Reported populations of Meloidogyne ethiopica in Europe identified as Meloidogyne luci

The tropical group of root-knot nematodes (RKN) including Meloidogyne ethiopica and M. luci is a highly polyphagus and damaging group of agricultural pests. M. ethiopica has been detected in several European countries (Slovenia, Italy, Greece) and also in Turkey. However, a description of a new sister species M. luci calls for reclassification of all European and Turkish M. ethiopica populations reported up to date as M. luci. Accurate identification can be accomplished through analysis of the esterase isozyme pattern, which is the most distinguishing character between the two otherwise very similar species. Both species display a three banded esterase pattern where the upper band is slightly shifted between the two species. In addition, molecular characterization of M. ethiopica and M. luci populations revealed that the ITS, SSU, and LSU of the rDNA regions are not appropriate markers for studying relationships among the tropical group of RKNs. However, the COII/lRNA region on mtDNA proved to be very useful for analyzing the phylogenetic relationship of these very closely related species/populations. Mitochondrial sequences with low levels of heteroplasmy allowed clustering of all M. luci populations in a monophyletic clade with a clear separation of this recently described species from M. ethiopica. At the same time, a very close relationship between M. ethiopica and M. luci was confirmed again.

First report of, and additional information on, Meloidogyne konaensis (Nematoda: Meloidogyninae) parasitising various crops in Brazil

In a survey for Meloidogyne spp. in different crops from 11 regions in Ceará State, Brazil, using esterase isozyme electrophoresis as a specific identification method, four atypical populations were characterised from cabbage, papaya, noni and canapum plants, all of which showed an esterase profile different from those previously detected in Brazil. Morphological studies showed typical characteristics of Meloidogyne konaensis. Perineal patterns of females were variable, similar to M. arenaria and M. incognita, stylet length 14-20 μm. In females, the knobs gradually merged with the shaft and the dorsal pharyngeal gland orifice (DGO) ranged from 4 to 7 μm. Although males are not frequently found, the stylet morphology provides the most useful source of diagnostic character for the species, having 6-12 large projections protruding from the shaft. The esterase pattern K3 is unique and species-specific with three major bands Rm 1.0, 1.17, 1.27 and a secondary band Rm 1.10. Some confusion about the true identity of this species was clarified in this study, including differentiation from M. paranaensis. A species-specific SCAR marker developed for M. paranaensis was tested and no amplification products were observed. In Neighbour-Joining analyses of ITS and D2-D3 rRNA sequences, M. konaensis from Brazil appeared clearly separated from M. paranaensis. Pathological tests indicated that coffee is not a host of M. konaensis as previously reported in the original description of this species.

Tissue esterases of Lamellidens corrianus (Fresh water mussel)

Polyacrylamide gel electrophoretic (PAGE) technique was used to examine the esterase pattern of Ctenidia, Hepatopancreas, Hemolymph, Intestine, Mantle. Foot of the Lamellidens corrianus. The zymograms revealed the varied pattern of esterase both in number and type. This varied pattern suggested several roles for these enzymes present in different tissues.

Enhancing taxonomic resolution: distribution dependent genetic diversity in populations of Meloidogyne

Root-knot nematodes (Meloidogyne) are one of the most damaging agricultural pests. The polyploid apomictic M. arenaria, M. javanica and M. incognita are particularly ubiquitous and exhibit an extreme polyphagy. The taxonomic position of these three species remains unclear, as does the phylogenetic relationships between them. To characterise phenotype variants among these three species, allozyme electrophoresis (α-EST, MDH, CAT, GPI, DIA, GOT, and SOD) was performed in populations from the Iberian Peninsula. A total of 50 multilocus enzyme electrophoresis (MLEE) phenotype variants were detected of which, according to the esterase pattern, 24 corresponded to M. arenaria, 15 to M. javanica and 11 to M. incognita. The phylogenetic relationships of these 50 MLEE variants were studied following the Neighbour-Joining (NJ) distance method based on an allelic frequencies matrix built using two different methodologies. In addition, Maximum-Parsimony (MP) and Maximum-Likelihood (ML) phylogenetic methods were done in order to corroborate the phylogenies obtained. Our results showed a great disparity in the NJ trees obtained, thus indicating that the monophyly of the parthenogenetic Meloidogyne spp. would seem to depend on the methodology used. Evolutionary and epidemiological implications of the recovered phylogenies are discussed.

Tissue-specific expression of esterases in Triatoma infestans (Triatominae, Heteroptera)

We examined the esterases present in the hemolymph and Malpighian tubules of "Kissing bug", Triatoma infestans (Triatominae, Heteroptera) by polyacrylamide gel electrophoresis. Six esterase bands were observed and were designated EST 1 to EST 6. EST 1, 4, 5 and 6 were exclusive to hemolymph, whereas EST 2 and 3 were found only in Malpighian tubules. Each tissue had a characteristic esterase pattern, which may be related to its functional role. The four hemolymph esterases hydrolyzed a-naphthyl acetate. One of these enzymes was classified as a carboxylesterase (EST 4), and another was an acetylesterase (EST 6). The other two enzymes (EST 1 and 5) could be either carboxylesterases or serino-proteases with an esterolytic function, as they were selectively inhibited by phenylmethylsulfonyl fluoride (PMSF). Absence of genetic variability could be due to high inbreeding.

Biotype determination of Spanish populations of Bemisia tabaci (Hemiptera: Aleyrodidae)

A survey was made to assess the biotype status of populations of the whitefly Bemisia tabaci (Gennadius) in Spain. The study involved observation of the squash silverleaf reaction, analysis of esterase patterns and application of a RAPD-PCR technique. The results obtained by the three methods were fully consistent and showed that the Spanish populations of B. tabaci were composed of two genetic types. One corresponded to populations of the B biotype, found in Tenerife (Canary Islands), Barcelona, Madrid, Malaga and Almeria. The other, showing a unique RAPD and esterase pattern, was found in Majorca (Balearic Islands), Seville, Valencia, Murcia and Almeria, as well as in the Algarve Region of Portugal. RAPD patterns of other populations from the rest of the world used for comparison showed that populations from Arizona (USA), Israel, France, Denmark, Italy, Netherlands and Japan have similar RAPD patterns typical of the B biotype. By contrast, populations from the Iberian Peninsula, Turkey, India, Pakistan and Arizona (A biotype), showed different and unique patterns.

Character inheritance and polymorphism in a wild oat (Avena fatua) population

A population of wild oats (Avena fatua L.) in a cultivated field was sampled once or twice a year between 1979 and 1983. Plants differing in seed morphology, seed avenin pattern, leaf esterase pattern, and vernalization requirements were crossed to study the inheritance of these traits (13 loci). The polymorphism of the population for each of these characters and 11 others was investigated as well as the frequency of each type of plant (phenotype). Forty-seven phenotypes were observed over the 5 years, but only five were consistently present in all samples. They represented 78% on average of the population. The observed increase of a phenotype correlatively to the decrease of another one is discussed as a function of cultural practices.

Inheritance and activity of some esterases associated with organophosphate resistance in mosquitoes of the complex of Culex pipiens L. (Diptera: Cnlicidae)

Eighteen strains of the complex of Culex pipiens L. from Africa, Asia and Europe were bioassayed for resistance to chlorpyrifos and electro-phoresed and stained for esterases. Susceptible strains showed only low activity esterase bands. The resistant strains of C. quinquefasciatus Say from hot countries (Liberia, Nigeria, Sri Lanka, Tanzania, Thailand) all showed the same two high intensity esterase bands (Rm 0·60 + 0·82). Different patterns of high esterase were found in resistant C. pipiens strains from cooler localities in Nairobi, Kenya (Rm 100), and Mont-pellier, France (Rm 0–50). Selection experiments on strains originally polymorphic for resistance and esterase pattern showed, without exception, that high esterase remained associated with resistance, and it is concluded that the association is almost certainly causal and not merely due to genetic linkage. The high intensity esterase bands were probably due to alleles of the loci Est-l, Est-2 and Est-3, separated by crossover distances of approximately 2·4 and 5·5 units, respectively. Strains monomorphic for what appeared to be the same high esterase pattern varied markedly in resistance level. Enzyme assays showed a direct relationship between levels of enzyme activity and resistance. Bioassays with fenthion and chlorpyrifos revealed differences in the relative resistance of C. quinquefasciatus from Colombo (Sri Lanka) and Dar-es-Salaam (Tanzania). Despite these differential degrees of cross-effectiveness, it is concluded that high intensity esterases are reliable indicators of organophosphate resistance in mosquitoes of the C. pipiens complex, although the possibility of other resistance mechanisms means that the lack of abnormally active esterases does not necessarily indicate the absence of resistance.

Varying electrophoretic mobility of an esterase caused by a factor in extracts of Bacillus stearothermophilus cells

The esterase pattern on polyacrylamide gel of extracts from Bacillus stearothermophilus grown at different temperatures from 45 to 71 °C was examined by slab gel electrophoresis. The esterase pattern showed the presence of eight esterase bands in the extracts from bacterial cells grown at 60 °C. These bands could be divided into two groups. One group included seven esterase bands which showed constant electrophoretic mobilities at different growth temperatures. The other group included one esterase band, Est-b, which showed different mobilities depending on growth temperature. A factor, which increased the mobility of Est-b, could be separated from cell extracts by gel filtration. The mobility of partially purified Est-b was regulated by addition of various amounts of the factor. At 70 °C, the thermostability of partially purified Est-b was increased by adding the factor; this was accompanied by competitive inhibition of the enzyme activity.