Tiny “Giant”

The terms Tubixaba and Tuxaua are synonymous with Morubixaba, whose translation from indigenous dialect into Portuguese is patrão, chief, cacique, meaning the chief of chiefs or chief of chiefs. Certainly, the chosen name was inspired by the body dimensions of adult nematodes, in particular their length, which can be more than one centimeter.

The nematode Tubixaba tuxaua (Aporcelaimidae) had its first report in the 80s, when described in association with the rhizosphere of soybean plants cultivar Bragg with symptoms of dwarfism. Because it is different from other phytoparasitic nematodes, T. tuxaua at the time of its description, it was considered a potential parasite of soybeans and wheat.

In addition to these cultures, T. tuxaua affects crops such as corn, cotton and cassava, as well as summer cover crops such as Dolichos lab-lab (labelabe), Crotalaria juncea (crotalaria), Mucuna lands (black mucuna), Mucuna deeringiana (dwarf mucuna), Canavalia ensiformis (jack beans) and winter cover crops such as The white wolf (white lupine), Lathyrus clymenum (forage vetch), Villosa vetch (hairy vetch), Pisum sativum there. arable cultivar Iapar 83 (common vetch) and Avena strigosa (black oats).

The wide circle of hostesses T. tuxaua This indicates that this nematode has a poorly specialized feeding habit, with a short and wide odontostylus, characteristic of omnivorous nematodes. Omnivorous nematodes obtain their food from different sources, including root hairs, but they are differentiated from phytoparasites because they do not feed on the roots of higher plants.

Certainly T. tuxaua it has adapted to coexistence with plants cultivated by man and has developed the ability to suck at its roots. This hypothesis is supported by the constant association of this nematode with cultivated plants that present, among other symptoms, marked dwarfism and also by trials carried out in controlled conditions involving the inoculation of the nematode in plants grown in pots.

During your feeding, T. tuxaua It inserts its short style superficially into root tissues, feeding on individual cells and causing them to die. After sucking the cellular contents, the nematode migrates to another location on the root, starting a new feeding process. A number greater than 100 T. tuxaua It can be found in the rhizosphere of plants grown in infested areas. However, few nematodes (20 nematodes/plant root) can cause visible symptoms in the field.

Considering the cultural management of T. tuxaua, barely Raphanus sativus there. oleiferus (forage turnip) has shown good development and contributed to the population reduction of the nematode when cultivated in infested areas. However, new research needs to be carried out in order to discover other plants with potential for use in rotation.

Fallowing with soil disturbance (plowing) can also be adopted as a control method in infested areas, contributing to the exposure of the nematode to sunlight and the removal of food (absence of cultivated plants and weeds).

As females T. tuxaua have a long life cycle (more than six months) and low oviposition rate, populations take longer to reach high population levels in the field. Therefore, management tactics involving the scarcity of nematode food can contribute to population reduction in the field.

In the presence of T. tuxaua in different municipalities in western Paraná is an indication that this nematode is widespread in this region. However, damage to soybean crops has also been attributed to nematodes of the genus Tubixaba in the states of Maranhão and Tocantins. However, confirmation of the identity of these species still requires future studies.

This article was published in issue 185 of Cultivar Grandes Culturas magazine. Click here to read the edition.