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Bidder’s organ has been cited as a structure present only in males of the toad family Bufonidae, and is used as a systematic characteristic. In this study, we examined females of Bufo ictericus in order to ascertain whether this structure also occurs in females. Macroscopic observations and light microscopy technique for paraffin embedding were performed. This study reveals that females of Bufo ictericus can have a Bidder’s organ with typical morphology, and in close spatial relationship with the ovary. This suggests that the Bidder’s organ is not an exclusive structure for male toads, but that it may also occur in active females.

Open Access
In: Contributions to Zoology

Summary

Meloidogyne enterolobii is a species capable of overcoming plant resistance moderated by the Mi-1 gene, which is effective against most species of root-knot nematode. This study evaluated the effect of induced resistance in tomato plants (Solanum lycopersicum ‘H-9553’) with the Mi-1 gene against the development and reproduction of M. enterolobii. Seedlings of tomato ‘H-9553’ were transplanted into pots, inoculated with 2000 eggs and second-stage juveniles (J2) of M. enterolobii and treated with Acibenzolar-S-Methyl, Bacillus subtilis, B. subtilis + B. licheniformis + Trichoderma longibrachiatum and extract of Reynoutria sachalinensis. The plants were collected at 5, 10, 15, 20, 25 and 30 days after inoculation (DAI) for the analyses of nematode penetration and development, and at 30 DAI for nematode reproduction. The use of B. subtilis increased fresh root weight when compared to the other treatments (20 DAI). There was a reduction in penetration of J2 in the roots of plants subjected to different resistance inducers. The population density of M. enterolobii was significantly reduced only when plants were treated with R. sachalinensis, indicating it as a potential resistance-inducing agent in tomato plants.

In: Nematology

Abstract

The root-knot nematode, Meloidogyne enterolobii, is a major disease of guava, Psidium guajava, in Brazil and other countries. Egg-pathogenic fungi are considered potential biological control agents of root-knot nematodes and are associated with suppression of Meloidogyne spp. Glasshouse experiments were conducted in order to evaluate the effect of the fungi Paecilomyces lilacinus and Pochonia chlamydosporia on a population of M. enterolobii growing on guava plants. Guava seedlings of about 15-20 cm growing in plastic bags were inoculated with 10 000 eggs of M. enterolobii plant−1. Two months later, three isolates of P. lilacinus and one isolate of P. chlamydosporia were inoculated in the infested plants. The effect of the treatments was evaluated 6 months later. Although plant infection by nematodes was not attenuated, the number of eggs (g roots)−1 fell significantly. The number of egg masses infected with the fungi was inversely correlated with the number of eggs found in the roots. The most effective result (61.5% of control) was obtained with the isolate CG1003 of P. chlamydoporia, which was originally isolated from eggs of M. enterolobii in Brazil, followed by P. lilacinus (CG959 and CG1038) with about 40% of control. These fungi showed the ability to colonise healthy guava roots in glasshouse experiments. These results suggest that P. chlamydosporia can be selected as a potential biological control agent to be employed with other strategies in integrated management to control M. enterolobii on guava.

In: Nematology

Summary

Root-knot nematodes (Meloidogyne spp.) are responsible for various significant crop losses, which require taking integrated control measures. The present study aimed to identify a possible sustainable approach to the management of Meloidogyne javanica in vegetable crops using an organic compound based on pequi (Caryocar brasiliense) fruit residues. A pot experiment was conducted using cultivars of tomato and lettuce susceptible to M. javanica, with three amendments including inorganic fertiliser, cattle manure and five doses of organic compost with pequi residues. All treatments were inoculated with second-stage juveniles of M. javanica to simulate the root-knot nematode disease in field conditions. Increasing doses of organic compost with pequi residues from 5 kg m−3 to 30 kg m−3 promoted a significant decrease in the nematode population in both cultures evaluated. Organic compost (30 kg m−3) reduced the numbers of galls and eggs of M. javanica by 41.6 and 46.5% in tomato roots, and by 80.3 and 59.2% in lettuce roots, respectively, compared with non-treated control. Organic compost also increased crop development considerably. In general, there was a 43.0% increase in plant development compared to non-treated control. Hence, organic compost of pequi residues could be an alternative to toxic chemical nematicides and recommended as eco-friendly management of M. javanica in vegetable crops.

In: Nematology