Identification of Nymphal Instars of emMecidea/em emmajor/em Sailer and Mecidea minor Ruckes (Hemiptera: Heteroptera: Pentatomidae: Mecideini) from the Southwestern and Central United States.

The mecideine stink bug genus Mecidea is represented in America north of Mexico by three species: Mecidea major Sailor, Mecidea minor Ruckes, and Mecidea longula Stål. M. major and M. minor are widely distributed, occurring collectively from the Midwest to California. M. longula is known only from south Florida. The life histories of M. major and M. minor have been published including laboratory rearing from egg to adult and descriptions of the immature stages. However, no key has been developed for identification of the nymphs of these two species. Here, we present a key to the nymphs of these taxa to the species and instar levels.

Systematic relationship between Piezodorus guildinii and P. hybneri (Hemiptera: Heteroptera: Pentatomidae) and diagnostic characters to separate species.

The pentatomid genus Piezodorus presently contains about 12 species, all of which, with one exception [i.e., P. guildinii (Westwood)], have been reported from the Old World; P. guildinii apparently is limited to the New World. P. guildinii and P. hybneri (Gmelin) are similar in appearance and have been considered by some as sister species. The following characteristics we consider valid as diagnostic to separate the two species: for males, the shape and length of the vesica, differences in the anatomy of the conjunctival appendages and penial plate, and shape of the pygophore and parameres; and for females, differences in the anatomy of the first and second gonocoxae, ninth paratergites, and spermathecae.

Life history of Mecideamajor with descriptions of nymphal instars (Hemiptera, Heteroptera, Pentatomidae).

The life history of the stink bug Mecideamajor Sailer was studied in the southern half of New Mexico primarily from January 2005 through December 2007, and the nymphal instars were described. This species was active throughout the year as adults and nymphs, including the winter months. It occurred on various species of grasses during this time but primarily on Lehmann lovegrass, Eragrostislehmanniana Nees; grama grasses, Bouteloua spp.; and tobosagrass, Pleuraphismutica Buckley. The times of occurrence and abundance of the eggs, nymphs, and adults suggest this species is bivoltine with the possibility of a third generation. Instars can be distinguished by several morphological features including body size and presence and relative development of wing pads.

Phylogenetic analysis of the alfalfa weevil complex (Coleoptera: Curculionidae) in North America.

The Eastern, Western, and Egyptian strains of alfalfa weevil are pests introduced to North America on three separate occasions, now they share partially overlapping geographic ranges, covering most of the continental United States. Behavior, susceptibility to parasites, and subtle morphological differences separate the strains. The difficulty in differentiating among these strains morphologically has led to the application of molecular phylogeny approaches including restriction fragment-length polymorphism characterization and sequencing of mitochondrial genes. While valuable for strain identification, this approach cannot identify interstrain hybrids because mitochondrial markers are maternally inherited. The work reported here extends previous findings by comparing over 7 Kb of sequence from two mitochondrial and four nuclear loci to increase the resolution of molecular phylogeny for these weevils. The related clover leaf weevil, also an occasional pest of alfalfa, was included in the analysis because the molecular phylogeny of this weevil has not been examined to date. Analysis of nuclear loci indicate that the clover weevil is a distinct species. Furthermore, while the three alfalfa weevil strains are separable based on mitochondrial sequence data they cannot be separated using nuclearloci suggesting that they are all recently diverged members of the same species. These data refine the relationships among these strains and may find application in design of better control strategies.

Strain distribution of alfalfa weevil (Coleoptera: Curculionidae) in an intergrade zone.

Strain distribution for the alfalfa weevil, Hypera postica (Gyllenhal), was determined for the five major alfalfa-growing regions of New Mexico. Mitochondrial DNA from field-collected weevils at each location was digested and sequenced to differentiate among strains. Eastern, Egyptian, and western strains were recovered, along with a population not matching any known strain. The majority of sites examined had populations of two strains intermingled within a field. This is the first confirmation of the presence of all three strains within the same geographic region. Possible implications for alfalfa weevil management are discussed.