Control Of Stored-product Insects Research Articles

Temperature Effect on the Growth and Development of Habrobracon hebetor Say (Hymenoptera: Braconidae) Reared on Ephestia elutella (Hübner) (Lepidoptera: Pyralidae) Larvae.

Augmentative release of parasitoids has been an important component of integrated insect management for stored product protection. Understanding the effect of different temperatures on the growth and development of parasitoids is in favor of mass rearing of parasitoids. Habrobracon hebetor Say (Hymenoptera: Braconidae) is a highly cosmopolitan, gregarious ecto-parasitoid of a variety of Lepidopterous larvae. Thus, the growth and development of H. hebetor reared on Ephestia elutella (Hübner) (Lepidoptera: Pyralidae) larvae were investigated at 15, 20, 25, 30, and 35 °C. Habrobracon hebetor could complete growth and development, and the developmental duration decreased with increasing temperature at 15, 20, 25, 30, and 35 °C. The development threshold temperatures of H. hebetor eggs, larvae, pupae, and egg-to-adult stages were 13.89, 6.39, 9.24, and 9.29 °C, and the effective accumulated temperatures were 23.33, 46.40, 142.68, and 240.31 °C·d, respectively. The total number of eggs laid by H. hebetor, the hatching rate of H. hebetor eggs, and the percentage of female offspring reached the maximum of 192.39, 83.89%, and 74.04% at 30 °C, respectively. There was no significant difference in pupal survival rate in the temperature range of 15 °C to 35 °C. At 30 °C, the pre-oviposition duration of H. hebetor was the shortest (0.87 d). Therefore, the optimal rearing temperature of H. hebetor was 30 °C. The present results are useful for the large-scale rearing of H. hebetor using E. elutella larvae as hosts and effectively implementing the biological control of stored-product insects.

Chemical Composition and Insecticidal Activities of Blumea balsamifera (Sambong) Essential Oil Against Three Stored Product Insects

Blumea balsamifera (L.) DC. (Asteraceae), also known as sambong, is a perennial herb used in China for medicinal purposes. The essential oil (EO) of B. balsamifera was extracted by hydrodistillation. Thirty chemical components of the EO were analyzed by gas chromatography-mass spectrometry (GC-MS) and GC, accounting for 88.0% (w/w) of the total oil. The EO of B. balsamifera was mainly composed of monoterpenes and sesquiterpenes, in which borneol (23.3%), β-caryophyllene (20.9%) and camphor (11.8%) were the major components. The insecticidal activities of the EO and its three main compounds against Tribolium castaneum, Lasioderma serricorne and Sitophilus oryzae were evaluated. The results of bioassays displayed that the EO of B. balsamifera did not have fumigant toxicity to the three target insects, but exhibited significant contact activity against L. serricorne (LD50 = 12.4 μg/adult) and S. oryzae (LD50 = 44.4 μg/adult). Meanwhile, the EO showed a notable repellent effect on T. castaneum at all testing concentrations and a general repellent effect on S. oryzae at high concentrations (78.63 nL/cm2). β-Caryophyllene showed the best performance in the contact toxicity bioassays against the three insects. The results indicated that B. balsamifera has the potential to be used as a source of botanical insecticides for the control of stored-product 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.

Mortality of Different Stages of Plodia interpunctella (Lepidoptera: Pyralidae) at Three Temperatures in Controlled Atmosphere of High Nitrogen.

The lethal exposure time to controlled atmospheres of high nitrogen at stored grain temperatures is an important information for control of stored-product insects. The mortality of 1-d-old egg, 1-wk-old (first or second instar) larva, 3-wk-old (fourth or fifth instar) larva, and 1-d-old pupa of Plodia interpunctella (Hübner) was determined at 18 ± 1, 23 ± 1, and 28 ± 1°C in 98% N2 mixed with air. At 18°C, the lethal exposure times to achieve 100% mortality were 12.7 ± 0.7, 16.3 ± 0.3, 19.7 ± 0.7, and 14.7 ± 0.7 d for 1-d-old egg, 1-wk-old larva, 3-wk-old larva, and 1-d-old pupa, respectively. Temperature had significant effect on the lethal exposure time, and increase of the temperature significantly decreased the lethal exposure time. The order of the insect stages from the highest to lowest for LT50 values was follows: 3-wk-old larva > 1-wk-old larva > 1-d-old pupa ≥ 1-d-old egg. The minimum lethal exposure times required to kill all stages of P. interpunctella were about 20, 16, and 12 d at 18, 23, and 28°C, respectively.

Pinene-rich essential oils from Haplophyllum dauricum (L.) G. Don display anti-insect activity on two stored-product insects

Continuous use of synthetic insecticides increases environmental contamination and resistance in many species. Botanical insecticides, such as essential oil, were considered to be suitable alternatives due to multiple modes of action and low mammalian toxicity. Haplophyllum dauricum is a overlooked plant for the control of stored-product insects. Five essential oils (EOs) from Haplophyllum dauricum collected in October and November, rich in pinene, were extracted and evaluated on anti-insect activity against two stored-product insects, Tribolium castaneum (Coleoptera: Tenebrionidae) and Lasioderma serricorne (Coleoptera: Anobiidae). The lethal doses (LD50 and LD90), lethal concentrations (LC50 and LC90) and percentage repellency (PR) were evaluated. The GC-MS analysis showed that pinene (α-pinene and β-pinene) were major constituent of the EOs (54.61% and 57.33% in fruits, 46.80% in stems + leaves, and 30.57% in leaves), followed by β-phellandrene (14.49% and 21.34% in fruits and leaves), 3-carene (26.84% in leaves) and limonene (15.77%, 11.09%, 12.40%, 7.59%, and 6.24% in five EOs, respectively). Five EOs and selected major compounds provided promising fumigant, contact and repellent activity against T. castaneum and L. serricorne. The EO of stems + leaves collected in October showed the strongest contact toxicity on T. castaneum (LD50 = 20.21μg/adult), as well as fumigant and contact toxicity on L. serricorne (LC50 = 17.17 mg/L air, LD50 = 25.46 μg/adult). All the five EOs exhibited effective repellent activity (PR>80%) against T. castaneum. The results highlight that the EOs from H. dauricum have a promising potential as eco-friendly botanical insecticides.

Insecticide treated packaging for the control of stored product insects

Improper or poor post-harvest handling and storage of stored grains contributes significantly to product loss, and bagged stored grain presents an option for safe storage and handling. Bagged grain is intended to maintain quality and safety, while protecting it from infestations. The objective of this research was to determine the effect of deltamethrin-treated packaging material on adults and larvae of common stored product pests. Adults or larvae of several species of stored product insects were exposed to deltamethrin-treated packaging for time intervals ranging from 1 h to 4 weeks. The percentage of affected Prostephanus truncatus, Callosobruchus maculatus and Rhyzopertha dominica adults was 96% larval death within 1-2 weeks.The major primary stored product insects were highly susceptible to the deltamethrin-treated storage bags, but there was variation in susceptibility between species and life stages tested. The deltamethrin-treated storage bags can offer protection of bagged grains and be used as a preventative measure to reduce infestations during storage.

Temperature: Implications for biology and control of stored-product insects: Presentation

Temperature: Implications for biology and control of stored-product insects: Presentation

Toxicity and repellency of essential oil from Evodia lenticellata Huang fruits and its major monoterpenes against three stored-product insects

In this work, the essential oil (EO) was extracted from the fruits of Evodia lenticellata, and the fumigant toxicity, contact toxicity and repellency against three stored-product insect species were evaluated for the obtained EO and several of its chemical components. The target insects were the adults of Tribolium castaneum (Coleoptera: Tenebrionidae), Lasioderma serricorne (Coleoptera: Anobiidae) and Liposcelis bostrychophila (Psocoptera: Liposcelididae). The EO was obtained with hydrodistillation and its chemical components were analyzed with the gas chromatography-mass spectrometry (GC-MS). Twenty-seven compounds, accounting for 83.1% of the total amount of the oil, were identified from the EO sample. The main compounds included linalool (12.0%), β-pinene (11.5%), 3-carene (9.6%), caryophyllene oxide (8.7%) and β-caryophyllene (7.9%). Among them, the amounts of monoterpenes and sesquiterpenes were as high as 52.7% and 22.7% to the total amount of EO respectively. The results of bioactivity test showed that the EO and its testing compounds had interspecific toxicity and repellent activity. So that, it might be expected that the EO extracted from the fruits of E. lenticellata could be developed to a new type of eco-friendly natural insecticide or repellent for the control of stored-product insects.

Residual efficacy of Deltamethrin against Sitophilus oryzae (L.), Rhyzopertha dominica (F.), Tribolium castaneum (Herbst) and Sitotroga cerealella (Oliv.) in wheat grain

Residual efficacy of the insecticide deltamethrin, an EC formulation containing 25 g/L AI + 225 g/L PBO (piperonyl butoxide synergist), against lab populations of Sitophilus oryzae, Rhyzopertha dominica, Tribolium castaneum and Sitotroga cerealella was investigated in the laboratory by applying product water solutions (0.25 mg AI/kg) to wheat grain (at 25?1?C and 60?5% r.h.). Adult mortality on 0, 7, 14 and 30 days old deposits was estimated after 2, 7 and 14 days of exposure to treated wheat grain and additional 7 days of recovery. Progeny reduction (PR, %) was also assessed. After 2 days of exposure to deposits of all ages, deltamethrin caused only 0-10% mortality of coleopterans (up to 37% after the recovery period) and 23-30% of S. cerealella, while mortality before and after recovery from 14 days of exposure was 95-50% for S. oryzae, 97-100% for R. dominica, 99-100% for T. castaneum and 100% for S. cerealella. Progeny production of S. oryzae was highest after parents contacted with 14 days old deposit of deltamethrin (PR, 76%), and lowest after contact with fresh deposit (PR, 95%), while R. dominica and T. castaneum had no progeny on any deltamethrin deposit age in wheat (PR, 100%), and S. cerealella had only a very low progeny (PR, 99%). The results showed that the synergised deltamethrin, applied at 0.25 mg/kg in wheat grain, is a highly effective insecticide for storedproduct insect control, while a higher dose is required for successful residual control of S. oryzae.

Efficacy of alpha-cypermethrin, chlorfenapyr and pirimiphos-methyl applied on polypropylene bags for the control of Prostephanus truncatus (Horn), Rhyzopertha dominica (F.) and Sitophilus oryzae (L.)

We examined the immediate and delayed mortality of adults of the larger grain borer, Prostephanus truncatus (Horn) (Coleoptera: Bostrychidae), the lesser grain borer, Rhyzopertha dominica (F.) (Coleoptera: Bostrychidae) and the rice weevil, Sitophilus oryzae (L.) (Coleoptera: Curculionidae) on surfaces of polypropylene storage bags under different treatment scenarios with alpha-cypermethrin, chlorfenapyr and pirimiphos-methyl. These scenarios were: only one surface of the bag was sprayed and insects were exposed on sprayed or unsprayed surface or both surfaces were sprayed. We evaluated the immediate mortality for 1, 3 and 5 days (d) of exposure. Then, we transferred the surviving adults to untreated surfaces of the same type of storage bags and measured the delayed mortality after 7 d of exposure. We also evaluated the effect of insecticidal treatments on the numbers of holes/bites made by the activity of P. truncatus and R. dominica on storage bags. In terms of immediate mortality, chlorfenapyr and pirimiphos-methyl were very effective against all three species and alpha-cypermethrin against P. truncatus. We noticed high mortality values of all species to chlorfenapyr and pirimiphos-methyl, even after 3 d of exposure, reaching 100% in many of the cases examined. For the majority of exposure intervals, insecticides and insects, we did not find significant differences in mortality counts between exposures on sprayed surfaces of the bag. Immediate mortalities of insects exposed on the untreated surface of the bag did not differ significantly with mortalities at the surface single treated with alpha-cypermethrin and pirimiphos-methyl. Concerning delayed mortality, all S. oryzae adults were found dead 7 d after their transfer to untreated bags irrespectively of the treatment. The delayed mortality of P. truncatus and R. dominica adults was either complete (after exposure to chlorfenapyr) or almost complete (after exposure to alpha-cypermethrin). The exposure of P. truncatus and R. dominica to alpha-cypermethrin almost completely suppressed the numbers of holes/bites. Our study indicates that the application of insecticides on polypropylene storage bags can be considered as an effective method for the control of stored-product insects.

Use of entomopathogenic fungi for the control of stored-product insects: can fungi protect durable commodities?

Entomopathogenic fungi are considered promising microbial control agents for the control of post-harvest insects, and their evaluation for this purpose has lately attracted a significant amount of research. They are naturally occurring, environmentally safe organisms that infect insects by contact. Insect fungal pathogens have a broad spectrum of hosts, can be mass-produced easily, rapidly and economically and can be applied with the same technical means as conventional contact insecticides. In this context, the most studied fungal species for the control of stored-product insect species are Beauveria bassiana and Metarhizium anisopliae. Both fungal species have a wide host range and have been tested against most of the major stored-product insect pests. The effect of biotic and abiotic factors on the virulence and success of entomopathogenic fungi in storage insect control, as well as the combined application of these agents with other pest control technologies, is reviewed here. Temperature and relative humidity influence the efficacy of entomopathogenic fungi, often with variable results, whereas the combined use of entomopathogenic fungi with diatomaceous earth in many cases has a synergistic or additive effect. Alternative methods of entomopathogenic fungi application, based on the lure-and-kill approach, are proposed, and future challenges for the use of entomopathogenic fungi against stored-product insects are highlighted.

The use of entomopathogenic nematodes in the control of stored-product insects

This review highlights the latest findings regarding the use of entomopathogenic nematodes against post-harvest insects. Due to their requirements for moisture, entomopathogenic nematodes had received, until lately, limited attention for application to the dry storage environment. Recent improvements of their formulation and application approaches, as well as the discovery of new, more virulent strains have enhanced the efficacy of entomopathogenic nematodes and renewed interest in using entomopathogenic nematodes in the stored-product environment. The nematode species tested against storage insects belong exclusively to the genera Steinernema and Heterhorhabditis. The virulence of entomopathogenic nematodes against post-harvest insects varies depending on the nematode species and strain. Usually, only a single-nematode species or strain is not equally effective against all major stored-product insect pests; therefore, one nematode strain or species cannot be suitable for controlling all species present in the storage environment, where several insect species coexist. The successful application of entomopathogenic nematodes in storage environments for controlling post-harvest insects is highly dependent on several biotic and abiotic factors, such as the host life stage, temperature, and relative humidity. Entomopathogenic nematodes have still to overcome substantial hurdles to become a reliable alternative for commercial applications in warehouses and storage facilities. However, the use of innovative, enhanced methods of formulation and application, such as encapsulation or bait traps, could boost the exploitation of entomopathogenic nematodes in storage facilities against post-harvest insects.

Efficacy of a Combination of Beta-Cyfluthrin and Imidacloprid and Beta-Cyfluthrin Alone for Control of Stored-Product Insects on Concrete

The insecticidal effect of Temprid, a formulation that contains beta-cyfluthrin and imidacloprid, was tested on concrete for control of seven stored-product insect species: the rusty grain beetle, Cryptolestes ferrugineus (Stephens); the sawtoothed grain beetle, Oryzaephilus surinamensis (L.); the red flour beetle, Tribolium castaneum (Herbst); the confused flour beetle, T. confusum Jacquelin du Val; the hide beetle, Dermestes maculatus (DeGeer); and the psocids Liposcelis bostrychophila Badonnel and L. paeta Pearman. Temprid, which contains 10.5% beta-cyfluthrin and 21% imidacloprid, was tested at the rate of 17.2 ml of formulation/4.1 liters of water/100 m2. Adults were exposed for 4, 8, 14, and 24 h, and then daily for 7 d, on untreated dishes or dishes treated with Temprid. In the untreated dishes, mortality of C. ferrugineus and O. surinamensis was lower when food was present, but food did not affect mortality of the other species. Presence of food did not affect mortality of any of the species tested in the treated dishes. C. ferrugineus, O. surinamensis, and the two psocid species were very susceptible to Temprid, with mortality of 97-100% after 7 d of exposure. In contrast, D. maculatus, T. castaneum, and T. confusum were tolerant to Temprid, as mortality did not exceed 57, 25, and 17%, respectively, at the 7-d exposure. A separate series of similar bioassays with Tempo, a formulation that contains 11.8% beta-cyfluthrin alone, which was applied at the same dose rate as Temprid, was conducted using O. surinamensis and T. castaneum as the target insect species, and results showed that Tempo was at least as effective as Temprid. Our results indicate that the simultaneous use of beta-cyfluthrin with imidacloprid is not more effective on concrete than beta-cyfluthrin alone, and efficacy of both formulations varies with the target species.

Chemical composition and toxicity of the essential oil of Cayratia japonica against two grain storage insects

During our screening program for new agrochemicals from Chinese medicinal herbs, essential oil of Cayratia japonica aerial parts was found to possess strong insecticidal activities against Sitophilus zeamais and Tribolium castaneum. A total of 37 components of the essential oil were identified by gas chromatography (GC) and GC–mass spectrometry (GC–MS). Linalool (19.4%), trans-α-ionene (11.4%), α-terpineol (7.9%), dihydroactinolide (7.8%) and geranial (5.8%) were the main components of the essential oil. The essential oil exhibited strong fumigant toxicity against S. zeamais and T. castaneum adults with LC50 values of 10.05 and 15.67 mg/L air, respectively. Cayratia japonica essential oil also possessed contact toxicity against S. zeamais and T. castaneum adults with LD50 values of 32.06 and 44.49 mg/adult, respectively. The essential oil C. japonica may have potential to be developed as a new natural fumigant/insecticide for the control of stored-product insects.

Proteomic analysis of peach fruit moth larvae treated with phosphine

Phosphine has been used worldwide for the control of stored-product insects for many years. However, the molecular mechanism of its toxicity is not clearly understood. In the current study, larvae of the peach fruit moth were fumigated with phosphine. Proteomic analysis was then performed to identify the regulated proteins. Our results confirmed the phosphine toxicity on the peach fruit moth. The median lethal time LT50 was 38.5 h at 330 ppm at 25 degrees C. During fumigation, the respiration of the peach fruit moth was extremely inhibited. Of the 26 regulated proteins, 16 were identified by MALDI-TOF mass spectrometry after a 24 h treatment. The proteins were classified as related to metabolism (25 %), anti-oxidation (6 %), signal transduction (38 %), or defense (19 %). The rest (13 %) were unclassified. Phosphine regulation of ATP and glutathione contents, as well as of ATP synthase and glutathione S-transferase 2 activities were confirmed by enzyme activity analysis. These results demonstrate that complex transcriptional regulations underlie phosphine fumigation. New theories on the mechanism of phosphine toxicity may also be established based on these results.

Proteomic analysis of peach fruit moth larvae treated with phosphine

Phosphine has been used worldwide for the control of stored-product insects for many years. However, the molecular mechanism of its toxicity is not clearly understood. In the current study, larvae of the peach fruit moth were fumigated with phosphine. Proteomic analysis was then performed to identify the regulated proteins. Our results confirmed the phosphine toxicity on the peach fruit moth. The median lethal time LT50 was 38.5 h at 330 ppm at 25 degrees C. During fumigation, the respiration of the peach fruit moth was extremely inhibited. Of the 26 regulated proteins, 16 were identified by MALDI-TOF mass spectrometry after a 24 h treatment. The proteins were classified as related to metabolism (25 %), anti-oxidation (6 %), signal transduction (38 %), or defense (19 %). The rest (13 %) were unclassified. Phosphine regulation of ATP and glutathione contents, as well as of ATP synthase and glutathione S-transferase 2 activities were confirmed by enzyme activity analysis. These results demonstrate that complex transcriptional regulations underlie phosphine fumigation. New theories on the mechanism of phosphine toxicity may also be established based on these results.

Alternative fumigants to methyl bromide for the control of pest infestation in grain and dry food products

The primary aim of the current study is to evaluate the potential use of the known isothyiocyanates (ITC) as compared to a new ITC isolated from Eruca sativa (salad rocket) as fumigants for the control of stored products insects. The biological activity of methyl iodide (CH 3 I), carbon disulphide (CS 2 ), benzaldehyde (C 7 H 6 0) and essential oils were also evaluated. The toxicity of the various fumigants was assessed against adults and larvae of a number of major stored-product insects. ITCs are potential candidates because only very low concentrations are needed for the control of stored-product insects. It should be mentioned that Eruca sativa is used worldwide as a food supplement. Methyl thio-butyl ITC the main bioactive component in this plant has high toxicity against insects, but lower mammalian toxicity as compared to other active ITCs. Comparative studies with CH 3 I, CS 2 and C 7 H 6 0 showed that the first was the mot active compound against stored-product insects followed by the second and the third. CH 3 I was found less sorptive and to be less penetrative in wheat than CS 2 . The activity of some essential oils was also evaluated. In this context, we should keep in mind that a general consensus is very difficult to achieve in order to introduce broadspectrum fumigants like methyl bromide or phosphine. Because of this, alternative fumigants could be developed against particular species of insects or to be used for specific food product commodity. Keywords : Fumigants; Isothiocyanates; Methyl iodide; Carbon disulfide; Benzaldehyde.

Biological control of stored-product insects in commodities, food processing facilities and museums

Non-chemical control methods have gained importance in integrated pest management, as policies aiming to minimize the application of residual chemical insecticides are being adopted by many companies, and a growing market of organic produce. The associations of organic farming have established self-restrictions concerning chemical control. Examples are given of how organically producing farms and processing companies function without synthetic chemical pesticides. Both non-chemical control methods for complete disinfestations and for suppression of re-infestation or residual infestations are needed. For complete disinfestations, heat treatment of buildings is now more widely used. Data on heat-tolerance of storedproduct pests and an example for a heat treatment of a mill will be given. For high-value products such as spices, tea or medical plants, deep freezing is applied. Temperature data are needed to apply product-specific freezing conditions to obtain complete control at the core of the bulk. An integrated management strategy is needed to keep products free from infestation following disinfestations, along the whole chain from the storage of raw products to the consumer. Biological control is a part of that strategy. A new branch of the biological control industry is developing in Europe. Natural enemies for stored-product pests are now produced in The Netherlands, Germany and Switzerland. Traditional pest control companies are using insect parasites and predators more and more to control stored-product insects, indicating an adoption of biological control. Homeowners throughout Europe are purchasing online Trichogramma sp. to control moth pests. Biological control is especially attractive to processing facilities that are not willing to stop production for pest control operations. Small farms with bulk grain stores that are not gas-tight apply parasitoids as well. Recommendations for the application of natural enemies are presented for these examples. Finally, recent developments on natural enemies both for stored-product pests, e.g. flour beetles, and museum and wood boring pests are presented. Keywords : Stored-product Pests, Material Destroying pests, Temperature modification, Biological control

Biological activity of essential oils of Alpinia conchigera rhizome against Sitophilus zeamais and Tribolium castaneum

Research dealing with plant products is a new direction as an alternative to conventional insecticides for stored-product insect control (Shaaya et al., 1991, 1997). Alpinia conchigera Griffin (Zingiberaceae) is a native plant in southern Thailand, and it has a wide variety of the essential oils (Ibrahim et al., 2009). The toxicity and repellency of the water distilled essential oils from rhizome of A. conchigera was evaluated against the major stored-product insect pests, maize weevil, Sitophilus zeamais Motschulsky and red flour beetle, Tribolium castaneum (Herbst) 1-14 day-old adults at 29+2 C and 65+5% r.h. In fumigation trials (Liu and Ho, 1999), the mortality was assessed at concentrations ranging from 74 to 667 μL/L in air with exposure times ranging from 3 to 24 h. There was complete mortality of S. zeamais at 222 μL/L after 24 h, whereas 593 μL/L for 24 h was required for complete mortality of T. castaneum. Sitophilus zeamais adults (LC50, fiducial limits: 121, 114-129 μL/L) were more susceptible to essential oils of A. conchigera than T. castaneum (295, 203-369 μL/L) (Table 1). Contact toxicity was assayed by topical application to insect thoraxes (Liu and Ho, 1999) at different concentrations (10 to 40%). Sitophilus zeamais adults (LC50, 27, 1840 μg/mg) had the same mortality as T. castaneum (LC50, 34, 28-47 μg/mg) (Table 2). A filter paper choice bioassay (Ko et al., 2009) of essential oils of A. conchigera in 100% ethanol showed that T. castaneum has repelled more than S. zeamais (Table 3).

Suitability of Five Species of Stored-Product Insects as Hosts for Development and Reproduction of the Parasitoid Anisopteromalus calandrae (Hymenoptera: Pteromalidae)

We investigated the ability of two populations of Anisopteromalus calandrae (Hymenoptera: Pteromalidae), to parasitize and develop on late instars of five different stored-product insects that typically complete their development inside seeds of grain or legume species or other dry commodity. The host species were the cigarette beetle, Lasioderma serricorne (F.); cowpea weevil, Callosobruchus maculatus (F.); rice weevil, Sitophilus oryzae (L.); lesser grain borer, Rhyzopertha dominica (F.); and Angoumois grain moth, Sitotroga cerealella (Olivier). Experiments were conducted in the laboratory in a no-choice design by using petri dishes (15 by 100 mm) as experimental arenas with 20 host larvae. A. calandrae females from populations originating in Georgia (GA) and Oklahoma (OK) were introduced singly into experimental arenas and allowed to sting and oviposit for 24 h. Parasitism by the OK population was greater than that for the GA population across all hosts. However, no or very low parasitism was found on Angoumois grain moth for either population in this experiment. The highest number of parasitoid progeny was recorded on cowpea weevil (15.9) followed by rice weevil (11.5) and cigarette beetle (10.8) for the OK population. A similar trend was observed in the GA population. The highest proportion of female progeny was produced on cowpea weevil (73.0%) by the OK population. Conversely, a higher proportion of female progeny was produced on rice weevil (64.6%) by the GA population than produced by the OK population. Parasitoid adults were significantly larger and heavier when they developed on cowpea weevil irrespective of parasitoid population. The possible application of these results for biological control of stored-product insects is discussed.