Studies on insect infestation in chocolates

The ability of stored-product pests including the cigarette beetle, Lasioderma serricorne, the sawtoothed grain beetle, Oryzaephilus surinamensis, the rust-red flour beetle, Tribolium castaneum, and the almond moth, Ephestia cautella, to infest chocolates under packaged and unpackaged conditions was investigated in the laboratory at 25±1 °C and 65±5% r.h. Four types of chocolates were investigated: milk, nut, dried fruit and nut, and wafer chocolates. Adults (beetles only, 20 per replicate) or eggs (30 per replicate) were released on unpackaged and packaged chocolates and infestation levels (number of living adults and larvae) were determined 45 days later. When adult beetles were released on unpackaged chocolates, the degree of infestation varied depending on the species and the type of chocolate. The highest infestation observed in unpackaged chocolate was that of O. surinamensis in wafer chocolate (mean 138.4). When eggs were released on unpackaged chocolates, the most numerous species was E. cautella in dried fruit and nut chocolate (mean population=180.8). With packaged chocolates exposed to adults or eggs, insect infestation was nil or negligible (mean population <6.0). Although infestation levels were low, infestations were found in 50% of treatments over all. Damage to the packaging material along the folds or edges was observed in infested chocolates. The study has shown that milk, nut, dried fruit and nut, and wafer chocolates can support insect infestation and therefore, insect-proof packing of the chocolates and storage under hygienic conditions are important to avoid customers’ complaints.     

Life history parameters of Lasioderma serricorne (F.) as influenced by food sources

Fecundity, egg to adult survival rate, developmental time, and adult body weight of the cigarette beetle, Lasioderma serricorne (Coleoptera: Anobiidae) were evaluated on seven food sources at 28 °C. Ground chili, paprika, cayenne pepper, chewing leaf tobacco, cigar tobacco, a commercial insect bait referred to as NOW bait, and wheat flour were used to evaluate mean lifetime fecundity. The highest fecundity (52.4±4.8 eggs/female) was observed in wheat flour, whereas the lowest fecundity (5.8±0.8 eggs/female) was observed in cigar tobacco. Among the seven food sources, beetles reared in wheat flour showed the highest survival rate of 91.0±2.7%. Only 15% of the eggs laid in NOW bait developed to the adult stage. In the three food sources containing Capsicum spp. the survival rate ranged from 30% to 40%. The egg, larval, and pupal development times varied from 3 to 5, 38 to 92 and 4 to 18 d, respectively, among food sources. Body weight and adult longevity studies showed that the heavier adults also had the longest life span. Ovipositing female L. serricorne appear to discriminate among different food sources. Although L. serricorne laid eggs in all food sources evaluated, larval and pupal survival were lowest in NOW bait. Information on the biology and host use pattern of L. serricorne may help to explain how various stored commodities are affected by this species and may lead to develop appropriate pest management strategies for this insect pest.     

Impact of physical and biological factors on susceptibility of Tribolium castaneum and Tribolium confusum (Coleoptera: Tenebrionidae) to new formulations of hydroprene

Three separate experiments were conducted to: (1) evaluate two new commercial formulations (202-080 and 202-084) of the insect growth regulator hydroprene, (2) determine residual efficacy of hydroprene-treated concrete stored at different environmental conditions, and (3) assess the impact of accumulated flour on residual efficacy. In the first test, late instars of Tribolium castaneum (Herbst), the red flour beetle, and Tribolium confusum (du Val), the confused flour beetle, were exposed on concrete treated with hydroprene. At 40% relative humidity (r.h.), there was no difference between species regarding the percentage of individuals that stopped development in the larval stage (arrested larvae), but at 75% r.h. there were more arrested T. castaneum than T. confusum in all treatments except the low rate of formulation 202-084. No adult T. castaneum lived after emergence (live adults) at either relative humidity, but the percentage of live adult T. confusum ranged from 1.0% to 41.0%, depending on treatment. In the second test, late instars of T. confusum were exposed at 6 and 12 weeks post-treatment on concrete treated with the two experimental formulations and stored under different environmental conditions. At 6 weeks there was no difference between formulations. At 12 weeks, fewer live adults and more dead emerged adults with gross morphological deformities were found on concrete treated with formulation 202-084 and stored at 32°C, 75% r.h. compared to other treatment combinations. In the final experiment, wheat flour was added to treated concrete for 5 weeks before the bioassays were conducted with late-instar T. confusum. There were few live adults produced in the initial bioassays, and dead adults with gross morphological deformities ranged from 83.1% to 97.6%. However, in bioassays conducted with late-instar larvae at 6 weeks, most adults eventually emerged with few deformities. The presence of the flour apparently compromised residual control and the hydroprene was no longer effective. In summary, the new hydroprene formulations were equivalent to the registered product Gentrol^®. Tribolium confusum was less susceptible than T. castaneum, and residual control of T. confusum on a clean surface without flour lasted about 6-12 weeks.     

Low and high temperatures for the control of cowpea beetle, callosobruchus maculatus (F.) (coleoptera: Bruchidae) in chickpeas

Chickpea (Cicer arietinum L.; Leguminasae) is an important pulse crop grown, around the world. The whole grain of chickpea is damaged by the cowpea seed beetle, Callosobruchus maculatus (Coleoptera: Bruchidae), which is the most important field-carry-over storage pest of pulses. The management of this insect in storage using chemicals leads to insecticide residues in grains and insecticide resistance development in insects. Thermal disinfestation is one of the means of physical insect control. Eggs, larvae, pupae and adults were held at 42 or 0 °C for varying durations. Pupae and adults were equally heat tolerant. The lethal time to reduce survival by 50% (LT₅₀) at 42 °C for eggs, larvae, pupae and adults were 18, 57, 78 and 71 h, respectively. Pupa was the most cold-tolerant stage. The LT₅₀ at 0 °C for eggs, larvae, pupae and adults were 3, 8, 10 and 4 d, respectively. The LT₅₀ for pupae were 4907, 4262, 336, 36 and 13 min at the grain temperature of 42, 45, 50, 55 and 60 °C, respectively. The LT₅₀ of pupae at 0,−5,−10 and −15 °C were 274, 122, 7 and 2 h, respectively.     

Effect of Pisum sativum fractions on the mortality and progeny production of nine stored-grain beetles

Yellow field pea (Pisum sativum L.) fractions that were mainly protein (50%), fibre (90%) or starch (85%) were obtained from a commercial pea mill and mixed with wheat kernels or wheat flour. Based on the mortality and the number of offspring produced, protein-rich pea flour was more toxic than fibre, which was more toxic than starch. For the protein-rich pea flour mixed with wheat kernels, the most sensitive insects were Sitophilus oryzae (L.), Sitophilus zeamais Motschulsky and Sitophilus granarius (L.), followed by Cryptolestes ferrugineus (Stephens) which was more sensitive than Tribolium castaneum (Herbst) and Rhyzopertha dominica (F.). For the protein-rich pea flour mixed with wheat flour, Cryptolestes pusillus (Schönherr) was most sensitive, followed by C. turcicus (Grouvelle) and T. confusum (Jacquelin du Val), with T. castaneum being the most resistant. Although protein-rich pea flour did not kill adults to a great extent when mixed with flour, it reduced offspring production significantly. Again C. pusillus was the most sensitive, followed by T. confusum, with T. castaneum offspring being the most resistant. The insecticidal activity of pea fractions decreased after treated wheat kernels were held at 30 °C, 70% r.h. for 8 months. The potential of using pea fractions to control stored-product insects is discussed.     

Distribution of the Medea factor M in populations of Tribolium castaneum (Herbst) in the United States

The distribution of the maternally acting, selfish gene Medea⁴ (M⁴) was determined in populations of the red flour beetle, Tribolium castaneum (Herbst), collected in the southern and midwestern United States. We found clear evidence for the existence of two major regional subpopulations, with a boundary that roughly corresponds to 33°N latitude. All 26 strains collected in 10 states north of this latitude were homozygous for the M⁴ allele, while only two of 29 strains collected in six states south of this latitude were homozygous for the allele. Of the remaining 27 southern strains, 21 lacked the M⁴ allele entirely, while six contained a mixture of M⁴ and non-M⁴ alleles. This is the first evidence of either the existence of biotypes or the presence of major barriers to gene flow in wild populations of this ubiquitous insect species.     

Efficacy of a volatile formulation of hydroprene (Pointsource™) to control Tribolium castaneum and Tribolium confusum (Coleoptera: Tenebrionidae)

Three- and 4-week-old Tribolium castaneum (Herbst), the red flour beetle, and Tribolium confusum (du Val), the confused flour beetle, were exposed at five different temperature-relative humidity (r.h.) combinations to a volatile formulation of the insect growth regulator (IGR) hydroprene (called Pointsource™). Typical effects associated with IGR exposure, such as arrested larval growth, morphological deformities in adults, twisted and deformed wings, and incomplete adult emergence were produced in both species. Tribolium castaneum and T. confusum were susceptible to Pointsource™, but T. castaneum appeared to be the more susceptible species. More 3-week-old larvae of both species were arrested in that stage compared to the 4-week-old larvae. Nearly all of the 3- and 4-week-old T. castaneum larvae that were able to complete development to the adult stage quickly died after they emerged and were grossly morphologically deformed. In contrast, some emerged adult T. confusum remained alive after they emerged and were not deformed in any manner or had only twisted and incomplete wings. A greater percentage of larvae of both species were arrested in the larval stage and more adults died after they emerged in exposure studies conducted at 32°C, 75% r.h. as compared with 32°C, 30% r.h., but the reverse was true for exposures conducted at 27°C. Pointsource™ appears to have excellent potential for use in controlling Tribolium species within indoor facilities.     

A simple technique to assess compounds that are repellent or attractive to stored-product insects

We have developed a simple and rapid technique that mimics storage conditions, and determines if products are repellent or attractive to stored-product insects. The technique determines the response of insects to potential repellents and attractants by measuring their movement from grain. The technique used a device consisting of a perforated cup (2 mm perforations) that holds 200 g of wheat. A Petri dish and cup collected the insects as they left the wheat. Several natural products were tested for repellency: diatomaceous earth (DE), ground peas (Pisum sativum), protein-rich pea flour, pea starch, and pea fibre. Adult insects of three species were tested: the rice weevil, Sitophilus oryzae, the red flour beetle, Tribolium castaneum, and the rusty grain beetle, Cryptolestes ferrugineus. DE at 0.01% was repellent to all insects tested. Pea fibre, pea protein, and ground pea at 1% caused increased emigration of C. ferrugineus from the wheat. Pea starch did not affect movement out of the grain for all three insects. Only pea fibre and ground pea increased the movement of T. castaneum out of the grain. For S. oryzae, there were no differences after 1 h, but after 24 h both pea protein and ground pea increased movement out of the grain. Several potential attractants were placed outside the grain and the emigration out of the grain noted. For R. dominica, the commercial R. dominica pheromone increased the emigration of insects from the grain; R. dominica adults on broken grain enclosed in a ventilated vial in the collection jar also increased emigration, but not as much as the synthetic pheromone. The commercial Tribolium pheromone did increase movement out of the grain for T. castaneum, but the other treatments were no different from the control. None of the potential attractants increased the movement of S. oryzae from the grain. The implications of this work are discussed with reference to controlling and sampling stored-product insect pests.     

小麦粉中虫卵的快速检测技术的研究与比较

为了建立一种快速检测小麦粉中昆虫虫卵的方法,比较研究了浮选法、尿酸检测法、几丁质检测法和染色法4种方法检测小麦粉中虫卵的效果及优缺点的比较。结果表明浮选法最高检出率为5.59%,不适用于虫卵检测;几丁质检测法只能证明虫卵中有几丁质,但无法定量;尿酸检测法中检测出的尿酸浓度与虫卵数成正相关,相关系数R2为0.998 6,最低检出限为0.1粒卵/g;利用溴甲酚绿和酸性品红将小麦粉染色的结果是溴甲酚绿将虫卵染成黄橙色,小麦粉染成褐绿色;酸性品红将虫卵和小麦粉都染成紫色,但小麦粉被染颜色更深。染色法虫卵检测率约为75%,初步可以用于小麦粉中虫卵的快速检测。随机取样的小麦粉检测与实际发生虫量比较发现尿酸检测法的检测率为73.3%,染色法的检测率为85%。说明了尿酸法和染色法可以初步用于小麦粉中昆虫虫卵的检测,其灵敏度和操作规范有待进一步优化和研究。     

Initial and delayed mortality of late-instar larvae, pupae, and adults of Tribolium castaneum and Tribolium confusum (Coleoptera: Tenebrionidae) exposed at variable temperatures and time intervals

Late-instar larvae, pupae, and adults of Tribolium castaneum (Herbst), the red flour beetle, or Tribolium confusum (DuVal), the confused flour beetle, were exposed for variable durations at 36-54 °C. Beetles were placed in laboratory ovens set at a baseline of 27 °C, the temperature was increased by 0.1 °C per minute until the target temperature was achieved, and beetles were then held for specified exposure durations. There was no mortality after initial exposure or after a 1-week holding period of any life stage of T. castaneum or T. confusum exposed for 32 h to 36, 39, or 42 °C. At 45 °C, there was no initial mortality of either species exposed for different time intervals except for those exposed for 28 h. However, there was a significant increase in mortality after the 1-week holding period of those beetles exposed initially for at least 16 h to 45 °C. There was a sharp increase in mortality after the initial exposures of 4 h at 48 °C; mortality of T. confusum larvae was 90.0±5.7% but was only 10.0±10.0% for larvae of T. castaneum, and no pupae of either species were dead. All life stages of both species were killed after the initial exposure of 12 h, and 1-week mortality of beetles exposed for 4 and 8 h was generally greater than initial mortality. At 51 and 54 °C, 2- and 1-h exposures, respectively, killed all life stages of each species. Mortality in conditions of gradual temperature increase was less than previous studies with sudden temperature increases.     

The effect of a new chitin synthesis inhibitor, novaluron, on various developmental stages of Tribolium castaneum (Herbst)

Novaluron, a novel chitin synthesis inhibitor (CSI), was tested against the various developmental stages of Tribolium castaneum (Herbst), at concentrations ranging from 0.1 to 100 ppm. It did not kill T. castaneum adults at these concentrations, but at 1.0 ppm it caused total mortality of third-instar larvae. Novaluron did not affect the number of eggs laid by T. castaneum adults that were exposed to treated wheat flour, but it totally inhibited their hatching after the third day of exposure at a concentration of 1 ppm. On the first day after infestation novaluron did not totally prevent hatching, even at the highest tested concentration of 100 ppm. The time needed to restore egg hatchability after adults were transferred to untreated flour depended on the concentration of novaluron used in the treatment. When the adults of T. castaneum were exposed to novaluron-treated whole wheat grains (at 1 ppm), similar effects to those of the treated flour at the same concentration were observed: egg hatching was drastically reduced. The effect of uptake via contact of adults with novaluron-treated surfaces was examined by exposing them to a mixture of untreated flour and 10% novaluron-treated sand at a concentration of 10 ppm, and only 1% of the eggs hatched after 18 days of exposure. When adults were removed from treated surfaces of Petri dishes to untreated flour, the hatching rate was again reduced by 100%. It was concluded that the contact penetration of novaluron into T. castaneum adults prevents the hatching of eggs subsequently laid.     

Insecticidal effect of Steinernema feltiae (Filipjev) (Nematoda: Steinernematidae) against Tribolium confusum du Val (Coleoptera: Tenebrionidae) and Ephestia kuehniella (Zeller) (Lepidoptera: Pyralidae) in stored wheat

The confused flour beetle, Tribolium confusum, and the Mediterranean flour moth, Ephestia kuehniella, are important pests of stored grain products. The insecticidal effect of three strains (UK 76 [=Nemasys], USA/SC, and Hawaii) of the entomopathogenic nematode Steinernema feltiae was determined in the laboratory, in wheat, against these pests. The nematodes were applied at three dose rates: 100, 300 and 900 nematodes/insect individual. The Hawaii strain was most virulent against T. confusum adults and larvae, with a significant dose effect in the case of the larvae. Larval mortality of this species reached 79% and 100% after 7 and 14 d of exposure to the nematodes, respectively, at the highest dose applied. On the other hand, adult mortality of T. confusum did not exceed 66%. In the case of E. kuehniella larvae, USA/SC performed best causing 52% and 69% mortality after 7 and 14 d exposure, respectively, at the highest dose tested. Since very few data are available on the effect of entomopathogenic nematodes against these pests, it is concluded that the Hawaii and USA/SC strains of S. feltiae should be further investigated as promising biological control agents for T. confusum and E. kuehniella.     

Comparative egg morphology of silvanid and laemophloeid beetles (Coleoptera) occurring in stored products

Eggs of eight pest species of Silvanidae and Laemophloeidae commonly occurring in stored products (grain and flour etc.) in Europe are described. Comparisons include overall appearance, size, surface sculpturing and changes in external appearance during development of the embryo. Morphological details are illustrated with scanning electron micrographs. A key for distinguishing eggs of these pests at generic level is provided. The study did not reveal structural characters of value for distinguishing eggs at the species level and thus the development of specific immunological or molecular identification methods is suggested.     

Predation by Blattisocius tarsalis (Berlese) (Acari: Ascidae) on eggs of Ephestia kuehniella Zeller (Lepidoptera: Pyralidae)

The mean predation rate of female B. tarsalis on eggs of E. kuehniella was determined at 15°C, 21°C, and 27°C with prey densities of 3, 5, 10 and 15 eggs. Young eggs less than 24 h old were used as prey. Under all experimental conditions most eggs were only partially consumed, confirming the general theory that predatory mites leave most of the food content unutilized. A mean predation rate of 2.2-7.0 eggs destroyed in 24 h was found, reflecting that a large proportion of the available prey was destroyed. The result supports the view that the predatory mite B. tarsalis could be a relevant biological control agent against E. kuehniella in flour mills. It was further demonstrated that frozen moth eggs can be considered as an appropriate food source.     

Evaluation of kaolinite-based particle films to control Tribolium species (Coleoptera: Tenebrionidae)

Adults of Tribolium castaneum (Herbst), the red flour beetle, and Tribolium confusum (du Val), the confused flour beetle, were exposed to kaolinite-based particle film dusts. When beetles were continuously exposed to the hydrophobic particle film M-96-018 at the rate of 0.1-0.5 mg/cm², all the T. castaneum at 0.1 mg/cm² were dead after 3 days, but 40±13.8% of the exposed T. confusum were still alive after 7 days. At higher concentrations, all the T. castaneum were dead after 2 days, but 5-6 days of exposure were needed to kill all T. confusum. In a subsequent test, adults of both species were exposed for 8-72 h to 0.5 mg/cm² of the particle film M-96-018, removed, then held without food for 1 week. No T. castaneum survived, while survival of the T. confusum ranged from 0 to 55±17.3%, depending on the exposure interval. In a test conducted at controlled conditions of 40%, 57% and 75% r.h., 27°C, T. confusum were exposed for 8-72 h to the particle film M-96-018 and a hydrophilic particle film M-97-009 at the rate of 0.5 mg/cm², then removed and held either with or without wheat flour for 1 week. All the T. confusum exposed to the particle film M-97-009 usually survived, while survival of the T. confusum exposed to the particle film M-97-018 after the 1-week holding period increased with increasing relative humidity and with the presence of food. The particle film M-96-018 was effective against both the Tribolium species, and appears to have a potential for use in management programs to control beetles within storage facilities.     

Penetration of polyethylene sheets coated with protein-enriched pea flour solution by two stored-product insects

Adults of Sitophilus oryzae (L.) and Rhyzopertha dominica (F.) penetrated polyethylene sheets (0.0635 mm thickness) coated with protein-enriched pea flour solution (water pH 8.5-9.0) at 0 (control), 1 and 5% levels, but did not penetrate the sheets coated with a 10% concentration. The potential of using protein-enriched pea flour in the manufacture of insect-proof factory impregnated plastic sheeting is discussed.     

Effect of damaged starch on acrylamide formation in whole wheat flour based Indian traditional staples, chapattis and pooris

Variation in acrylamide content of two Indian traditional products, chapatti and poori was observed with respect to the damaged starch content in whole wheat flour of different wheat varieties from which these products were prepared. Wheat cultivar ‘lokwan’ was milled by altering mill aperture, feed rate and moisture content to obtain whole wheat flour with damaged starch contents ranging from 6.23% to 28.12%. Acrylamide content of the chapatti and pooris prepared from such flours ranged from 12.5 to 65.5 μg/kg in chapatti, and 25.5 to 130.5 μg/kg in pooris. Impact of several additives showed 10 μmol/g flour citric acid, and 100 μmol/g flour calcium chloride to reduce acrylamide in pooris by approximately 54% and 72%, respectively, without altering the sensory analysis of the products.     

Feeding bioassay for stored-product insect pests using an encapsulated food source

A procedure that was developed to encapsulate liquid and semiliquid diets was used to encapsulate dry diet for use in a feeding bioassay for beetles that are pests of stored products. Vacuum was used to form Parafilm^® into numerous 6 mm diameter wells. The wells were filled with clean sand (control) or ground dry dog food (test), and the Parafilm^® sealed to produce individual pellets. A single pellet was then placed in the center of a 9 cm diameter Petri dish and feeding activity of groups of ten adults of Sitophilus oryzae (L.), the rice weevil; Oryzaephilus surinamensis (L.), the sawtoothed grain beetle; and Tribolium castaneum (Herbst), the red flour beetle, was tested. The number of insects on the encapsulated pellet and the amount of food or sand scattered were checked hourly for the first 8 h of the study and after 24 h. Few insects were observed on pellets containing sand and little or no sand was observed scattered outside of the pellet, so the presence of dog food in the pellet was needed for insects to feed on the pellet. In tests with encapsulated dog food, the amount of food scattered provided a better quantitative measure of feeding than the number of insects on the pellet. Insects that were starved for 48 h caused greater amounts of food scatter than insects starved for 24 h prior to the test. In direct comparisons among all three species, T. castaneum responded the most slowly and the bioassay may be improved by increasing the amount of time starved. Sitophilus oryzae responded very quickly and the entire pellet was essentially consumed within the first 4-5 h of the study. The encapsulated diets provide a promising method to evaluate feeding behavior of stored-product insect pests.     

Residual efficacy of synergized pyrethrin + methoprene aerosol against larvae of Tribolium castaneum and Tribolium confusum (Coleoptera: Tenebrionidae)

Wheat flour and different packaging surfaces (cardboard, flour bag, muslin bag, paper bag, pallet wrap, plastic overwrap, polyethylene) were exposed to aerosol formulations of either 1% active ingredient (AI) pyrethrin (synergized with piperonyl butoxide)+ 33.6% (AI) methoprene or 3% (AI) pyrethrin + 33.6% AI methoprene. The mixture was formulated as specified on the insecticide labels to give a 100 to 1 ratio of active ingredient pyrethrin to methoprene. Residual bioassays were conducted every two weeks for 16 weeks post-exposure to the aerosol by placing four-week-old larvae of the red flour beetle, Tribolium castaneum (Herbst), or the confused flour beetle, Tribolium confusum (Jacqueline duVal), on treated flour or a treated packaging surface with untreated flour added. T. castaneum was clearly the more susceptible of the two species. Less than 2% of T. castaneum larvae exposed to aerosol-treated flour or packaging surfaces emerged as normal adults, regardless of the pyrethrin concentration. Most of the T. castaneum larvae on treated flour did not advance to the pupal stage because they were either developmentally arrested or died as larvae. They were able to develop further on the treated packaging surfaces, but still could not emerge as adults. T. confusum larvae exposed to aerosol-treated flour or packaging surfaces were able to develop to the pupal or adult stage. Emergence of normal-appearing adults from T. confusum larvae exposed on the packaging surfaces treated with 1% pyrethrin + methoprene gradually increased (range of 29.7 ± 2.9 to 49.0 ± 6.7%, depending on the surface), whereas adult emergence of larvae exposed to treated flour peaked at 10 weeks post-exposure. However, when T. confusum was exposed to 3% pyrethrin + methoprene treated flour or packaging surfaces, adult emergence was reduced. Overall there were few significant differences attributable to the individual packaging surfaces.     

Methoprene and synergized pyrethrins as aerosol treatments to control Plodia interpunctella (Hübner), the Indian meal moth (Lepidoptera: Pyralidae)

Aerosol insecticides (also known as ULV or fogging treatments) delivered through an ultra-low-volume application system, are available commercially to control insect pests such as Plodia interpunctella Hübner, the Indian meal moth. However, little is known about the susceptibility of eggs of P. interpunctella to aerosol insecticides applied in active field sites. We conducted several trials by exposing eggs of P. interpunctella to synergized pyrethrins, alone and in combination with the insect growth regulator methoprene. Eggs in diets and packaging materials containing the food products were directly exposed to the aerosols. There was significant variation among the food products, as assessed by adult emergence from exposed eggs, but in general there was no difference in adult emergence from eggs exposed to a 1% versus a 3% pyrethrin formulation when methoprene was included. There was no difference in efficacy between diets and diet packages placed in open areas versus areas that were in some way obstructed to the aerosol. Adult emergence was generally reduced in the treatment combinations compared to untreated controls. A partial budget analysis indicated that the combination treatment of 1% pyrethrins + methoprene represented the lowest risk, lowest cost, and would seem to be the optimum combination. Results show that field applications of aerosols could be used to control P. interpunctella in storage facilities.