Laying hens fed mycotoxin-contaminated feed produced by Fusarium fungi (T-2 toxin and fumonisin B1) and Saccharomyces cerevisiae lysate: Impacts on poultry health, productive efficiency, and egg quality.

Mycotoxins represent substantial challenges to the farming industry. These include toxins produced by Fusarium fungi, particularly trichothecenes (toxin T-2) and fumonisin (FB1). In the present study, we determined the effects of addition on Saccharomyces cerevisiae lysate (SCL) added to feed contaminated with T-2 and FB1 in terms of health, productive efficiency, and egg laying quality. We used 60 Hy-line Brown laying hens, and divided them into five groups with four repetitions per group and three birds per repetition. There was one group with no contamination with toxin (NoC). The four other groups included combinations of mycotoxin (4 ppm T-2, and 20 ppm FB1): A contamination group was used as control (the C+ group), and another two contained 500 g/ton of SCL (Detoxa Plus®) (the C + D500 group) or 1000 g/ton of SCL (the C + D1000 group). Finally, one group received feed containing 500 g/ton of Detoxa Plus® and 1000 g/ton of Uniwall® MOS 25 (the C + D500 + U1000 group). The experimental period was 84 days, divided into three productive cycles of 28 days each. The NoC hens had greater egg production than the other groups. Hens that consumed feed with SCL had greater egg production than did the C+ group. The NoC hens produced eggs with greater weights than did the C hens; however, C + D1000 and C + D500 + U1000 birds produced greater egg weights than did the C+ group. The C+ group produced lower egg masses than did the NoC and C + D500 + U1000 groups. The feed intake (FI) was lower in hens that ingested mycotoxin. The use of SCL in feed minimized the negative effects of mycotoxin on feed conversion ratio (FI/dozen). Effects of treatment were detected for feed conversion ratio (kg/kg). The hens that consumed mycotoxin had lower shell resistance and thickness compared to those in the NoC group. The red color of egg yolk was greater in the control groups. There were fluctuations in levels of liver enzymes when birds consumed mycotoxin (sometimes reduced and sometimes increased); nevertheless, the cumulative effect increased the activity of alanine aminotransferase. The serum concentration of reactive oxygen species was greater in hens that ingested mycotoxin only on d 84 compared to the NoC group. Serum glutathione S-transferase activity was greater on d 56 in C + D500 and C + D1000 hens than in the others. We conclude that, in general, the consumption of mycotoxin impaired the performance and quality of the eggs of the hens; the addition of the S. cerevisiae lysate and the addition organic acids, yeast cell wall and mineral carrier minimized some of the negative effects caused by T-2 and FB1.

Acute Toxicity and Sublethal Effects of Lemongrass Essential Oil and Their Components against the Granary Weevil, Sitophilus granarius.

In the present work, we evaluate the toxic and repellent properties of lemongrass (Cymbopogon citratus (DC. ex Nees) Stapf.) essential oil and its components against Sitophilus granarius Linnaeus as an alternative to insecticide use. The lethal dose (LD50 and LD90), survivorship, respiration rate, and repellency on adults of S. granarius exposed to different doses of lemongrass oil and some of its components were evaluated. The chemical composition of the essential oil was found to have the major components of neral (24.6%), citral (18.7%), geranyl acetate (12.4%), geranial (12.3%), and limonene (7.55%). Lemongrass essential oil (LD50 = 4.03 µg·insect-1), citral (LD50 = 6.92 µg·insect-1), and geranyl acetate (LD50 = 3.93 µg·insect-1) were toxic to S. granarius adults. Survivorship was 99.9% in insects not exposed to lemongrass essential oil, decreasing to 57.6%, 43.1%, and 25.9% in insects exposed to LD50 of essential oil, citral, and geranyl acetate, respectively. The insects had low respiratory rates and locomotion after exposure to the essential oil, geranyl acetate, and citral. Our data show that lemongrass essential oils and their components have insecticidal and repellent activity against S. granarius and, therefore, have the potential for application in stored grain pest management schemes.

Side effects of Bacillus thuringiensis on the parasitoid Palmistichus elaeisis (Hymenoptera: Eulophidae).

The endoparasitoid wasp Palmistichus elaeisis Delvare & LaSalle (Hymenoptera: Eulophidae) is used to control defoliating lepidopteran pests. Chemical insecticides are not compatible with natural enemies, but bioinsecticides, such as Bacillus thuringiensis Berliner (Bt), have great potential for use in integrated pest management. However, interactions between Bt and P. elaeisis still need to be investigated. This study aimed to evaluate the effects of Bt on parental and first-generation P. elaeisis parasitizing Bt-susceptible and -resistant Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae). An additional aim was to determine the toxicity of Bt to susceptible third-instar S. frugiperda larvae. Larvae were exposed to lethal concentrations (LC50 and LC90) of Bt and then allowed to be parasitized by P. elaeisis. Parasitoid longevity, immature production, reproductive performance, and behavioral responses were evaluated. Bt repelled P. elaeisis and reduced immature production. Parental and first filial generation parasitoids of both sexes emerged from Bt-treated larvae showed lower survivorship than controls. Parasitoids had poorer reproductive performance in Bt-susceptible and -resistant pupae than in untreated pupae. Palmistichus elaeisis emerged from Bt-susceptible and -resistant S. frugiperda showed altered host-searching behavior and reproductive parameters, which indicates low compatibility between the bioinsecticide agent and the parasitoid wasp.

Exposure to Insecticides Reduces Populations of Rhynchophorus palmarum in Oil Palm Plantations with Bud Rot Disease.

The South American palm weevil (SAPW), Rhynchophorus palmarum Linnaeus (Coleoptera: Curculionidae) is the main pest of Elaeis guineensis and damages palm trees with bud rot disease in the Americas. The effects of six neurotoxic insecticides (abamectin, carbaryl, deltamethrin, fipronil, imidacloprid and spinosad) were evaluated against SAPW for toxicity, survival, reproduction, and mortality. Abamectin (LC50 = 0.33 mg mL-1), Carbaryl (LC50 = 0.24 mg mL-1), deltamethrin (LC50 = 0.17 mg mL-1), and fipronil (LC50 = 0.42 mg mL-1) were the most toxic to SAPW. Adult survival was 95% without exposure to insecticides, decreasing to 78-65% in insects treated with the LC25 and 49-35% in insects exposed to LC50. Sublethal doses of carbaryl, fipronil and imidacloprid showed significant effect on the reproduction of this insect. Mortality of SAPW populations caused by insecticides had similar effects in the laboratory and field conditions. The results suggest that carbaryl, deltamethrin, fipronil, and imidacloprid caused significantly higher mortality as compared to the control in SAPW and may be used to control its populations in oil palm trees where bud rot appears as the key disease for SAPW attraction and infestation.

Terpenoid constituents of cinnamon and clove essential oils cause toxic effects and behavior repellency response on granary weevil, Sitophilus granarius.

This study evaluated toxic effects, repellency and respiration rate caused by terpenoid constituents of cinnamon and clove essential oils and against Sitophilus granarius L. (Coleoptera: Curculionidae). The lethal concentrations (LC50 and LC90), repellent effect, and behavior repellency response on adults of S. granarius after exposure to six concentrations of each essential oil and terpenoids were evaluated. The chemical composition of the cinnamon oil was also determined and primary compounds were eugenol (10.5%), trans-3-caren-2-ol (10.2%), benzyl benzoate (9.99%), caryophyllene (9.34%), eugenyl acetate (7.71%), α-phellandrene (7.41%), and α-pinene (7.14%). In clove essential oil, the primary compounds were eugenol (27.1%), caryophyllene (24.5%), caryophyllene oxide (18.3%), 2-propenoic acid (12.2%), α-humulene (10.8%), γ-cadinene (5.01%), and humulene oxide (4.84%). Cinnamon and clove essential oil was toxic to S. granarius. In toxic terpenoids compounds, eugenol has stronger contact toxicity in S. granarius than caryophyllene oxide, followed by α-pinene, α-humulene, and α-phellandrene. Insects reduced their respiratory rates after being exposed to essential oil terpenoids and avoided or reduced their mobility on terpenoid-treated surfaces. Cinnamon and clove essential oil, and their terpenoid constituents were toxic and repellent to adult S. granarius and, therefore, have the potential to prevent or retard the development of insecticide resistance.