Performance of four <Emphasis Type="Italic">Trichogramma</Emphasis> species (Hymenoptera: Trichogrammatidae) as biocontrol agents of <Emphasis Type="Italic">Heliothis virescens</Emphasis> (Lepidoptera: Noctuidae) under various temperature regimes

Trichogramma spp. are major parasitoids of lepidopteran pest eggs, but there is large variation in efficacy toward a given pest among the numerous described Trichogramma species. It is important to select the Trichogramma species that most effectively parasitize and develop in target pest eggs for biological control. In this context, Trichogramma pretiosum, T. exiguum, T. atopovirilia and T. acacioi were studied in Heliothis virescens eggs under different thermal conditions. The parasitoids were reared at constant temperatures of 20, 25 and 30°C and tested at these respective temperatures, while parasitoids reared at 25°C were also tested at 20 and 30°C, for a total of 20 species–temperature combinations. About 30 H. virescens eggs were offered to the parasitoids for 24 h. Among the four species, parasitism rate by T. atopovirilia was highest at all temperature conditions, whereas T. acacioi had the lowest rates of parasitism at 25°C and 25/30°C. Parasitism ranged from 13.8 to 43.8% among all species–temperature combinations. Viability (emerged parasitoids) ranged from 80.8 to 98.4%, and was deemed satisfactory. The emergence rates of T. exiguum and T. acacioi were affected by temperature. Temperature also affected the sex ratio of T. exiguum at 25/30°C, whereas T. pretiosum and T. acacioi produced females predominantly independent of temperature. Overall, the parasitoid T. atopovirilia was the most efficient in parasitizing H. virescens eggs, though the levels of parasitism obtained might not ensure its successful use in biological control programs. The temperature-related differences in biological traits observed in the four Trichogramma species tested hint at the importance of making careful choices regarding climatic conditions where the parasitoid is going to be used when selecting a species for biological control programs.     

Acute and chronic effects of endosulfan on the haemato-immunological and histopathological responses of a threatened freshwater fish, spotted murrel, Channa punctatus

Two experiments, one short-term and one long-term, were conducted to elucidate the acute and chronic effects, respectively, of endosulfan exposure on the haemato-immunological and histopathological responses of Channa puncatatus. In the short-term study, fish were exposed to sublethal endosulfan (8.1 μg l⁻¹) for 12, 24, 36, 48, 72 and 96 h. In the long-term study, fish were fed with normal diet and simultaneously either exposed to endosulfan (1.2 μg l⁻¹) for 90 days or not. Results showed that the ascorbic acid levels in both the liver and the muscle decreased significantly (P < 0.05) by acute and chronic endosulfan exposure. The haemoglobin (Hb) level reduced significantly (P < 0.05) by 15.5% within 12 h of acute endosulfan exposure, further decreased by 25.8% after 24 h of exposure, however, thereafter the values increased and at the end of 72 h returned to normal levels. Almost similar trend was observed for the erythrocyte (RBC) count. The WBC count and the nitroblue tetrazolium (NBT) value showed a general increasing trend with increase in the duration of acute endosulfan exposure. The chronic exposure of C. punctatus to endosulfan significantly (P < 0.05) lowered the Hb level, RBC and WBC counts, NBT reduction value and the plasma parameters such as plasma protein, albumin (A) and globulin (G) compared with that of the control (except for A/G ratio). Endosulfan exposure also severely altered the liver histological structure. Overall results indicated that both short-term acute and long-term chronic endosulfan exposure had a significant impact on the haemato-immunological parameters and tissue histopathology of C. punctatus.     

An overview of male-sterility systems in pigeonpea [<Emphasis Type="Italic">Cajanus cajan</Emphasis> (L.) Millsp.]

For commercial development of hybrids the four pre-requisites are; availability of perfect male-sterility system, efficient mass pollen transfer mechanism, hybrid vigor, and the large scale seed production of hybrids for commercialization. The type of male-sterility governs the acceptance of hybrids by farmers. Genetic male-sterility (GMS) system was not accepted by farmers due to the economics of large scale seed production. The major drawback was rouging of fertile counterpart from the female plot, which was time consuming and labor intensive. Cytoplasmic-genic male-sterility (CMS) system usually was a better option for large scale seed production. Hybrid vigor has been utilized in some cereal and vegetable crops. Pigeonpea (Cajanus cajan) displays considerable natural out-crossing and now CMS lines are available with different cytoplasmic backgrounds. This mini-review reports the research on development of CMS lines and CMS-based hybrids in pigeonpea.     

木豆胞质雄性不育系柱头活力研究

在中国南部地区南宁市(位于北纬22°49′、东经107°45′)大田生产条件下对2个木豆胞质雄性不育系ICPA 2039和ICPA 2043花期柱头活力进行研究,发现柱头活力始于开花前2d并维持至开花后4d,活力峰值出现在开花当日;人工授粉成荚率ICPA 2039和ICPA 2043分别为84.0 %和82.0 %;柱头活力期可通过花冠/花萼长度比来判定,ICPA 2039和ICPA 2043分别为2.75±0.075和2.60±0.283.柱头活力周期越长,获得虫媒授粉的异交机会越多,因此柱头活力周期是杂交育种成功率的一个重要技术参数,长的活力周期也是种子生产获得高产的保证.     

An overview of aflatoxicosis of poultry: Its characteristics,prevention and reduction

Aflatoxicosis represents one of the serous diseases of poultry, livestock and other animals. The cause of this disease in poultry and other food-producting animals has been attributed to the ingestion of various feeds contaminated with A. flavus. This toxigenic fungus is known to produce a group of extremely toxic metabolites, of which aflatoxin B₁ (AFB₁) is most potent. Avian species especially chickes, goslings, ducklings and turkey poults are most susceptible to AFB₁ toxicity. The toxic effects of AFB₁ are mainly localized in liver as manifested by hepatic necrosis, bile duct proliferation, icterus and hemorrhage. Chronic toxicity in those birds is characterized by loss of weight, decline in feed efficiency, drop in egg production and increased susceptibility to infections. The incidence of hepatocellular tumors, particularly in ducklings, is considered to be one of the serious consequences of aflatoxicosis. Even though prevention and avoidanve are the best way to control aflatoxicosis, natural contamination of crops with A. flavus is sometimes unavoidable. Such aflatoxin-contaminated feeds can be decontaminated using various methods which mainly focus on physical removal or chemical inactivation of the toxins in the feeds. Moreover, dietary additives such as activated charcoal, phenobarbital, cysteine, glutathione, betacarotene, fisetin and selenium have also been reported to be effective in the reduction of aflatoxicosis in poultry.     

Microbial levan in the diet of Labeo rohita Hamilton juveniles: effect on non-specific immunity and histopathological changes after challenge with Aeromonas hydrophila

A 60-day feeding trial was conducted to study the immuno-protective effect of microbial levan on Labeo rohita juveniles challenged with Aeromonas hydrophila. Six purified diets were prepared with different levels of microbial levan: control (no levan), T1 (Basal + 0.25%), T2 (Basal + 0.50%), T3 (Basal + 0.75%), T4 (Basal + 1%) and T5 (Basal + 1.25%), fed to six groups of fish in triplicate. Among the treatment groups the haemoglobin content and total leucocyte count were increased with a dietary supplementation of levan at 1% or more. An increasing trend for total erythrocyte count was observed with increasing level of dietary levan. Lower levan-supplemented groups showed a higher albumin/globulin ratio. As the levan supplementation was increased, there was a gradual increase in serum lysozyme activity and respiratory burst activity [nitroblue tetrazolium (NBT) assay] reduction values. The highest lysozyme activity and NBT were observed in the T5 group although this was similar to the T4 group ( P  > 0.05). No significant histo-architectural changes were associated with dietary levan levels. After challenge with A. hydrophila , moderately degenerated hepatocytes, oedema and leucocytic infiltration in parenchymatous tissues, and extensive haemorrhage and haemosiderosis in the kidney were observed in the control group. However, the T5 group supplemented with 1.25% levan showed infiltrating leucocytes in the liver while the kidney showed only moderate degeneration of renal tubules. The relative survival per cent of juveniles after challenge with A. hydrophila was the highest in the T5 group followed by T4. This suggests that microbial levan at 1.25% can be used as dietary immunostimulant for L. rohita juveniles.     

Water soaking and exogenous enzyme treatment of plant-based diets: effect on growth performance, whole-body composition, and digestive enzyme activities of rohu, Labeo rohita (Hamilton), fingerlings

A 2 × 2 × 2 factorial experiment was conducted to delineate the main effect of water soaking of plant ingredients, phytase, cellulase, and their interactions on the growth and digestive enzyme activities of Labeo rohita fingerlings. Two basal diets were prepared using water-soaked (S) or unsoaked (US) plant-based ingredients. Feed of US ingredients was supplemented with phytase (U kg⁻¹) and cellulase (%) at the level of 0, 0 (C_us); 500, 0 (T₁); 0, 0.2 (T₂); 500, 0.2 (T₃), and feed of S ingredients at 0, 0 (C_s); 500, 0 (T₄); 0, 0.2 (T₅), and 500, 0.2 (T₆), respectively. Three hundred and sixty fingerlings were randomly distributed into eight treatments, each with three replicates. Soaking of the ingredients for 24 h significantly reduced the tannin content. However, feeding of S diets did not improve the fish growth. Highest performance was recorded in the T₃ group. A significant interaction between dietary phytase and cellulase was observed for apparent net protein utilization. Tissue crude protein, ether extract, and ash content of the fingerlings were observed highest in the T₃ group. Activities of amylase, protease, and lipase were recorded highest in the T₃ group. Results suggested that soaking of plant-based ingredients reduces tannin content; however, growth and digestive enzyme activities of group fed soaked diet were not improved, possibly due to leaching of soluble nutrients. Probably, a shorter duration soaking may be effective in reducing tannin content and avoiding nutrients leaching.     

Toxicity of dietary monensin in quail

Quail were fed monensin to determine liver damage, as measured by changes in activities of serum enzymes and liver microsomal enzymes. Monensin fed at a therapeutic level of 110 ppm for 2 weeks produced an increase in cytochrome P-450 and cytochrome b5 and induction of the activities of benzphetamine N-demethylase, aminopyrine N-demethylase, and aniline hydroxylase, with no changes in the activities of serum sorbitol dehydrogenase (SDH), alanine aminotransferase (ALT), and aspartate aminotransferase (AST). On the other hand, quail fed 110 ppm, 220 ppm, and 330 ppm monensin in feed for 6 weeks showed a significant rise in SDH and AST activities at 330 ppm but not at 110 ppm and 220 ppm. The manifestations of liver toxicity observed at 330 ppm were accompanied by a significant decrease in all the aforementioned hepatic microsomal mixed-function oxidases. In contrast, quail fed monensin at 110 ppm and 220 ppm for 6 weeks produced no change in these parameters except for benzphetamine N-demethylase, aminopyrine N-demethylase, and aniline hydroxylase, which were significantly increased in birds fed 220 ppm of monensin.     

Comparative studies on the effect of fenbendazole on the liver and liver microsomal enzymes in goats,quail and rats

To compare the effect of fenbendazole on the liver and liver microsomal mono-oxygenases of goats, quail and rats, an oral dose of 25 mg/kg was administered to the animals daily for 9 consecutive days. On the tenth day, blood samples and livers were collected from both the control and the treated animals for preparation of serum and microsomes respectively. Determination of the activities of sorbitol dehydrogenase (SDH), alanine aminotransferase (ALT) and aspartate aminotransferase (AST) in the serum samples showed that there was no significant increase in the activities of these enzymes in the treated animals as compared to their corresponding controls, suggesting no liver damage. Similarly, no significant difference in the amount of microsomal cytochrome P-450 was found between the control and the treated animals of the same species. Compared to their respective controls, the activities of microsomal benzphetamine N-demethylase and aniline hydroxylase were almost unchanged in the treated goats and rats. However, fenbendazole treatment appeared to enhance the activity of these two microsomal enzymes in quail. The results indicate that fenbendazole is not liver toxic to goats, quail or rats at a dose rate of 25 mg/kg.