RESUMO
This study was conducted at Oklahoma State University, Stillwater, OK, to evaluate the response to deltamethrin concentrations for adults of three stored-product insects, Tribolium castaneum (Herbst), Sitophilus oryzae (L.), and Rhyzopertha dominica (F.). In insect toxicological studies, knockdown is the state of intoxication and partial paralysis as a result of exposure to an insecticide. Deltamethrin concentrations ranging from 0.48 to 140 mg/m(2) (1 to 3,000 ppm) were sprayed on glass Petri dishes. After the dishes dried, 20 adult insects of each species were placed on the treated dishes to determine the contact toxicity of deltamethrin. Assessments for knockdown were made at 15-min intervals for up to 8 h after initial exposure and then again after 24 or 48 h. Insects were then transferred to clean untreated Petri dishes with diet and observed from 0.5 to 72 h. Mortality was assessed 72 h after transfer to untreated dishes with food material. Deltamethrin was highly effective against all three species tested and achieved 99% knockdown of insects of all species within 4 h after exposure at concentrations ≥1.2 mg/m(2) Although some insects recovered from initial knockdown at concentrations ≤48 mg/m(2), nearly all the insects were killed at 140 mg/m(2) when exposed for 48 h. LC95 values for all species tested, for the 48-h exposure period, were <140 mg/m(2), the concentration of deltamethrin that could potentially be present in new ZeroFly Storage Bag fabric. ZeroFly bags are used for stored-product insect pest control.
Assuntos
Besouros , Controle de Insetos , Inseticidas , Nitrilas , Piretrinas , Animais , Relação Dose-Resposta a Droga , Tribolium , GorgulhosRESUMO
The objective was to analyze the association between disease occurrence during early lactation and reproductive performance and survival of dairy cows in high-producing herds, under different management practices in three geographic regions of Chile. Data included 30,757 lactation records of cows calving from January 2013 to June 2014 in three different locations: Central (C) area (n = 6198 cows in eight herds), Central-South (CS) area(n = 17,234 cows in 12 herds), and South (S) area (n = 7325 cows in six herds). Data were analyzed using logistic regression and ANOVA, considering cow as the experimental unit. Covariables offered to the models included parity number, season of calving, cow and herd relative milk yield, geographic location, and management system. Average milk yield (305 ME) per cow were 12,091, 11,783, and 6852 kg for C, CS, and S regions, respectively. Time from calving to first service and time to conception were consistently greater for cows with at least one disease event within 50 days in milk (DIM), for cows that were reported lame, or for cows that had mastitis or metritis. The odds (95% confidence interval) of pregnancy at 150 DIM (P150) and the odds of survival until 150 DIM (S150) for cows that had at least one disease event within 50 DIM were 0.84 (0.79-0.91) times the odds of pregnancy and 0.25 (0.22-0.28) times the odds of survival for healthy cows. The odds of P150 for cows located in the C and CS areas were 1.56 (1.36-1.80) and 1.16 (1.04-1.30) times the odds of P150 for cows in the S area. The odds of S150 for cows located in the C and CS areas were 0.48 (0.37-0.62) and 0.54 (0.42-0.67) times the odds of S150 for cows in the S area. These data suggested that cow health status and geographic location are significantly associated with reproductive performance and survival in this population of Chilean dairy cows.