Morphological and Molecular Characterization of \u3ci\u3eMeloidogyne mayaguensis\u3c/i\u3e Isolates from Florida

The discovery of Meloidogyne mayaguensis is confirmed in Florida; this is the first report for the continental United States. Meloidogyne mayaguensis is a virulent species that can reproduce on host cultivars bred for nematode resistance. The perineal patterns of M. mayaguensis isolates from Florida show morphological variability and often are similar to M. incognita. Useful morphological characters for the separation of M. mayaguensis from M. incognita from Florida are the male stylet length values (smaller for M. mayaguensis than M. incognita) and J2 tail length values (greater for M. mayaguensis than M. incognita). Meloidogyne mayaguensis values for these characters overlap with those of M. arenaria and M. javanica from Florida. Enzyme analyses of Florida M. mayaguensis isolates show two major bands (VS1-S1 phenotype) of esterase activity, and one strong malate dehydrogenase band (Rm 1.4) plus two additional weak bands that migrated close together. Their detection requires larger amounts of homogenates from several females. Amplification of two separate regions of mitochondrial DNA resulted in products of a unique size. PCR primers embedded in the COII and 16S genes produced a product size of 705 bp, and amplification of the 63-bp repeat region resulted in a single product of 322 bp. Nucleotide sequence comparison of these mitochondrial products together with sequence from 18S rDNA and ITS1 from the nuclear genome were nearly identical with the corresponding regions from a M. mayaguensis isolate from Mayaguez, Puerto Rico, the type locality of the species. Meloidogyne mayaguensis reproduced on cotton, pepper, tobacco, and watermelon but not on peanut. Preliminary results indicate the M. mayaguensis isolates from Florida can reproduce on tomato containing the Mi gene. Molecular techniques for the identification of M. mayaguensis will be particularly useful in cases of M. mayaguensis populations mixed with M. arenaria, M. incognita, and M. javanica, which are the most economically important root-knot nematode species in Florida, and especially when low (\u3c25) numbers of specimens of these species are recovered from the soil

Assessing the impact of shellfish harvesting area closures on neurotoxic shellfish poisoning (NSP) incidence during red tide (Karenia brevis) blooms

•Karenia brevis produces brevetoxins which may accumulate in molluscan shellfish.•The risk for NSP increases during blooms with ingestion of contaminated shellfish.•The current management strategy is effective for commercially harvested shellfish.•NSP is occurring at a higher rate among non-commercial harvesters.•These include out-of-area state-resident visitors and out-of-state visitors to the SW Florida. Neurotoxic shellfish poisoning (NSP) is caused by the consumption of molluscan shellfish meat contaminated with brevetoxins produced by the dinoflagellate, Karenia brevis (K. brevis). During a prolonged and intermittent K. brevis bloom starting in 2005 lasting through early 2007 in the Gulf of Mexico off southwest Florida coast, there were 24 confirmed cases of NSP linked to the consumption of clams recreationally harvested in, or in close proximity to, regulated shellfish harvesting areas; these shellfish beds had already been officially closed to harvesting due to the presence of the K. brevis bloom. The majority of NSP cases (78%) were in “visitors,” either non-Florida residents or Florida residents living outside the county of harvest. The number of confirmed NSP cases was likely an underestimate of the actual number of cases. Current management strategy appears to be effective in limiting the number of NSP cases associated with shellfish harvested commercially during red tide events. In contrast, public notification that shellfish beds are closed to harvest, due to red tides or pathogens, is not reaching all recreational shellfish harvesters and consumers, particularly visitors from outside the county or state. The constantly changing closure status of shellfish harvesting areas in combination with overlooked notifications may lead to an apparent disregard of harvesting restrictions. It is important, therefore, to provide the general public, including visitors and those with language barriers, with improved access to up-to-date information concerning the daily openings and closings of shellfish harvesting areas. Furthermore, the risks of consuming potentially toxic shellfish should be disseminated more broadly

Nonhomogeneous products and the law of one price

Law of One Price (LOP) is important in the theory of international trade. It is important in LOP studies to have data that accurately represents homogeneous products (i.e., the product in one country has the same product characteristics as the product in another country). We present a theoretical model that determines fresh grapefruit prices Free on Board (FOB) at the packinghouse. The first order conditions show that the FOB packinghouse prices are equal for products with the same product characteristics. The theoretical conditions show a difference in FOB prices when the product characteristics are different. The product characteristics that are varied include packing costs and pack-out rates. The results from a nonlinear programming optimization routine demonstrates the importance of using data that accurately represents homogeneous products for LOP studies. Different packing costs and pack-out percentages are shown to cause different FOB packinghouse prices for fresh grapefruit destined for domestic and export markets. [JEL Classification: Q11, Q13, F14]. © 2007 Wiley Periodicals, Inc. Agribusiness 23: 407-420, 2007.

The Mediterranean Fruit Fly and the United States: Is the Probit 9 Level of Quarantine Security Efficient?

"Cold treatment periods, and associated levels of quarantine security, that maximize net US welfare under USDA's current medfly detection and control program are examined using a deterministic bioeconomic optimization model"". As anticipated, the efficient level of quarantine security is shown to increase with indices of medfly pressure (initial infestation rates) in areas in which the medfly is known to exist (the QCs)"". Efficient cold treatment periods and weighted mean medfly survival rates are 8, 11, and 12 days and 5.0 � 10-super--2, 1.7 � 10-super--3, and 5.2 � 10-super--4 under low, moderate, and high initial infestation rates, respectively. When model output is averaged across initial infestation rates, an 11-day cold treatment period, resulting in a weighted mean medfly survival rate of 1.6 � 10-super--3, maximizes US welfare. These findings suggest that the current minimum cold treatment period of 14 days and the current objective of US cold treatment policy-the probit 9 level of quarantine security-are economically inefficient. Adopting the 11-day cold treatment period is shown to increase US social surplus by an annual $24.9 million, of which$21.5 and $3.4 million would accrue to US consumers and producers, respectively, and QC producer surplus by an annual$24.8 million." Copyright 2007 Canadian Agricultural Economics Society.