PARTICLE SIZE OF INSECTICIDAL SUSPENSIONS AND THEIR CONTACT TOXICITY III. TEMPERATURE COEFFICIENTS AND TESTS BY INJECTION

Aqueous DDT suspensions containing particles of different sizes gave different temperature coefficients of mortality in dipping tests against adult Oryzaephilus surinamensis and Tribolium castaneum. In the range 12–30°C., colloidal DDT showed a large negative coefficient, but the coefficient for a suspension of DDT crystals of 400μ was smaller ( T. castaneum ) or negligible ( O. surinamensis ). Thus, although a suspension of crystalline DDT was more toxic than colloidal DDT to warm insects, it was less toxic than the colloid to cool insects.
A test was made of rotenone suspensions against adult milkweed bugs ( Oncopeltus fasciatus Dall.) by application of measured droplets under the wings. Colloidal rotenone was more toxic than a crystalline suspension. Milkweed bugs could not be killed in this way by DDT suspensions.
Tests were also made by injecting suspensions of rotenone, DDT and its fluorine analogue (DFDT) into milkweed bugs. A suspension of rotenone crystals was equitoxic with colloidal rotenone against insects kept for 3 days at 27°C. after treatment. The same was true of crystalline and colloidal DDT suspensions. If the bugs were kept at 10°C., colloidal rotenone was much more toxic than crystalline rotenone 2 days after treatment. But if the insects were kept for about 3 weeks and inspected at intervals, the first apparent difference in toxicity grew smaller, and in the end it nearly disappeared. With DDT the time for this to occur was about 10 days; and suspensions of colloidal and crystalline DFDT were equitoxic after only 2 days, even at 10°C.
In the application test, the difference between colloidal and crystalline rotenone was a real difference in toxicity. It did not disappear with the lapse of time; but in the injection tests the two forms of each poison differed only in speed of action, and not in ultimate toxicity.     

Effect of acrolein vapors on stored-product insects and wheat seed viability

In laboratory experiments, toxicity of acrolein vapors was investigated against four species of stored-product insects. In empty-space trials, estimates of the median lethal doses of acrolein against adults of Oryzaephilus surinamensis (L.), Sitophilus oryzae (L.), Rhyzopertha dominica (F.), and Tribolium castaneum (Herbst), were 1.87, 2.35, 3.12, and 6.65 mg/liter, respectively. Penetration tests revealed that acrolein vapors could penetrate into the wheat mass and kill concealed insects in interkernel spaces. Comparison of LD50 values between empty-space tests and penetration experiments after 24-h exposure indicated that the increase in penetration toxicity was 6.34-, 6.31-, 7.17-, and 4.54-fold for O. surinamensis, S. oryzae, R. dominica, and T. castaneum, respectively. In the hidden infestation trials, the acrolein vapors destroyed all the developmental stages of S. oryzae and R. dominica concealed inside the wheat kernels, resulted in a complete control with dose of 80 mg/liter for 24 h, and subsequently observed during 8 wk after the exposure. Wheat germination rate was diminished by fumigation with acrolein. The plumule length was reduced after exposure to all doses of acrolein. Together, the data suggest acrolein could be a potential compound for empty-space fumigations.     

Toxicity of propylene oxide at low pressure against life stages of four species of stored product insects

The relative toxicity of propylene oxide (PPO) at a low pressure of 100 mm Hg to four species of stored product insect at 30 degrees C over a 4-h exposure period was investigated. PPO at 100 mm Hg was toxic to all four species tested: Tribolium castaneum (Herbst), Plodia interpunctella (Hübner), Ephestia cautella (Wlk.), and Oryzaephilus surinamensis (L.). There were differences in susceptibility between the life stages of the tested insect species. Mortality tests on all life stages of the insects resulted in LD99 values ranging from 4.7 to 26.1 mg/liter. The pupal stage of E. cautella, O. surinamensis, and T. castaneum was the most tolerant stage with LD99 values of 14.4, 26.1, and 25.7 mg/liter, respectively. For P. interpunctella, the egg stage was most tolerant, with a LD99 value of 15.3 mg/liter. Generally, PPO at 100 mm Hg was more toxic to P. interpunctella and E. cautella than to O. surinamensis and T. castaneum. A 99% mortality of all life stages of the tested species was achieved at a concentrations x time product of 104.4 mg h/liter. These findings indicate that a combination of PPO with low pressure can render the fumigant a potential alternative to methyl bromide for rapid disinfestation of commodities.     

Progeny production by Tribolium castaneum (Coleoptera: Tenebrionidae) and Oryzaephilus surinamensis (Coleoptera: Silvanidae) on maize previously infested by Sitotroga cerealella (Lepidoptera: Gelechiidae)

A laboratory experiment was conducted to quantify the effects of infestation of maize by Sitotroga cerealella (Olivier) on progeny production by two common secondary colonizers of grain, Tribolium castaneum (Herbst) and Oryzaephilus surinamensis (L.). Adults of both secondary pest species were allowed to oviposit for 3 wk on intact kernels of 'DeKalb 689', mechanically split kernels, kernels that had been infested for 3 mo by S. cerealella, and kernels that had been infested for 6 mo. Progeny of both species reached highest numbers on 6-mo infested maize. Prior infestation for 6 mo by S. cerealella makes maize a more suitable medium for reproduction by T. castaneum and O. surinamensis, much more than can be accounted for by mere disruption of kernel integrity resulting from larval feeding. The results highlight the importance of limiting establishment by S. cerealella on maize in storage.     

D.D.T. Impregnation of Sacks for the Protection of Stored Cereals Against Insect Infestation

Cotton flour sacks, jute flour sacks, jute bran sacks and jute grain sacks have been impregnated with 1 and 5 % by weight of D.D.T. Treated and untreated sacks, each containing 1 cwt. of a mixture of grain (5 parts) and weatings (1 part), were exposed to severe infestation by adults of Calandra granaria, Tribolium castaneum, Ptinus tectus, Oryzaephilus surina-mensis and Ephestia elutella . After storage for 15 weeks at a mean temperature of 21.3 C. and a mean relative humidity of 65 %, the numbers of adult insects in each sack were determined by sieving the contents.
The results with Ephestia elutella were inconclusive. The results with the four species of beetles showed that the eventual degree of infestation of the contents of the sacks was dependent upon the closeness of weave and the D.D.T. content of the sacking material. Impregnation of sacking with 1 % of D.D.T. should afford adequate protection against insect infestation to clean bagged goods stored in stowages which are not heavily infested. Impregnation with 5 % of D.D.T. should offer a very high degree of protection at all times and can almost entirely prevent infestation, if the treated material is of sufficiently close weave to afford some mechanical hindrance to penetration by insects.     

RESISTANCE TO GRAIN PROTECTANTS AND PHOSPHINE IN COLEOPTEROUS PESTS OF GRAIN STORED ON FARMS IN NEW SOUTH WALES

Tribolium castaneum (Herbst), T. confusum Jacquelin du Val, Sitophilus oryzae (L.), S. granarius (L.), Oryzaephilus surinamensis (L.) and Rhyzopertha dominica (F.) were collected from farms in grain-growing areas in southern and northern N.S.W. and bioassayed for resistance to the grain protectants malathion, fenitrothion, bioresmethrin, carbaryl, pirimiphos-methyl, chlorpyrifos-methyl and the fumigant phosphine.
Results showed that resistance on farms in N.S.W. is similar to resistance reported elsewhere in Australia's grain handling system during the past decade. The only new resistance of practical significance was detected in O. surinamensis where 50% of populations were resistant to fenitrothion (maximum R.F. 68.4x). Fenitrothion resistance was uncommon or not detected in other species. Pirimiphos-methyl resistance was detected in 70% of O. surinamensis populations (maximum RF 44.2x) and in 1 population of T. castaneum (maximum RF 3.1x). Resistance to chlorpyrifos-methyl was detected in 39% of the O. surinamensis populations (maximum RF 8.4x), the only species tested. Low level phosphine resistance was detected in all species (maximum RF 2.2x). Malathion resistance was detected in all species except S. granarius . Resistance to bioresmethrin and carbaryl was not detected in R. dominica , the only species tested.     

食品级惰性粉对三种储藏物害虫生长发育的影响

应用粉剂药膜法,一种食品级惰性粉——4号粉相应剂量处理赤拟谷盗Tribolium castaneum(Herbst)、烟草甲Lasioderma serricorne(Fabricius)、锯谷盗Oryzaephilus surinamensis(Linnaeus)的卵和1龄幼虫,赤拟谷盗、锯谷盗、烟草甲的卵平均孵化率均在97%以上,处理后卵孵化的1龄幼虫平均死亡率均在96%以上;处理3种害虫的1龄幼虫其平均死亡率均在99%以上。结果表明食品级惰性粉对3种试虫卵的孵化率几乎没有影响,但对其1龄幼虫有较好的防治效果。通过混粮法应用正交试验研究发现,惰性粉剂量和小麦含水量对赤拟谷盗F1代防治效果均有显著影响。当小麦处于安全水分时(含水量12%¹4%),10014%),100¹50 mg/kg 4号粉能有效防治赤拟谷盗F1代。     

Beauveria bassiana infection of eggs of stored-product beetles

Beauveria bassiana (Balsamo) Vuillemin was tested under maximum challenge conditions with an estimated dose of 1.1 × 10⁵ conidia/mm² for its effects on eggs of four of the major beetle pests of stored grain and grain products. When ambient relative humidity (RH) was 92%, hatch of fungus-treated Rhyzopertha dominica (Fabricius) eggs was 13% versus 58% for control eggs, and hatch of treated Tribolium castaneum (Herbst) was 17% versus 51% for controls. There was no fungus effect at RH of 48 and 73%. Fungus treatment of Cryptolestes ferrugineus (Stephens) and Oryzaephilus surinamensis (Linnaeus) eggs had no effect. Sectioned T. castaneum eggs demonstrated that the fungus penetrates and infects them.     

ANNONA SPECIES AS INSECTICIDES

By extraction and precipitation from several solvents the toxic principle present in Annona reticulata and A. squamosa seeds and roots has been concentrated up to one hundred-fold. A preliminary chemical examination of this concentrate is described, leading to the conclusion that the toxicity is due to a glyceride or glycerides of a hydroxylated unsaturated acid or acids of high molecular weight.
These extracts have been examined for contact and stomach poison and ovicidal properties in a variety of media. When used as a contact insecticide against Aphis fabae, Macrosiphoniella sanborni and Macronphum solanifolii , the concentrate exhibited a toxicity of the same order as that of rotenone, but against Oryzaephilus surinamensis the toxicity was considerably less. As a stomach poison the ether extract was both toxic and repellent to Plutella maculipennis larvae, but was neither toxic nor repellent to Diataraxia oleracea larvae. Ovicidal tests against the eggs of Plutella maculipennis and of Ephestia kühniella were inconclusive. The potency of this concentrate is therefore of a limited nature and although of roughly the same order as that of rotenone to certain aphides, it has neither the intensity of effect nor the range of insecticidal action of that compound.     

Microwave radar detection of stored-product insects

A microwave radar system that senses motion was tested for capability to detect hidden insects of different sizes and activity levels in stored products. In initial studies, movements of individual adults or groups of Lasioderma serricorne (F.), Oryzaephilus surinamensis (L.), Attagenus unicolor (Brahm), and Tribolium castaneum (Herbst) were easily detected over distances up to 30 cm in air. Boxes of corn meal mix and flour mix were artificially infested with 5-100 insects to estimate the reliability of detection. The likelihood that a box was infested was rated by the radar system on a quantitative scale. The ratings were significantly correlated with the numbers of infesting insects. The radar system has potential applications in management programs where rapid, nondestructive targeting of incipient insect infestations would be of benefit to the producers and consumers of packaged foods.     

Efficacy of ozone fumigation against the major grain pests in stored wheat

Field experiments were conducted in steel bins containing 13,600 kg of hard red winter wheat, Triiticum aestivum L. One bin was treated with ozone and the second bin served as a control. Stored grain insects were placed in bins for 1-, 2-, 3-, and 4-d exposure periods in sampling tubes to test ozone concentrations of 0, 25, 50, and 70 parts per million by volume (ppmv). Ozone treatments on eggs and larvae of Plodia interpunctella (Hübner) were not effective, but pupae were more susceptible. Sitophilus oryzae (L.) adults were the most susceptible species with 100% mortality reached after 2 d in all ozone treatments. However, some progeny were produced at all concentrations and exposure periods. Tribolium castaneum (Herbst) adults had 100% mortality only after 4 d at 50 or 70 ppmv. No T. castaneum progeny were produced after 2-4 d at 70 ppmv. For Rhyzopertha dominica (F.), Cryptolestes ferrugineus (Stephens), and Oryzaephilus surinamensis (L.), 100% mortality was never achieved and progeny were produced at all ozone concentrations. Laboratory experiments, testing the effectiveness of ozone in controlling psocids, were conducted in two polyvinyl chloride cylinders each containing 55 kg of hard red winter wheat. Ozone treatment at a concentration of 70 ppmv was highly effective against adult female Liposcelis bostrychophila Badonnel and Liposcelis paeta Pearman after only 1 d of exposure. However, it was not effective against eggs of both species at all exposure periods. Ozonation has potential for the control of some stored grain insect pests on wheat.     

Effectiveness of spinosad against seven major stored-grain insects on corn

In January 2005, the United States Environmental Protection Agency registered spinosad as a stored grain protectant. No referenced data on the efficacy of spinosad on corn in suppressing major stored-grain insects have been published. In this paper, we evaluated the efficacy of spinosad against seven major stored-grain insects on shelled corn in the laboratory. Insect species tested were the red flour beetle, Tribolium castaneum （Jacquelin duVal）; rusty grain beetle, Cryptolestesferrugineus （Stephens）; lesser grain borer, Rhyzopertha dominica （F.）; sawtoothed grain beetle, Oryzaephilus surinamensis （L.）; rice weevil, Sitophilus oryzae （L.）; maize weevil, Sitophilus zeamais （Motschulsky）; and Indian meal moth, Plodia interpunctella （Htibner）. Corn kernels were treated with spinosad at 0, 0. 1, 0.5, 1, and 2 active ingredient （a.i.） mg/kg for controlling the seven species. Beetle adults or P. interpunctella eggs were introduced into each container holding 100 g of untreated or insecticide-treated corn. The seven insect species survived well on the control treatment, produced 28 to 336 progeny, and caused significant kernel damage after 49 days. On spinosad-treated corn, adult mortality of C. ferrugineus, R. dominica, 0. surinamensis, S. oryzae, and S. zeamais was 〉 98% at 1 and 2 mg/kg after 12 days. Spinosad at≥ 0.5 mg/kg completely suppressed egg-to-larval survival after 21 days and egg-to-adult emergence of P. interpunctella after 49 days, whereas 16% T. castaneum adults survived at 1 mg/kg after 12 days. Spinosad at 1 or 2 mg/kg provided complete or near complete suppression of progeny production and kernel damage of all species after 49 days. Our results indicate that spinosad at the current labeled rate of 1 mg/kg is effective against the seven stored-grain insect pests on corn.     

Synergized bifenthrin plus chlorpyrifos-methyl for control of beetles and psocids in sorghum in Australia

The efficacy of bifenthrin (0.5 mg/kg) + piperonyl butoxide (7 mg/kg) + chlorpyrifosmethyl (10 mg/kg) against beetle and psocid pests of sorghum was evaluated in silo-scale trials in southeast Queensland, Australia. The pyrethroid bifenthrin was evaluated as a potential new protectant in combination with the organophosphate chlorpyrifos-methyl, which is already registered for control of several insect pests of stored cereals. Sorghum (approximately 200 metric tons) was treated after both the 1999 and 2000 harvests and sampled at intervals to assess treatment efficacy and residue decline during up to 7 mo of storage. Generally, test strains of the beetles Rhyzopertha dominica (F.), Tribolium castaneum (Herbst), Oryzaephilus surinamensis (L), and Cryptolestes ferrugineus (Stephens) were prevented from producing live progeny for up to 7 mo. The treatment failed against one strain of R. dominica known to be resistant to bioresmethrin and organophosphates. Two malathion-resistant strains of O. surinamensis were marginally controlled with 94-100% fewer adult progeny produced. For psocids, no strains of Liposcelis bostrychophila Badonnel, Liposcelis decolor (Pearman), or Liposcelis paeta Pearman produced live progeny, although the control of a field strain of Liposcelis entomophila (Enderlein) was generally poor. Results show that this treatment should protect sorghum for at least 7 mo against most prevalent strains of grain insect in eastern Australia, although control may be limited in areas in which L. entomophila or pyrethroid-resistant R. dominica are present.     

Effectiveness of spinosad on four classes of wheat against five stored-product insects

Spinosad is a commercial reduced-risk pesticide that is naturally derived. Spinosad's performance was evaluated on four classes of wheat (hard red winter, hard red spring, soft red winter, and durum wheats) against adults of the lesser grain borer, Rhyzopertha dominica (F.); rice weevil, Sitophilus oryzae (L.); sawtoothed grain beetle, Oryzaephilus surinamensis (L.); red flour beetle, Tribolium castaneum (Herbst); and larvae of the Indianmeal moth, Plodia interpunctella (Hübner). Beetle adults (25) or P. interpunctella eggs (50) were exposed to untreated wheat and wheat treated with spinosad at 0.1 and 1 mg (AI)/kg of grain. On all untreated wheat classes, adult beetle mortality ranged from 0 to 6%, and P. interpunctella larval mortality ranged from 10 to 19%. The effects of spinosad on R. dominica and P. interpunctella were consistent across all wheat classes. Spinosad killed all exposed R. dominica adults and significantly suppressed progeny production (84-100%) and kernel damage (66-100%) at both rates compared with untreated wheat. Spinosad was extremely effective against P. interpunctella on all wheat classes at 1 mg/kg, based on larval mortality (97.6-99.6%), suppression of egg-to-adult emergence (93-100%), and kernel damage (95-100%), relative to similar effects on untreated wheats. The effects of spinosad on S. oryzae varied among wheat classes and between spinosad rates. Spinosad was effective against S. oryzae, O. surinamensis and T. castaneun only on durum wheat at 1 mg/kg. Our results suggest spinosad to be a potential grain protectant for R. dominica and P. interpunctella management in stored wheat.     

Persistence and efficacy of spinosad residues in farm stored wheat

Degradation and insecticidal effectiveness of spinosad residues were evaluated in Kansas during November 2000 to November 2001 in farm bins holding wheat (34-metric ton capacity). About 50 kg of hard red winter wheat from each of three bins were brought to the laboratory and treated separately with 1-ml aqueous suspensions of spinosad to provide rates of 0.1, 0.5,1, 3, 6 mg (AI)/kg of wheat. Wheat treated with distilled water served as the control treatment. Untreated and spinosad-treated wheat samples (250 g each) were placed in three plastic pouches of two different mesh sizes, and buried 2.5 cm below the grain surface. Pouches with large mesh openings were used to monitor insect infestations and kernel damage in untreated and spinosad-treated samples. Pouches with small mesh were used for extracting spinosad residues and for conducting laboratory bioassays with adults of the lesser grain borer, Rhyzopertha dominica (F.) and red flour beetle, Tribolium castaneum (Herbst) at 28 degrees C and 65% RH. Wheat temperature and relative humidity near the pouches during the 1 yr of storage ranged from -10 to 32 degrees C and 50 to 70%, respectively. Moisture of wheat samples varied from 12.4 to 13%. Observed spinosad residues on wheat samples were 25% less than the calculated rates of 0.1 to 6 mg/kg. However, these residues were stable during the 1 yr of storage, and killed all R. dominica adults exposed for 14 d in the laboratory. Mortality of T. castaneum adults increased with an increase in spinosad rate. The linear regression slope of LD50s (0.3-2.7 mg/kg) against storage time was not significantly different from zero, indicating no loss in spinosad toxicity to T. castaneum adults. Insect species, insect numbers, and kernel damage over time in wheat samples inside pouches with large mesh openings were highly inconsistent, and failed to accurately characterize spinosad performance. Laboratory bioassays with R. dominica and T castaneum adults using grain from pouches with small mesh openings accurately gauged spinosad persistence and insecticidal activity under the field conditions.     

Bioactivities of the leaf essential oil of Curcuma longa (var. ch-66) on three species of stored-product beetles (Coleoptera)

Essential oil extracted from the leaves of turmeric, Curcuma longa L., was investigated for contact and fumigant toxicity and its effect on progeny production in three stored-product beetles, Rhyzopertha dominica F. (lesser grain borer), Sitophilus oryzae L. (rice weevil), and Tribolium castaneum Herbst (red flour beetle). Oviposition-deterrent and ovicidal actions of C. longa leaf oil were also evaluated against T. castaneum. The oil was insecticidal in both contact and fumigant toxicity assays. The adults of R. dominica were highly susceptible to contact action of C. longa leaf oil, with LD50 value of 36.71 microg/mg weight of insect, whereas in the fumigant assay, adults of S. oryzae were highly susceptible with LC50 value of 11.36 mg/liter air. Further, in T. castaneum, the C. longa oil reduced oviposition and egg hatching by 72 and 80%, respectively at the concentration of 5.2 mg/cm2. At the concentration of 40.5 mg/g food, the oil totally suppressed progeny production of all the three test insects. Nutritional indices indicate >81% antifeedant action of the oil against R. dominica, S. oryzae and T castaneum at the highest concentration tested.     

X-linked and autosomal inheritance patterns of homologous genes in two species ofTribolium

The tenebrionid beetles Tribolium castaneum and T. confusum are representative of two distinct species groups within their genus. It has been suggested [Smith, S.G. (1952). J. Morphol. 91:325] that the 8AA + neo-XY karyotype of T. confusum was derived from the ancestral 9AA + XY formula, still present in T. castaneum, via the fusion of one pair of autosomes with the X and Y chromosomes during the early divergence of the confusum and castaneum species groups. In the present paper, electrophoretic variation in malic enzyme and hexokinase-1, detected in laboratory strains in Tribolium, is described. Evidence is presented that the genes encoding variation in both enzymes are autosomal in T. castaneum but are X linked in T. confusum. These species-specific patterns of inheritance of homologous gene loci are consistent with the hypothesized karyotypic history of the genus.     

Toxicity, feeding deterrence, and effect of activity of 1,8-cineole from Artemisia annua on progeny production of Tribolium castanaeum (Coleoptera: Tenebrionidae)

1,8-Cineole isolated from Artemisia annua was tested against Tribolium castaneum (Herbst) for contact toxicity, fumigant toxicity, and antifeedant activity. The adults of T. castaneum were more susceptible than larvae to both contact and fumigant toxicity of 1,8-cineole, and LD50 and LC50 values of 108.4 microg/mg body weight of adult insect and 1.52 mg/liter air were found, respectively. Furthermore, 14-d-old T. castaneum larvae were more tolerant than 16- and 18-d-old larvae and adults to the contact toxicity of 1,8-cineole, but the 16- and 18-d-old larvae have similar susceptibility. In contrast, all the larvae (14-18 d old) of T. castaneum were much more tolerant than the adults to the fumigant action, but larvae of different ages had similar susceptibility. The compound 1,8-ciineole applied to filter paper at a concentration of 3.22-16.10 mg/cm2 significantly (P < 0.05) reduced the hatching of T. castaneum eggs and the subsequent survival rate of the larvae. Adult emergence was also reduced by 1,8-cineole. Feeding deterrence of 81.9% was achieved in T. castateum adults by using a concentration of 121.9 mg/g food, whereas larvae showed 68.8% at the same concentration.     

Bioactivities of methyl allyl disulfide and diallyl trisulfide from essential oil of garlic to two species of stored-product pests, Sitophilus zeamais (Coleoptera: Curculionidae) and Tribolium castaneum (Coleoptera: Tenebrionidae)

Two of the major constituents of the essential oil of garlic, Allium sativum L., methyl allyl disulfide and diallyl trisulfide, were tested against Sitophilus zeamais Motschulsky and Tribolium castaneum (Herbst) for contact toxicity, fumigant toxicity, and antifeedant activity. The contact and fumigant toxicities of diallyl trisulfide were greater than that of methyl allyl disulfide to the adults of these two species of insects. These two compounds were also more toxic to T. castaneum adults than to S. zeamais adults. Older T. castaneum larvae were more susceptible to the contact toxicity of the two compound, whereas younger larvae were more susceptible to the fumigant toxicity of these compounds. Both compounds reduced egg hatching of T. castaneum and subsequent emergence of progeny. Diallyl trisulfide totally suppressed egg hatching at 0.32 mg/cm2, and larval and adult emergence at 0.08 mg/cm2. Methyl allyl disulfide significantly decreased the growth rate, food consumption, and food utilization of adults of both insect species, with feeding deterrence indices of 44% at 6.08 mg/g food for S. zeamais and 1.52 mg/g food for T. castaneum. However, it did not affect any nutritional indices of T. castaneum larvae. Diallyl trisulfide significantly reduced all of the nutritional indices in all of the insects tested. Feeding deterrence indices of 27 and 51% were obtained in S. zeamais adults and T. castaneum larvae, respectively, at the concentration of 2.98 mg/g food, whereas feeding deterrence of 85% was achieved in T. castaneum adults at a much lower concentration of 0.75 mg/g food. Hence, diallyl trisulfide is a more potent contact toxicant, fumigant and feeding deterrent than methyl allyl disulfide.