Ant cues affect the oviposition behaviour of fruit flies (Diptera: Tephritidae) in Africa

Abstract. Although most studies on fruit fly oviposition behaviour focus on horizontal interactions with competitors and cues from host plants, vertical interactions with predators are poorly documented. The present study provides direct evidence indicating that the oviposition behaviour of the two main mango fruit fly species, Ceratitis cosyra (Walker) and Bactrocera invadens Drew‐Tsurata & White, is affected by secretions of the dominant arboreal ant Oecophylla longinoda (Latreille). When offered ant‐exposed and unexposed mangoes in the absence of the ants, both fly species are reluctant to land on ant‐exposed fruits and, when having landed, often take off quickly and fail to oviposit. The number of puparia collected from unexposed mangoes is approximately eight‐fold higher than from ant‐exposed ones. The results obtained from laboratory experiments and field observations confirm that adult fruit flies are more affected through repellence by ant cues than by direct predation. The use of cues by fruit flies in predator avoidance has implications for evolutionary ecology, behavioural ecology and chemical ecology.     

Phylogeny and biogeography Eupholidoptera Mařan (Orthoptera,Tettigoniidae): morphological speciation in correlation with the geographical evolution of the eastern Mediterranean

Recently, the systematics and biogeography of the Mediterranean biota have received much attention. This paper deals with Eupholidoptera Ma?an, a Mediterranean lineage of Tettigoniidae. The genus is restricted to the northern and eastern basin of the Mediterranean, with a significant number of species found on the Aegean islands. To produce a phylogeny and use it to make assumptions about the historical biogeography of Eupholidoptera, material of 46 species from several collections was studied. A phylogenetic analysis based mainly on morphological characters suggested two lineages in the genus: the E. chabrieri and the E. prasina groups. Based on the consistency between historical geographical events and branching events on the phylogenetic tree, Eupholidoptera is assumed to have evolved from an ancestor present in the Aegeid plate in the Mid‐Miocene. The division of the Aegeid plate into Anatolia and Greece in the Tortonian, the reoccurrence of terrestrial corridors between these mainlands in the Messinian, the regression of the Aegean area in the Pliocene and sea level changes in the Pleistocene are assumed to have been the main palaeogeographical events directing speciation in Eupholidoptera. As most of the species are allopatric, vicariance is suggested to be the main pattern. By combining the nature of the characters used in the phylogenetic analysis, the phylogenetic tree produced and the biogeographical assumptions, four tentative conclusions can be made: (i) radiation in the genus is a result of divergence in morphology; (ii) because the main character source is male genitalia, there has possibly been intensive sexual selection, which leads to morphological speciation; (iii) as the difference in temporal parameters of the song is prominent in sympatric/parapatric species pairs only, co‐occurrence is suggested to be the main reason driving divergence in the song; (iv) there seems to be a negative correlation between the size of the distribution range and the evolutionary rate in speciation; this may be the reason why the E. prasina group (restricted to a small part of the range of the genus) is more diverse than the E. chabrieri group, which is distributed over the entire range.     

Self-organized flocking in mobile robot swarms

In this paper, we study self-organized flocking in a swarm of mobile robots. We present Kobot, a mobile robot platform developed specifically for swarm robotic studies. We describe its infrared-based short range sensing system, capable of measuring the distance from obstacles and detecting kin robots, and a novel sensing system called the virtual heading system (VHS) which uses a digital compass and a wireless communication module for sensing the relative headings of neighboring robots. We propose a behavior based on heading alignment and proximal control that is capable of generating self-organized flocking in a swarm of Kobots. By self-organized flocking we mean that a swarm of mobile robots, initially connected via proximal sensing, is able to wander in an environment by moving as a coherent group in open space and to avoid obstacles as if it were a “super-organism”. We propose a number of metrics to evaluate the quality of flocking. We use a default set of behavioral parameter values that can generate acceptable flocking in robots, and analyze the sensitivity of the flocking behavior against changes in each of the parameters using the metrics that were proposed. We show that the proposed behavior can generate flocking in a small group of physical robots in a closed arena as well as in a swarm of 1000 simulated robots in open space. We vary the three main characteristics of the VHS, namely: (1) the amount and nature of noise in the measurement of heading, (2) the number of VHS neighbors, and (3) the range of wireless communication. Our experiments show that the range of communication is the main factor that determines the maximum number of robots that can flock together and that the behavior is highly robust against the other two VHS characteristics. We conclude by discussing this result in the light of related theoretical studies in statistical physics.     

Effects of long-term exposure to 900 megahertz electromagnetic field on heart morphology and biochemistry of male adolescent rats

The pathological effects of exposure to an electromagnetic field (EMF) during adolescence may be greater than those in adulthood. We investigated the effects of exposure to 900 MHz EMF during adolescence on male adult rats. Twenty-four 21-day-old male rats were divided into three equal groups: control (Cont-Gr), sham (Shm-Gr) and EMF-exposed (EMF-Gr). EMF-Gr rats were placed in an EMF exposure cage (Plexiglas cage) for 1 h/day between postnatal days 21 and 59 and exposed to 900 MHz EMF. Shm-Gr rats were placed inside the Plexiglas cage under the same conditions and for the same duration, but were not exposed to EMF. All animals were sacrificed on postnatal day 60 and the hearts were extracted for microscopic and biochemical analyses. Biochemical analysis showed increased levels of malondialdehyde and superoxide dismutase, and reduced glutathione and catalase levels in EMF-Gr compared to Cont-Gr animals. Hematoxylin and eosin stained sections from EMF-Gr animals exhibited structural changes and capillary congestion in the myocardium. The percentage of apoptotic myocardial cells in EMF-Gr was higher than in either Shm-Gr or Cont-Gr animals. Transmission electron microscopy of myocardial cells of EMF-Gr animals showed altered structure of Z bands, decreased myofilaments and pronounced vacuolization. We found that exposure of male rats to 900 MHz EMF for 1 h/day during adolescence caused oxidative stress, which caused structural alteration of male adolescent rat heart tissue.     

EFFECTS OF DIETARY SUPPLEMENTAL L-CARNITINE AND ASCORBIC ACID ON PERFORMANCE,CARCASS COMPOSITION AND PLASMA L-CARNITINE CONCENTRATION OF BROILER CHICKS REARED UNDER DIFFERENT TEMPERATURE

The present study was initiated to determine whether dietary supplemental L-carnitine and ascorbic acid affect growth performance, carcass yield and composition, abdominal fat and plasma L-carnitine concentration of broiler chicks reared under normal and high temperature. During the experiment, two temperature regimes were employed in two experimental rooms, which were identical but different in environmental temperature. The regimes were thermoneutral (20-22°C for 24 h) or recycling hot (34-36°C for 8 h and 20-22°C for 16 h). One-day-old broiler chicks (ROSS) were used in the experiment. A 2 x 2 x 2 factorial arrangement was employed with two levels (0 and 50 mg/kg) of supplemental L-carnitine and two levels (0 or 500 mg/kg) of supplemental ascorbic acid in drinking water under thermoneutral or high temperature regimes. Body weight gain was affected by high temperature. However, body weight gain was significantly improved in animals receiving supplemental L-carnitine, ascorbic acid or L-carnitine + ascorbic acid compared to animals receiving unsupplemented diet under high temperature. On the other hand, supplemental L-carnitine or L-carnitine + ascorbic acid reduced body weight gain under thermoneutral condition. Supplemental ascorbic acid significantly improved feed conversion efficiency, the improvement was relatively greater under high temperature. The L-carnitine content in the plasma was higher in the groups receiving supplemental L-carnitine and ascorbic acid under high temperature, while broilers fed supplemental L-carnitine and ascorbic acid had a decreased level of plasma L-carnitine concentration under normal temperature. It is concluded that dietary supplemental L-carnitine or L-carnitine + ascorbic acid may have positive effects on body weight gain, carcass weight under high temperature conditions.     

Some metals inhibit the glutathione S‐transferase from Van Lake fish gills

Glutathione S‐transferases (GSTs) are the superfamily of multifunctional detoxification isoenzymes and play important role cellular signaling. The present article focuses on the role of Cd²⁺, Cu²⁺, Zn²⁺, and Ag⁺ in vitro inhibition of GST. For this purpose, GST was purified from Van Lake fish (Chalcalburnus tarichii Pallas) gills with 110.664 EU mg^?1 specific activity and 79.6% yield using GSH‐agarose affinity chromatographic method. The metal ions were tested at various concentrations on in vitro GST activity. IC₅₀ values were found for Cd⁺², Cu⁺², Zn⁺², Ag⁺ as 450.32, 320.25, 1510.13, and 16.43 μM, respectively. K _i constants were calculated as 197.05 ± 105.23, 333.10 ± 152.76, 1670.21 ± 665.43, and 0.433 ± 0.251 μM, respectively. Ag⁺ showed better inhibitory effect compared with the other metal ions. The inhibition mechanisms of Cd²⁺ and Cu²⁺ were non‐competitive, whereas Zn²⁺ and Ag⁺ were competitive. Co²⁺, Cr²⁺, Pb²⁺, and Fe³⁺ had no inhibitory activity on GST.     

Interspecific diversity in root antioxidative enzyme activities reflect root turnover strategies and preferred habitats in wetland graminoids

Antioxidant enzymes protect cells against oxidative stress and are associated with stress tolerance and longevity. In animals, variation in their activities has been shown to relate to species ecology, but in plants, comparative studies with wild species are rare. We investigated activities of five antioxidant enzymes – ascorbate peroxidase (APX), catalase (CAT), glutathione reductase (GR), peroxidase (POX), and superoxide dismutase (SOD) – in roots of four perennial graminoid wetland species over a growing season to find out whether differences in root turnover or habitat preferences would be associated with variation in seasonal patterns of antioxidant enzyme activities. The investigated species differ in their root turnover strategies (fine roots senesce in the fall or fine roots survive the winter) and habitat preferences (nutrient‐poor vs. productive wetlands). Roots were collected both in the field and from garden‐grown plants. Antioxidant enzyme activities were higher and lipid peroxidation rates lower in species with annual root systems, and for species of the nutrient‐poor wetland, compared with perennial roots and species of productive wetlands, respectively. There was variation in the activities of individual antioxidant enzymes, but discriminant analyses with all enzymes revealed a clear picture, indicating consistent associations of antioxidant enzyme activities with the type of root turnover strategy and with the preferred habitat. We conclude that antioxidant enzyme activities in plant roots are associated with the species' ecological strategies and can be used as traits for the characterization of the species' position along plant economics spectrum.     

Determination of the inhibitory effects of N-methylpyrrole derivatives on glutathione reductase enzyme

Glutathione reductase (GR) is a crucial antioxidant enzyme which is responsible for the maintenance of antioxidant GSH molecule. Antimalarial effects of some chemical molecules are attributed to their inhibition of GR, thus inhibitors of this enzyme are expected to be promising candidates for the treatment of malaria. In this work, GR inhibitory properties of N-Methylpyrrole derivatives are reported. It was found that all compounds have better inhibitory activity than the strong GR inhibitor N,N-bis(2-chloroethyl)-N-nitrosourea, especially three molecules, 8?m, 8 n, and 8 q, were determined to be the most powerful among them. Findings of our study indicates that these Schiff base derivatives are strong GR inhibitors which can be used as leads for designation of novel antimalarial candidates.