Search

Se evaluaron dos acaricidas por su efectividad para controlar las poblaciones de la garrapata sureña Boophilus microplus en ganado lechero en Santa Cruz, Islas Virgenes Americanas. Se asperjaron dos concentraciones diferentes de una formulación microencapsulada (ME) de permetrína (0.05 y 0.10% ia) y una concentración de coumaphos concentrado emulsificable (0,117% ia) sobre novillas Holstein que presentaban una infestación natural de garrapatas. La actividad residual del coumaphos y la permetrina ME (0.05% ia) fue por lo menos de cuatro días y la de permetrina ME (0.10% ia) fue de por lo menos siete días. El largo del periodo residual de la permetrina ME sobre el Boophilus microplus no aumentó en comparación con experimentos de campo con otras formulaciones de permetrinas. El porcentaje de control para los tres tratamientos desde los días 4 al 21 fue: permetrina ME (0.05% ia), 96%; permetrina ME (0,10% ia), 97%; coumaphos, 98.3%. Las diferencias entre las medias de los diferentes tratamientos no fueron significativas (F= 2.21; g.l. = 2,17, P> 0.10). Esta investigación confirma que la permetrina es una alternativa para el control de B. microplus en poblaciones de ganado.

Larvae of the darling beetle (lesser mealworm) were exposed to turkey feces from an enteritis-affected flock and determined to contain turkey enterovirus and rotavirus. Growth depression and increased mortality were observed in turkey poults which fed on the exposed larvae. Exposed larvae which had been surface-sterilized also produced clinical signs of enteritis after consumption by the poults, indicating that pathogens were able to survive within the larvae. This experiment demonstrated the capacity of the larva of the darkling beetle to serve as a mechanical vector for enteric pathogens of turkeys.

The ovipositional biology and egg development of the tropical horse tick, Dermacentor (Anocentor) nitens (Neumann), was observed at four temperatures (20, 25, 30, and 35 degrees C) and relative humidities (40, 61, 75, and 91% RH). Relative humidity had little effect on length of preoviposition and oviposition periods. With increased rearing temperatures, there was a decrease in both preoviposition and oviposition periods. Oviposition rate increased with temperature and was not affected by relative humidity. Instantaneous rates of oviposition were calculated for each temperature by fitting the data to the logistic growth function. High percentage egg hatch was observed in low saturation deficit environments, and decreased when saturation deficit was increased.

Experiments were conducted to determine the effects of feeding larvae of the darkling beetle (lesser mealworm), Alphitobius diaperinus (Panzer) (Coleoptera: Tenebrionidae) to broiler chicks on chick growth. Chicks readily fed on the larvae and exhibited reduced growth in the absence of other feed. Chicks 3 to 8 d old restricted to a diet of only larvae consumed 1,552 +/- 172 (mean +/- SD) larvae per chick per day and their body weights were significantly less (mean = 84 g) at the end of the 6 d than for chicks on starter feed during the same time. After return to starter feed for 8 d after feeding on larvae for 6 d, the chicks did not compensate for the reduced weight and their body weights were significantly less (mean = 170 g) than for chicks on starter feed for the 14 d. Chicks from age 2 through 9 d were given a choice between broiler starter feed and darkling beetle larvae. The numbers (mean +/- SD) of larvae consumed per chick per day were: 389 +/- 18, 631 +/- 14, 496 +/- 20, and 287 +/- 33, for Days 2 to 3, 4 to 5, 6 to 7, and 8 to 9, respectively. The body weight of chicks feeding on starter feed and larvae was significantly greater than the weight of chicks consuming feed only. In the presence of larvae, the mean feed consumption per chick was less than for chicks provided with only starter feed. The beetle larvae were 68% crude protein and 21% fat (DM basis) and had higher amounts of 18 amino acids than the starter feed.

Experiments were conducted to determine the effects of feeding larvae of the darkling beetle (lesser mealworm), Alphitobius diaperinus (Panzer) [Coleoptera:Tenebrionidae], to turkey poults on poult growth and of beak trimming on poult feeding on the larvae. Young turkey poults readily fed on the larvae and exhibited reduced growth in the absence of other feed. Poults 3 to 5 d old restricted to a diet of only larvae consumed 259 +/- 99 (+/- SD) larvae per poult per day and their body weights were significantly lower (mean = 30 g) at the end of the 3 d than for poults on starter feed during the same time. After return to starter feed for 16 d after feeding on larvae for 3 d, the poults did not compensate for the weight loss although weight gains were normal. Poults from 2 through 10 d of age were given a choice between starter turkey feed and darkling beetle larvae. The numbers of larvae consumed per poult per day were: 174 +/- 8 for Days 2 to 4, 221 +/- 3 for Days 5 to 7, and 189 +/- 80 for Days 8 to 10. There was no significant difference between the body weight of poults feeding on larvae and starter feed compared with that of poults consuming feed only. In the presence of larvae, the mean feed consumption per poult was lower than for poults provided with only starter feed. The beetle larvae were 68% crude protein and 21% fat (DM basis) and had higher amounts of 18 amino acids than the starter feed. Poults that were beak trimmed consumed only about one-third as many larvae as poults with intact beaks. Poults (1 to 3 d old) with intact beaks consumed 169 +/- 20 larvae per poult per day; poults with trimmed beaks consumed 58 +/- 23 larvae per poult per day.

The survival period for larvae of Boophilus annulatus (Say), Boophilus microplus (Canestrini) and hybridized Boophilus ticks was determined by exposure to various combinations of temperature (20, 25, 30 and 35 degrees C) and relative humidity (32, 63, 75, 84 and 97% RH) in the laboratory. Results indicated that within a given temperature and RH regime, there was no difference (P greater than 0.05) in larval survival among the three species tested, indicating that these ticks respond similarly over a wide range of temperature and RH combinations. Larval survival in all three species was longest (P less than 0.05) at 20 degrees C and either 84 or 97% RH. With each increase in temperature at the 84 and 97% RH treatment levels, there was a corresponding significant (P less than 0.05) decrease in larval survival. When the temperature reached 35 degrees C at all humidities or when the RH was 63% or less at all temperatures, the mean larval survival period was 43 days or less in all cases and little difference (P greater than 0.05) was observed among the treatment regimes included. Results suggest that at a RH of 75% and more, the temperature is the determining factor in larval survival, whereas at a RH of 63% and less the RH is the determining factor in larval survival, regardless of temperature.

The relationship between types of contruction of high rise caged layer houses and insulation damage produced by the lesser mealworm, Alphitobius diaperinus (Panzer), was examined. There were no infestations in polyurethane insulation that had heavy weight paper glued to the surface of the insulation and installed with tape to seal off the seam between insulation boards. High rise houses with pit walls constructed of concrete block had lower insulation infestations than houses with wooden walls forming the pits. Houses that had pit wall foundations built of both types of materials had intermediate lesser mealworm infestations. Houses with the support structure set on top of the concrete block pit wall had lower infestations than houses where the support structure was set directly into the earth. There was a reduced gradient of damage with height of insulation above the pit; insulation installed in the pit was the most severely infested. Extruded polystyrene insulation exposed to 10 years or more of lesser mealworm infestation suffered a substantial loss of volume in the corner area of the insulation panels, resulting in a 9.1 to 30.8% reduction from an original volume of 84,838 cm3. Additionally, there was a significant reduction in R-value of infested insulation.

Observations were made on the effect of manure moisture and high rise caged layer house manure pit wall construction on adult and larval lesser mealworm, Alphitobius diaperinus (Panzer) (Coleoptera: Tenebrionidae) dispersal behavior. Larvae preferred to remain in manure habitats of 30 and 40% moisture, and dispersal from the manure significantly increased when manure moisture was increased to 50 and 60% levels. Adults were more active than larvae in the 30 and 40% manure moisture treatments, and the adult rate of dispersal also significantly increased with increased manure moisture levels. Larvae could climb a significantly greater distance up a vertical wooden surface than up a vertical concrete block surface. These data suggest that high rise houses built with wood pit walls and support beams that are set directly into the ground are predisposed to greater levels of insulation damage than houses built with concrete block foundations.

Adult European corn borer, Ostrinia nubilalis (Hubner), moth flight was observed in Bedford County (1980–1981) and at Painter, Va. (1958–1981, inclusive). Average weekly catches of moths taken from black light traps were plotted as a function of cumulative degree-days (above 10°C). For the 2-year period in Bedford County, peak adult moth flight occurred at 307, 1,084, and 1,516 degree-days, and peak moth flight was observed at 232, 807, and 1,440 degree-days over the 24-year period at Painter. Equations resulting from regression of the probit of cumulative percentage of adult moth flight on cumulative degree-days may be used to predict adult European corn borer phrenology in Virginia.

The oviposition site selection by the European corn borer and the within-field pattern of egg mass distribution were studied on field corn in western Virginia. Nearly all egg masses were found on the lowest six leaves of the plant. The within-field distribution of egg masses was found to be a random distribution, as interpreted from the variance/ mean ratio, the method of Taylor and Green's coefficient of dispersion.

Six granular insecticidal treatments were compared for efficacy in the control of Northern corn rootworm larvae in field corn (Trojan TB115). The test was conducted in a no-till field (rye cover) which had received no treatments of soil insecticides in the past. Corn had been planted continuously for 5 years in this field. The treatments were arranged in a completely randomized design. Each treatment was replicated 4 times in 12 ft wide x 50 ft long plots (4 rows/plot, 30 in spacing). A Gandy granular applicator was used for in-furrow and banded placement of the products. On Jun 30, 40 root systems/treatment were dug from the ground (10 systems/plot x 4 replicates, from 2 center rows), washed of soil and visually rated using the 1-6 damage system (1 = no feeding damage and 6 = 3 or more root nodes pruned to 1.5 in of plant stem).

Three granular insecticides were evaluated for the control of European corn borer in Bedford Co, VA, in conventionally tilled field corn (Pioneer 3147A). All treatments were applied with a Gandy granular applicator and were arranged in a completely randomized design. Each treatment was replicated 4 times in 12 ft x 50 ft plots (4 rows/plot, 32 in spacing). On Jul 15, 80 randomly selected stalks/treatment (20 stalks/plot, from 2 center rows) were split lengthwise, and the number of tunnels per plant was recorded.

Three tests were conducted in Montgomery Co, VA, in Jul, Aug, and Sep with insecticides in dust bags applied to mixed breed beef cattle to measure control of face and horn flies. In Test A 2 dust bags containing 12 lb each of 1% Co-Ral (Coumaphos) were suspended 30 in above the ground at 2 entrances to a mineral box on Jul 24. Thirty mixed breed heifers were in the treated herd.

Dyfonate 20G, Thimet 20G, Furadan 10G, Pounce 3.2EC, Cymbush 3EC,and Ambush 2EC were tested for the control of European corn borer in Bedford Co, VA, in Jun 1980. Insecticides were applied on Jun 10 to field corn in plots 50 ft x 4 rows (36 in spacing) with 4 replicates in a randomized block design. Granular insecticides were applied over the whorl with a Gandy applicator. Liquids were applied with a Solo backpack sprayer operating at 3 mph, using 30 psi, in 40 gal of water/acre. Chemicals were applied when the corn was 28 in high, with a 61% infestation of ECB in the lst-2nd instar. Five plants showing signs of heavy infestation were chosen from each plot and dissected 14 days after treatment to determine the number of dead and living larvae.

An evaluation was conducted for the insecticidal control of black cutworm larvae in field corn (Northrup King PX79) on the VPI&SU Agronomy Farm, Montgomery Co, VA. The soil type in the test area was composed of Lodi loam, porous substrate plus Landisburg and Greendale silts. The plots were on land that had been in sod for several years. A tank-mix of Paraquat, Atrazine, and Dual was applied prior to planting. The treatments consisted of a seed treatment, granular (7 in band), broadcast, and postemergence. The treated seed was planted the same day as the untreated corn seed. Each insecticide was replicated 4 times in completely randomized plots measuring 12 ft x 50 ft (38 in rows). All granular insecticides were applied with a Gandy applicator on May 18. The postemergence foliar applications were sprayed on May 28 with a Solo backpack sprayer at 30 psi using 20 gal of water per acre.

‘Northrup King PX79’ field corn was sod-planted on May 15, on the VPISSU Agronomy Farm, Montgomery Co, VA. The land had been in sod for several years. At the time of planting the water content of the soil was 26.25% and the pH was 6.3. A tank-mix of Paraquat, Atrazine, and Dual was applied prior to planting. Three rates of BAS 263 11 I (3.6, 2.4, 1.2 oz ai/1000 ft) were applied on May 18 with a Gandy granular applicator using a 7-in band at the height of 5 in. Treatments were replicated 4 times on completely randomized plots measuring 12 ft x 5(1 ft (each plot was 4 rows wide - 36 in rows). White grub populations were estimated before planting by taking 4-in core samples over the entire treat area. The grub population averaged 12 grubs per 4-in core. Control was evaluated on Jul 23. Ten cores (4 in), consisting of 1 corn root system and the associated soil, were taken from each plot (40 cores per treatment) to determine the average number of white grubs per core.