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Pepper weevil infestation of three size classes (small = 10–14 mm, medium = 19–22 mm, large = 26–31 mm) of jalapeno pepper was examined. When all size classes were presented simultaneously to cohorts of three female and two male weevils, 19.5 ± 1.1 adults emerged from small peppers, 10.0 ± 1.0 from medium peppers, and 3.3 ± 0.5 from large peppers, and each of these values was significantly different. When presented sequentially such that only one size class at a time was available for oviposition, emergence of progeny from small and medium peppers did not differ and exceeded emergence from large peppers. Infestation data are discussed with respect to the length of time peppers are susceptible to pepper weevil oviposition in the field. Mean time to adult emergence was significantly shorter on small peppers (14.4 ± 0.1 days) than on medium peppers (15.9 ± 0.2 days), which in turn was significantly shorter than on large peppers (19.4 ± 0.6 days). Limitations to these findings are discussed.
This study was designed to evaluate the effect of Russian wheat aphid Biotype 1 on yield to determine how pure a resistant wheat cultivar needs to be to avoid significant yield loss. The study was conducted during the 2002–2003 growing season at Akron, Fort Collins, and Lamar, Colorado and consisted of five levels of resistance (0, 25, 50, 75, and 100%) in mixtures of the resistant wheat cultivar, Prairie Red, and the susceptible wheat cultivar, TAM 107. Yield loss was found to be linear, and proportional to percentage of resistant plants. At Fort Collins and Lamar, mixtures with any level of resistance supported fewer Russian wheat aphids than the pure susceptible stand, with the least number of aphids found on the pure resistant stand at the 10X infestation level. At Fort Collins, yields were lower when mixtures contained 0 to 25% of the resistant cultivar at the 1X and 10X infestation levels. Yields at the 10X infestation level were greater in the pure resistant stand. As expected, when Russian wheat aphids are abundant, wheat mixtures with 100% resistant plants yielded most.
Greenhouse and field studies were conducted to estimate survival rates of crawler stage Bemisia tabaci (Gennadius) Biotype B (=B. argentifolii Perring & Bellows) on cotton (Gossypium hirsutum L.) plants to enable more accurate life tables to be constructed for this important insect pest. The survival of crawlers did not differ significantly between still-air and artificial wind treatments in the greenhouse and averaged 90%. Overall, 99.5% of the crawlers settled on the abaxial surface of leaves, and 99.9% settled on the leaf where eggs were oviposited. Out of 4,125 nymphs, only five settled on leaves other than the leaf of origin, and they all moved to leaves lower on the plant. Assuming that these individuals crawled rather than fell, the mean distance moved was at least 200 mm. Using a combination of cohort-based life table studies to measure egg mortality and recruitment studies to measure egg to settled first instar mortality in the field, crawler survival was estimated to average 89.2% over three study sites in Phoenix and Maricopa, AZ. Overall results suggest that crawlers move very little on cotton and that survival of the crawler stage is relatively high under both greenhouse and field conditions. Generational mortality rates estimated from previous life table studies in the field that excluded crawler mortality would increase by only 0.8% with the addition of this minor mortality component.
Tomato (potato) psyllid, Bactericera (=Paratrioza) cockerelli (Sulc) (Hemiptera: Psyllidae) has emerged as an important and potentially limiting pest of greenhouse-grown tomatoes in Colorado and effective methods of monitoring have not been developed for the crop. To better assist detection of tomato psyllid in greenhouses a series of trials were conducted to evaluate optimal trap design and placement. Eighteen different colors were evaluated as were effects of shading, orientation to sunlight and height of trap placement. Color trap trials indicated that neon-green, neon-orange and standard yellow were most attractive to psyllids. Traps hung near the top of tomato plants (150-cm) caught significantly more psyllids than lower placed traps (30-cm). Traps partially shaded caught more psyllids than traps that were fully exposed to the sun. Traps oriented to the north caught more psyllids than traps oriented to the south; there were no differences between east and west orientation. This information can improve tomato psyllid pest management by providing monitoring methods that effectively trap adults.
The blow flies, Phaenicia eximia (Wiedemann) and Cochliomyia macellaria (F.), oviposited nocturnally on ground beef under artificial lighting of at least 1,500 footcandles at temperatures 26°C or higher during onsets of low-atmospheric pressure at study sites near Snook, Texas, during 2003. Nocturnal oviposition was replicated five times during 14 spring season experiments and three times during 14 summer season experiments conducted under similar conditions.
The hitherto unknown female and first-instar larva of the deer bot fly Cephenemyia albina Taber and Fleenor (Diptera:Oestridae), recently described on the basis of four male specimens, are described and compared with C. phobifera (Clark) with which it co-occurs in east-central Texas. One larviparous female of each species and additional males of C. albina were collected from the latter's type locality in Malaise traps baited with dry ice.
Entomopatogenic fungi are a promising alternative for the control of agricultural pests. We evaluated the pathogenicity of three isolates of Paecilomyces fumosoroseus (Wize) Brown and Smith (Pf1, Pf2, and Pf3) and six isolates of Lecanicillium (= Verticillium) lecanii (Zimmermann) Zare and Gams (VI1, VI2, VI3, VI4, VI5, and VI10) on eggs, second, third, and fourth nymphal instars of the greenhouse whitefly, Trialeurodes vaporariorum (Westwood). Three of the nine isolates (Pf1, VI3, and VI5) produced 11–26% infections of eggs, while the remaining isolates had no significant effect (Pf3 and VI10) or were unable (Pf2, VI1, VI2, and VI4) to infect this developmental stage. Pf1, Pf2, and Pf3 caused homogeneous pathogenicity in all nymphal instars tested, while L. lecanii isolates showed high variability. Pf1, Pf2, and Pf3 were usually the most pathogenic, but their activity correlated inversely with increasing nymphal instars. The pathogenicity (number of living nymphs recovered from treated plots) of Pf2 on T. vaporariorum nymphs was evaluated on zucchini squash plants in two experimental trials. Survival of whitefly nymphs decreased by 19 and 28% after the first and second fungal applications, respectively, in one trial, and by 62 and 71% in the other trial. Based on these results, we concluded that the use of fungal preparations based on the Pf2 isolate could be feasible for controlling T. vaporariorum.