COI barcode based species-specific primers for identification of five species of stored-product pests from genus Cryptolestes (Coleoptera: Laemophloeidae)

Flat grain beetles of the genus Cryptolestes (Coleoptera: Laemophloeidae) are one of the economically most important stored-product pests which feed on many kinds of agricultural products, especially grains. Nine of more than 40 described Cryptolestes species are recognized as stored-product pests and two of the pest species have a cosmopolitan distribution. Given the rapid growth in global trade of food products, ecological barriers to the spread of pests are easily overcome. Therefore, development of reliable systems for routine quarantine inspection and early infestation detection is vital. In the present study, we established a new rapid and accurate cytochrome c oxidase subunit I-based system for molecular identification of five common stored-product Cryptolestes species, namely, Cryptolestes capensis, Cryptolestes ferrugineus, Cryptolestes pusilloides, Cryptolestes pusillus and Cryptolestes turcicus. Five species-specific primer pairs for traditional uniplex polymerase chain reaction assay are described and their specificity and sensitivity for the identification process is evaluated using larval samples of 12 different populations from three continents (Asia, Europe and North America).

Bionomics of Cheyletus eruditus (Schrank) (Acarina: Cheyletidae), a predator of Lepidoglyphus destructor (Schrank) (Acarina: Glycyphagidae), at three constant temperatures

The duration and mortality of immature stages of the predatory mite Cheyletus eruditus (Schrank) were examined at 14, 18.5, 22, and 25 °C and 76% RH. Life tables and schedules of female eggs laid by each female per day were made from records of daily oviposition and adult mortality. The net reproductive rate (ratio of total female births in two successive generations) of C. eruditus varies from 40.7 at 18.5 °C to 74.4 at 25 °C and brackets the net reproductive rates of the prey Lepidoglyphus destructor (Schrank). Mean generation time and finite rates of increase (multiplication per female each day) varied from 52.2 days and 1.073 at 18.5 °C to 24.2 days and 1.194 at 25 °C. Maximum longevity was 107, 67, and 56 days at 18.5, 22, and 25 °C, respectively. Cheyletus eruditus also consumed first-instar larvae of the rusty grain beetle, Cryptolestes ferrugineus (Stephens), and first- and second-instar larvae of the flour mill beetle, Cryptolestes turcicus (Grouvelle).

THE INFLUENCE OF SOME FUNGI IN FLOUR, AND HUMIDITY ON THE SURVIVAL AND DEVELOPMENT OF CRYPTOLESTES TURCICUS (COLEOPTERA: CUCUJIDAE)

The flour mill insect, Cyrptolestes turcicus (Grouvelle), was reared on seven diets at 28 ± 1 °C and at relative humidities of 90% and 60% as follows: flour from a mill previously infested with C. turcicus, commercial flour sterilized with propylene oxide, unenriched commercial flour, and four laboratory-prepared diets each containing a different concentration of fungi isolated from the previously-infested flour.At 90% relative humidity, larvae developed fastest on the infested flour and on the prepared flour–fungi diets, and slowest in sterilized flour. Fungal concentration and rate of larval development were inversely correlated. The highest survival of larvae occurred on the flour–fungi diets and the highest mortality on the flour from the infested mill. There was no clear relationship between rate of pupal development and concentration of fungus. Of the prepared diets, that with the largest concentration of fungus promoted the fastest rate of pupal development. Survival of pupae was about 20% higher on the flour–fungi diets than on the sterilized flour. At 60% relative humidity about 50% of larvae and pupae survived and completed development on the flour–fungi diet containing 1% by weight of fungi, and on the flour from the infested mill but none survived on any of the other diets. Sixty per cent of larvae and 83% of pupae survived and developed on the flour from the infested mill. None of the larvae survived on any of the other diets.

REPRODUCTIVE CAPACITY OF TWO STRAINS OF CRYPTOLESTES TURCICUS (COLEOPTERA: CUCUJIDAE)

Cryptolestes turcicus (Grouvelle), an insect pest of flour mills and warehouses, is distributed in Canada from Alberta to Quebec (Sinha 1965). Barker (1967) showed a difference in susceptibility to methyl bromide between two strains of C. turcicus; one of these was from the Pest Infestation Laboratory, Slough, England, and the other was from a local flour mill. A fortuitous observation suggested that there might be a difference between the reproductive capacities of these two strains. A randomized block design experiment was designed to test this hypothesis. Reproduction was observed in three sets of beetles differing in population density; each set was replicated four times.

BIONOMICS OF BLATTISOCIUS KEEGANI (FOX) (ACARINA: ASCIDAE), A PREDATOR ON EGGS OF PESTS OF STORED GRAINS

The life history of Blattisocius keegani (Fox) was studied at 60, 72, and 80 °F, and at relative humidities (r.h.) of 70 to 75% and 95 to 100%. A life cycle of 6 to 7 days was found at 80 °F. Oviposition was studied at 80 °F and 70 to 75% r.h.; the finite rate of increase (λ) was 3.33 female offspring per female per week. Approximately three Cryptolestes turcicus (Grouvelle) eggs were required to rear one B. keegani to adulthood at 80 °F and 70 to 75% r.h. Female B. keegani that consumed one C. turcicus egg per day were able to oviposit. The hosts investigated included eggs of six species of beetles, and two species of mites that infest stored grains.