Population Growth and Development of Psocid \u3ci\u3eLepinotus reticulatus\u3c/i\u3e at Constant Temperatures and Relative Humidities

We investigated the effects of temperature and relative humidity on population growth and development of the psocid Lepinotus reticulatus Enderlein. Part of this study assessed the effects of marking psocids by using methylene blue, chalk powder, and fluorescent powder to differentiate nymphal stages during development. We found that marking psocids by using methylene blue increased mortality and took twice as long to accomplish compared with marking by using fluorescent powder. Using chalk powder shortened the duration of third and fourth nymphal instars. Marking psocids by using fluorescent powder had no effect on mortality or duration of nymphal instars. Therefore, we recommend using fluorescent powder for marking psocids. L. reticulatus did not survive at 32, 43, and 55% RH, whereas populations increased from 22.5 to 32.5°C at 75% RH. The largest population growth was recorded at 30 and 32.5°C, whereas only 9% of nymphs developed to adults and populations declined at 35°C. We developed temperature-dependent developmental equations for eggs, individual nymphal, combined nymphal, and combined immature stages. These equations showed predicted optimal temperatures for the development of eggs, combined nymphal, and combined immature stages to be 32.3, 34.5, and 34.4°C, respectively; development at these temperatures was completed in 6.3, 16.7, and 23.3 d, respectively. Our study shows that psocids that consume their exuviae develop faster than those that do not, and this effect is more pronounced at lower temperatures. These data give us better understanding of L. reticulatus population dynamics, and they can be used to develop effective management strategies for this psocid

Efficacy of dust formulations of spinosad for controlling insects infesting stored wheat

Laboratory experiments were conducted to compare the efficacy of three new dust formulations (B1, C3, and D1) of spinosad as grain protectants on stored wheat. Evaluations were conducted on grain that was held for 1 d and 12, 24, 39, and 52 wk after insecticide treatments were applied. Bioassays for adult mortality and progeny production were conducted at 28°C and about 65% r.h. Dust formulations B1 and C3 effectively controlled adult Rhyzopertha dominica and prevented progeny development for 52 wk while formulation D1 was less effective. Only formulation B1 controlled Sitophilus oryzae adults (> 91% parental mortality) but did not prevent progeny production. None of the dust formulations were effective against Tribolium castaneum adults but progeny production was lower on grain treated with formulations B1 and C3. Egg mortality of Plodia interpunctella was similar for all treatments although overall progeny production was less on grain treated with formulation B1. The type of dust formulation of spinosad is critical in controlling stored grain insects.Keywords: Spinosad dust formulations, Rhyzopertha dominica, Sitophilus oryzae, Tribolium castaneum,Plodia interpunctell

Population Growth and Development of Psocid \u3ci\u3eLepinotus reticulatus\u3c/i\u3e at Constant Temperatures and Relative Humidities

We investigated the effects of temperature and relative humidity on population growth and development of the psocid Lepinotus reticulatus Enderlein. Part of this study assessed the effects of marking psocids by using methylene blue, chalk powder, and fluorescent powder to differentiate nymphal stages during development. We found that marking psocids by using methylene blue increased mortality and took twice as long to accomplish compared with marking by using fluorescent powder. Using chalk powder shortened the duration of third and fourth nymphal instars. Marking psocids by using fluorescent powder had no effect on mortality or duration of nymphal instars. Therefore, we recommend using fluorescent powder for marking psocids. L. reticulatus did not survive at 32, 43, and 55% RH, whereas populations increased from 22.5 to 32.5°C at 75% RH. The largest population growth was recorded at 30 and 32.5°C, whereas only 9% of nymphs developed to adults and populations declined at 35°C. We developed temperature-dependent developmental equations for eggs, individual nymphal, combined nymphal, and combined immature stages. These equations showed predicted optimal temperatures for the development of eggs, combined nymphal, and combined immature stages to be 32.3, 34.5, and 34.4°C, respectively; development at these temperatures was completed in 6.3, 16.7, and 23.3 d, respectively. Our study shows that psocids that consume their exuviae develop faster than those that do not, and this effect is more pronounced at lower temperatures. These data give us better understanding of L. reticulatus population dynamics, and they can be used to develop effective management strategies for this psocid

Effects of Diet on Population Growth of Psocids \u3ci\u3eLepinotus reticulatus\u3c/i\u3e and \u3ci\u3eLiposcelis entomophila\u3c/i\u3e

We investigated the suitability of 11 diets as culture media for the psocids Lepinotus reticulatus Enderlein (Psocoptera: Trogiidae) and Liposcelis entomophila (Enderlein) (Psocoptera: Liposcelididae). The culture media comprised six diets made of plain cereals, namely, wheat (Triticum aestivum L.), corn (Zea mays L.), milo Sorghum bicolor (L.), barley (Hordeum vulgare L.), oats (Avena sativa L.), and rice (Oryza sativa L.), and five artificial diets. We found that, with the exception of corn, L. reticulatus population increase was greater on plain cereal diets than on artificial diets, and the greatest population growth was on oats. There was an inverse relationship between L. reticulatus population growth and diet compactness. L. entomophila populations grew fastest on wheat, barley, and a mixture of cracked wheat, rice krispies, and brewer\u27s yeast (97:2:1, wt:wt). The proportion of females was greater in diets that were less suitable for L. entomophila population growth compared with that in the more suitable diets. Diet compactness had a weak effect on L. entomophila population growth. This study also has established the relative level of suitability of damaged wheat, corn, milo, barley, oats, and rice to L. reticulatus and L. entomophila

Ecological Studies of the Psocids Liposcelis brunnea, L. rufa, L. pearmani, and Lepinotus reticulatus

Psocids (Psocoptera) are an emerging problem in grain storages, grain processing facilities, and product warehouses in the United States and many other countries. Development of effective pest management programs for psocids is dependent on having sound knowledge of their ecology. Given the limited information available on the ecology of psocids, we conducted ecological studies of four psocid species namely, Liposcelis brunnea (Liposcelididae), Liposcelis rufa, Liposcelis pearmani and Lepinotus reticulatus (Trogiidae). We conducted population growth studies of these four psocid species at different temperatures and relative humidities; development studies of L. brunnea, L. rufa, and L. reticulatus at different temperatures; and investigated the effects of temperature on reproductive parameters of L. reticulatus. Our studies provide important data on life history and reproductive parameters of four storedproduct psocid pests. Because these parameters affect population dynamics, these data can be used in simulation models to predict psocid population dynamics and thereby aid in the development of more effective management strategies

Insecticidal Effect of Diatomaceous Earth Against Three Species of Stored-Product Psocids on Maize, Rice, and Wheat

We evaluated the efficacy of three diatomaceous earth (DE) formulations, Dryacide, Protect-It, and Insecto, against three Psocoptera species, Liposcelis entomophila (Enderlein) (Liposcelididae), Lepinotus reticulatus Enderlein (Trogiidae), and Liposcelis decolor (Pearman), in the laboratory. Bioassays were conducted in three grain commodities, wheat, rice and maize, at 30°C and 75% RH, and the DEs were applied at the recommended dose rates of 1,000, 400, and 500 ppm for Dryacide, Protect-It, and Insecto, respectively. Differences in adult mortality were found among grains and DEs for L. entomophila and L. reticulatus, but these trends were not consistent for all combinations tested. Type of grain and DE did not affect L. decolor mortality significantly. Moreover, mortality increased with increasing exposure time for L. entomophila and L. reticulatus, but there was no effect of exposure time on L. decolor. After 7 d of exposure, mortalities of L. entomophila, L. reticulatus, and L. decolor were 56, 55, and 40%, respectively, and the respective mortality levels after 14 d were 63, 71, and 42%. Progeny production after 30 d was significantly suppressed for all species in the treated grains. However, progeny production was still high in the treated grains and reached 54, 42, and 76 individuals/10 g of grain for L. entomophila, L. reticulatus, and L. decolor, respectively. Progeny production did not vary with commodity. Our results suggest that DEs, when used alone, will not provide effective control of psocids

Technical appraisal of some maize shellers in Oyo and Kwara States of Nigeria

This study assessed the performance of some maize shellers in use in grain markets in Oyo and Kwara States, Nigeria. A preliminary survey conducted identified shellers in use as basic maize sheller (BMS) without blower, maize sheller with blower attachment (MSB) and the multi-purpose sheller (MPS). The shelling/cleaning performance of the shellers were assessed using yellow maize (SWAN 1 variety) and some key equipment parameters, which impact performance were measured. The air velocity for MSB and MPS ranged between 0.4 and 2.4 m/s which was not sufficient for efficient cleaning of chaff from shelled grains. Shaft speed for BMS, MSB and MPS were 845, 920 and 820 rpm, respectively. Average throughput for BMS, MSB and MPS was 1,714, 600 and 840 kg/hr, respectively with mean shelling efficiencies of 92.9, 82.7 and 97.9%, respectively. Mean cleaning efficiencies were 54.0 and 57.7% for MSB and MPS, respectively. The percentage grain loss for BMS, MSB and MPS were 17, 7.1 and 1.9%, respectively. It was observed that many fabricators do not consult agricultural engineers when producing machines, relying more on previous experience. Additionally, there was a lack of consideration for operator safety with the exposure of moving parts of the equipment in all the designs evaluated. A key recommendation from this study is that sheller designs should be standardized to ensure the provision of quality and highly efficient machinery for processors

Effectiveness of the Zerofly storage bag fabric against stored-product insects

The ZeroFly Storage Bag is a woven polypropylene bag (PP) that has deltamethrin incorporated in its fibers, and represents a novel approach to reducing stored-product insect pest-related postharvest losses. Fabric samples from ZeroFly bags, polypropylene (PP) bags, jute bags, malathion-treated PP bags, malathion-treated jute bags and GrainPro bags were affixed to the bottom of 9-cm Petri dishes and 20 adults of either Sitophilus oryzae (L.) or Tribolium castaneum (Herbst) were introduced to determine contact sensitivity of insects exposed to ZeroFly bag fabric. Knockdown, mortality and number of progeny were recorded for different exposure periods (24, 48 or 72 h) and oviposition periods (7, 14 or 21 d). Additionally, mini bags were made from ZeroFly bags, PP bags, laminated PP bags and jute bags, and used to determine ability of adult S. oryzae, T. castaneum and Rhyzopertha dominica (F.) to chew through the bags and efficacy of ZeroFly bags at preventing insect infestations from outside and to contain infestations within bags. Knockdown assessment for ZeroFly bag fabric showed that time required to knockdown 99% of S. oryzae and T. castaneum was <3 h. For 72-h exposure to ZeroFly bag fabric, mortalities for S. oryzae and T. castaneum were 76.7 and 62.2%, respectively; mortality was </=6% in other fabrics. ZeroFly bag fabric also significantly suppressed progeny production by S. oryzae and T. castaneum for all exposure periods. No insects from the three species tested were able to chew through miniature ZeroFly bags, indicating the bag fabric will prevent entry or exit of insects.Peer reviewedEntomology and Plant Patholog

Effects of Diet on Population Growth of Psocids \u3ci\u3eLepinotus reticulatus\u3c/i\u3e and \u3ci\u3eLiposcelis entomophila\u3c/i\u3e

We investigated the suitability of 11 diets as culture media for the psocids Lepinotus reticulatus Enderlein (Psocoptera: Trogiidae) and Liposcelis entomophila (Enderlein) (Psocoptera: Liposcelididae). The culture media comprised six diets made of plain cereals, namely, wheat (Triticum aestivum L.), corn (Zea mays L.), milo Sorghum bicolor (L.), barley (Hordeum vulgare L.), oats (Avena sativa L.), and rice (Oryza sativa L.), and five artificial diets. We found that, with the exception of corn, L. reticulatus population increase was greater on plain cereal diets than on artificial diets, and the greatest population growth was on oats. There was an inverse relationship between L. reticulatus population growth and diet compactness. L. entomophila populations grew fastest on wheat, barley, and a mixture of cracked wheat, rice krispies, and brewer\u27s yeast (97:2:1, wt:wt). The proportion of females was greater in diets that were less suitable for L. entomophila population growth compared with that in the more suitable diets. Diet compactness had a weak effect on L. entomophila population growth. This study also has established the relative level of suitability of damaged wheat, corn, milo, barley, oats, and rice to L. reticulatus and L. entomophila