The Influence of Reflective Mulches and Lettuce Types on the Incidence of Aster Yellows and Abundance of its Vector, \u3ci\u3eMacrosteles Fascifrons\u3c/i\u3e (Homoptera: Cicadelidae), in Minnesota

Five commercial lettuce cultivars representing different genetic types were grown through aluminum-coated paper, through black polyethylene film, and on bare soil. For each variety, the aluminum mulch reduced the numbers of Macrosteles fascifrons (St~l), reduced the incidence of aster yellows, and increased yields when compared to uncovered controls. The head lettuce cultivar \u27Minetto\u27 was most susceptible on unmulched plots (74.3%) while the leaf cultivar \u27Grand Rapids\u27 was least susceptible (33.8%). The latter also had the greatest infestation of leafhoppers which may indicate either resistance to the aster yellows agent or shorter feeding times by the vector leafhopper. The abundance of aster leafhoppers on the romaine cultivar \u27Valmaine\u27, the butter head cultivar \u27Buttercrunch\u27, and the bibb cultivar \u27Summer Bibb\u27 was much lower than that of the other two and might explain the lower percentage of aster yellows on these types as compared with \u27Minetto\u27

Tuta Absoluta The South American Tomato Leafminer

The South American tomato leafminer Tuta Absoluta is a serious and devastating pest of both fresh market and processing tomatoes. Tuta continues to spread throughout the tomato-growing areas of the world. Computer models have predicted that this pest has a moderate likelihood of establishing itself in the commercial tomato producing areas of California, Arizona, and the southern United States. This publication explains the host plants, life cycle, damage of the pest along with monitoring an management methods

Volatile codes: Correlation of olfactory signals and reception in Drosophila-yeast chemical communication.

Drosophila have evolved strong mutualistic associations with yeast communities that best support their growth and survival, resulting in the development of novel niches. It has been suggested that flies recognize their cognate yeasts primarily based on the rich repertoire of volatile organic compounds (VOCs) derived from the yeasts. Thus, it remained an exciting avenue to study whether fly spp. detect and discriminate yeast strains based on odor alone, and if so, how such resolution is achieved by the olfactory system in flies. We used two fly species known to exploit different niches and harboring different yeasts, D. suzukii (a pest of fresh fruit) and D. melanogaster (a saprophytic fly and a neurogenetic model organism). We initially established the behavioral preference of both fly species to six Drosophila-associated yeasts; then chemically analyzed the VOC profile of each yeast which revealed quantitative and qualitative differences; and finally isolated and identified the physiologically active constituents from yeast VOCs for each drosophilid that potentially define attraction. By employing chemical, behavioral, and electrophysiological analyses, we provide a comprehensive portrait of the olfactory neuroethological correlates underlying fly-yeast coadaptation in two drosophilids with distinct habitats

Vitis vinifera (Vitales: Vitaceae) as a Reproductive Host of Spissistilus festinus (Hemiptera: Membracidae).

Feeding by the three-cornered alfalfa hopper, Spissistilus festinus (Say) (Hemiptera: Membracidae) results in girdling of grapevine petioles and shoots. Its significance as an economic pest of grape has increased since it was shown to transmit Grapevine red blotch virus (GRBV) in a greenhouse study. However, the status of grapevines as a reproductive host for S. festinus remained undetermined. Adult S. festinus were caged onto three regions of the grapevines: apical shoot, green shoot, and dormant cane. Their ability to reproduce was determined by weekly destructive sampling for 7 wk. Successful oviposition and nymphal emergence were observed on apical and green shoots, but not on dormant canes. However, insect development beyond the second nymphal instar did not occur. Knowledge of S. festinus reproduction on grapevines will be an important consideration in designing management guidelines to minimize the spread of GRBV in vineyards

Pests and Agricultural Commodity Losses: Evaluating Alternative Approaches to Damage Function Estimation

Estimating the economic impact of a pest requires linking biological and economic systems via a damage function. The most common damage function approach links exogenous pest populations to cumulative commodity yield losses at harvest. This type of representation is a reduced form because is not pest population levels per se that drive damage, but the underlying factors that affect pest populations and the susceptibility of the host. We specify and estimate a structural damage function and compare the results with those of the reduced form. We do so using two alternative models, one that explains the level of crop damage from a pest, and one that explains the timing of that damage during the host’s growing season. We address our objectives within an empirical application to the olive fruit fly in California. In formulating the structural damage function, we draw from current scientific literature on olive fly and olive fruit phenology. The structural damage function takes into account the feedback between climate, host susceptibility, and pest populations. Moreover, the structural approach disaggregates damage rates across space and time, unlike the typical reduced form. The estimation results indicate that endogeneity is a salient concern in both the timing of initial crop damage, and in the levels of damage evidenced in some cultivars. The structural damage function dominates the trapping-based reduced form in terms of explanatory power in every model estimated.Crop Production/Industries,

Potentially Hygroreceptive Sensilla on the Anal Stylus of the Glassy-Winged Sharpshooter, Homalodisca vitripennis

This study begins to elucidate the cues and mechanisms by which the glassy-winged sharpshooter, Homalodisca vitripennis (Germar) (Hemiptera: Cicadellidae), select host plants for feeding and oviposition. The electrophysiological response of the anal styli of male and female H. vitripennis to water vapor was examined using a modified electroantennography (EAG) device (stylogram). A strong electrophysiological response of the anal stylus to water vapor was found. Scanning electron microscopic examination of the anal stylus revealed the presence of long mechanosensory hairs, many small coeloconic-type sensilla, and masses of secretory granules termed brochosomes. Each coeloconic sensillum is located in a pit from which protrude finger-like projections. The pit is often blocked by masses of brochosomes and an unidentified dense material. Based on the electrophysiological response of the anal stylus to water vapor, we hypothesize that the coeloconic sensilla on the stylus may be hygroreceptors. H. vitripennis are xylem feeders and may use the sensilla to assist in host selection for the purpose of feeding or oviposition based on detected plant water status. Furthermore, H. vitripennis oviposit into the leaf epidermis, and may use these sensilla to evaluate moisture content to determine host suitability for both oviposition and subsequent feeding of emerged progeny. Understanding the cues and underlying mechanisms of host selection is an important consideration for predicting the movement of H. vitripennis between crops and disease epidemiology

Tuta absoluta (Lepidoptera: Gelechiidae) success on common solanaceous species from California tomato production areas

Tuta absoluta (Meyrick) is a devastating pest of tomato that has invaded many regions of the world. To date, it has not been detected in North America, but the pest reached Costa Rica in 2014 and seriously threatens the southern, southwestern, and western United States including California. Although the primary host of T. absoluta is tomato, several other species of Solanaceae may serve as alternative hosts. In our study, we aimed to assess the potential risk that other solanaceous crops and wild species that are often present in and around California tomato fields could serve as hosts. To accomplish this, we conducted greenhouse and laboratory studies to determine whether two common cultivars of fresh market tomato, two common cultivars of tomatillo, and the wild plants, Solanum nigrum L., Solanum sarrachoides (Sendtner), and Datura stramonium L., are suitable hosts for reproduction and development of the pest. According to our results, D. stramonium and tomatillo were unable to sustain T. absoluta larval development in either greenhouse studies or laboratory studies, and therefore, they are not likely to contribute to T. absoluta establishment during an invasion. On the contrary, the two other solanaceous weeds, S. nigrum and S. sarrachoides, share a similar potential as tomato to be reproductive and developmental hosts of T. absoluta, and might play an important role in the establishment of the pest in California.info:eu-repo/semantics/acceptedVersio