Performance of Hermetia illucens (Diptera: Stratiomyidae) larvae reared on organic waste diets and pupal chitin and chitosan yield.

Recently, much research has been oriented towards the influence of different food wastes and agricultural by-products on the final larval biomass and chemical composition of the insect species Hermetia illucens L. (Diptera: Stratiomyidae). However, there is a gap in the literature regarding the possible relationship between the feeding substrate of H. illucens larvae and chitin. In this context, in the present study, larvae of H. illucens derived from two populations (i.e., UNIPI and UTH), were reared on different diets composed of fruits, vegetables, and meat. Based on the results, the larval survival was high for all diets tested. Larval growth in terms of weight gain, larval length, and feed conversion ratio (FCR) depended on the composition of each diet. The chitin and chitosan composition of larvae, reared on different substrates, did not reveal significant differences. Given the fact that the feeding substrate represent a significant cost in the industrial production of insects, its correlation with a high value product (i.e. chitosan) is important. On the other hand, as the prepupal stage of H. illucens is currently used as animal feed, the metabolization of chitin by farmed animals when the larvae or prepupae were offered as feed could have adverse effects. Thus, depending on the final product that is to be produced, industries could benefit from the establishment of a suitable diet.

Valorization of local agricultural by-products as nutritional substrates for Tenebrio molitor larvae: A sustainable approach to alternative protein production.

In pursuit of sustainable protein sources, the agricultural sector and emerging edible insect industry intersect in the valorization of agricultural by-products. Establishing a mutually beneficial relationship involves utilizing agricultural by-products as feeding substrates for insect farming, potentially enhancing the sustainability of both sectors. In the present study, by-products from beer, rice, oat, maize, sunflower, and lucerne, as well as mill residues and spent mushroom substrate from the regions of Thessaly and Central Macedonia (Greece) were investigated as nutritional sources for the larvae of the yellow mealworm (Tenebrio molitor). Results show that the suitability of the tested by-products for rearing T. molitor larvae varies greatly, with larvae surviving better in some by-products than in others. The highest survival rate and the highest weight of larvae were recorded for larvae reared on rice bran, spent grains, and oat by-products. Similarly, high feed conversion and growth rate were observed when the larvae were fed with rice bran and spent grains. Thus, this research promotes cost-effective and sustainable T. molitor rearing, aligning with circular economy principles.

Residual Efficacy of Two Diatomaceous Earths from Greece for the Control of Sitophilus oryzae (L.) (Coleoptera: Curculionidae) and Rhyzopertha dominica (F.) (Coleoptera: Bostrychidae) on Wheat and Maize.

We evaluated the persistence and efficacy of two different, in granulometry and content of diatoms, diatomaceous earth (DE) formulations (i.e., DE5 and DE6), against two major beetle species of stored products, i.e., Sitophilus oryzae (L.) (Coleoptera: Curculionidae) and Rhyzopertha dominica (F.) (Coleoptera: Bostrychidae). The formulations were applied as powders in soft wheat and maize in two doses of 500 and 1000 mg kg-1 (ppm). Samples of the treated grains were taken on the day of application and every 30 days until completion of the six-month period of storage. Adults of S. oryzae and R. dominica were exposed to the treated grains at 25 °C and 55% relative humidity, and the mortality was measured after 7, 14, and 21 days of exposure. Rhyzopertha dominica survival was not affected by any combination of DE formulation, dose, and commodity. Contrariwise, the DEs caused significant adult mortality of S. oryzae, in most of the cases tested. We observed that DE6 was equally effective in both wheat and maize, and no considerable variations were observed in S. oryzae mortality during the 6-month experimental period. Furthermore, DE6 was more effective against S. oryzae than DE5, a difference that could have potentially contributed to the variations in the diatom granulometry between these two DEs. Thus, a DE treatment of 1000 ppm was shown to provide long-term protection of wheat and maize against S. oryzae, but this is strongly dependent on the DE formulation, commodity, and insect species. Overall, such natural resource-based inert silicaceous deposits could be used with success in stored-product protection with only some minor modifications, such as sieving and drying of the raw deposit.

Larval performance of Zophobas morio (F.) (Coleoptera: Tenebrionidae) on various diets enriched with post-distillation residues and essential oils of aromatic and medicinal plants.

The increasing demands for resources driven by the global population necessitate exploring sustainable alternatives for affordable animal protein over the use of traditional protein sources. Insects, with their high protein content, offer a promising solution, especially when reared on agricultural post-distillation residues for enhanced sustainability and cost-effectiveness. We assessed the development of Zophobas morio (F.) (Coleoptera: Tenebrionidae) larvae on diets enriched with essential oils and post-distillation residues from Greek aromatic and medicinal plants. Two aromatic plant mixtures (A and B) were examined. Mixture A consisted of post-distillation residues, while Mixture B incorporated these residues along with essential oils. Insect rearing diets were enriched with different proportions (10, 20, and 30 %) of these mixtures, with wheat bran serving as the control. Enrichment positively influenced larval development without compromising survival. Larval weight remained unchanged with Mixture A, but improved with Mixture B. No adverse effects were detected in the case of the enriched diets, although higher concentrations of Mixture B prolonged development time.

Go local: Enhancing sustainable production of Tenebrio molitor through valorization of locally available agricultural byproducts.

Insects receive increasing attention as an alternative source of protein for animals and humans, and thus, the production of low-cost insects for meeting the dietary demand on sustained basis is an ever-growing concept. This study aims to design dietswith locally available agricultural byproducts from Greece as feed for larvae of the yellow mealworm, Tenebrio molitor L. (Coleoptera: Tenebrionidae). This will considerably reduce the cost of insect feed and the environmental impact of insect farming by using locally available agricultural byproducts as economic insect feedstock. More specifically, five agricultural byproducts derived from the production of cereals and legumes were utilized to design twelve different diets at two protein levels, i.e., 17.4 and 22.5% protein content. All diets were evaluated both at laboratory scale, but also at pilot scale. Based on the obtained results, both bioassays revealed that the diets contained one legume and one cereal byproduct (i.e., lupin and triticale as well as lupin and oat) supported more efficiently the growth and performance of the larvae, irrespective of the protein level. Indicatively, individual larval weight of the best performed larvae from both groups ranged from 132 to 142 mg. Moreover, our results highlight the fact that data derived from laboratory scale bioassays are not always easy to be extrapolated to industrial production. For instance, the total harvest of larvae, a parameter assessed in the tray scale bioassay, exhibited a disparity between diet A2 (910 g) and diet A3 (749 g), despite both being deemed optimal in the laboratory-scale experiment. Our study aims to promote a circular approach for the industrial rearing of insects through integration of local agricultural byproducts into specific diets for T. molitor larvae.

Diet replacement with whole insect larvae affects intestinal morphology and microbiota of broiler chickens.

Insect-based diets are gaining interest as potential ingredients in improving poultry gut health. This study assessed the dietary treatment with whole dried Tenebrio molitor larvae (TM) on broiler chickens' gut microbiota and morphology. 120 Ross-308 broilers received treated diets with 5% (TM5) and 10% (TM10) replacement ratio in a 35-day trial. Intestinal histomorphometry was assessed, as well as claudin-3 expression pattern and ileal and caecal digesta for microbial community diversity. Null hypothesis was tested with two-way ANOVA considering the intestinal segment and diet as main factors. The TM5 group presented higher villi in the duodenum and ileum compared to the other two (P < 0.001), while treated groups showed shallower crypts in the duodenum (P < 0.001) and deeper in the jejunum and ileum than the control (P < 0.001). Treatments increased the caecal Firmicutes/Bacteroidetes ratio and led to significant changes at the genus level. While Lactobacilli survived in the caecum, a significant reduction was evident in the ileum of both groups, mainly owed to L. aviarius. Staphylococci and Methanobrevibacter significantly increased in the ileum of the TM5 group. Results suggest that dietary supplementation with whole dried TM larvae has no adverse effect on the intestinal epithelium formation and positively affects bacterial population richness and diversity.

Combined Dietary Supplementation of Tenebrio molitor Larvae and Chitosan in Growing Pigs: A Pilot Study.

Nowadays, the global animal industry faces considerable challenges in securing sufficient feed resources. Responding to consumer demands for reduced use of antibiotics in animal nutrition, better animal welfare status, and reduced impact on the environment, there is an increased urgency to develop innovative functional feeds with a reduced environmental footprint and the ability to improve meat quality and safety. In an effort to explore innovative feed ingredients for growing pig diets, the combined dietary supplementation of Tenebrio molitor larvae and chitosan was investigated. An experimental trial was performed with 48 weaned pigs (34 days of life; mixed sex) that were randomly assigned to four treatment groups (with six males and six females each): Group A (control), Group B (supplemented with T. molitor larvae at 10%), Group C (supplemented with chitosan at 0.05%), and Group D (supplemented with both ingredients at 10% and 0.05%, respectively). On the 42nd day of the experimental trial, samples of blood, feces, and carcass parts were taken for analysis. The results indicated that the insect larvae meal significantly improved (p < 0.05) overall performance, increased (p < 0.05) blood red blood cell content, increased meat phenolic content (p < 0.05), improved meat oxidative stability (p < 0.05), and affected meat fatty acid profile (p < 0.05). On the other hand, chitosan had no significant effect on overall performance (p > 0.05), but it significantly increased blood lymphocyte content (p < 0.05), affected the fecal microbiota (p < 0.05), improved meat oxidative stability (p < 0.05), increased meat phenolic content (p < 0.05), and affected meat fatty acid composition (p < 0.05) and (p < 0.05) meat color. Finally, the combined use of both T. molitor and chitosan significantly affected some important zootechnical parameters (p < 0.05), fecal microbial populations (p < 0.05), meat color (p < 0.05), and fatty acid profile (p < 0.05). Further investigation into the potential interaction between insect larvae meals and chitosan in pig diets is advised.

Effects of low temperatures on quiescence in Trichogramma evanescens Westwood and T. chilonis Ishii reared on Plodia interpunctella (Hübner): implications for mass rearing.

The egg parasitoids of the genus Trichogramma are important potential biological control agents for a wide range of lepidopteran pests. Cold storage of host eggs has been proposed as a valuable technique for ensuring the release of sufficient parasitoid numbers whenever it is needed. In this context, the impact of low temperatures to induce quiescence in T. evanescens Westwood and T. chilonis Ishii was studied using eggs of Indian meal moth Plodia interpunctella (Hübner). Prepupae of the parasitoids were stored for 15, 30, 45, 60 and 75 d at 4 °C, following a 7 d period of acclimation at 10 °C. Both parasitoid species seem to survive unfavorable temperature conditions by entering a state of quiescence. Parasitism, adult emergence, sex ratio and progeny quality were not affected by cold storage in either parasitoid species for up to 30 d of storage. Parasitized host eggs of P. interpunctella can be stored for up to 60 d at 4 °C for both parasitoids, but there was no emergence at 75 d. General productivity values gradually decreased as the duration of storage lengthened for both species. Our results clearly reveal that the eggs parasitized by these species can be stored for up to 30 d at 4 °C in a state of quiescence without much loss of their performance compared to the control eggs.

Development, application and evaluation of three novel TaqMan qPCR assays for phosphine resistance monitoring in major stored product pests Tribolium castaneum and Rhyzopertha dominica.

BACKROUND: Stored product protection from insect pests relies heavily on the use of phosphine. The most serious drawback of phosphine is the development of resistance in major stored product insects worldwide, including the red flour beetle, Tribolium castaneum (Herbst) and the lesser grain borer, Rhyzopertha dominica (F.). Two genetic loci are responsible for phosphine resistance: the rph1 (S349G mutation in the cyt-b5-r homolog) in T. castaneum and the rph2 (P45/49S mutation in the dihydrolipoamide dehydrogenase (dld) gene) in T. castaneum and R. dominica. RESULTS: In this study, we have developed and applied high-throughput, practical and specific molecular diagnostics (TaqMan qPCR) for monitoring mutations S349G, P45S and P49S. In our pilot monitoring application, we have included phosphine-resistant and susceptible populations from different parts of the world (USA, Australia, Brazil) and European strains from Greece and Serbia. Our results for the resistant T. castaneum showed a P45S mutant allele frequency (MAF) of 100% and 75.0% in the populations from Serbia and Brazil, respectively. Regarding the susceptible T. castaneum, P45S was detected in Greece (MAF = 62.5%) and was absent in Australia (MAF = 0.0%). Additionally, the S349G mutation was found to be fixed in all resistant populations, while it was also detected in susceptible ones (frequencies: 65.0% and 100.0%). The only case where both mutations were fixed (100%) was a resistant population from Serbia. In R. dominica, the P49S mutation was found only in the two resistant R. dominica populations from Serbia and Greece (50.0% and 100%) and was absent from the susceptible one from Greece; thus, P49S seems to be a satisfactory indicator for monitoring phosphine resistance. CONCLUSIONS: Our P49S detection assay in R. dominica seems to be a viable option in this direction, yet its utilization needs additional large-scale confirmatory work. The identification of additional resistance markers also should be prioritized. © 2023 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Competition of Rhyzopertha dominica and Sitophilus oryzae on six sorghum varieties.

We tested the effect of simultaneous infestation by adults of the lesser grain borer, Rhyzopertha dominica (F.) and the rice weevil, Sitophilus oryzae (L.) on six sorghum varieties. For this purpose, vials containing sorghum and either each species alone or both species were placed at 30 °C and 65% relative humidity. After ten days, all parental adults were removed and the vials were returned to the same conditions. Five weeks later the vials were emptied, to record adult emergence, the percentage of insect damaged kernels (IDK), and frass weight. Our results indicated that progeny production capacity for both species was not affected by the simultaneous presence of R. dominica and S. oryzae, and that adult emergence was more of a variety- mediated parameter. Both species had previously shown similar preferences towards specific sorghum varieties. IDK and frass were higher in vials containing R. dominica alone rather than S. oryzae alone, but these indicators were not always related to progeny production. Specifically, the most and the least frass production was noted on Sumac and PE sorghum varieties for both species, respectively. When the two species were placed together in the same vial, the most frass production was noted in the Non-Waxy Burgundy and Sumac varieties. Our results suggest that varietal resistance in sorghum could be utilized to help reduce post-harvest infestations by S. oryzae and R. dominica.

Mating compatibility and offspring traits evaluation among different strains of Tenebrio molitor.

The fast-growing sector of insects for food and feed stimulates researchers and the industry to explore uncharted territories, such as insect breeding, to improve economically important insect fitness traits. The yellow mealworm, Tenebrio molitor L., is one of the most thoroughly studied insect species as food and feed. However, data on mating compatibility and the effect of cross-breeding between different strains on the performance and fitness of the hybrids are scarce. In the present study, we comparatively evaluated the mating compatibility between two T. molitor inbred strains (Greek and Italian) and their outbred strains, i.e., Italian (♀)-Greek (♂) and Greek (♀)-Italian (♂), as well as the performance of their hybrid offspring. Based on the results, there is good mating compatibility among adults of the strains tested. Offspring performance, quantified as larval survival and final larval weight, followed a similar pattern among the crossings examined. Even though differences were insignificant, the outbreeding of females of the Italian strain resulted in a higher cumulative number of eggs and hatching rate and higher offspring weight. The present study sheds light on the mating compatibility of different T. molitor strains and their hybrids' economically important life table characteristics to take the mass production of insects one step further.

Breeding Substrate Containing Distillation Residues of Mediterranean Medicinal Aromatic Plants Modulates the Effects of Tenebrio molitor as Fishmeal Substitute on Blood Signal Transduction and WBC Activation of Gilthead Seabream (Sparus aurata).

This work assesses the dietary use of two insect meals of Tenebrio molitor (TM) larvae reared in conventional (TM-10) or MAP-enriched substrates (MAP-TM-10) as fish meal replacements (10%) in the diets of gilthead seabream (Sparus aurata). Fish (n = 4500; 207.19 ± 1.47 g) were divided into three groups with triplicates: control (fed conventional diet), TM-10, and MAP-TM-10 groups. The fish were reared in floating cages for 12 weeks and the dietary effects on white blood cell activation, heat shock proteins, MAPKs, and apoptosis of the fish were evaluated. The MAP-TM-10 group exhibited the highest eosinophilic induction. Phosphorylated levels of p38 MAPK, p44/42 MAPK, HSP70, and HSP90 increased in the TM-10 and MAP-TM-10 groups. In terms of apoptosis, Bax levels were lower in the TM groups compared to the control, and the MAP-TM-10 group showed even lower levels than the TM-10 group. Bcl-2 levels increased in the TM-10 group compared to the control, and further increased in the MAP-TM-10 group. The Bax/Bcl-2 ratio, an apoptosis indicator, decreased in the TM groups, with the MAP-TM-10 group showing a further decrease compared to TM-10. These findings suggest that insects' breeding substrate being enriched with MAPs modulated the effect of TM on cellular stress and apoptosis.

Insecticidal Effect of Diatomaceous Earth Formulations for the Control of a Wide Range of Stored-Product Beetle Species.

Diatomaceous earth (DE) formulations are promising alternatives over the use of traditional insecticides. In the present study, a series of laboratory bioassays was carried out to assess the efficacy of three diatomaceous earth formulations, i.e., Silicid, Celatom® MN-23, and SilicoSec®, for the control of a wide range of stored-product insect species in soft wheat. The species tested were Tribolium confusum, Tribolium castaneum, Sitophilus oryzae, Sitophilus granarius, Rhyzopertha dominica, Oryzaephilus surinamensis, and Alphitobious diaperinus. Different dose rates, i.e., 0 (control), 100, 300, 500, and 1000 ppm, were used for each of the aforementioned dust formulations. Mortality levels of the exposed individuals were assessed after 3, 7, 14, and 21 days of exposure. Moreover, progeny were counted 65 days later. Based on our results, dust formulations were effective for the control of most of the stored-product beetle species tested. Among the DE formulations tested, Silicid could adequately control the stored-product insect species. Complete suppression of offspring was observed only for secondary species (T. confusum, T. castaneum, O. surinamensis, and A. diaperinus). For primary species (S. oryzae, S. granarius, and R. dominica), the lowest number of progeny was observed in wheat treated with Silicid. For instance, in the case of R. dominica, significantly fewer individuals were produced in Silicid-treated wheat at the highest dose rate. The results of the present study aim to encourage the utilization of DE in stored-product protection as an integrated pest management tool. Additional experimentation is required to apply the tested DE formulations in the field and on different surfaces.

Enhancing the Nutritional Profile of Tenebrio molitor Using the Leaves of Moringa oleifera.

Nowadays, more and more research is being carried out on various feeds of Tenebrio molitor larvae, in order to increase their nutritional value and render them a valuable component of the human diet. In this study, Moringa oleifera leaves were used in different proportions (up to 50%) to substitute wheat bran (the usually employed feed), in order to evaluate their effect on the growth and development of the larvae, as well as on their composition in crude protein, fat and fatty acids, ash, vitamins, and antioxidants. It was found that the addition of M. oleifera leaves in the feed had no negative impact on the development and survival of the insects, while an increase in their nutritional value was recorded. More specifically, an increase in the crude protein of up to 22.61% and vitamin C and A contents of up to 40.74% and 491.63%, respectively, was recorded. Therefore, the use of M. oleifera leaves as a feed additive is highly recommended for rearing T. molitor larvae to enhance the nutritional value of the insects.

Effect of Nitrogen on Stored-Product Insect Control at Industrial Scale.

In this study, we evaluated the insecticidal effect of nitrogen against Sitophilus granarius (L.), Sitophilus oryzae (L.), Rhyzopertha dominica (F.), Prostephanus truncatus (Horn), Tribolium confusum Jacquelin du Val, and Oryzaephilus surinamensis (L.). Four trials were conducted in chambers containing flour in bags or sacks with >99% nitrogen level. Adults of all the above species, as well as immature life stages (eggs, larvae, and pupae) of T. confusum were used in the trials. Our results showed that nitrogen caused high mortality for all species and life stages tested. Some survival was recorded for R. dominica and T. confusum pupae. Low progeny production was recorded for S. granarius, S. oryzae, and R. dominica. In conclusion, our trials indicated that a high nitrogen environment can provide satisfactory control of various primary and secondary stored-product insect species.

Utilization of Tenebrio molitor Larvae Reared with Different Substrates as Feed Ingredients in Growing Pigs.

The procurement of adequate feed resources is one of the most important challenges for the animal industry worldwide. While the need for feeds rich in protein is constantly increasing, their production cannot readily keep up. Consequently, to overcome this challenge in a sustainable way, it is necessary to identify and develop new feeding strategies and feed ingredients, such as insect meals. In the present study, Tenebrio molitor larvae that were reared on two different substrates (standard and enriched with medicinal aromatic plant material) were used as feed ingredients for growing pigs. A total of 36 weaned pigs (34 days old) were randomly allocated to three treatment groups and fed either the control diet (A) or diets supplemented at 10% with one of the two insect meals (B and C). At the end of the trial (42 days), blood, feces, and meat samples were collected for analysis. The insect meal supplementation did not affect (p > 0.05) overall performance but significantly modified (p < 0.001) the fecal microflora balance and the blood cholesterol (p < 0.001), while the rest of the blood parameters tested were not affected. Moreover, this dietary supplementation significantly affected some microbial populations (p < 0.001), improved the total phenolic content (p < 0.05), and the fatty acid profile (p < 0.001) of the meat cuts, but did not affect (p > 0.05) meat color or proximate composition. Further research is needed to evaluate the different types and levels of inclusion of insect meals in pig nutrition.

Comparison of different traps and attractants in 3 food processing facilities in Greece on the capture of stored product insects.

Certain lures are marketed toward particular pests or classes of pests, while others might be multi-species lures. Investigative aims for this study included both which trap was most sensitive and whether different combinations of traps and attractants were delivering novel information about the stored product insect community. Comparisons were made for all combinations of 3 commercial traps and 4 different attractants plus an untreated control on the capture of stored-product insects for 2 consecutive years in 3 food processing facilities in Central Greece. The traps used in the experiments were Dome Trap (Trécé Inc., USA), Wall Trap (Trécé) and Box Trap (Insects Limited, Ltd., USA). The attractants that were evaluated were 0.13 g of (i) PantryPatrol gel (Insects Limited), (ii) Storgard kairomone food attractant oil (Trécé), (iii) wheat germ (Honeyville, USA), and (iv) Dermestid tablet attractant (Insects Limited). The traps were inspected approximately every 15 days and rotated. A total of 34,000+ individuals were captured belonging to 26 families and at least 48 species. The results indicated that Indian meal moth, Plodia interpunctella (Hübner), red flour beetle, Tribolium castaneum (Herbst), and cigarette beetle, Lasioderma serricorne (F.) were the most abundant. Although there were noticeable differences among the different traps and attractants for specific species, all combinations provided similar information on population dynamics. Generally, Dome traps baited with either the oil or the gel, were found to be the most sensitive. The results of the present study demonstrate the importance of long-term trapping protocols, as a keystone in IPM-based control strategies in food processing facilities.

Evaluation of the susceptibility of Alphitobius diaperinus meal to infestations by major stored-product beetle species.

The projections for the production of insects as food and feed show an enormous increase for insect production in the near future, which will subsequently lead to the increase of the stored quantities of insect meals and related products. However, information on the susceptibility of insect meals to infestations by stored-product insects is rather limited. To this end, the objective of the present study was to evaluate the potential of major storage insect species to grow and reproduce on insect meals that are based on larvae of the lesser mealworm, Alphitobius diaperinus. The progeny production of thirteen stored-product insects on A. diaperinus meal, as well as their instantaneous rate of increase, as a measure of population growth, was recorded for each species. Based on the results, six out of the thirteen examined insect species (A. diaperinus, Tenebrio molitor, Trogoderma granarium, Lasioderma serricorne, Tribolium confusum, and Tribolium castaneum) were able to infest pure A. diaperinus meal, as they grew well and developed progeny on the insect meal substrate. Tribolium confusum, T. castaneum, and especially T. granarium gave the highest progeny production numbers in the A. diaperinus meal with the latter giving an instantaneous rate of increase of 0.067. Expecting the upcoming increase in the production of insect-based products globally, further research in this field is needed for improved production and storage facilities, detection and estimation methods, and technologies to minimize insect infestations without causing negative effects to farmed insects.

Efficacy of deltamethrin and pirimiphos-methyl in proportionally layer-treated maize against the larger grain borer and the maize weevil.

Two insecticides (deltamethrin and pirimiphos-methyl) were evaluated in laboratory assays as grain protectants when applied as a total percentage of a maize mass to control adult Prostephanus truncatus and Sitophilus zeamais. All experiments were conducted at the University of Thessaly in Greece at 30°C and 65% RH under continuous darkness. Either insecticide was applied to 20 g of maize placed in a vial or to the upper one half, one fourth, or one-eighth layer of the maize, then insects were either added to the vials before or after the maize in a completely randomized block design CRBD with n = 9 replicates. Mortality, progeny production, and insect damaged kernels (IDK) were then evaluated for each vial. Insect introduction method (before or after) did not have any impact on any of the variables. Mortality was nearly 100% for all treatments for both insecticides for P. truncatus. Subsequently, progeny production and the number of insect damaged kernels were very low or zero for P. truncatus. Mortality of S. zeamais remained low across layer treatments for deltamethrin. However, S. zeamais was easily controlled by pirimiphos-methyl. The results of this laboratory study show that while deltamethrin and pirimiphos-methyl have some effectiveness as a layer treatment on a column of maize, efficacy will be dependent on the target species, and the depth of the treated layer, as well as the location on which the insects are present.

Quick knockdown results in high mortality: is this theory correct? A case study with phosphine and the red flour beetle.

BACKGROUND: The fumigant phosphine is used all over the world for disinfestation of stored grains and commodities. Adults of 23 different populations of Tribolium castaneum from 10 different countries were evaluated for phosphine resistance using a modification of the Detia Degesch Phosphine Tolerance Test Kit (DDPTTK). Adults were exposed to 3000 ppm and recorded for 5-270 min for their mobility. RESULTS: Among the tested populations, high levels of phosphine resistance were recorded in populations from Brazil, Serbia, and Spain. No survivals were recorded after 7 days post exposure for eight of 23 in a tested population. CONCLUSIONS: Our work revealed four scenarios: 1, quick knockdown-low (or no) recovery; 2, Slow knockdown-high recovery; 3, Quick knockdown-high recovery; and 4, Slow knockdown-low recovery. Our data indicate that post exposure period is critical for the evaluation and characterization of phosphine resistance. © 2023 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.