Alejandro González-Hernández

Morphometry of Diaphorina citri (Hemiptera: Liviidae) on Six Rutaceae from Veracruz, Mexico

ABSTRACT The objective of this study was to characterize Diaphorina citri Kuwayama (Hemiptera: Liviidae) morphometrically, as well to determine whether the host has a relationship to a specific morphometric variation. The traits measured were body length, antenna length, lengths and widths of genal processes, and forewing length and width. Females and males were analyzed separately. The measures obtained were subjected to an analysis of variance and principal components analysis. The greatest morphometrical variation and smallest sizes were found in males collected from non-prefered hosts such as Citrus limetta Risso, C. sinensis (L.) ‘Selection 8’ and C. paradisi Macfad.; while, the least variations and largest sizes were found on C. sinensis (L.) Osbeck cv. ‘Marrs’, C. sinensis (L.) cv. ‘Valencia’ and Murraya paniculata (L.) Jack. The traits with notable variation were lengths and widths of forewings and genal processes. Greater morphometrical variations were found in males than in females. The results indicate that D. citri is a species with morphometrical variants and probably the host is a determinant in the definition of characters.

Effects of tree species diversity and genotypic diversity on leafminers and parasitoids in a tropical forest plantation

The effects of tree diversity on herbivore–enemy interactions have received relatively little attention and even fewer studies have compared the relative influence of tree intra‐ versus interspecific diversity on such dynamics. We evaluated the effects of mahogany (Swietenia macrophylla) genotypic diversity and tree species diversity on parasitoid attack and species richness associated with Phyllocnistis meliacella, a specialist herbivore on mahogany, in a forest diversity experiment consisting of 74 plots (21 × 21 m2; 64 plants/plot). We sampled 34 of such plots classified as: mahogany monocultures of one maternal family (i.e. genotype), mahogany monocultures of four families and polycultures of four species (including mahogany). We surveyed leafminer abundance and collected mined leaves to estimate parasitism and parasitoid species richness. Leafminer abundance was not influenced by either type of diversity. Similarly, there were no effects of genotypic diversity or species diversity on parasitism or parasitoid species richness. Plant diversity effects on parasitoids were probably absent because the species attacking P. meliacella are dietary generalists that likely recruited to multiple host species (in addition to P. meliacella) and their responses to diversity could have cancelled each other out. Future work should explicitly investigate how predator and parasitoid traits mediate the effects of plant diversity on tritrophic interactions.

Géneros de Trichogrammatidae1 en México Asociados a Cultivos Agrícolas y Áreas Naturales Aledañas

Abstract. Trichogrammatid parasitoids were collected from agricultural and adjacent natural areas from the states of Coahuila, Durango, Sinaloa, Chihuahua, Nuevo León, Sonora, Jalisco, Guerrero, Hidalgo, and Zacatecas, in Mexico, during 2006-2008. Insect samples were obtained by sweeping the vegetation and by collecting eggs of nine crop pest species from several host plants for the states of Sonora, Chihuahua, Coahuila, and Tamaulipas, during 2007 and 2008. All wasps were placed and preserved in 1.5-ml plastic vials containing 70% ethanol. Some specimens were mounted on slides for further identification. A total of 1,535 trichogrammatid specimens was collected, which were identified to 20 genera of Trichogrammatidae. The genus Trichogramma Westwood was the most abundant (24.6%), followed by Paracentrobia Howard (23.8%), Oligosita Walker (19.0%), and Ufens Girault (12.5%). The remaining 16 genera comprised 20.1% of the insect specimens collected. From four to 15 genera of trichogrammatids were found in each of the states sampled. Thirteen genera of trichogrammatids were collected in 25 agricultural crops, where the genera Trichogramma, Oligosita, Paracentrobia, and Ufens were present in a greater number of agricultural crops. Crops such as orange, Citrus spp.; pecans, Carya illinoinensis (Wangenh.) K. Koch; grapes, Vitis vinifera L.; alfalfa, Medicago sativa L.; and maize, Zea mays L., had the greatest number of trichogrammatids. Furthermore, the genera Paracentrobia, Trichogramma, Ufens, and Haeckeliania Girault were obtained from eggs of nine insect pest hosts. The genus Trichogrammatella Girault is a new record for México. Another 15 genera are reported for the first time for some states, in particular for Guerrero and Hidalgo. Most of the genera found constitute new records.

Morphological and genetic variation in Mexican wild populations of Tamarixia radiata (Hymenoptera: Eulophidae)

Abstract We analyzed the morphological and genetic variation of the Asian citrus psyllid nymphal ectoparasitoid Tamarixia radiata (Waterston) (Hymenoptera: Eulophidae) in 2 regions of Mexico, in the northeast (represented by the states of Nuevo León and Tamaulipas) and the west (represented by the states of Colima and Michoacán). We found that the morphological variation of the specimens lay mainly in body color traits. The morphometric study indicated that in comparison with females, males presented heterogeneity, and it was concentrated in the state of Colima. Despite the morphological variation found in the species, it was not exclusively associated with any of the geographical regions. Molecular analysis revealed the presence of 2 haplotypes (H1 and H2), which were the same found in previous research among strains introduced to Florida. Haplotype H2 was found in both studied regions and more frequently than haplotype H1, which was collected only in the northeast (Tamaulipas state), suggesting possible points of gene flow between Mexico and the USA. Our results have implications for the extensive use of T. radiata in biological control programs of the Asian citrus psyllid.

Differentiation and Phylogeny of Trichogrammatidae (Hymenoptera: Chacidoidea) from Mexico Based on ITS2 and 18S Molecular Markers of rDNAr and COII of the mDNA

Abstract. A great diversity of trichogrammatids (35 genera) has been reported for Mexico. Particularly, several species of the genus Trichogramme are widely used as biological control agents in integrated agricultural pest management programs in Mexico. The identification of trichogrammatid wasps based on morphological characters is complicated. A feasible alternative to those taxonomic problems is the utilization of molecular techniques. Therefore, the objectives of the present study were to differentiate the most common genera of Trichogrammatidae, and infer their phylogeny, based on the molecular markers ITS2 and 18S of the rDNA and COII of the mDNA. Thus, individual wasps of Ittys, Aphelinoidea, Paracentrobia, Pseudoligosita, Ufens, Burksiella, Zagella, and Trichogramma were subjected to DNA extraction, DNA amplification by PCR, and phylogenetic analysis by the maximum parsimony (MP) method, based on the use of the molecular markers ITS2 and 18S of ribosomal DNA (rDNA) and COM of mitochondrial DNA (mDNA). PCR-product sizes of the region ITS2 varied from 450 to 700 bp for the more common genera of Trichogrammatidae from Mexico, which is useful for the taxonomic studies of these parasitic wasps. On the contrary, PCR-product sizes of the regions 18S and COII did not vary among genera, whose values were about 790 and 300 bp, respectively. PCR-product sizes of the regions ITS2 Y COII for most of trichogrammatid genera are reported for the first time. Phylogenies obtained based on the sequences of the ITS2 region were congruent with the current classification of Trichogrammatidae based on morphological characters. Resumen. Una gran diversidad de tricogramátidos (35 géneros) se han reportado para México. Particularmente varias especies del género Trichogramme se utilizan ampliamente como agentes de control biológico en los programas de manejo integrado de plagas agrícolas en México. La identificación de las avispas tricogramátidos mediante caracteres morfológicos es compleja. Una alternativa factible a la problemática anterior, es la utilización de técnicas moleculares. Por lo anterior el objetivo del presente estudio fue diferenciar los géneros de Trichogrammatidae más comunes de México, e inferir su filogenia basándose en los marcadores moleculares ITS2 y 18S del ADNr y COII del ADNm. Los tamaños de los fragmentos de PCR de la región ITS2 del ADNr variaron de 450 a 700pb en los géneros de Trichogrammatidae, lo cual es de gran utilidad en estudios taxonómicos de estas avispas parasíticas. Por el contrario, las regiones 18S del ADNr y COII del ADNm no mostraron variación en los tamaños de los fragmentas de PCR, siendo éstos de alrededor de 790 y 300pb, respectivamente, para los diferentes géneros. Se reporta por primera vez los tamaños de productos de PCR de las regiones ITS2 Y COII para la mayoría de los géneros analizados. Las filogenias inferidas mediante el mátodo de maxima parsimonia (MP), difirieron entre marcadores moleculares. Las filogenias inferidas mediante las secuencias de la región ITS2 fueron congruentes con la clasificación basada en caracteres morfológicos de géneros de Trichogrammatidae actualmente aceptada.

Review of the Mexican species of Erythmelus (Hymenoptera: Mymaridae), with description of two new species

The Mexican species of Erythmelus Enock (Hymenoptera: Mymaridae) are revised. A key to females of 13 species is provided in both English and Spanish. Two new taxa are described--E. maya Guzmán-Larralde & Triapitsyn, sp. n. and E. tigres Guzmán-Larralde & Triapitsyn, sp. n. Six species are newly recorded from Mexico--E. angustatus Ogloblin, E. cingulatus Ogloblin, E. clavatus Ogloblin, E. gracilis (Howard), E. nanus Dozier, and E. noeli (Dozier), besides new geographic records for E. miridiphagus Dozier, E. picinus (Girault), E. psallidis Gahan, and E. rex (Girault) which were previously known from the country.