Resistance and susceptibility of various wheat varieties to <Emphasis Type="Italic">Sitobion avenae</Emphasis> (Hemiptera: Aphididae) in Iran

The English grain aphid, Sitobion avenae (Fabricius), is a severe pest of wheat plants in temperate countries. Therefore, we carried out primary screening to assess the resistance or susceptibility of 23 commonly grown wheat varieties to this aphid at greenhouse and laboratory conditions in Iran. Also, population attributes of this aphid were evaluated on six wheat varieties, namely Saysonz, Arta, Moghan3, Zagros, Sardari and Shirodi. The aphids were colonized on the Hirmand wheat variety in a growth chamber at 20 ± 1°C, 60 ± 5% R.H. and a photoperiod of 14:10 (L:D). The tested varieties were grouped into three major classes including A (e.g., Shirodi, Falat and Moghan2), B (e.g., Sardari, Zagros and Tagan) and C (e.g., Arta, Saysonz, Moghan3 and Pishtaz). Also, the results of the life history traits showed that the developmental time of nymphal stage ranged from 7.5 days on Zagros to 10.8 days on Saysonz. The intrinsic rate of increase (r _m ) of S. avenae varied from 0.133 (day⁻¹) on Saysonz to 0.210 (day⁻¹) on Shirodi. Jackknife estimates of other population parameters on these varieties were evaluated. As a result, our findings showed that the varieties Saysonz, Arta and Moghan3 were partially resistant against S. avenae, whereas Shirodi, Zagros and Sardari were relatively susceptible.     

Studies on naturally-occurring ovine fascioliasis in the Sudan

Haematological, biochemical and pathological changes were investigated in 214 sheep naturally infected with Fasciola gigantica in an endemic area in the Sudan together with 82 uninfected controls. Infected animals showed a clear decrease in erythrocyte counts, haemoglobin concentration and packed cell volume, a normochromic, normocytic anaemia, leucocytosis and eosinophilia. Serum concentrations of the enzymes glutamate dehydrogenase, sorbitol dehydrogenase and glutamate oxaloacetic acid transaminase were also elevated in the infected group, indicating hepatic damage. This was confirmed by histopathological changes, which comprised degenerative and necrotic changes in hepatocytes associated with haemorrhage, fibrosis, increased lobulation of the liver, mononuclear cell infiltration with haemosiderin deposition in fluke tracks and portal areas and the formation of granulomata around fluke eggs and fluke remnants. In the infected group there was slight hyperglobulinaemia and a marked hypoalbuminaemia, with a decrease in A/G ratio. A slight rise in the level of serum bilirubin was also observed.     

Cataclysta lemnata Linnaeus, 1758 (Lepidoptera: Crambidae) expanded its host range feeding on invasive aquatic ferns,species of Azolla Lamarck, 1783 (Hydropteridales: Azollaceae): fitness factors and costs

Cataclysta lemnata Linnaeus, 1758 is a semi-aquatic moth that feeds on Lemnaceae and few of other aquatic plants. In recent years, this moth has been seen feeding on Azolla Lamarck, 1783 Lamarck, J.B. (1783), Encyclopedie methodique: botanique, 1, Paris: Panckouche. 752 pp. [Google Scholar] in Iran in high numbers. The effect of the host plant on preference and performance of the moth was assessed under laboratory conditions. Despite the high survival rate of the young larvae, due to high mortality of the late instars and pupa on Lemna Linnaeus, 1753, the total survival rate on Azolla was higher. Feeding on Azolla increased the development time by almost a week and reduced fertility to half. However, by consuming more food, regulating the egg laying dynamic, and increasing emergence period, the moth retrieved most of the losses and adapted to feed on Azolla. A week before pupation, feeding activity increased between 2 and 8 times in all treatments and on Azolla, the larvae growth rate was slightly higher.     

Investigation of sex ratio and adult longevity of Habrobracon hebetor Say in relation to some conventional and biorational insecticides

Habrobracon hebetor Say (Hymenoptera: Braconidae) is one of the most important natural enemies that has been used for biological control of lepidopteran pests, so the sub-lethal effects of imidacloprid, abamactin and Bacillus thuringiensis Berliner (Bt) on progeny sex ratio (male/total) and adult longevity of H. hebetor were examined under laboratory conditions. It was found that the progeny sex ratio changed to male bias significantly by Bt treatment. Also, the adult longevity of the wasp was affected adversely by insecticides treatment and it was longest in Bt treatment. In conclusion, the current results indicated that the sub-lethal concentration of these insecticides affected the progeny sex ratio and adult longevity and the best strategies for reduction of hazard to the H. hebetor in combination with Bt is to avoid their application before Bt spraying.     

Functional response of Chrysoperla carnea (Neuroptera: Chrysopidae) to Helicoverpa armigera (Lepidoptera: Noctuidae): Effect of prey and predator stages

Abstract Understanding predator–prey interactions has a pivotal role in biological control programs. This study evaluated the functional response of three larval instars of the green lacewing, Chrysoperla carnea (Stephens), preying upon eggs and first instar larvae of the cotton bollworm, Helicoverpa armigera Hübner. The first and second instar larvae of C. carnea exhibited type II functional responses against both prey stages. However, the third instar larvae of C. carnea showed a type II functional response to the first instar larvae of H. armigera, but a type III functional response to the eggs. For the first instar larvae of C. carnea, the attack rate on H. armigera eggs was significantly higher than that on the larvae, whereas the attack rate of the second instar C. carnea on H. armigera larvae was significantly higher than that on the eggs. For the third instar larvae of C. carnea, the attack rate on the larvae was 1.015 ± 0.278/h, and the attack coefficient on the eggs was 0.036 ± 0.005. The handling times of the third instar larvae on larvae and eggs were 0.087 ± 0.009 and 0.071 ± 0.001 h, respectively. The highest predation rate was found for the third instar larvae of C. carnea on H. armigera eggs. Results of this study revealed that the larvae of C. carnea, especially the third instar, had a good predation potential in controlling H. armigera eggs and larvae. However, for a comprehensive estimation of the bio‐control abilities of C. carnea toward H. armigera, further field‐based studies are needed.     

Effect of vermicompost on nutrition and intermediary metabolism of Colorado potato beetle,Leptinotarsa decemlineata (Say) (Coleoptera: Chrysomelidae)

Colorado potato beetle (CPB) is the important pest of potato throughout the world. The study showed the effects of vermicompost on nutritional indices, digestive enzyme activities and intermediary metabolism of the larvae and the adults of CPB. Vermicompost affected significantly the efficiency of conversion of ingested food (ECI) and efficiency of conversion of digested food (ECD) in addition to activities of carbohydrases and proteases in both larvae and adults. Amount of total phenol compounds increased in the leaves of the potatoes grown on the soil containing 30% of vermicompost compared to control and it were amended by 15% of vermicompost. In case of intermediary metabolism, activities of aspartate aminotransferase and γ-glutamyl transferase showed no significant differences in the control and the treated larvae, but those were fluctuated upper and lower when 15% of vermicompost was added into growth plots. The amount of low-density lipoproteins (LDL) and high-density lipoproteins (HDL) in the larvae of CPB showed no significant differences among treatments. However, the amounts of LDL, HDL, glycogen and protein of the adults significantly increased using 30% of vermicompost. Results of the current study clearly revealed significant effects on some physiological processes in CPB fed on the plants grown in the different vermicompost treatments.     

Localization of mRNAs coding for mitochondrial proteins in the yeast Saccharomyces cerevisiae

Targeted mRNA localization is a likely determinant of localized protein synthesis. To investigate whether mRNAs encoding mitochondrial proteins (mMPs) localize to mitochondria and, thus, might confer localized protein synthesis and import, we visualized endogenously expressed mMPs in vivo for the first time. We determined the localization of 24 yeast mMPs encoding proteins of the mitochondrial matrix, outer and inner membrane, and intermembrane space and found that many mMPs colocalize with mitochondria in vivo. This supports earlier cell fractionation and microarray-based studies that proposed mMP association with the mitochondrial fraction. Interestingly, a number of mMPs showed a dependency on the mitochondrial Puf3 RNA-binding protein, as well as nonessential proteins of the translocase of the outer membrane (TOM) complex import machinery, for normal colocalization with mitochondria. We examined the specific determinants of ATP2 and OXA1 mRNA localization and found a mutual dependency on the 3' UTR, Puf3, Tom7, and Tom70, but not Tom20, for localization. Tom6 may facilitate the localization of specific mRNAs as OXA1, but not ATP2, mRNA was mislocalized in tom6Δ cells. Interestingly, a substantial fraction of OXA1 and ATP2 RNA granules colocalized with the endoplasmic reticulum (ER) and a deletion in MDM10, which mediates mitochondria-ER tethering, resulted in a significant loss of OXA1 mRNA localization with ER. Finally, neither ATP2 nor OXA1 mRNA targeting was affected by a block in translation initiation, indicating that translation may not be essential for mRNA anchoring. Thus, endogenously expressed mRNAs are targeted to the mitochondria in vivo, and multiple factors contribute to mMP localization.     

Algal flora of certain gravel pits in the Thames Valley,U.K.

Summary Detailed analyses are presented of the phytoplankton of two pairs of gravel pits in the Surrey-Middlesex area of the Thames Valley. One of each pair has been recently excavated while the other is much older.Gravel dredging was fairly localised during the investigation, so that it was possible to study an area of disturbed water and an area of undisturbed water in each pit.The distribution of the algae in general and the frequency of the principal members of the phytoplankton were correlated, as far as possible with the physical and chemical features of the environment.Certain algae were found to favour the new or alternatively the old pits and there was some indication that some of the algae recorded in larger numbers thrived best in the disturbed or otherwise the undisturbed water of a pit.The total number of species observed in the new pits was considerably smaller than that in the old pits. Estimates of the total phytoplankton indicates that the new pits are richer, but less varied than the old pits.All the pits were flooded once by Thames water during the course of the investigation. Reasons are given for concluding that this flooding did not cause undue contamination with river phytoplankton.     

The protective effect of irradiated metacercariae of Fasciola gigantica against homologous challenge in sheep

Five lambs were each sensitized with 400 metacercariae of Fasciola gigantica irradiated at 3 kr gamma rays. Eight weeks later, they were each challenged together with 5 controls with 500 non-irradiated metacercariae. Eight weeks later, all of the animals were necropsied and the worm burdens determined. The lambs which received the sensitizing infections had 80% less worms than the controls. The sensitized lambs also showed less hepatic damage compared with the controls as indicated by lower levels of the serum enzyme glutamate dehydrogenase. The blood indices showed insignificant reductions in the sensitized lambs whereas marked reductions were found in the erythrocytes, packed cell volume and haemoglobin values of the challenge controls. Bilirubinaemia was also evident in this latter group.