Zeamais Adults Research Articles

Efficacy of Piper guineense (Schum & Thonn) seed extract against maize weevil, Sitophilus zeamais (Motschulsky) as influenced by different extraction solvents

The seed extract of black pepper Piper guineense Schum & Thonn was evaluated for its biological activity against the maize weevil Sitophilus zeamais Motschulsky at 30°C, 65 ± 2% R.H and 12:12-h light:dark regimes in the laboratory. The different solvents used for the extraction were acetone, ethanol, n-hexane, petroleum ether (60:80) and distilled water at 0.3% dosage level. The acetone extract had the highest toxicity (100%), while the control showed no toxicity at 28 days post treatment. All of the treatments significantly reduced adult emergence and grain damage compared with the control. Grain germination with the solvents was significantly higher than with the aqueous extract (49%), which was significantly superior to the control (39%). Piper guineense extract with the different organic solvents caused acute mortality in S. zeamais adults.

Penetration of Sitophilus zeamais (Coleoptera: Curculionidae) through diatomaceous earth-treated bulk maize grain

The penetration of adult Sitophilus zeamais Motschulsky through maize grain bulks (0.75m deep), treated with Protect-Itw, a diatomaceous earth (DE) at 0, 0.05, 0.1 and 0.2% (w/w), was determined 12 weeks after weevils were released at the upper surface of the grain. Maize was stored in columns in polyvinyl chloride (PVC) pipes, under controlled conditions of 26 ^ 28C and 70 ^ 10% RH. Grain samples were collected from various pre-determined depths and the numbers of S. zeamais adults counted. Differences in insect numbers between treatments and at different depths from which samples were collected were highly significant (P , 0.001). The bottom 2–3 layers (0.65–0.75m deep)had significantly more insects than the upper layers for all the DE concentrations. No significant differences in total insect numbers (live þ dead) were found between the DE concentrations. Dead S. zeamais weevils were found at the bottom of grain treated with Protect-Itw, indicating that insects can penetrate through DE-treated grain 0.75m deep but then subsequently die. There was no strong evidence that DEs admixed with bulk grain restrict S. zeamais movement within the grain

Bioatividade da erva-de-santa-maria, Chenopodium ambrosioides L., sobre Sitophilus zeamais Mots. (Coleoptera: Curculionidae)

Este trabalho teve como objetivo avaliar a influencia do po e do extrato aquoso de Chenopodium ambrosioides L. sobre o comportamento e a sobrevivencia do gorgulho-do-milho, Sitophilus zeamais Mots. As plantas de C. ambrosioides foram cultivadas na area experimental do Departamento de Entomologia, Fitopatologia e Zoologia Agricola da ESALQ/USP. Foram obtidos pos de folhas, ramos, frutos e da planta inteira (com frutos), quando a planta estava no estagio de frutificacao. Os insetos utilizados nos ensaios foram obtidos de criacao mantida em graos de trigo. Foi avaliado o efeito do po das diferentes estruturas vegetais e da planta inteira (com frutos) sobre o comportamento (atratividade e/ou repelencia) e atividade inseticida nos adultos. Foi avaliado tambem o potencial inseticida do extrato aquoso das diferentes estruturas e da planta inteira (com frutos) sobre as fases imatura e adulta de S. zeamais. Os resultados obtidos foram: a) pos de frutos, ramos e folhas de C. ambrosioides nao apresentaram repelencia para adultos de S. zeamais; b) os pos de frutos e da planta inteira (com frutos) apresentaram atividade inseticida sobre adultos de S. zeamais; c) os extratos aquosos dessas estruturas vegetais nao afetaram a sobrevivencia e a emergencia de adultos de S. zeamais.

Effect of Volatile Constituents from Securidaca Longepedunculata on Insect pests Of Stored Grain

Securidaca longepedunculata Fers (Polygalaceae) is commonly used as a traditional medicine in many parts of Africa as well as against a number of invertebrate pests, including insects infesting stored grain. The present study showed that S. longepedunculata root powder, its methanol extract, and the main volatile component, methyl salicylate, exhibit repellent and toxic properties to Sitophilus zeamais adults. Adult S. zeamais that were given a choice between untreated maize and maize treated with root powder, extract, or synthetic methyl salicylate in a four-way choice olfactometer significantly preferred the control maize. Methyl salicylate vapor also had a dose-dependant fumigant effect against S. zeamais, Rhyzopertha dominica, and Prostephanus truncates, with a LD100 achieved with a 60microl dose in a 1-l container against all three insect species after 24 hr of exposure. Probit analyses estimated LD50 values between 34 and 36 microl (95% CI) for all insect species. Furthermore, prolonged exposure for 6 days showed that lower amounts (30 microl) of methyl salicylate vapor were able to induce 100% adult mortality of the three insect species. The implications are discussed in the context of improving stored product pest control by small-scale subsistence farmers in Africa.

Comparison of Toxic and Repellent Effects of Lantana Camara L. with Tephrosia Vogelii Hook and a Synthetic Pesticide Against Sitophilus Zeamais Motschulsky (Coleoptera: Curculionidae) in Stored Maize Grain

The insecticidal and repellent properties of Lantana camara and Tephrosia vogelii were evaluated against Sitophilus zeamais Motschulsky (Coleoptera: Curculionidae) in stored maize grain. Five treatment rates (1.0, 2.5,5.0,7.5 and 10.0% w/w) of each powdered plant material, an untreated control and a synthetic insecticide (Actellic Super™ 2% dust) were used to investigate treatment efficacy on mortality of the adult insect (five to eight days old), F1 progeny emergence and repellency against S. zeamais adults. After 21 days, L. camara and T. vogelii caused 82.7–90.0% and 85.0–93.7% insect mortality, respectively. The mean lethal exposure times (LT50) to achieve 50% mortality varied from five to six days (7.5–10.0% w/w) to seven to eight days (2.5–5.0% w/w) for both plants. Probit regression analysis showed a significant relationship between plant powder concentration and insect mortality. The plant powders and synthetic insecticide reduced adult F1 insects by more than 75% compared to the untreated control. Tephrosia vogelii was most repellent to S. zeamais at 7.5–10.0% (w/ w), repelling 87.5% of the insects, followed by T. vogelii at 2.5% w/w and L. camara at 10% w/w which repelled 65.0 and 62.5% of insects respectively. The implications of these results are discussed in the context of smallscale farmer usage of these plants for stored product protection.

Feeding deterrents from Dictamnus dasycarpus Turcz against two stored-product insects.

The screening for insecticidal principles from several Chinese medicinal herbs showed that the root bark of Dictamnus dasycarpus possessed significant feeding deterrence against two stored-product insects (Tribolium castaneum and Sitophilus zeamais). From the methanol extract, two feeding deterrents were isolated by bioassay-guided fractionation. The compounds were identified as fraxinellone and dictamnine from their spectroscopic data. Fraxinellone was demonstrated to possess feeding deterrent activity against adults and larvae of T. castaneum as well as S. zeamais adults with EC50 values of 36.4, 29.1, and 71.2 ppm, respectively. Dictamnine was shown to have feeding deterrent activity against adults and larvae of T. castaneum as well as S. zeamais adults with EC50 values of 57.6, 47.9, and 91.7 ppm, respectively.

Insecticidal properties of eugenol, isoeugenol and methyleugenol and their effects on nutrition of Sitophilus zeamais Motsch. (Coleoptera: Curculionidae) and Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae)

Eugenol, isoeugenol and methyleugenol showed similar contact toxicity to Sitophilus zeamais (LD50 values approximately 30 μg/mg insect). For Tribolium castaneum, the order of potency of these chemicals compared by the LD50 level was isoeugenol>eugenol>methyleugenol. Furthermore, S. zeamais was generally more susceptible than T. castaneum to these three compounds except for isoeugenol based on the LD50 level. When sublethal doses (doses that produce no appreciable mortality) of eugenol, isoeugenol and methyleugenol were topically applied to adults of either species of beetles pre-treated with deltamethrin, the toxicity of deltamethrin was enhanced. A flour disc bioassay using no-choice tests was employed to assess, in terms of food consumption and growth rate, the susceptibility of S. zeamais and T. castaneum to media treated with eugenol, isoeugenol, and methyleugenol. Only eugenol significantly (P<0.05) reduced food consumption (RCR) in the adults of S. zeamais at a concentration of 13.2 mg/g food. However, it reduced the growth rate (RGR), food consumption and food utilisation (ECI) in adults and larvae of T. castaneum at concentrations of 35 and 99 mg/g food, respectively. Isoeugenol reduced the RGR and RCR in S. zeamais adults and T. castaneum adults and larvae, in a concentration-dependent manner, but only reduced ECI in the adults of T. castaneum at the concentration of 76 mg/g food. In comparison, methyleugenol reduced the RGR and RCR in the three groups of insects, and the ECI of S. zeamais adults and T. castaneum larvae.

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.

Bioactivities of essential oil from Elletaria cardamomum (L.) Maton. to Sitophilus zeamais Motschulsky and : Tribolium castaneum (Herbst)

Contact and fumigant toxicities and antifeedant activity of the essential oil of cardamom, Elletaria cardamomum, to two stored-product insects, Sitophilus zeamais and Tribolium castaneum, were investigated. Topical application was employed for contact toxicity studies, and filter paper impregnation was used for testing fumigant action. The adults of S. zeamais and T. castaneum were equally susceptible to the contact toxicity of the oil at the LD 50 level, with LD 50 values of 56 and 52 μg mg −1 insect respectively. However, S. zeamais was more susceptible than T. castaneum at the LD 95 level. For fumigant toxicity, S. zeamais adults were more than twice as susceptible as T. castaneum adults at both LD 50 and LD 95 levels. Furthermore, 12-day larvae of T. castaneum were more tolerant than the adults to the contact toxicity of the oil, but 14- and 16-day larvae had the same susceptibility as the adults. The susceptibility of the larvae to contact toxicity increased with age. In contrast, all the larvae (12–16 days old) of T. castaneum were much more tolerant than the adults to the fumigant action, and larvae of different ages had similar susceptibility. Cardamom oil applied to filter papers in the concentration range 1.04–2.34 mg cm −2 significantly ( P<0.05) reduced the hatching of T. castaneum eggs and the subsequent survival rate of the larvae. Adult emergence was also drastically reduced by cardamom oil. When applied to rice or wheat, the oil totally suppressed F1 progeny production of both insects at a concentration of 5.3×10 3 ppm. Feeding deterrence studies showed that cardamom oil did not have any growth inhibitory or feeding deterrence effects on either adults or larvae of T. castaneum. However, it significantly reduced all the nutritional indices of the adults of S. zeamais, but with very slight feeding deterrence (27%) at a concentration of 1.44×10 4 ppm.

Bioactivity of the essential oil extracted from Evodia rutaecarpa Hook f. et Thomas against the grain storage insects, Sitophilus zeamais Motsch. and Tribolium castaneum (Herbst)

The toxic, repellent and feeding deterrent activities of the essential oil extracted from Evodia rutaecarpa Hook f. et Thomas, were evaluated against Sitophilus zeamais adults and Tribolium castaneum larvae and adults. Contact toxicity assayed by topical application showed that S. zeamais adults were significantly more susceptible (LD 50=0.043 μg/mg body wt) to the essential oil than T. castaneum adults (LD 50=0.118 μg/mg body wt) and larvae (LD 50=0.093–0.126 μg/mg body wt). However, in the fumigation assays, S. zeamais (LC 50=41 μg/L air) was less susceptible to the essential oil than T. castaneum (LC 50=11.7 μg/L air). When compared with larvae of various ages, T. castaneum adults were more susceptible to the fumigant toxicity of the essential oil. Also, in the treated filter paper repellency test, the essential oil was more repellent to T. castaneum than to S. zeamais. A flour disk bioassay demonstrated that the essential oil of E. rutaecarpa had a weaker feeding deterrent action against T. castaneum adults than against T. castaneum larvae and S. zeamais adults. The reduction in growth rate of T. castaneum larvae and S. zeamais adults was mainly due to a behavioural (feeding deterrent) action rather than to post-ingestive toxicity of the oil.

Bioactivities of Safrole and Isosafrole on Sitophilus zeamais(Coleoptera: Curculionidae) and Tribolium castaneum(Coleoptera: Tenebrionidae)

Sitophilus zeamais Motschulsky and Tribolium castaneum (Herbst) adults were equally susceptible to contact toxicity of either safrole or isosafrole. Safrole also possessed equal fumigant toxicity to adults of both species. However, adults of S. zeamais were twice as tolerant as T. castaneum to the fumigant toxicity of isosafrole. In both contact and fumigant tests, 12- and 14-d-old larvae of T. castaneum showed similar susceptibility to each of the compounds, but 16-d-old larvae became more tolerant than the younger larvae. Isosafrole was generally more toxic than safrole to the insects tested. In flour disk bioassays, safrole showed very slight feeding deterrence against S. zeamais adults, and it had no feeding deterrence against T. castaneum adults and larvae. In contrast, isosafrole was a more effective feeding deterrent than safrole, with feeding deterrence indices of 31% for S. zeamais adults at 5.4 mg/g of food, and 72 and 40% for T. castaneum adults and larvae, respectively, at 10.8 mg/g of food. It reduced relative growth rate, relative consumption rate, and efficiency of conversion of ingested food of adults of both species, but only relative growth rate and relative consumption rate of T. castaneum larvae. Isosafrole was a stronger feeding deterrent against S. zeamais than against T. castaneum. Both of the compounds showed inhibitory effects on -amylase activity from T. castaneum larvae in vitro. Safrole also inhibited the larval -amylase in vivo. However, isosafrole inhibited -amylase activity at the lower concentration but activated it at the higher concentration in vivo.

Toxic and Antifeedant Effects of Allyl Disulfide on Tribolium castaneum (Coleoptera: Tenebrionidae) and Sitophilus zeamais (Coleoptera: Curculionidae)

Toxicity and antifeedant activity of allyl disulfide, a volatile compound from garlic, Allium sativum L., to adults and larvae of Tribolium castaneum (Herbst) and adults of Sitophilus zeamais Motschulsky were investigated. Topical application was used for contact toxicity, filter paper impregnation for fumigant toxicity, and a flour disk bioassay for antifeedant activity. The filter paper impregnation bioassay also was used to study the effects on egg hatch and the subsequent progeny emergence of T. castaneum. Adult T. castaneum were more susceptible to allyl disulfide than adult S. zeamais in both toxicity tests. Allyl disulfide was 3 times more potent to T. castaneum adults than to S. zeamais in contact toxicity tests, with LD50s of 7.16 and 22.47 μg/mg insect, respectively. In the fumigant bioassay, allyl disulfide was ≈5 times more effective to the adults of T. castaneum than to S. zeamais, with LC50 values of 0.030 and 0.146 μmg/cm2, respectively. The larvae of T. castaneum were more tolerant of allyl disulfide treatment than the adults in both toxicity tests. Egg hatching and subsequent progeny emergence from treated eggs were reduced with increasing concentrations. Allyl disulfide was a more potent antifeedant to T. castaneum adults than either T. castaneum larvae or S. zeamais adults. A concentration of 7.43 mg/g of food deterred feeding by 85.7% among the T. castaneum adults, but feeding was deterred only by 31.5% at 12.77 mg/g of food and 21.2% at 29.15 mg/g of food for T. castaneum larvae and S. zeamais adults, respectively.

Toxicity and antifeedant activities of cinnamaldehyde against the grain storage insects, Tribolium castaneum (Herbst) and Sitophilus zeamais Motsch.

A methylene chloride extract of the spice, cinnamon, Cinnamomum aromaticum Nees, was shown to be insecticidal to Tribolium castaneum (Herbst) and Sitophilus zeamais Motsch. The contact, fumigant and antifeedant effects of cinnamaldehyde were tested against T. castaneum adults and larvae and S. zeamais adults. T. castaneum and S. zeamais adults showed similar susceptibility to the contact toxicity of cinnamaldehyde, both having an LC 50 of 0.7 mg cm −2 and an LC 95 of 0.9 mg cm −2. However, cinnamaldehyde had a higher level of fumigant toxicity to T. castaneum than to S. zeamais, with LC 50 values of 0.28 and 0.54 mg cm −2, respectively, and LC 95 values of 0.32 and 1.78 mg cm −2, respectively. T. castaneum adults were more susceptible than larvae to the contact and fumigant actions of cinnamaldehyde. The larvae became less susceptible to both contact and fumigant toxicity of cinnamaldehyde with age. A flour disk bioassay using no-choice tests was employed to study the antifeedant activity of cinnamaldehyde against the insects and effects on consumption and utilisation of food by the insects. Cinnamaldehyde had no significant ( P > 0.05) effects on diet consumption and growth of T. castaneum adults and had no antifeedant action against them at concentrations of up to 13.6 mg g −1 food. However, this compound significantly ( P < 0.05) reduced food consumption, growth and dietary utilisation in T. castaneum larvae, and had obvious antifeedant action against the larvae at concentrations of 27.2 and 54.4 mg g −1 food. For S. zeamais adults, it only significantly ( P < 0.05) reduced food consumption at a concentration range of 6.8 to 13.6 mg g −1 food, but had no significant ( P > 0.05) effects on the insects' growth and food utilisation. Antifeedant action was observed to increase with increasing cinnamaldehyde concentrations. The combined contact, fumigant and antifeedant properties of cinnamaldehyde make it a potentially useful grain protectant.

Toxic and antifeedant action of nutmeg oil against Tribolium castaneum (Herbst) and Sitophilus zeamais Motsch

The essential oil extracted from nutmeg seeds using steam distillation was tested against the stored product insect pests, Tribolium castaneum (Herbst) and Sitophilus zeamais Motsch., for contact toxicity, fumigant toxicity and antifeedant activity. Filter paper impregnation was employed for contact and fumigant toxicity studies, whereas a flour disc bioassay was used to investigate antifeedant effects. Adults of S. zeamais were about ten times more susceptible than T. castaneum adults to contact action (LC 50 values of 1.7 mg/cm 2 and 18 mg/cm 2 respectively). However, S. zeamais adults were only 1.7 times more susceptible than T. castaneum adults to fumigant action (LC 50 values of 4.5 mg/cm 2 and 7.7 mg/cm 2 respectively). Furthermore, the larvae (10–16 days old) of T. castaneum were more susceptible than the adults, but the susceptibility of the larvae decreased with age. Nutmeg oil also significantly ( P < 0.05) affected the hatching of T. castaneum eggs and the subsequent survival of the larvae in the concentration range 1.4–3.2 mg/cm 2. The production of F1 progeny of both T. castaneum and S. zeamais exposed to media treated with nutmeg oil was significantly ( P < 0.05) reduced at all concentrations tested. F1 progeny production was totally suppressed at nutmeg oil concentrations of 1.05 g/100 g rice for T. castaneum and 0.35 g/100 g wheat for S. zeamais. Nutritional studies showed that nutmeg oil significantly ( P < 0.05) affected the growth rate and food consumption of both insect species, depending on the concentrations used, but the antifeedant activity was more pronounced against S. zeamaisthan against T. castaneum. At 20 g nutmeg oil/100 ml, the feeding deterrence index of T. castaneum was only about 7%, whereas that of S. zeamaiswas 33%. These results suggest that nutmeg oil may be useful as a grain protectant with contact, fumigant and antifeedant activities against these insects.

The oil of garlic, Allium sativum L. (Amaryllidaceae), as a potential grain protectant against Tribolium castaneum (Herbst) and Sitophilus zeamais Motsch

Fresh garlic cloves were steam-distilled to obtain the essential oil. The garlic oil was tested for toxicity against the eggs, larvae and adults of Tribolium castaneum and adults of Sitophilus zeamais. T. castaneum egg mortality increased with garlic oil concentration, complete kill of eggs being achieved at 4.4 mg/cm2, using the filter paper impregnation bioassay. The eggs were the most susceptible stage, followed by adults, 10-day old larvae and older larvae. T. castaneum adults were more susceptible to garlic oil than S. zeamais adults, with KD50 values of 1.32 mg/cm2 and 7.65 mg/cm2, respectively. When rice and wheat were treated with garlic oil, eggs that were laid in the media failed to produce F1 progeny at concentrations of > 2000 ppm in rice for T. castaneum and 5000 ppm in wheat for S. zeamais. The weights of F1 adults of T. castaneum and S. zeamais in treated media were not significantly different (P > 0.05) from those of the controls. The potential of garlic oil, and the bioactive compounds therein, as an effective grain protectant is discussed.

Star anise, Illicium verum Hook f. as a potential grain protectant against Tribolium castaneum (Herbst) and Sitophilus zeamais Motsch

Abstract Dried fruits of star anise, Illicium verum, were extracted with hexane and methanol to obtain non-polar and polar fractions, respectively. The insecticidal activity of non-polar crude extracts was tested against eggs, larvae and adults of Tribolium castaneum and adult Sitophilus zeamais. T. castaneum eggs were all killed at 0.01 g ml−1 extract. The adults were more susceptible than the larvae, and younger larvae more susceptible than older ones. S. zeamais adults were twice as tolerant to the non-polar extract as T. castaneum adults. High mortality (70%) of T. castaneum adults occurred in rice treated with the non-polar extract after 21 days' exposure. The effects of polar extracts on the two species of insects were not significant. Adults were allowed to lay eggs in extract-treated rice medium for two days and were then removed. F1 progeny production was monitored. Non-polar extracts completely suppressed F1 adult emergence in both species, while polar extracts only caused a significant reduction in F1 adult emergence. The potential of non-polar star anise extracts as a grain protectant, particularly as an ovicide, is discussed.

Potential of cloves (Syzygium aromaticum (L.) Merr. and Perry as a grain protectant against Tribolium castaneum (Herbst) and Sitophilus zeamais Motsch

The flower buds of cloves were extracted with methanol or hexane. The methanol (polar) extracts were tested against Tribolium castaneum and Sitophilus zeamais adults via topical application. The hexane (non-polar) extracts were tested against the two insect species by filter paper impregnation. No contact toxicity of polar extracts was observed for either insect species. However, 100 g/100 ml [100% (w/v)] non-polar extracts caused 90% mortality in S. zeamais but had no effect on T. castaneum. Both polar and non-polar clove extracts were applied to milled rice which was then exposed to the two species of beetles separately in treated medium tests. The polar fractions had no effect on the mortality of both species of insects. However, with the non-polar extracts, mortalities of 13% and 44% in T. castaneum were obtained after 7-day and 21-day exposure periods respectively. For S. zeamais mortalities of 43% and 53% were observed after 7 and 21 days of exposure respectively to rice treated with the non-polar extracts. After removal of the treated adults of both species at the end of the 7-day exposure period, the emergence of the F1 progeny was monitored. No progeny of T. castaneum emerged from the rice treated with non-polar extracts while extremely low emergence of S. zeamais was observed.