The development of gall shapes has been attributed to the feeding behavior of the galling insects and how the host tissues react to galling stimuli, which ultimately culminate in a variable set of structural responses. A superhost of galling herbivores, Copaifera langsdorffii, hosts a bizarre "horn-shaped" leaflet gall morphotype induced by an unidentified species of Diptera: Cecidomyiidae. By ...

Many hypotheses have been proposed to explain the diversity of gall-midge insects (Diptera: Cecidomyiidae), some of them taking into account plant diversity. This study aims to test the importance of size, age and composition of host plant taxa in the diversity of Cecidomyiidae. For this we used inventories data on the diversity of galling and host plants in Brazil. We found that Asterales, Myr...

Terminated small grain cover crops are valuable in light textured soils to reduce wind and rain erosion and for protection of young cotton seedlings. A three-year study was conducted to determine the impact of terminated small grain winter cover crops, which are hosts for Meloidogyne incognita, on cotton yield, root galling and nematode midseason population density. The small plot test consiste...

A host suitability study of 32 plant species to Meloidogyne konaensis included 54 vegetable cultivars, 12 field crop cultivars, one Gardenia sp., and two weed species. Host suitability was classified according to a M. konaensis reproductive factor: final population density (Pf) (eggs + J2) / initial population density (Pi) (eggs). The number of eggs per gram dry root, and a galling index was al...

The influence of various cropping sequences on population densities of Meloidogyne hapla and carrot yield was studied in organic soil under microplot-and field conditions. Spinach, radish, barley, oat, and wheat were poor or nonhosts for M. hapla. Population densities of M. hapla were maintained or increased on cabbage, celery, lettuce, leek, marigold, and potato. Marketable percent-age and roo...

The nematicide fosthiazate was evaluated over a 3-year period for management of Meloidogyne incognita race 3 (site 1) and M. arenaria race 2 (site 2) in flue-cured tobacco. Fosthiazate was applied broadcast and incorporated at rates ranging from 22 to 88 g a.i./100 m(2), and compared with the nematicides fenamiphos (67 g a.i./100 m(2)), 1,3-D (56.1 L/ha, 670 ml/100-m row), and an untreated cont...

The Columbia root-knot nematode Meloidogyne chitwoodi parasitizes several plant species, including grasses that have been developed for semiarid environments, and substantially reduces the productivity of cereals and the longevity of perennial grasses growing under semiarid conditions throughout the intermountain region. Thirty-two auto- and allotetraploid (2n = 28) taxa in the perennial Tritic...

Overman and Woltz (3) indicated that amino acid antimetabolites applied to tile soil suppressed reproduct ion of Paratrichodorus minor (Trichodorus christiei) and root galling caused by Meloidogyne incognita on tomatoes. Eight DL-amino acid antimetabolites similarly decreased the population of Aphelenchoides ritzemabosi on Lucerne, whereas DL-alanine suppressed the populat ion of Heterodera spp...

Hyphae of Dactylella oviparasitica proliferated rapidly through MeIoidogyne egg masses, and appressoria formed when they contacted eggs. The fungus probably penetrated egg shells mechanically, although chitinase production detected in culture suggested that enzymatic penetration was also possible. In soil, D. oviparasitica invaded egg masses soon after they were deposited on the root surface an...

Microplot and field experiments were conducted to determine relationships of population densities of Meloidogyne spp. to performance of flue-cured tobacco. A 3-yr microplot study of these interactions involved varying initial nematode numbers (P(i)).and use of ethoprop to re-establish ranges of nematode densities. Field experiments included various nematicides at different locations. Regression...