The effect of a piperonyl butoxide/tau-fluvalinate mixture on pollen beetle (Meligethes aeneus) and honey bees (Apis mellifera)

BACKGROUND: Previous work has characterised pyrethroid resistance in pollen beetle (Meligethes aeneus F.) as principally an oxidative mechanism. Piperonyl butoxide (PBO) can synergise this resistance in the field, but its effects on the honey bee are thought to be unacceptable. RESULTS: A field trial in Poland was conducted to show that a mixture of PBO and tau‐fluvalinate at the registered rate gave increased and longer‐lasting control of resistant pollen beetle. Four days after spraying with tau‐fluvalinate, only 20% of pollen beetles were controlled, compared with 70% if the tau‐fluvalinate/PBO mixture was used. No detriment to honey bee health was observed using the same mixture. CONCLUSIONS: PBO, if used in conjunction with a pyrethroid of relatively low bee toxicity, can successfully overcome pyrethroid resistance in pollen beetle without incurring an increased loss of honey bees, even if they are present at the time of spraying. Copyright © 2012 Society of Chemical Industry     

Effect of insecticide injection on pyruvate kinase of the insect Tenebrio molitor (Coleopteran)

In the present study, we report on the changes observed in the kinetic properties of pyruvate kinase (PK) from whole body homogenate in the three developmental stages of the insect Tenebrio molitor after insecticide or acetone injection, and after injury and 24 h starvation. The apparent K_m value of the enzyme towards phosphoenolpyruvate was higher in the pupae stage than in the rest developmental stages although the same enzyme type appears to be present throughout the life span of the insect as judged by its V_max and sensitivity towards ATP and Alanine. The highest specific activity, twice as high as that of larvae and pupae, was observed in adults. Starvation resulted to activation of the enzyme by increasing the K_m value in the two feeding stages, namely larvae and adult, while injury had the opposite effect. Acetone injection did not have any significant effect at any stage. Insecticide injection had varying effects, depending upon the developmental stage, the dose and the type of the insecticide. In larvae, low doses of methyl paraoxon and methyl parathion activated the enzyme but as the dose increased the K_m value returned to normal levels. Low dose of decamethrin activated the enzyme also but at high dose it caused a severe inactivation as judged by a fivefold increase of the observed K_m. In pupae, decamethrin had no effect, methyl parathion had similar effects to those observed in larvae, and methyl paraoxon caused activation of the enzyme at any dose given. In the adult stage none of the injected insecticides had any effect on the K_m value although V_max and specific activity were significantly altered.     

Hotspots, complementarity or representativeness? designing optimal small-scale reserves for biodiversity conservation

Reserve networks are a major tool of ecological management aiming at biodiversity conservation. Maximizing the number of species conserved with the minimum land sacrifice is a primary requirement in reserve design. In this study, we examine the efficiency of five different scenarios to conserve: (i) the biodiversity of one target group and (ii) the overall biodiversity of an area. The study was conducted in Dadia Reserve, in northern Greece. Six groups of species were selected to represent its biodiversity: woody plants, orchids, Orthoptera, aquatic and terrestrial herpetofauna, and small terrestrial birds. The scenarios examined represent different conservation approaches to select network sites. For each approach, the starting point was one of the above six groups of species, considered as the target group. In scenario A, which reflects the hotspot approach, the sites richest in species are selected. Scenario B selects the sites most complementary in terms of species richness. The next two scenarios use the principle of environmental representativeness, expressed in terms of habitat (scenario C) or vegetation (scenario D). Under scenario E, sites forming the network are selected at random. The rank of scenarios in terms of preserving the species of the target group was always B > A > C > D > E, irrespective of the group considered as target group. Their rank, when preservation of the total biodiversity was the issue, was B, A > C, D > E.     

A Study of Glycemic Response to Corinthian Raisins in Healthy Subjects and in Type 2 Diabetes Mellitus Patients

This study was designed to evaluate the metabolic response to Corinthian raisins in healthy and in patients with type 2 diabetes mellitus. Healthy subjects (n?=?15) and diabetic patients (n?=?15) received 74 g raisins or 50 g glucose as reference food. Blood samples were collected at time 0 (before the consumption) and 30, 60, 90, 120, 150 and 180 min after raisin or glucose consumption. There was no significant difference in baseline glucose and insulin between raisins and reference in both groups. The difference at glucose peaks between raisins and reference was significant in healthy and in diabetics. Glycemic and insulinemic responses were decreased after raisin consumption compared to reference. An estimate of the glycemic index would be 66.3?±?3.4.     

The interactions between piperonyl butoxide and E4, a resistance‐associated esterase from the peach‐potato aphid,Myzus persicae Sulzer (Hemiptera: Aphididae)

BACKGROUND: It has been reported previously that piperonyl butoxide (PBO) can inhibit both P450 and esterase activity. Although the method by which PBO combines with cytochrome P450 has been identified, the way in which it acts as an esterase inhibitor has not been established. This paper characterises the interactions between PBO and the resistance‐associated esterase in Myzus persicae, E4. RESULTS: After incubation with PBO/analogues, hydrolysis of 1‐naphthyl acetate by E4 is increased, but sequestration of azamethiphos is reduced. Rudimentary in silico modelling suggests PBO docks at the lip of the aromatic gorge. CONCLUSIONS: PBO binds with E4 to accelerate small substrates to the active‐site triad, while acting as a blockade to larger, insecticidal molecules. Structure–activity studies with analogues of PBO also reveal the essential chemical moieties present in the molecule. © 2012 Society of Chemical Industry     

Sesamolinol glucoside, disaminyl ether, and other lignans from sesame seeds

The application of a procedure based on XAD-4 adsorption resin permitted the obtainment of an enriched polyphenolic extract from Sesamum indicum seeds. Chemical analysis of the obtained extract led to the identification of 12 lignans. Among them, 2 lignans, (+)-sesamolinol-4'-O-β-D-glucoside and disaminyl ether, are reported for the first time as natural compounds. Their structure has been determined by spectroscopic methods, mainly by the application of one-dimensional (1D) and two-dimensional (2D) nuclear magnetic resonance (NMR) techniques [heteronuclear multiple-quantum coherence (HMQC), heteronuclear multiple-bond correlation (HMBC), and nuclear Overhauser effect spectrometry (NOESY)] and mass spectroscopy. The isolated compounds were evaluated for their antimutagenic activity. Among the tested lignans, the most active lignan was found to be sesamolin, followed by sesamolinol and samin, against H(2)O(2). Additionally, some of the tested lignans showed desmutagenic activity against benzo[a]pyrene (BaP).     

Influence of prefermentative treatments to the major volatile compounds of Assyrtiko wines

A study of the volatile fraction of Assyrtiko wines, using gas chromatography coupled with olfactometry, was realized. Twenty-seven volatile compounds were identified as potent odorants, most of them originating from the fermentation process. Quantification of the major volatile compounds was realized developing a rapid analytical method based on fractionation of a 50 mL wine aliquot using C 18-reversed phase adsorbent. After elution of the volatile compounds with pentane-diethyl ether and concentration under nitrogen, the final wine extract was injected in a gas chromatography-flame ionization detection system. The method allows satisfactory determination of more than 15 volatile compounds of wine. The linearity of the method gave a typical r (2) between 0.990 and 0.999, while reproducibility ranged from 5.1 to 12.2% (as relative standard deviation) with 9.5% as the average. The method was applied to wines produced by Assyrtiko grapes (AOC Santorini), for two consecutive years, to compare the effect of skin contact prior to fermentation and the must clarification process. Direct press and skin contact wines were differentiated analytically; however, highly significant differences were not. Inversely, the differences found between direct press/clarified and nonclarified wines were significant. Wines produced by direct press and clarified must presented significantly higher levels of ethylic esters and fusel alcohol acetates but lower fusel alcohol levels, leading probably to more fruity wines. This difference, between clarified and nonclarified grape musts, was not significant in the case of the wines produced by skin contact of Assyrtiko berries. These findings were validated by preference sensory analysis tests.     

Determination of Acidic Pesticides in the Drinking Water of Greece Using Capillary Gas Chromatography-Mass Spectrometry

There is no data currently available on acidic pesticides in the drinking water of Greece, although considerable quantities of them are in use. In this study, the occurrence of the six most important acidic herbicides in the drinking water of Greece was investigated. The target compounds studied include four chlorophenoxy herbicides, namely mecoprop, dichlorprop, MCPA and 2,4-D, and two other acidic herbicides, i.e. bromoxynil and bentazone. Analysis was carried out at a concentration level of 100 ng L^?1 using capillary gas chromatography-mass spectrometry (GC-MS) with selected ion monitoring (SIM). The method involved a pre-concentration with solid phase extraction and derivatization with pentafluorobenzyl bromide. Thirty-eight samples of drinking water from nine regions in Greece were screened. No herbicides were detected although fortification experiments with parallel water samples resulted in recovery rates better than 70%. The detection limits of the recovered compounds were found to be between 10 and 50 ng L^?1.