174,264 research outputs found
The Value of Bt Corn in Southwest Kansas: A Monte Carlo Simulation Approach
No full textWhile most Corn Belt farmers consider planting Bt corn to control European corn borer, southwestern Kansas farmers must also take into account an array of other insect pests, including corn rootworm, spider mites, and southwestern corn borer. This research uses a decision analysis framework to estimate the expected economic value of Bt corn in southwest Kansas. Mean per acre Bt values ranged from 34.60, well above the technology fee assumed to be 5.25 per acre at a seeding rate of 30,000 seeds per acre. The minimum value over all scenarios was $8.69 per acre. Using Monte Carlo simulation, it was shown that European and southwestern corn borer infestation probabilities, expected corn price, and expected pest-free yields are important determinants of the value of Bt corn.Bt corn, decision analysis, European corn borer, integrated pest management, Monte Carlo simulation, southwestern corn borer, Crop Production/Industries,
Relations between two rice borers in Surinam, Rupela albinella (Cr.) and Diatraea saccharalis (F.), and their hymenopterous larval parasites
No full textIn many tropical countries, lepidopterous stem borers are major pests of the rice crop. Study of the rice borers in Surinam, Rupela albinella and Diatraea saccharalis, was made in the Paramaribo area, at the experimental station 'CELOS' during 1971, 1972 and 1973, since data on the ecology and economic importance of these borers were incomplete and almost lacking for the small holders rice areas. Special attention was paid to the role of the parasites of these borers.I. R. albinellaThis 'white rice borer' deposits its scale-covered egg masses on the leaves. Newly hatched larvae disperse in a very active way both on plants and on the water surface and they may also use the flow of water. They bore into the stem cavity within 24 hours after hatching. Development to maturity takes place inside one internode. There are five larval instars and only the last two can not be separated by head capsule width. The full-grown larva cuts an exit opening in the stem wall for escape of the adult. The duration of the different developmental stages was determined.Normally the percentage of larvae which entered diapause proved to be very low. It was not clear which factor was reponsible for diapause induction. A correlation with a slightly higher temperature (about 2°C) was detected but the data are still too limited to accept the temperature as a basic factor.Moths are active during darkness and are attracted by ordinary incandescent light, but are seldom captured during the period of full moon.Since Rupela requires an adequate stem cavity for its development, rice plants become vulnerable to attack only 60 days after sowing when a proper internodal space may be present. Rice varieties having a total growth period of only 105 days automatically possess an 'escape resistance', because the larval and pupal development takes about 50 days.Generally R. albinella is well adapted to the rice plant. Crop losses are very small since the stem tissue is only attacked superficially.Four parasites of R. albinella were found, viz.:1. Telenomus sp., an egg parasite with a short life cycle. This insect was not further studied.2. Venturia ovivenans, an egg-larval parasite with a high reproduction capacity, parasitizes the eggs. The growth of the parasite larva is moderate until the host is full-grown. Rapid growth follows and the larva leaves its host and pupates inside the stem.Development of host and parasite are well sychronized, both in nondiapause and diapause situations. The average time of emergence of the wasp is two days earlier than of the moth.The species is very common throughout Surinam.3. Strabotes rupelae, a larval and pupal parasite, deposits its eggs near the fullgrown host larva or pupa. The wasp even crawls into the water in search for hosts. The ectoparasitic larva grows very rapidly and sucks out its host. The duration of the life cycle is one third that of the host. The adult life span may be as long as two months.The parasite was quite common at the 'CELOS' research centre with its continuous rice cultivation program.4. Heterospilus sp., a gregarious and ectoparasitic wasp, lays its eggs in the stem cavity near a full-grown host larva. Larval growth is very rapid and the total life cycle is one third of that of its host.The parasite was common at the 'CELOS' research centre.The interactions between R. albinella and its parasites are schematically given in Figure 15.The greatest mortality occurs in the L 1 during dispersal and penetration of the host plant. Later on, the effect of parasites as well as pupal mortality are important.The succession of the generations of the borer and its parasites under the 'CELOS' continuous rice cultivation system is given in Figure 18. Over a period of slightly more than two years, borer infestation slowly increased whereas parasitization of the borer slowly decreased. The percentage composition of the parasitic complex remained stable in these two years.II. D. saccharalisAn existing aseptical diet for the 'brown borer' was improved and made it possible to rear large numbers of borers. The following good rearing results were obtained: total developmental time (35-38 days), pupal weights (males 75 mg, females 125 mg) and egg production (400 eggs/female). A clear correlation was found between pupal weight and egg production.It was not possible to accurately separate the 6 larval instars by means of head capsule width. The behaviour of the larvae was followed. Moths emerged before midnight and sometimes copulated the same night. A male copulates once a night and at most, three successive nights. Copulation always occurs late in the night. The first eggs are laid the night after mating.Larval and pupal mortality was very high under field circumstances.Agathis stigmaterus was the only important parasite. It was reared in large quantities in host larvae feeding on the diet mentioned above. The wasp deposits its eggs in 6-14 day-old hosts. An average of 100 hosts were parasitized per wasp. The parasite first grows slowly; it then leaves the nearly full-grown host and sucks it out within a few hours. There is a good synchronization between the host and the parasite. Only 2 % of the wasps were males.Ant nests were present in about 15 % of the rice hills. These ants, Paratrechina sp., feed on the young borer larvae.Although D.saccharalis incidentally may cause some local losses, the overall damage is negligible
The Syntactic Domain of Content
No full textBorer, H. in press. 'The Syntactic Domain of Content.' In Becker, Misha, John Grinstead and Jason Rothman (eds.), Generative Linguistics and Acquisition: Studies in honor of Nina M. Hyams. 2013. vi, 355 pp. + index (pp. 205–248).
http://benjamins.com/#catalog/books/lald.54.09bor/details
***This chapter has been accepted for publication in a book that is under copyright and the publisher should be contacted for permission to re-use or reprint the material in any form.***Borer, H. in press. "The syntactic domain of Content." In M. Becker, J. Grinstead, J. Rothman & B.D. Schwartz (eds.) Generative Linguistics and Acquisition: Studies in Honor of Nina M. Hyams. Philadelphia: John Benjamins.Borer, H. in press. "The syntactic domain of Content." In M. Becker, J. Grinstead, J. Rothman & B.D. Schwartz (eds.) Generative Linguistics and Acquisition: Studies in Honor of Nina M. Hyams. Philadelphia: John Benjamins.Borer, H. in press. "The syntactic domain of Content." In M. Becker, J. Grinstead, J. Rothman & B.D. Schwartz (eds.) Generative Linguistics and Acquisition: Studies in Honor of Nina M. Hyams. Philadelphia: John Benjamins.Borer, H. in press. "The syntactic domain of Content." In M. Becker, J. Grinstead, J. Rothman & B.D. Schwartz (eds.) Generative Linguistics and Acquisition: Studies in Honor of Nina M. Hyams. Philadelphia: John Benjamins.Borer, H. in press. "The syntactic domain of Content." In M. Becker, J. Grinstead, J. Rothman & B.D. Schwartz (eds.) Generative Linguistics and Acquisition: Studies in Honor of Nina M. Hyams. Philadelphia: John Benjamins.Borer, H. in press. "The syntactic domain of Content." In M. Becker, J. Grinstead, J. Rothman & B.D. Schwartz (eds.) Generative Linguistics and Acquisition: Studies in Honor of Nina M. Hyams. Philadelphia: John Benjamins.Borer, H. in press. "The syntactic domain of Content." In M. Becker, J. Grinstead, J. Rothman & B.D. Schwartz (eds.) Generative Linguistics and Acquisition: Studies in Honor of Nina M. Hyams. Philadelphia: John Benjamins.Borer, H. in press. "The syntactic domain of Content." In M. Becker, J. Grinstead, J. Rothman & B.D. Schwartz (eds.) Generative Linguistics and Acquisition: Studies in Honor of Nina M. Hyams. Philadelphia: John Benjamins.A main motivation for relegating Word Formation to the lexicon is the fact that its output is often non-compositional. The present article, however, presents a serious challenge to the presumed contradiction between non-compositionality and syntactic combinatorial processes. The investigation of N–N Constructs in Hebrew shows that equally syntactically complex expressions nonetheless interact differently with non-compositionality. Crucially, it is the syntactic differences between these expressions that give rise to distinct Content properties, with non-compositionality correlating not with syntactic structure as such, but with the absence of functional structure. The emerging syntactic domain of ‘word’ Content in turn allows the language learner to make informed decisions on where to look for non-compositionality and to draw the appropriate structural conclusions from its presenc
MANAGING PEST RESISTANCE: THE POTENTIAL OF CROP ROTATIONS AND SHREDDING
No full textThe current debate over resistance management plans mandated by the Environmental Protection Agency for transgenic crops ignores management practices that are complementary to refuge schemes. A dynamic production model is developed that measures the costs and benefits of crop rotation and shredding in terms of delaying resistance to Bt corn.biotechnology, common property resource, crop rotation, European Corn Borer, externalities, insecticide resistance, integrated pest management, intertemporal optimization, Crop Production/Industries, Research and Development/Tech Change/Emerging Technologies,
Semiochemicals used in host location by the coffee berry borer, Hypothenemus hampei
No full textThe coffee berry borer, Hypothenemus hampei is a serious pest in many coffee growing countries. Electrophysiological and behavioral responses of H. hampei to volatiles of different phenological stages of coffee, Coffea arabica, fruits were studied in order to identify volatile semiochemicals used in host location. Volatiles were collected from different phenological stages of C. arabica fruit by air entrainment. Electrophysiological recordings were made from insect antennae. Behavioral assays were carried out using a Perspex four-arm olfactometer. Insects spent significantly more time in the region of the olfactometer where ripe and dry fruit volatiles were present compared to control regions. Coupled gas chromatography—electroantennography revealed the presence of six electrophysiologically active compounds in C. arabica volatiles. These were identified by using GC and GC-MS as methylcyclohexane, ethylbenzene, nonane, 1-octen-3-ol, (R)-limonene, and (R)-3-ethyl-4-methylpentanol. In the olfactometer bioassay, H. hampei showed a significant response to 3-ethyl-4-methylpentanol, methylcyclohexane, nonane, ethylbenzene, and a synthetic blend of these four compounds. Attraction to the synthetic blend was comparable to that for the natural sample. The significance of the study is discussed in terms of semiochemical based pest management methods of the coffee berry borer
MANAGING EUROPEAN CORN BORER RESISTANCE TO BT CORN WITH DYNAMIC REFUGES
No full textWe develop a dynamic bioeconomic model of temporally optimal dynamic refuge recommendations for resistance management when a backstop technology arrives at a known date. The impact of the characteristics of the backstop on the use of the current technology, and the difference between static and dynamic refuges are examined.Crop Production/Industries,
Effects of artificial shade on attack by the mahogany shoot borer, Hypsipyla robusta (Moore)
No full textSwietenia macrophylla King (Meliaceae: Swietenioideae) provides one of the premier timbers of the world. The mahogany shoot borer Hypsipyla robusta Moore (Lepidoptera: Pyralidae) is an economically important pest of S. macrophylla throughout Asia, Africa and the Pacific. No viable method of controlling this pest is known. Previous observations have suggested that the presence of overhead shade may reduce attack by H. robusta, but this has not been investigated experimentally. This research was therefore designed to assess the influence of light availability on shoot-borer attack on S. macrophylla, by establishing seedlings under three different artificial shade regimes, then using these seedlings to test oviposition preference of adult moths, neonate larval survival and growth and development of shoot borer larvae.\ud
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Oviposition preference of shoot borer moths was tested on leaves from seedlings grown under artificial shade for 63 weeks. A significant difference in choice was recorded between treatments, with 27.4 ± 1.5 eggs laid under high shade and 87.1 ± 1.8 under low shade.\ud
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Neonate larval survival on early flushing leaflets of S. macrophylla did not differ significantly between shade treatments. Larval growth rate, estimated by measuring daily frass width, was significantly higher for those larvae fed on seedlings from the high and medium shade treatments (0.1 mm/day), than the low shade treatment (0.06 mm/day). In laboratory-reared larvae, the total mass of frass produced was significantly higher in the high shade treatment (0.4 g) than under the low shade treatment (0.2 g).\ud
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Longer tunnel lengths were bored by larvae in plants grown under high shade (12.0 ± 2.4 cm) than under low shade (7.07 ± 1.9 cm). However, pupal mass under low shade was 48% higher than that under the high shade treatment, suggesting that plants grown under high shade were of lower nutritional quality for shoot borer larvae.\ud
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These results indicate that shading of mahogany seedlings may reduce the incidence of shoot borer attack, by influencing both oviposition and larval development. The establishment of mahogany under suitable shade regimes may therefore provide a basis for controlling shoot borer attack using silvicultural approaches
The European Corn Borer
No full textThe European corn borer was first recorded from South Dakota i n the summer of 1946. At that time Hr. H. C. Severin and the author found borers in corn in Union and Lincoln and Minnehaha counties. Less than half of one percent of the stalks in the fields were infested at that time. During the summer of 1948 the infestation had spread over most of the corn producing area of our state. By the fall of that year 36 counties were known to be infested . Several fields in the southeastern part of the state had 100 per cent of the stalks showing borer injury
MANAGING THE RISK OF EUROPEAN CORN BORER RESISTANCE TO TRANSGENIC CORN: AN ASSESSMENT OF CONTROVERSIAL REFUGE RECOMMENDATIONS
No full textA bioeconomic model is developed to evaluate the tradeoff between the risk of resistance and increased productivity when refuge is planted in conjunction with transgenic pesticidal corn. The model is used to evaluate controversial refuge recommendations when producers are allowed to treat refuge in years of high pest pressure.Productivity Analysis, Research and Development/Tech Change/Emerging Technologies, Risk and Uncertainty,
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