Antimicrobial properties and chemical composition of four citrus fruit essential oils to control Paenibacillus larvae, the causal agent of American foulbrood disease (AFB) were determined. This honeybee larvae disease occurs throughout the world and is found in many beekeeping areas of Argentina. Citrus fruit essential oils tested were those from grapefruit (Citrus paradisi), sweet orange (Citrus sinensis), mandarin (Citrus nobilis) and lemon (Citrus limon). The components of the essential oils were identified by SPME-GC/MS analysis. The antimicrobial activity of the oils against P. larvae were determined by the broth microdilution method. Two way ANOVA tests for minimum inhibitory concentrations (MICs) data and minimal bactericide concentrations (MBCs) data, indicated significant differences between the strains and the oils tested. The antimicrobial assays showed that the oil of C. paradisi inhibited the bacterial strains at the lowest concentrations tested, MICs and MBCs averages of 385.0 mg/l and 770.0 mg/l, respectively. This property could be attributed to the kind and percentage of the volatile components of the oil, like limonene (69.9%) and myrcene (9.6%). The use of essential oils or their specific volatile components individually against pests related to food provision may represent an alternative scope for the control of this serious disease because it does not leave toxic chemical residues in honey nor in its by products.

When this article was originally published the legend for Figure 1 was incorrect. The correct legend and figure are printed below. The publisher regrets this error. 66°64°62°60°58°56°54°W 44°4 2°4 0°3 8°N Mar del Plata San Matías Gulf 200 m 100 m 50 m S o u t h w e s t e r n A t l a n t i c O c e a n South America Figure 1. Map of the study area on the northern Argentine continental shelf, showing bottom trawl locations where Patagonian skate, Bathyraja macloviana, were not (open squares) or were (filled squares) caught. The rectangle in the inset represents the study area.

The diet, feeding strategy, and dentition of the Patagonian skate, Bathyraja macloviana, on the northern continental shelf of Argentina were studied from specimens collected during research cruises in September and October 2001. Of a total of 81 stomachs examined, only 3.7% were empty. Cumulative prey curves showed that sample sizes were adequate to describe the main prey items of the diet. Quantitative analysis, a graphical method, and trophic niche breadth indicated the species to be a specialized feeder. The most important prey items were polychaetes, followed by gammarid amphipods, isopods, and crabs. Cumaceans, ophiuroids, and hydrozoans were likely incidentally consumed by mature females. Sexual dimorphism in dentition was observed; mature males had longer and sharper tooth cusps than females or immature males. However, there was a high degree of dietary overlap between mature males and mature females, indicating that dental sexual dimorphism in the species is more important in reproductive behaviour than in differential prey consumption.

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