No abstract

Plant essential oils from 43 plant species were tested for their nematicidal activities against the pine wood nematode, Bursaphelenchus xylophilus. Responses varied with plant material and concentration. Good nematicidal activity against male, female and juvenile nematodes of B. xylophilus was achieved with essential oils of Cinnamomum verum, Leptospermum petersonii, Asiasarum sieboldi, Boswellia carterii, Pimenta racemosa, Cymbopogon citratus, Mentha spicata, clove and garlic. Garlic and cinnamon oils showed the most potent nematicidal activity among the plant essential oils. Analysis by gas chromatography-mass spectrometry led to identification of three major compounds from garlic and two from cinnamon oil. These five compounds from two essential oils were tested individually for their nematicidal activities against the pine wood nematode. Responses varied with compounds and dose. LC50 values of diallyl trisulphide, diallyl disulphide and cinnamyl acetate against juvenile nematode were 2.79, 37.06 and 32.81 μl−1, respectively. The essential oils described herein merit further study as potential nematicides against the pine wood nematode.

: Hemocytes are the immune effectors in clams, directing cellular but also humoral defences. In the Manila clam (Ruditapes philippinarum) and the carpet shell clam (Ruditapes decussatus), two phenotypically similar venerid species, fishery and aquaculture importance motivated scientific studies to improve knowledge about the participation of hemocytes in immune response. Currently, gaps still persist concerning the classification of hemocyte sub-populations as well as their non-immune activities. This review summarizes current knowledge about hemocytes of the Manila clam and the carpet shell clam, suggests some probable misinterpretations arising from extrapolations from other bivalves and vertebrates, and suggests future research prospects. The susceptibility of hemocytes to environmental modifications as well as biological and chemical toxicants is also re-evaluated. Hemocytes of bivalves are not limited in function to immunity and should be considered in a wider scheme including the environment and whole-animal physiology.

No abstract

No abstract

The Antarctic marine environment is characterized by extreme seasonality in primary production, and herbivores must cope with a prolonged winter period of food shortage. In this study, tissue mass and biochemical composition were determined for various tissues of the bivalve Laternula elliptica (King & Broderip) over a 2 yr period, and its storage and use of energy reserves were investigated with respect to seasonal changes in food level and water temperature. Total ash-free dry mass (AFDM) accumulated rapidly following phytoplankton blooms (with peak values immediately before and after spawning) and was depleted considerably during the spawning and winter periods. Most of the variation was in the muscle, gonads and digestive gland. Spawning peaked in January and February and caused considerable protein and lipid losses in the muscle, gonads and digestive gland. In winter (March to August), the muscle and digestive gland lost considerable mass, while gonad mass increased; this suggests that the muscle tissue and digestive gland serve as major energy depots for both maintenance metabolism and gonad development in winter. There were also marked year-to-year differences in the seasonal patterns of mass variation and reproduction. Overall, the relative and absolute tissue-mass values were positively correlated with chlorophyll concentration, and were not related to water temperature; thus, for the first time, this study clearly shows that food is an important factor governing growth and gonad maturation in this bivalve. It is also noteworthy that protein, constituting ~75% of AFDM, served as the major energy reserve throughout the study, closely following the AFDM variation. In particular, during the winter months, protein comprised >60% of AFDM loss, while lipids and glycogen served as minor (< 20% each) reserves. Protein loss was most substantial in the muscle tissue, which comprised half of the body tissue. Thus, protein use, with muscle tissues as a depot for protein reserves, may be a result of selective pressure on Antarctic marine herbivores undergoing a prolonged period of food shortage in winter.

Plant essential oils from 40 plant species were tested for their insecticidal activities against larvae of Lycoriella ingénue (Dufour) using a fumigation bioassay. Good insecticidal activity against larvae of L. ingenua was achieved with essential oils of Chenopodium ambrosioides L., Eucalyptus globulus Labill, Eucalyptus smithii RT Baker, horseradish, anise and garlic at 10 and 5 microL L(-1) air. Horseradish, anise and garlic oils showed the most potent insecticidal activities among the plant essential oils. At 1.25 microL L(-1), horseradish, anise and garlic oils caused 100, 93.3 and 13.3% mortality, but at 0.625 microL L(-1) air this decreased to 3.3, 0 and 0% respectively. Analysis by gas chromatography-mass spectrometry led to the identification of one major compound from horseradish, and three each from anise and garlic oils. These seven compounds and m-anisaldehyde and o-anisaldehyde, two positional isomers of p-anisaldehyde, were tested individually for their insecticidal activities against larvae of L. ingenua. Allyl isothiocyanate was the most toxic, followed by trans-anethole, diallyl disulfide and p-anisaldehyde with LC(50) values of 0.15, 0.20, 0.87 and 1.47 microL L(-1) respectively.

No abstract