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Predator exclusion was used to measure the impact of the red imported fire ant, Solenopsis invicta Buren, on abundance of corn earworm, Helicoverpa zea (Boddie), eggs and larvae feeding on ears of maize, Zea mays L., and on corn earworm pupae in the soil in north-central Texas. Large field plots were treated with Amdro® Fire Ant Bait insecticide to selectively suppress fire ant abundance without impacting other arthropods or their behavior. Abundance of corn earworm eggs, larvae and pupae were determined in maize in which abundance of fire ants was significantly reduced and compared with the abundance of corn earworm life stages in maize with extant populations of fire ants. Fire ants had little or no measurable effect on abundance of corn earworm eggs or larvae on ears of maize in the three fields studied during two years. The mean total number of foraging fire ants and abundance of corn earworm pupae in the soil were significantly and negatively related. This result suggests that fire ants prey on pre-pupal corn earworm larvae as they crawl on the soil surface or prey on pupae in cells in the soil. The role of red imported fire ant as both a pest and beneficial in production of maize in central Texas is discussed.
Since the first report on introductions to Texas of Pseudacteon decapitating flies, a variety of participants have released flies in a range of sites. The expansions of Pseudacteon populations have been systematically and widely monitored. Before 2002, the widely released initial species P. tricuspis Borgmeier did not become established. Severe drought in 1996–2001 and host-size-dependent sex ratio were proposed constraints in establishing this species. In recent years, however, these limitations have been lifted in some areas by favorable weather, irrigation of release sites, and/or by use of a smaller Pseudacteon species, P. curvatus Borgmeier, not reliant on larger fire ant workers to produce females. Beginning in 2002, the USDA-APHIS collaboration with USDA-ARS and Texas Cooperative Extension programs began to supplement release sites in Texas beyond those initiated by the University of Texas, Austin phorid fly project. In 2005, private citizens began to participate in the spread of Pseudacteon to new sites. By fall 2006, P. tricuspis, expanding from releases between 1999 and 2001, was found on more than 3 million hectares of Central and Coastal Texas, while P. curvatus, with its later start, is only now beginning to expand at some sites. Pseudacteon that established more easily in mesic and moderate climates has difficulty surviving unfavorable weather in South Texas. However, two sites where flies “failed” to become established were revealed to be false negatives after the record rains of summer 2007. Starting in late 2006, the first releases of P. obtusus Borgmeier in North America established, and three to five additional species are being released.
We determined active ground beetle species in 2002 and 2003 in experimental dryland cropping systems near Akron, Briggsdale, and Lamar, CO. The experiment compared five crops; wheat, sunflower, sorghum, millet, and corn in fallow, two- and three-year cropping systems. Comparisons were made between all crops and fallow within locations. Pitfall traps were used to collect active ground beetles in plots for seven, seven-day sampling periods in both 2002 and 2003. A total of 3,929 carabids was collected; 1,684 and 2,245 in 2002 and 2003, respectively. A total of 59 species was collected, 51 and 49 in 2002 and 2003, respectively. In 2002, the five most active species (in decreasing order) were Pasimachus californicus Chaudoir, Amara carinatus LeConte, Harpalus pensylvanicus DeGeer, Harpalus desertus LeConte, and Pasimachus elongates LeConte. The five most active species (in decreasing order) in 2003 were H. pensylvanicus, Harpalus caliginosus Fabricius, H. desertus, Cratacanthus dubius Beavois, and Harpalus amputatus Say. Seven species were common to Akron, Briggsdale, and Lamar in both 2002 and 2003. Ten and eight species were specific to 2002 and 2003, respectively. Eight, fourteen, and four species were specific to Akron, Briggsdale, and Lamar, respectively. Crops and dates influenced ground beetle activity, but two- and three-year cropping systems did not.
A field study was conducted at Munday in Knox County, TX, during 2004 and 2005 to identify thrips species present on cotton, Gossypium hirsutum L., during early development stages. Thrips have been one of the most important pests during past years because they are known to cause damage to cotton seedlings in early season. A plant-wash technique was used to recover the different species of thrips from cotton. Morphological keys were used to identify species when possible. Nine species were found across years; however, only seven thrips species were found in each individual year. A detailed explanation of the species found is given, and some distinguishing characteristics for species identification are provided. Thrips were very abundant at the beginning of the season, but abundance slowly decreased both years during the four weeks of sampling.
Sequential sampling plans were developed for the sweep net and the visual sampling methods “long stick” and “sweep stick.” Relative cost-reliability that incorporates probability of adoption showed that sampling with the long stick is more cost-reliable than with the sweep net. Two passes of the sweep stick was less cost-reliable than the sweep net method at low densities but was more cost-reliable at densities of eight or more adult O. pugnax per ten sweep net sweeps. For sweep net sampling, comparison of the currently used fixed sample size plan (n=10) and sequential sampling showed that sequential sampling reduced the number of sample units required to reach a decision by 56%.
A Berlese-sample survey was conducted over an 8-month period to determine the manner in which a prescribed burn affected arthropod abundance in a relict pine-oak forest of central Texas. One arthropod taxon (i. e., Diplopoda) was more abundant in the burned section than in the control, one (i. e., Psocoptera) was less abundant, and juvenile stages of holometabolous taxa in general were found in much lower numbers in the burned section, but there was no significant difference between numbers of adults of most taxa even during this nearly immediate post-burn analysis. Such findings are of interest to those concerned with the preservation of the endangered Houston toad, Bufo houstonenis Sanders, and to those who wish to restore the forest to a more natural condition with increased plant and animal diversity through the agency of prescribed burns.
A new species of Poecilanthrax Osten Sacken is described from south-central Arizona. Poecilanthrax arizonensis Taber was collected near the top of Usery Peak in Maricopa County, in upland Sonoran Desert. Similar species include Poecilanthrax arethusa (Osten Sacken), Poecilanthrax effrenus (Coquillett), and Poecilanthrax signatipennis (Cole). Photographs and descriptions are provided to distinguish the new species from other bee flies.