggests that X. parthenus and X. yepesara are distinct species contrary to their previous subspecific status.

REAÇÃO DA PINHA (Annona squamosa L.) A TRÊS ESPÉCIES DE FITONEMATÓIDES

The host reaction of custard apple (Annona squamosa) to three species of nematodes was studied. The plants were inoculated with 10,000 specimens per plant of Radopholus similis, Rotylenchulus reniformis or Meloidogyne exigua. Nematode population and plant growth parameters were evaluated three months later. The results showed that custard apple was resistent to Rotylenchulus reniformis and Meloidogyne exigua but intolerant to Radopholus similis.

Additional data on Aorolaimus banoae (Rashid, Geraert & Sharma, 1987) from the Brazilian Atlantic forest

A population of the little-known species Aorolaimus banoae was collected in the municipality of Cananeia, Sao Paulo state, Brazil, in a remnant of the once far more extensive Brazilian Atlantic Forest. As the original description of this species was based on only three females and nine males, additional morphometric and morphological data, including SEM studies, are presented. It is suggested that A. banoae is a member of the original fauna associated with the coastal Atlantic forest.

Alcachofra: nova planta hospedeira de Pratylenchus penetrans no estado de São Paulo, Brasil

It is reported the occurrence of lesion nematode, Pratylenchus penetrans on artichoke in the State of Sao Paulo, Brazil. The population density estimated was 224 specimens in the soil (250cm3) and 720 in the roots (10g). Attacked plants showed growth reduction.