Aphid parasitism in winter wheat fields in a heterogeneous agricultural landscape.

The number, timing, and fitness of colonizing parasitoids in fields of ephemeral crops often depend on factors external to the fields. We investigated cereal aphid parasitism in 23 winter wheat fields using sentinel plants infested with bird cherry-oat aphids, Rhopalosiphum padi (L.) (Hemiptera: Aphididae), and we investigated the effect of parasitoids on cereal aphid population growth using exclusion and parasitoid-accessible cages infested with bird cherry-oat aphids.

Ecological Interactions of Predatory Mites, (Schrank) (Trombidiformes: Cheyletidae) and Oudemans, and Prey, (Pearman) (Psocodea: Liposcelididae), under Different Thermo-Hygrometric Regimes.

Predator-prey interactions are linked through trophic relationships, and individual population dynamics are a function of multiple interactions among many ecological factors. The present study considered the efficacy of the predatory mites (Schrank) (Trombidiformes: Cheyletidae) and Oudemans to manage (Pearman) (Psocodea: Liposcelididae). Prey population suppression and progeny replacement efficiency of the predators were assessed under different predator-prey ratios (0:20, 1:20, 2:20, 4:20, and 10:20), temperatures (20, 24, 28, and 32 °C), and relative humidities (RH) (63, 75, and 85%) over 40 days under laboratory conditions of 0:24 (L:D) photoperiod.

Numerical responses of the predatory mites, Cheyletus eruditus (Trombidiformes: Cheyletidae) and Cheyletus malaccensis, to Liposcelis decolor (Psocodea: Liposcelididae).

Predatory mites display diverse ecological mechanisms to suppress pest population density below certain thresholds known to cause economic loss. The current study explored the numerical responses of the predatory mites, Cheyletus eruditus (Schrank) (Trombidiformes: Cheyletidae) and Cheyletus malaccensis Oudemans, to Liposcelis decolor (Pearman) (Psocodea: Liposcelididae). The numerical responses of these 2 cheyletid mites to nymphs, adult males, and adult females of L.

Natural Enemies, Mediated by Landscape and Weather Conditions, Shape Response of the Sorghum Agroecosystem of North America to the Invasive Aphid .

The sorghum ( [L.]) agroecosystem of North America provided an opportunity to evaluate agroecosystem response to an invading insect herbivore, (Theobald) (sorghum aphid) (previously published as Zehntner) (Hemiptera: Aphididae) onto a widely planted crop that experiences a range of agro-landscape and weather conditions. Initial sorghum risk assessments after 's invasion in the mid-2010s provided forecasts of range expansion and annual migration, which were based on aphid life history, extent of sorghum cultivation and susceptibility to , and weather (aphid-plant-weather [APW] risk scenario).

Differential responses of sorghum genotypes to sugarcane aphid feeding.

The findings of this study suggest that known resistant sorghum genotypes compensate for feeding pressure of sugarcane aphid by maintaining/increasing photosynthetic capacity and/or have higher chlorophyll content than susceptible genotypes. Knowledge of the physiological response of sorghum, (Sorghum bicolor (L.) Moench), to sugarcane aphid (SCA), Melanaphis sacchari (Zehnter) feeding will provide baseline information on defense responses and resistance mechanisms.

Development of Binomial Sequential Sampling Plans for Sugarcane Aphid (Hemiptera: Aphididae) in Commercial Grain Sorghum.

The sugarcane aphid (Melanaphis sacchari Zehntner) is a significant economic pest of grain sorghum (Sorghum bicolor (L.) Moench) in the Southern United States. Current nominal and research-based economic thresholds are based on estimates of mean aphids per leaf.

Categories of Resistance to Sugarcane Aphid (Hemiptera: Aphididae) Among Sorghum Genotypes.

The sugarcane aphid Melanaphis sacchari (Zehnter) (Hemiptera: Aphididae) has emerged as a potential threat to sorghum (Sorghum bicolor (L.) Moench) production in the United States. Since the late summer of 2013, finding and advancing M.

Behavioral and Ovipositional Response of Diaeretiella rapae (Hymenoptera: Braconidae) to Rhopalosiphum padi and Brevicoryne brassicae in Winter Wheat and Winter Canola.

Winter canola Brassica napus L. (Brassicales: Brassicaceae) was introduced to U.S.

Landscape Context Affects Aphid Parasitism by Lysiphlebus testaceipes (Hymenoptera: Aphidiinae) in Wheat Fields.

Winter wheat is Oklahoma's most widely grown crop, and is planted during September and October, grows from fall through spring, and is harvested in June. Winter wheat fields are typically interspersed in a mosaic of habitats in other uses, and we hypothesized that the spatial and temporal composition and configuration of landscape elements, which contribute to agroecosystem diversity also influence biological control of common aphid pests. The parasitoid Lysiphlebus testaceipes (Cresson; Hymenoptera: Aphidiinae) is highly effective at reducing aphid populations in wheat in Oklahoma, and though a great deal is known about the biology and ecology of L.

Incorporating biological control into IPM decision making.

Of the many ways biological control can be incorporated into Integrated Pest Management (IPM) programs, natural enemy thresholds are arguably most easily adopted by stakeholders. Integration of natural enemy thresholds into IPM programs requires ecological and cost/benefit crop production data, threshold model validation, and an understanding of the socioeconomic factors that influence stakeholder decisions about biological control. These thresholds are more likely to be utilized by stakeholders when integrated into dynamic web-based IPM decision support systems that summarize pest management data and push site-specific biological control management recommendations to decision-makers.

Molecular markers for species identification of Hessian fly males caught on sticky pheromone traps.

Pheromone traps have been widely used to monitor insect population activity. However, sticky pheromone traps for the Hessian fly (Mayetiola destructor), one of the most destructive pests of wheat, have been used only in recent years. Hessian fly male adults are small and fragile, and preserving specimens during sorting of sticky pheromone traps is a challenge when intact specimens are often required to visually distinguish them from related insects such as fungus gnats.

Virulence and biotype analyses of Hessian fly (Diptera: Cecidomyiidae) populations from Texas, Louisiana, and Oklahoma.

Hessian fly, Mayetiola destructor (Say, 1817), is a major pest of wheat, and is controlled mainly through deploying fly-resistant wheat cultivars. The challenge for the plant resistance approach is that virulence of Hessian fly populations in the field is dynamic, and wheat cultivars may lose resistance within 6-8 yr. To ensure continuous success of host plant resistance, Hessian fly populations in the field need to be constantly monitored to determine which resistance genes remain effective in different geographic regions.

Effects of relay-intercropping sorghum with winter wheat, alfalfa, and cotton on lady beetle (Coleoptera: Coccinellidae) abundance and species composition.

Creating conditions that enhance the abundance of resident populations of natural enemies in agroecosystems is considered critical to the efficiency of biological control of insect pests. We conducted a study to determine the potential of relay-intercropping for enhancing the abundance of aphidophagous lady beetles in sorghum. A relay-intercropping system consisting of alfalfa, winter wheat, and cotton as intercrops and sorghum as a main crop was compared with sorghum monoculture plots at two study sites in OK from 2003 to 2006.

Virulence analysis of Hessian fly populations from Texas, Oklahoma, and Kansas.

In recent years, the number of wheat, Triticum aestivum L., fields heavily infested by Hessian fly, Mayetiola destructor (Say), has increased in the Great Plains of the United States. Historically, resistance genes in wheat have been the most efficient means of controlling this insect pest.

Supercooling points of Lysiphlebus testaceipes and its host Schizaphis graminum.

Supercooling points (SCPs) were measured for various life stages of male and female Lysiphlebus testaceipes (Cresson) parasitoids, along with mummies and its aphid host, Schizaphis graminum (Rondani). Some parasitoids were acclimated (4 h at 10 degrees C before cooling down to the SCP) to determine whether this could significantly lower the SCP. Acclimation did not improve SCPs for L.

Larval life history responses to food deprivation in three species of predatory lady beetles (Coleoptera: Coccinellidae).

We studied life history responses of larvae of three coccinellid species, Coleomegilla maculata (DeGeer), Hippodamia convergens Guerin-Meneville, and Harmonia axyridis (Pallas), when deprived of food for different periods of time during the fourth stadium. The coccinellid species did not differ in starvation resistance when larvae were starved throughout the stadium; however, for larvae fed only on day 1 of the stadium, H. convergens had the highest starvation resistance, followed by H.

Parasitism of Greenbug, Schizaphis graminum, by the parasitoid Lysiphlebus testaceipes at winter temperatures.

Functional responses by Lysiphlebus testaceipes (Cresson), a common parasitoid of small grain aphids, on greenbug, Schizaphis graminum (Rondani), were measured at seven temperatures (14, 12, 10, 8, 6, 4, and 2 degrees C) during a 24-h period (12-h light: 12-h dark). Oviposition by L. testaceipes ceased at temperatures <4 degrees C.

Transformations of count data for tests of interaction in factorial and split-plot experiments.

In applied entomological experiments, when the response is a count-type variable, certain transformation remedies such as the square root, logarithm (log), or rank transformation are often used to normalize data before analysis of variance. In this study, we examine the usefulness of these transformations by reanalyzing field-collected data from a split-plot experiment and by performing a more comprehensive simulation study of factorial and split-plot experiments. For field-collected data, significant interactions were dependent upon the type of transformation.

Estimation of hymenopteran parasitism in cereal aphids by using molecular markers.

Polymerase chain reaction (PCR) primers were designed and tested for identification of immature parasitoids in small grain cereal aphids and for estimation of parasitism rates. PCR technique was evaluated for 1) greenhouse-reared greenbugs, Schizaphis graminum (Rondani), parasitized by Lysiphlebus testaceipes Cresson and 2) aphids collected from winter wheat fields in Caddo County, Oklahoma. For greenhouse samples, parasitism frequencies for greenbugs examined by PCR at 0, 24, and 48 h after removal of L.

Development of a sampling plan in winter wheat that estimates cereal aphid parasitism levels and predicts population suppression.

From 1998 to 2001, the relationship between the proportion of tillers with >0 mummified aphids (Ptm) and the proportion of cereal aphids parasitized (Pp) was estimated on 57 occasions in fields of hard red winter wheat located in central and western Oklahoma. Both original (57 fields) and validation data (34 fields; 2001-2002) revealed weak relationships between Ptm and Pp, however, when Ptm > 0.1, Pp always exceeded the recommended parasitism natural enemy threshold of 0.

Influence of alfalfa cultivar on suitability of Acyrthosiphon kondoi (Homoptera: Aphididae) for survival and development of hippodamia convergens and Coccinella septempunctata (Coleoptera: Coccinellidae).

Hippodamia convergens Guérin-Méneville and Coccinella septempunctata L. (Coleoptera: Coccinellidae) larvae were supplied daily with 1, 2, 4, or 16 mg of Acyrthosiphon kondoi Shinji (Homoptera: Aphididae) reared on one of two susceptible ('OK08' or 'CUF-101') or one resistant ('54H55') alfalfa cultivar (IMedicago sativa L.) .

Interactions between an introduced and indigenous coccinellid species at different prey densities.

Coccinella septempunctata L. (Coleoptera: Coccinellidae), a Palearctic coccinellid, has established and rapidly spread throughout the United States. This quantitative examination of larval interactions between C.