Life History of Immature Maize Weevils (Coleoptera: Curculionidae) on Corn Stored at Constant Temperatures and Relative Humidities in the Laboratorv

Life history of immature maize weevils, Sitophilus zeamais Motschulsky, was studied at 10-40°C and 43-76% RH. The optimal quantity of corn for minimizing density effects and the optimal observation frequency for minimizing disturbance effects were determined at 30°C and 75% RH. The quantity of corn (32-256 g) provided to five females ovipositing for 24 h did not affect duration of development, but the number of progeny produced increased asymptotically as the quantity of corn provided increased. Frequency of observation (from 1- to 14-d intervals) did not affect duration of development or number of progeny produced. Using moisture contents measured in the life history study, an equation was developed for predicting equilibrium moisture content of corn from temperature and relative humidity. Duration of immature development did not vary with sex, but did vary with test. This suggests that insect strain or chemical composition of the corn must be included as factors in a model predicting effects of environment on duration of immature development. Survival from egg to adult emergence was greatest at 25°C. Sex ratio of emerging adults did not differ from 1:1. The number of multiply-infested kernels was low at all environmental conditions, and survival from egg to adult emergence in these kernels averaged 18%. Maximum daily rate of fecundity, duration of development, and number of progeny produced were optimal at 30°C and 75% RH. An index of environmental suitability indicated that 30°C and 75% RH was the optimal environment for growth of maize weevil populations on corn. Implications of the results for managing maize weevil populations are discussed

A Bibliography of the Rusty Grain Beetle, \u3ci\u3eCryptolestes ferrugineus\u3c/i\u3e (Stephens) (Coleoptera: Cucujidae)

Rusty grain beetles are major pests of stored products throughout most of the world. This bibliography lists 239 papers published about these beetles. Citations are grouped by subject and are indexed by geography, host, and author

Effects of Noncatastrophic Control Technologies that Alter Life History Parameters on Insect Population Growth: A Simulation Study

I investigated the effects of noncatastrophic control technologies that alter life history parameters (such as the use of resistant plant varieties) on the growth of insect populations. I used a computer model to simulate population dynamics of the flat grain beetle, Cryptolestes pusillus (Schonherr). The effects of increasing duration of larval development (by 5, 10, 15, or 20 d) or decreasing fecundity or larval survival (by 25, 50, or 75%) on population growth were simulated. Growth curves for populations with reductions in fecundity or larval survival were nearly identical. The effects of decreasing fecundity or larval survival were apparent during the first generation, whereas the effects of increasing duration of larval development did not become apparent until the second generation. Altering any of the life history parameters resulted in as much as 99% reduction in population levels at constant temperatures and as much as 87% reduction in population levels at actual temperatures in a grain bin. The results indicate that use of control technologies that cause even a small change in a life history parameter may have a significant effect on population growth when applied over a growing or storage season. The combination of such technologies with other methods of control may improve the cost effectiveness of pest management techniques, even if the noncatastrophic control techniques do not provide adequate control when used alone

Automated Nondestructive Detection of lnternal lnsect Infestation of Wheat Kernels by Using Near-Infrared Reflectance Spectroscopy

Wheat kernels infested internally with larvae of 3 primary insect pests of grain, the rice weevil, Sitophilus oryzae (L.); the lesser grain borer, Rhyzopertha dominica (F.); and the Angoumois grain moth, Sitotroga cerealella (Olivier), were scanned with a near-infrared spectrometer incorporated into a single kernel characterization system to determine differences in absorption due to the presence of larvae. The single kernel characterization system delivers kernels into the spectrometer viewing area at the rate of 1 per 4s. We were able to differentiate uninfested kernels from kernels infested with larvae of all 3 species by using this automated system. Moisture content, protein content, or wheat class did not affect classification accuracy. The calibration included spectral characteristics in the wavelength ranges of 1,000-1,350 and 1,500-1,680 nm. Larval size was a factor in the sensitivity of the system, with 3rd and 4th instars rice weevil being detected with 95% confidence. In contrast to many other procedures used to detect internal insect infestations in grain, this system could be incorporated into the current grain inspection process and provide the grain industry with quantitative data on internal insect infestations in wheat

Development Rates for the Seed Maggots Delia platura and D. florilega (Diptera: Anthomyiidae)

Duration of immature stages of seedcorn maggots (SCM), Delia platura (Meigen), and bean seed maggots (BSM), D. florilega(Zetterstedt), was determined at eight constant temperatures from 5 to 40°C. No SCM or BSM survived to second instar at either 5 or 40°C. No BSM survived to the adult stage at 35°C. Duration of immature stages varied from 240 days at 10°C to 17 days at 35°C. A computer model developed using the SCM development rate data closely simulated SCM development in the field during the growing seaso

Development of Maize Weevils (Coleoptera: Curculionidae) on Corn Lines Resistant to an Aflatoxin-Producing Fungus

Susceptibility to the maize weevil, Sitophilus zeamais Motschulsky, of corn lines bred for their resistance to the aflatoxin-producing fungus Aspergillus flavus Link ex Fries was determined in the laboratory. Duration of maize weevil development, number of progeny produced, and an index of susceptibility varied with corn line; number of eggs laid and survivorship from egg to adult emergence did not vary with corn line. Soluble carbohydrate, kernel hardness, lipid, soluble nitrogen, free and bound phenolic acids, Kjeldahl protein, and protein/carbohydrate ratio varied with corn line; equilibrium moisture content did not vary with corn line. The only relationship between biological parameters of maize weevils and chemical and physical properties of the stored corn that was predictable was that maize weevil development time increased as lipid content of the corn increased. Susceptibility to A. flavus infection in the field was not correlated with susceptibility to maize weevil population growth or with chemical or physical properties of the stored corn. Predicted weevil population growth over a 180-d period varied 50-fold among the corn lines. Some of the corn lines that are less susceptible to infection by A. flavus in the field were also less susceptible to maize weevils (particularly Mp420 and SC54)

Emergence Patterns of the Seedcorn Maggot, Delia platura (Diptera: Anthomyiidae)

Time of emergence of seedcorn maggot (SCM), Delia platura (Meigen), adults that developed from eggs laid in field plots from May through October 1981, was determined during 1981, 1982, and 1983. Some SCM that developed from eggs laid as early as May 1981, overwintered, and the proportion of SCM overwintering increased when eggs were laid June to October. Adults emerged from overwintered pupae from April through October 1982, and in May and June 1983. Adults of the closely related bean seed maggot (BSM), D. florilega (Zetterstedt), also emerged in the plots, but in smaller numbers than SCM. BSM males emerged in 1981 only in plots planted during May 198

Development Rates for the Seed Maggots \u3ci\u3eDelia platura\u3c/i\u3e and \u3ci\u3eD. jlorilega\u3c/i\u3e (Diptera: Anthomyiidae)

Duration of immature stages of seedcorn maggots (SCM), Delia platura (Meigen), and bean seed maggots (BSM), D. florilega (Zetterstedt), was determined at eight constant temperatures from 5 to 40°C. No SCM or BSM survived to second instar at either 5 or 40°C. No BSM survived to the adult stage at 35°C. Duration of immature stages varied from 240 days at 10°C to 17 days at 35°C. A computer model developed using the SCM development rate data closely simulated SCM development in the field during the growing season

SEASONAL FLIGHT ACTIVITY OF THE MAIZE WEEVIL, \u3ci\u3eSITOPHlLUS ZEAMAIS\u3c/i\u3e MOTSCHULSKY (COLEOPTERA: CURCULIONIDAE), AND THE RICE WEEVIL, \u3ci\u3eS. ORYZAE\u3c/i\u3e (L.), IN SOUTH CAROLINA

Flight activity of Sitophilus zeamais Motschulsky (Coleoptera: Curculionidne) and S. oryzae (L.) was monitored during 1987-88 with sticky traps at three sites in South Carolina. Weevils were caught from late March to early November. The results indicate that temperature is the major factor determining seasonal flight activity of these weevils. More S. zeamais than S. oryzae were trapped at all sites. Sitophilus oryzae were abundant only at the site at which wheat was stored. There was no apparent pattern to flight activity within a storage site. The results indicate that there is little night activity around bins in which recommended pest control practices are followed

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