Effects of Diet and Temperature on the Life History of the Redlegged Ham Beetle (Coleoptera: Cleridae).

We investigated the effects of various foods and different rearing temperatures on the survival and development of the redlegged ham beetle Necrobia rufipes (De Geer) (Coleoptera: Cleridae), a serious pest of dry-cured hams. The diets tested were dried pet food, finely shredded copra, shredded cheese, dry-cured ham, ground fish meal, and mature larvae of Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae). As indicated by the growth index and k-values, N. rufipes populations grew fastest on the pet food and slowest on the copra. On the other hand, N. rufipes fed both ham and T. castaneum larvae produced significantly heavier larvae. The adult beetles lived significantly longer on cheese compared to other foods. Studies conducted to determine the developmental rates of N. rufipes fed pet food at temperatures of 22, 25, 28, and 31°C showed that the total developmental time and longevity of N. rufipes significantly varied at different temperatures tested. The shortest developmental time (93.32 d) was observed at 28°C. Oviposition rate was highest for females reared at 25°C while lowest at 22°C. Based on the development, reproduction, and thermal requirements, the most suitable temperature for N. rufipes was between 28 and 31°C. The results also revealed that larval cannibalism prevailed among adult beetles.

Ozone as a Potential Fumigant Alternative for the Management of Sitophilus oryzae (Coleoptera: Curculionidae) in Wheat.

Gaseous ozone, an oxidizing agent used as a disinfectant in food processing and preservation, has potential for the control of stored product insects. In this study, we investigated ozone for the management of the rice weevil, Sitophilus oryzae (L.) (Coleoptera: Curculionidae), a serious stored product insect pest. We exposed eggs, immature stages within wheat kernels, and adults of the rice weevil to 200-ppm ozone for 12, 24, 36, 48, and 60 h. Insects were placed at 5, 15, or 25 cm depth within a wheat mass in PVC pipes (10 cm in diameter, 30 cm in height) and exposed to ozone. Egg eclosion was recorded 10 d after treatment (DAT), and immature stages were observed for adult emergence 28 DAT. Adults were observed for survival immediately after ozone exposure and again at 1 and 2 DAT. Egg eclosion was significantly lower at 5 cm compared with 25 cm at all exposure times, but not the 12-h exposure time. For each exposure time tested, significantly lesser adults developed from kernels and none of the adults survived at the 5 cm depth compared with the 15 and 25 cm depths. Survival rate of adults was significantly higher at 25 cm depth than at 15 cm depth at the 24-60 h. The deeper the insect in the grain mass, the higher the survival rate. The work reported suggests that ozone is effective in killing all life stages of S. oryzae; however, the efficacy of the gas is dependent on the concentration, exposure time, depth, and gas loss.

Effect of Delayed Mating on Longevity and Reproductive Performance of Lasioderma serricorne (Coleoptera: Anobiidae).

In recent times, research has focused on integrated pest management approaches using nonchemical alternatives such as mating disruption for the control of stored product insect pests. In this study, we examined the effect of imposed delayed mating on the longevity and reproductive performance of the cigarette beetle, Lasioderma serricorne (F.), a serious insect pest of value added grain-based products, tobacco products, and spices. Delayed mating, progressing 0-14 d, was imposed on both sexes simultaneously, on males only, and on females only. Insects were observed daily for longevity, and F1 progeny was recorded 7-10 wk after mating pairs were placed together. Unmated adults lived significantly longer than mated adults, and mated females lived significantly longer than mated males. However, the length of the period of mating delay did not significantly affect the longevity of mated adults. Progeny production decreased with the age of adults at mating. The number of progeny produced when mating delay was imposed on both sexes simultaneously or on females only was significantly lower than when mating delay was imposed on males only. Hence, females were more adversely affected by delayed mating than males. Findings from this study may provide information for the development of mating disruption techniques that can delay mating and may be effective in keeping populations of L. serricorne below levels that would warrant a control action.

Efficacy of Ozone Against the Life Stages of Oryzaephilus mercator (Coleoptera: Silvanidae).

Ozone is a highly oxidizing gas with insecticidal activity and it is a potential alternative to conventional fumigants, such as phosphine and methyl bromide, for managing stored product insects. Susceptibility of the merchant grain beetle, Oryzaephilus mercator (Fauvel; Coleoptera: Silvanidae), an important pest of stored products, to ozone treatments is unknown. In this study, we investigated the efficacy of ozone for controlling O. mercator. We determined concentration-mortality relationships for all stages of O. mercator exposed to 100-400 ppm for 1 h (1 g/m3 = 467 ppm). We also determined time-mortality relationships for adults exposed to 100 ppm for 1-6 h. Mortality was recorded as percentages of eggs that failed to hatch 10 days after treatment (DAT), larvae or pupae that failed to develop into adults 20 or 15 DAT, respectively, and adults that died 2 DAT. Generally, mortality increased with an increase in ozone concentration. Mortality was higher when insects were treated without food. When food was not provided, a minimum of 11030 ppm for 1 h is required to kill 99% of eggs, the most tolerant stage, whereas 500 ppm for 1 h is required to kill 99% of larvae, the least tolerant. When provided with food, adults were the most tolerant and larvae the least tolerant. Adults require exposure time of 7.7 h of 100 ppm ozone to kill 99% of insects in the absence of food. The work reported suggests that ozone could be an alternative fumigant for the management of all O. mercator life stages.

Dispersal of Rhyzopertha dominica (Coleoptera: Bostrichidae) in different habitats.

The lesser grain borer, Rhyzopertha dominica (F.) (Coleoptera: Bostrichidae), a serious pest of stored cereal grains, is widely distributed and has been collected in different habitats in North America, such as those from agricultural and nonagricultural settings. Our objective was to study the dispersal distances and direction of dispersal by R. dominica after external marking using fluorescent powder, releasing marked beetles, and recapturing adults using pheromone traps in distinctively different ecological habitats, wooded sites and open grasslands, for 2 consecutive yr. The recapture rate of marked beetles ranged from 6 to 26% in both sites and was generally higher in the wooded site than the open field site for both years. There was a significant difference in dispersal distances between wooded and open sites. Mean dispersal distances in the wooded site ranged from 337 to 375 m, whereas in the open site, they varied from 261 to 333 m. Trap captures for both marked and feral beetles were related to the ambient temperature such that increase in trap captures occurred with increasing temperature. Significant differences were observed for directional movement of R. dominica in both sites and indicated that most beetles dispersed in the northwest direction. Correlation analyses showed that the relationship between numbers of marked-released-recaptured beetles significantly decreased with increasing trap distances. Understanding dispersal distances and directions provide insight to flight behavior of R. dominica and to the relationship between ecologically diverse breeding habitats. Knowledge of R. dominica habitat ecology outside of grain storage facilities may be useful in designing suitable management tactics to minimize the onset of infestations in grain storages.