Efficacy of methoprene for multi-year protection of stored wheat,brown rice,rough rice and corn

Hard red winter wheat, brown rice, rough rice, and corn were treated with the insect growth regulator (IGR) methoprene at rates of 1.25 and 2.5 ppm, held for 24 months at ambient conditions in buckets on the floor of a grain bin, and sampled every two months. Bioassays were done by exposing 10 mixed-sex adults of Rhyzopertha dominica (F.), the lesser grain borer, and Tribolium castaneum (Herbst), the red flour beetle, on wheat, R. dominica and Sitotroga cerealella (Oliver), the Angoumois grain moth, on brown rice and rough rice, and T. castaneum and S. cerealella on corn. Sample size for all commodities was about 80 g, and these samples were held for 3 months at 27°C-60% r.h. Both rates of the IGR completely suppressed adult progeny development of R. dominica with little resulting feeding damage, sample weight loss, or insect damaged kernels (IDK). Some adult progeny production of S. cerealella and resulting IDK occurred at both rates on rough rice, brown rice, and corn, but was far less than in untreated controls. There was little adult progeny production but some feeding damage caused by larval T. castaneum in the treated wheat and corn but again far less than in untreated control. Allowing continual exposure of parental adults on grains treated with an IGR, rather than exposing those parental adults for a short time period, may give more accurate evaluations of residual efficacy. Results show that methoprene used as a grain protectant will give residual control of stored product beetles for 24 months, but complete control of S. cerealella may require inclusion of a contact insecticide.     

Efficacy of diflubenzuron plus methoprene against Sitophilus oryzae and Rhyzopertha dominica in stored sorghum

The efficacy of diflubenzuron (1 mg kg⁻¹)+methoprene (1 mg kg⁻¹) against Sitophilus oryzae (L.) and Rhyzopertha dominica (F.) in sorghum was evaluated in a silo-scale trial in southeast Queensland, Australia. Sorghum is normally protected from a wide range of insects by mixtures of grain protectants. The chitin synthesis inhibitor diflubenzuron was evaluated as a potential new protectant for S. oryzae in combination with the juvenile hormone analogue methoprene, which is already registered for control of R. dominica. Sorghum (ca 200 t) was treated after harvest in 2000 and assessed for treatment efficacy and residue decline during 6.5 months storage. The reproductive capacity of S. oryzae and R. dominica was greatly reduced in bioassays of treated sorghum throughout the trial, and efficacy remained relatively stable during the trial. An initial exposure of S. oryzae adults to treated sorghum for 2 weeks reduced F₁ progeny production of all strains by 80.8-98.8%, but a second exposure of 4 weeks reduced F₁ progeny production by 98.5-100%. In addition, the reproductive capacity of any S. oryzae progeny produced was greatly reduced. Exposure of R. dominica adults to treated sorghum for 2 weeks reduced F₁ progeny production of all strains by 99.6-100%, including a methoprene-resistant strain. The results indicate that S. oryzae or R. dominica adults invading sorghum treated with diflubenzuron (1 mg kg⁻¹)+methoprene (1 mg kg⁻¹) would be incapable of producing sustainable populations.     

Evaluation of methoprene-treated packaging against Trogoderma granarium Everts and Trogoderma inclusum LeConte larval development and packaging penetration or invasion

Trogoderma granarium Everts, khapra beetle, and Trogoderma inclusum LeConte, larger cabinet beetle, are highly destructive insect species that can infest a variety of food sources. Methoprene is an insect growth regulator, IGR, and recently has been incorporated into packaging materials as a treatment option for packaged grain, food, birdseed, and feed products, and labeled for this use by the US Environmental Protection Agency. The objective of this research was to investigate the effect of continual exposure to this novel packaging technology on the development of T. inclusum and T. granarium larvae, and its potential use as a packaging treatment to prevent the penetration or invasion of T. inclusum and T. granarium into food packages. The methoprene-treated packaging incorporated into Kraft paper, woven bag material, polyethylene-polyethylene (PE-PE) material, and a polyethylene terephthalate-polyethylene (PET-PE) material, reduced normal adult emergence of exposed larvae. No normal adult emergence was observed on the inside surface of the PET-PE material. The polymer-based materials were the most effective at preventing penetration or invasion by Trogoderma spp. Only 2% of packages were invaded among all packaging treatment combinations compared to 16.7% invasion of untreated packages. The materials were ranked in effectiveness as Kraft < woven < PET-PE < PE-PE, however, all materials demonstrated significant positive results on Trogoderma spp. This novel packaging could easily be adopted as a packaging control strategy against these and other stored product insects in packaged products destined for commercial, international, and smallholder farm storage of cereal grains, feed, and other food products.     

Susceptibility of Tribolium castaneum and Trogoderma variabile larvae and adults exposed to methoprene-treated woven packaging material

Methoprene is an insect growth regulator (IGR) registered in the United States for direct application to stored raw grains, as an aerosol or residual contact insecticide, and for use as a coating for protection of packaged products. A series of tests was conducted to determine the adverse effects of short term exposure, sub-lethal exposure, and continual exposure of the red flour beetle, Tribolium castaneum (Herbst) and warehouse beetle, Trogoderma variabile Ballion, on methoprene-treated woven packaging material at 27 and 32 °C and 60% r.h. In the first test, larvae of both species were added to individual arenas and exposed for different time intervals, removed and resulting adult emergence was assessed. In the second test, eggs of both species were exposed on the packaging surfaces to determine percent egg hatchability. In the third test, adults of T. castaneum and T. variabile were added to arenas and held for 7 and 3 d, respectively, to determine number of eggs laid per female and subsequent egg hatchability. The eggs were held in arenas to determine the effect of continual exposure on egg-to-adult emergence. Results showed normal adult emergence decreased with increasing exposure time and temperature. Exposure to methoprene-treated packaging did not adversely affect fecundity of T. variabile adults, but did affect fecundity of T. castaneum. Continual exposure gave 100% suppression of T. castaneum adult emergence and a reduction of T. variabile emergence. This study indicated that methoprene-treated packaging could be a valuable addition to an existing integrated pest management program to increase protection of packaged products.     

Efficacy of reduced risk insecticides on penetration into jute and polyethylene bags by Lasioderma serricorne (F.) (Coleoptera: Anobiidae)

This study investigated the efficacy of DE, pea protein, methoprene, pyrethrins and DEET at label rates to reduce penetration of stored-product insect Lasioderma serricorne (F.) (Coleoptera: Anobiidae) to jute and polyethylene woven bags. The survival of eggs and young larvae of L. serricorne were measured. The insecticides caused 27–67% mortality of eggs and larvae. There was no difference between insecticides, but all caused higher mortality than controls. A second test measured the ability of adults to penetrate the jute and polyethylene materials treated with the various insecticides. After 24 h, approximately 85% of adults L. serricorne had penetrated through the untreated jute and polyethylene materials. Fewer insects penetrated through the treated jute materials; DEET (12.5 ± 4.8%), pyrethrins (20 ± 4%), methoprene (30 ± 4%), pea protein (42.5 ± 4.8%), and DE (52.5 ± 4.8%). While, the percentage of adults L. serricorne penetrated the treated polyethylene materials were; DEET (20 ± 4%), pyrethrins (35 ± 6.4%), methoprene (50 ± 4%), pea protein (62.5 ± 4.8%), and DE (62.5 ± 4.8%). A third test measured the ability of insecticides to prevent the infestation of flour in jute and polyethylene bags. Fewer insects emerged from flour in jute and polyethylene bags treated with insecticides. All insecticides reduced infestation from 49 to 83%, with DEET being the most effective.     

5%可保特在仓储烟叶中残留分析

采用气相色谱法,FID检测器对仓储烟叶中可保特(methoprene)进行分析。其最小检出量为5×10-11g、最小检出浓度为5×10-2mg/kg。气相色谱的响应值与进样量呈正相关。回收率在82.44%～87.91%之间,变异系数在7.01%以下。可保特在仓储烟叶中半衰期为40～79d,80d时的消解率为47.96%～66.61%,残留量均在3.214mg/Kg以下。两年两地试验结果表明,可保特在仓储烟叶中使用,对吸烟者无害。     

5%烯虫酯水乳剂的研制

通过对乳化剂等助剂的筛选,确定了5%烯虫酯水乳剂的最佳配方,各项指标均达到相关标准。     

Effect of methoprene treated polymer packaging on fecundity,egg hatchability,and egg-to-adult emergence of Tribolium castaneum and Trogoderma variabile

The fecundity, egg hatchability, and egg-to-adult emergence of the red flour beetle, Tribolium castaneum (Herbst) and warehouse beetle, Trogoderma variabile Ballion, were evaluated on untreated and methoprene-treated polyethylene-to-polyethylene (PE-PE) and polyethylene terephthalate-to-polyethylene (PET-PE) packaging at 27 and 32 °C and 60% r.h. Inside and outside surfaces of the packaging were fit into ∼62 cm² Petri dishes, and 500 mg of flour (T. castaneum) or vanilla shake mix diet (T. variabile) were added to arenas as food for developing larvae. On methoprene-treated PE-PE packaging, hatchability of added T. castaneum eggs was consistently lower than on untreated packaging. On PET-PE packaging, hatchability of T. castaneum eggs on inside surfaces at both temperatures was significantly lower than on untreated packaging. No consistent trends were observed in T. variabilile hatchability between the packaging types, temperatures, and on inside and outside surfaces of untreated and methoprene-treated packaging. The fecundity of T. variabile was not significantly different between the packaging types. None of the T.castaneum eggs on inside and outside surfaces of the PE-PE methoprene-treated packaging emerged as adults. Methoprene-treated PET-PE packaging reduced fecundity of T. castaneum. Generally, hatchability of eggs laid by both species was not significantly different among the treatment combinations. Only the inside surface of PET-PE packaging gave 100% suppression of egg-to-adult adult emergence of T. castaneum. Development of T. variabile larvae was arrested at the pupal stage at both temperatures on the outside surface of methoprene-treated PE-PE packaging, whereas on the inside surface larvae completed development to adulthood. A 87–97% reduction in egg-to-adult emergence of T. variabile was observed on the inside surface of the PET-PE packaging relative to emergence in corrresponding control treatments at both temperatures. The packaging types evaluated in this study can potentially protect food products stored in these packages from infestations of T. castaneum and T. variable.     

Effects of methoprene and synergized pyrethrin aerosol applications on Tribolium castaneum (Herbst) populations

The occurrence of horizontal transfer of the insect growth regulator (IGR) methoprene on confined populations of Tribolium castaneum (Herbst), either with or without hidden refugia, was determined through a series of experiments. Multiple applications were made with the IGR alone or combined with synergized pyrethrin, and compared to untreated controls which received no insecticide applications or were treated with the carrier Isopar M that was a component of the pyrethrin formulation. The total number of living beetles from test colonies inoculated with adults that were treated with Isopar M or with no adults (control) was significantly greater than those colonies that were inoculated with adults treated with either synergized pyrethrin or methoprene (P < 0.05). There was no difference in the number of living individual in the larval, pupal, and adult stages and the instantaneous rate of increase (r_i) in established populations treated with methoprene and containing a hidden refugia compared to those which received the pyrethrin applications (P ≥ 0.05). Sanitation levels of two different flour quantities nested inside the treatment groups also had no effects (P ≥ 0.05), suggesting that populations in hidden refugia can persist even with multiple applications of methoprene and synergized pyrethrin. Populations with an accessible hidden refugia that were exposed to synergized pyrethrin and methoprene had a lower number of living adult and a lower r_i value than populations that were exposed to synergized pyrethrin alone (P < 0.001). Additionally, populations which received one, two, or three aerosol applications had similar numbers of living adults and r_i but were significantly different from populations which received four aerosol applications. Results suggest multiple applications of methoprene and synergized pyrethrin could be more effective than synergized pyrethrin alone for control of T. castaneum.     

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.