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The lesser mealworm, Alphitobius diaperinus(Panzer) (Coleoptera: Tenebrionidae), is an important pest of stored products and at the same time a species with great potential as food and feed that has recently attracted increasing interest as nutrient source. Future predictions show a massive increase of insect meals’ production in the near future, therefore, as expected in the case of other durable stored products, insect meals may get infested by insects during their storage. In this context and as a continuance of our previous study on the susceptibility of meal of the yellow mealworm, Tenebrio molitorL. (Coleoptera: Tenebrionidae), to storage insect infestations, the objective of this study was to test the susceptibility of A. diaperinusmeals to infestations of three stored products pests, namely A. diaperinusitself, T. molitor, and the red flour beetle, Tribolium castaneum(Herbst) (Coleoptera: Tenebrionidae). The population growth of the three species was evaluated on pure A. diaperinusmeal, as well as on A. diaperinusmeal-based substrates with different percentages of wheat bran (0, 25, 50, 90, and 100% bran). Our results showed that all three insect species tested were able to grow and develop on the A. diaperinusmeal-based substrates evaluated, giving in a short time high population densities. This study confirms again our initial theory for insect infestations during storage of insect-based products.

The lesser mealworm, Alphitobius diaperinus(Panzer), is a serious pest, but at the same time has been authorized in European Union (EU) for feed in aquaculture. In this study, we investigated, in laboratory bioassays, the population growth of this species, on a wide variety of commodities. In four series of bioassays, we studied the development of A. diaperinuspopulation on various intact cereal grains, on soft wheat grains with different percentages of cracked kernels, on non-grain amylaceous commodities and on a variety of non-amylaceous commodities. Briefly, 20 g of each commodity were put separately inside plastic cylindrical vials. Then, 20 A. diaperinusadults were placed inside each vial and all vials were incubated at 30°C and 55% r.h. After 30 d, the vials were opened and the progeny production was evaluated. Alphitobius diaperinusshowed a clear preference in amylaceous commodities, but in contrast, poor development was recorded on the non-amylaceous commodities tested. Hence, it developed well in most of the cereal intact grains tested, with the hard and soft wheat being the most suitable. Additionally, most non-grain amylaceous commodities were suitable, to a various degree, for the population growth of A. diaperinus.The increase of the percentage of cracked wheat positively affected the population growth of A. diaperinus. To our knowledge, this is the first study that examined the suitability of a wide range of commodities for the population growth of A. diaperinus.

Laboratory experiments were conducted to evaluate the prey stage preference and the daily consumption of each stage of the coccinellid predatorStethorus punctillumWeise (Coleoptera: Coccinellidae) feeding on the two-spotted spider miteTetranychus urticae(Koch) (Acari: Tetranychidae). Groups of different life stages of the prey were offered (eggs, larvae, nymphs and adults). The prey preference varied with the stage ofS. punctillum. First larval instars had no significant preference among theT. urticaestages offered. Second larval instars consumed significantly more spider mite larvae in comparison with nymphs. In contrast, third larval instars indicated a strong preference for mite eggs. Significantly fewerT. urticaelarvae were consumed by the fourth larval instars ofS. punctillum, in comparison with the three other mite stages. Finally, adult predators consumed significantly more mite eggs than the other stages offered. This preferential trend was similar for all adults tested, whether during the pre-oviposition or the oviposition period.

Samples were taken during a 2-year period (Sept. 1998 to Sept. 2000) from 17 ginning mills, located in the main cotton production regions in Greece. The material was examined in order to determine the presence and relative abundance of mites in stored seed cotton and its products: cotton fiber, cottonseed and cotton gin trash. Twenty-two mite taxa were found, with the predominance of mite species on each type of stored commodity differing significantly. Fifteen taxa were recorded in seed cotton, where the most abundant species wereTyrophagus putrescentiae(Schrank) andTarsonemus waiteiBanks. In contrast, only four species were found in cotton fiber, withT. putrescentiaebeing the dominant one. Nine taxa were recorded in the cottonseed samples, where the most abundant species was by farLepidoglyphus destructor(Schrank).Caloglyphussp. was the most abundant species in cotton gin trash, where a total of 13 taxa were found. Most mites were found in gin trash, followed by cottonseed and seed cotton; very few mites were detected in cotton fiber.

Studies were conducted in a flat storeroom in central Greece, filled with approx. 90 tons of wheat, in order to evaluate insect and mite species abundance, and changes in population density and distribution among sampling units and locations. The surface of the grain bulk was divided into two sampling zones: the central and the peripheral (edge). At 10-day intervals, five wheat samples were taken from the central zone and eight from the peripheral zone, with a non-partitioned grain trier (1.6-m length, 250-g capacity). Fifteen insect species and 12 mite taxa were found during the sampling period, (June 1999–Feb. 2000). The most abundant insect species wereSitophilus oryzae(L.),Cryptolestes ferrugineux(Stephens),Tribolium castaneum(Herbst) andLatheticus oryzaeWaterhouse; the most abundant mite species wereAcarus siroL.,Lepidoglyphus destructor(Shrank), and the predatorsBlattisocius tarsalis(Berlese) andB. keeganiFox. Grain temperature decreased during the storage period, more slowly in the central than peripheral zone; grain moisture content increased. The highest population densities for both insects and mites were recorded during September and October. The most numerous species of insects and mites showed an aggregated spatial pattern, as indicated by Iwao’s Patchiness Regression.

The introduction of propylene glycol, DDVP and water inside perforated probe traps was evaluated on the basis of their effectiveness in trapping adults of six species of Coleoptera infesting stored cereals. Adults ofSitophilus oryzae, Tribolium castaneum, Cryptolestes ferrugineus, Tenebroides mauritanicus, Rhyzopertha dominicaandOryzaephilus surinamen-siswere placed in plastic cylindrical bins each containing 14 kg of wheat. One probe trap was then introduced into each container and the adults trapped were counted 72 h later. Experiments were conducted at two population densities, of 30 adults (approx. one insect per 0.5 kg of wheat) and 90 adults (approx. three adults per 0.5 kg of wheat) of each species per container. The highest percentage of adults trapped was observed forC. ferrugineusandT. castaneum, and the lowest forR. dominicaandS. oryzae.No significant differences in number of adults captured (% of the total number of adults) was noted between the two population density levels. At the lower density, the presence of killing agents in the traps did not increase the captures significantly; on the other hand, at the higher density, the killing agents helped to increase significantly the catches of 5.oryzae, T. castaneum, T. mauritanicusandO. surinamensis, as compared with the catches in the control traps. No significant differences were noted forC. ferrugineusandR. dominica.

Keys for the identification of genera and species of the subfamily Aphidiinae which occur in Greece as well as the observed parasitoid — aphid relations on various host plants are presented.

In this study, we evaluated phosphine efficacy against two strains of the confused flour beetle, Tribolium confusum Jacquelin du Val (Coleoptera: Tenebrionidae), one laboratory strain, with no previous exposure to phosphine, and one field strain, originated from the flour mill on which we performed the fumigation. The standard Detia Degesh Phosphine Resistance Kit showed that the adults of the field strain of T. confusum required 4.4 × longer time to be knocked down than the laboratory strain. In order to assess the efficacy of phosphine in the field against these strains, aluminium phosphide (AlP) was applied in a flour mill in Czech Republic, in 2014. In this application, temperature among the six floors of the flour mill varied between 20 and 30°C, relative humidity (RH) between 44 and 78%, and phosphine concentration-time-products (CtP) between 24 and 38 g.m−3.h−1. Moreover, the insects were bioassayed in dishes that contained either no commodity or 1, 3, and 5 cm of flour. Nevertheless, despite these variations, all adults and larvae from both strains were dead, regardless of the floor, the quantity of the commodity, and the conditions prevailing. However, larval emergence from eggs that were used in the bioassays for both strains was recorded in some of the locations tested. In addition, larval emergence was negatively correlated with both temperature and RH. At the same time, emergence was generally similar between strains. The results of the present study illustrate that highly visible dead adults and larvae after the application of phosphine falsely imply good fumigation efficacy, given that a considerable number of eggs are very likely to survive in a wider range of conditions, and the concomitant larval emergence may result in rapid population grown right after the fumigation.

To assess the spatiotemporal distribution of insects in a flat storage containing wheat (Triticum spp.), probe traps were suspended in the wheat bulk and inspected for captured insects at 15-d intervals, from June 2001 to August 2002. The grain bulk was 1 m in height, and traps were placed at the upper and the lower 0.5 m of the bulk. During the entire trapping period, 17 insect taxa were recorded. The most abundant species were Ephestia kuehniella Zeller (Lepidoptera: Pyralidae) and its larval parasitoids Harbobracon hebetor (Say) (Hymenoptera: Braconidae) and Venturia canescens (Gravenhorst) (Hymenoptera: Ichneumonidae). Most individuals were found in the upper bulk part. The highest E. kuehniella trap catches were found between August and November 2001 and during June and July 2002. Of the two parasitoids, H. hebetor was more abundant than V. canescens, with the exception of winter and early spring, when both species occurred at low numbers, especially H. hebetor. Spatial analysis by distance indices (SADIE) spatiotemporal analysis showed significant clustering of species, especially during summer and autumn. Early in the season and during spring 2002, at low host numbers, V. canescens occupied the locations where E. kuehniella mainly aggregated, but with the increase of E. kuehniella population, H. hebetor occupied these host groups and replaced V. canescens. Although the two parasitoids competed for the same host species, both species coexisted in the storage facility during the entire trapping period.

Laboratory bioassays were conducted to evaluate the susceptibility of seven populations (strains) of the confused flour beetle, Tribolium confusum Jacquelin du Val (Coleoptera: Tenebrionidae), to five commercially available diatomaceous earth (DE) formulations: Insecto, Protect-It, Protector, PyriSec, and SilicoSec. These DEs were applied on wheat, Triticum durum Desf., at two dose rates, 500 and 1000 ppm. The six beetle strains were obtained from Denmark, United Kingdom, Greece, Germany, Italy, and Portugal, whereas a seventh strain came from the Greek strain after laboratory selection with SilicoSec-treated wheat for six generations. Adults of the above-mentioned strains were exposed for 7 d to wheat treated with each DE formulation, and mortality was assessed after exposure. For all DE–dose combinations, significant differences were noted in mortality levels among strains. Generally, the strains from Denmark, United Kingdom, and Germany were the most susceptible to the DEs used, whereas the strain from Portugal was the least susceptible. No significant differences were noted in susceptibility level between the initial Greek strain and the laboratory-selected Greek strain, with the exception of Protector, where the selected strain was significantly more tolerant than the initial strain for both dose rates tested.