Testing banker plants for biological control of mites on roses

We tested whether plant species used in a banker plant system influence the success of a biological control program with predatory mites. Banker plants (BP) may sustain a reproducing population of predators and provide long-term pest suppression. In an experiment lasting 12 weeks, we analyzed the responses of the predatory mite Amblyseius californicus and the pest mite Tetranychus urticae to eight species of potential BP with different morphological structures. Every BP was paired with a rose plant and infested with pest and predatory mites. The measured parameters were vitality and growth of the plants and numbers of predators, pests and their eggs. Reproduction and establishment of the pest and predatory mites differed among plant species as well as plant growth and vitality. Vitis riparia and Viburnum tinus were the most efficient BP in this combination of pest–predator species. Their presence resulted in best health of the rose crops, highest number of predatory mites and lowest number of pests. Both these BP possess domatia which may be responsible for the efficiency in hosting predatory mites. Overall, the species which fulfilled the requirements of a BP best was the local shrub V, tinus, which bore no pests and a very large number of predators and has a compact growth form suited for application in greenhouses. Although our study gives only evidence for an artificial system with a high BP:crop ratio, high numbers of introduced predators and short distances between plants, this study contributes to knowledge of BP systems and to improve the understanding of the criteria for the choice of local plant species to be used as BP for biological control in IPM.     

Genetic and Phenotypic Diversity in the Graminaceous Cyst Nematode Complex, Inferred from PCR-RFLP of Ribosomal DNA and Morphometric Analysis

Graminaceous cyst nematodes form a group of eleven valid species including Heterodera avenae, Heterodera filipjevi and Heterodera latipons and constitute major pests to cereals. They are widely spread in circum-mediterranean areas where they are presumed to cause yield losses on bread and durum wheat. The objective was to document the diversity of these cereal cyst nematodes, in particular samples from Mediterranean regions, in comparison to species which develop on cultivated or wild grasses (H. arenaria, H. hordecalis, H. mani) and on rice or sugarcane (H. sacchari). Studies involved PCR-RFLP of ITS and morphometrics of the juvenile and cyst characters. UPGMA analysis of molecular data showed that the isolates segregated in two main clusters which seem to represent different evolutionary lineages. The H. avenae sensu lato cluster (I) contained H. arenaria, H. avenae, H. filipjevi and H. mani. The second cluster (II) contained isolates of H. hordecalis and H. latipons. Within H. avenae sensu lato, H. filipjevi was separated from the other related species with significant bootstrap value. The differentiation of H. arenaria, recognized for the first time based on molecular data, and H. mani with few restriction enzymes were the least significant. Intraspecific polymorphism allowed differentiation of isolates originating from Australia within H. avenae sensu stricto. The group H. hordecalis–H. latipons showed the greatest genetic variability between and within isolates. Two representatives of Heterodera sacchari, taxonomically included in the schachtiigrave group, were genetically as distant to this group as to the other graminaceous species belonging to either H. avenae sensu lato or H. hordecalis–H. latipons group. Results inferred from multivariate analysis applied on morphometrics of the cysts and juveniles showed agreement between genetic and phenotypic classifications. This study demonstrates the utility of combined molecular and classical methods to enhance our knowledge about the diversity within the complex of graminaceous cyst nematodes and to establish robust techniques to identify a wider set of nematode species.     

Cash refunds in farm supply co-operatives: Experience from the United States

This study evaluated the effects of various cash refund policies on the financial position of co-operatives and co-operative members in Mississippi. Questionnaires were mailed to 25% of the farm supply co-operatives having over one million dollars of annual sales and to 25% of those having less than one million dollars of annual sales. In addition, financial data and parameters for three firms typical of co-operatives in the state were secured. These data were used to develop a hypothetical co-operative for analysis in a cash flow simulation model.The after-tax present values of the patron's investments were calculated and then the option of varying the cash refund percentage was analysed in order to evaluate its impact on the firm's financial position.It was found that members derive benefit from their co-operatives, as shown by the after-tax present value of yearly benefits to patrons. Also, increasing the cash patronage refund resulted in lower patron benefits and had an adverse effect on the financial structure of the co-operative. Therefore, increasing the percentage of cash refund to members will probably weaken the co-operative's ability to serve its members in the future.     

Variation in transmission of two BYDV-MAV isolates by multiple clones of Rhopalosiphum padi L.

Vector efficiency of up to 17 Rhopalosiphum padi L. clones originating from Europe, North America and North Africa, was evaluated by transmitting two isolates of the serotype MAV for which this species is normally an inefficient vector. When test plants were inoculated by batches of 3 aphids, both isolates were rather well transmitted by one clone (Rp5), isolate MAV2 was poorly transmitted by all other clones tested and isolate MAV11 was not transmitted by eight clones and poorly transmitted by two clones. When eight aphids were used by test plants, all clones transmitted both isolates. The epidemiological consequences of MAV transmission by some R. padi clones are discussed, as well as the interest of these clones for studying aphid-derived components of luteovirus transmission.     

Imidacloprid impairs memory and brain metabolism in the honeybee (Apis mellifera L.)

Imidacloprid is a chloronicotinyl insecticide which interacts with insect nicotinic acetylcholine receptors. Thirty minutes after oral treatment of honeybees with imidacloprid, the olfactory learning performances in a proboscis extension reflex (PER) procedure were impaired. In parallel, an increase of the cytochrome oxidase labelling was found into the calyces of the mushroom bodies. Imidacloprid administered 15 min or 1 h after a one-trial conditioning of PER impaired the medium-term olfactory memory. By contrast, the short-term (30 s or 3 min conditioning-treatment time interval) and long-term (24 h conditioning-treatment time interval) memories were unaffected. The impairment of medium-term olfactory memory by imidacloprid is discussed in the context of neural circuits suspected to mediate memory formation in the honeybee brain.     

Mushroom-derived maitake PETfraction as single agent for the treatment of lymphoma in dogs

BACKGROUND: Maitake PETfraction is a standardized essence extracted from the mushroom Maitake (Grifola frondosa) that has antitumor activity in tumor-bearing mice. In addition, PETfraction induces apoptosis in human prostate and bladder cancer cells and suppresses the proliferation in vitro of several canine tumor cell lines, such as lymphoma (Cl-1), mammary gland (CF33), and connective tissue (CF21). HYPOTHESIS: Maitake PETfraction is effective as a single agent in dogs with lymphoma. ANIMALS: Fifteen dogs with confirmed intermediate or high-grade lymphoma were enrolled into this prospective, noncontrolled, clinical trial. Inclusion criteria were an expected survival time of at least 2 weeks and no major organ dysfunction. METHODS: Maitake PETfraction was administered at a dose of 3 drops/kg/day divided into 2 doses given 1 hour before feeding. Dogs were evaluated by physical examination with tumor measurement, body weight, CBC, and chemistry profile before treatment and after 2, 4, 8, and 12 weeks. At each visit, owners completed a questionnaire addressing overall quality of life, appetite, and any adverse effects noted. RESULTS: A decrease in lymph node size of greater than 50% (objective response) was not seen in any of the dogs. Thirteen dogs developed progressive disease before the 4th week. The median treatment duration was 27 days (range, 9-228). PETfraction was well accepted, and minimal adverse effects were observed. Two dogs developed hyphema. It was not known if this was related to progressive lymphoma or was an adverse effect of treatment. CONCLUSIONS: No objective responses were observed to administration of Maitake PETfraction, and the drug was well tolerated in these dogs.     

Late-entry commercial thinning effects on Pinus banksiana:growth,yield, and stand dynamics in Québec,Canada

We studied late-entry commercial thinning effects on growth, yield, and regeneration in a 48-year-old jack pine(Pinus banksiana Lamb.) stand. Applied thinning intensities were 27, 32, and 47% of merchantable basal area(BA) excluding skidding trails. After 15 years, mean diameter at breast height of surviving trees in the 47% BA removal increased by 4.9 cm(25%) compared to the unthinned control. The 47% BA removal also increased gross merchantable volume(GMV) tree-1by 46% compared to the control. The 27% BA removal had twice as much GMV ha-1compared to the 47% BA removal after15 years. Moreover, cumulative GMV ha-1was much higher in the 27% BA removal than in the unthinned control. The highest thinning intensity produced larger trees on average, while the lowest thinning intensity maximized volume production per hectare. Maintenance of acceptable growing stock throughout the 15-year period in the 27% BA removal could provide other ecosystem functions such as biodiversity enhancement or wildlife habitat by delaying senescence. Regeneration data showed that a shift in species composition occurred in the understory. After 15 years, the understory was dominated by black spruce(Picea mariana(Mill.) B.S.P.), white birch(Betula papyrifera Marsh.), and trembling aspen(Populus tremuloides Michx.). If regenerating jack pine is an objective after final overstory removal, additional efforts will be needed to re-establish this species.     

A Parasitological Survey of Oysters Along Salinity Gradients in Coastal Louisiana

Oysters were collected along salinity gradients within four major oyster producing watersheds in Louisiana (Lake Calcasieu, Terrebonne Bay, Barataria Bay and Lake Borgne) and examined for parasites in relation to oyster condition and reproductive state. The percentage of Infection by Perkinsus marinus, Nematopsis prytherchi, N. ostrearum, Bucephalus cuculus , prokaryotic inclusion bodies, and ciliates was recorded for each site. Average pigment cell number, oyster condition, gonadal index, and the percentage of oysters with atrophic digestive diverticula were also determined.
In general, oysters experienced higher levels of parasitism in higher salinity waters. Perkinsus marinus Occurrence was correlated with salinity, an atrophied condition of the oysters, and Nematopsis spp. occurrence. Oysters in poor condition had higher concentrations of pigment cells, greater atrophy of the digestive diverticula, and increased parasitism by N. ostrearum .