Stored-product Coleoptera Research Articles

Efficacy of Essential Oils Against Three Stored Product Coleoptera in Wheat Stored in Superbags

This study evaluates the efficacy of essential oils against Sitophilus oryzae (L.), Rhyzopertha dominica L. and Tribolium castaneum Herbst in wheat stored in superbags under laboratory condition. The results reveal that the essential oil of Chenopodium botrys, Citrus reticulata, Lantana camara, and Pinus roxburghii at 0.4% alone or in combination of C. botrys + C. reticulata, C. reticulata + P. roxburghii, L. camara + P. roxburghii, C. botrys + P. roxburghii at 0.2% each completely check the feeding and breeding of these pests. The essential oil of C. botrys, C. reticulata, L. camara, and P. roxburghii at 0.4% either alone or in combination (as above) at 0.2% check the infestation and weight loss, up to twelve months of storage.

Fumigant toxicity of essential oils and their combinations on population buildup of three stored product coleoptera in stored wheat and effect on quality of wheat

Experiments carried out to find the fumigant toxicity of three essential oils and their combinations from Murraya koenigii, Citrus reticulata, Curcuma longa on population buildup of Sitophilus oryzae, Rhyzopertha dominica, Tribolium castaneum in stored wheat at different days of infestation. The oil of M. koenigii, C. reticulata at 0.2% and M. koenigii+C. reticulata, M. koenigii+C. longa at 0.1% each were found highly effective against S. oryzae fumigated after 5, 10, 15 and 20 days. The oil of M. koenigii and C. reticulata at 0.2% M. koenigii+C. reticulata, M. koenigii+C. longa, C. reticulata+C. longa at 0.1% each and M. koenigii+C. reticulata+C. longa at 0.07% each were found highly effective against R. dominica fumigated after 5, 10, 15 and 20 days. Only M. koenigii at 0.2% was found highly effective against T. castaneum fumigated after 5, 10, 15 and 20 day. The fumigation of grain with M. koenigii at 0.2% completely suppress the infestation and weight loss when it was fumigated after 5, 10, 15 and 20 days while very low infestation and weight loss was observed in grain treated with M. koenigii +C. reticulata at 0.1% each and not affect the organoleptic properties and germination of wheat.

VOC emissions influence intra- and interspecific interactions among stored-product Coleoptera in paddy rice

Olfaction is a pivotal sense for insects and granivorous pests may exploit grain volatiles for food selection. Tribolium confusum, is a secondary pest of stored cereals that benefits from primary pests’ infestation, as other secondary feeders, triggering competition. This study aimed to evaluate the preferences of T. confusum females toward different-infested paddy rice, highlighting the impact of intra- and interspecific competition. Tribolium confusum showed positive chemotaxis toward rice infested by larvae of a primary pest (Sitophilus zeamais), but not for grain attacked by adults alone. Furthermore, kernels concurrently infested by a primary (S. zeamais) and a secondary pest (T. confusum or Cryptolestes ferrugineus) were evaluated in Y-tube bioassays, highlighting that both food-sources were innately attractive for T. confusum females. Moreover, females positively oriented toward rice infested by conspecifics, while they avoided grain infested by C. ferrugineus, averting an extremely competitive habitat. Behavioural responses of T. confusum females and volatile emissions of different-infested rice highlighted the occurrence of plant-mediated interactions among insects from the same trophic guild. Seventy volatiles were identified and significant differences among the tested food-sources were recorded, emphasizing the presence of 6 putative attractants and 6 repellents, which may be useful biocontrol tools.

Insecticidal effect of spinetoram against six major stored grain insect species

Spinetoram is a novel insecticide that belongs to the spinosyn class of insecticidal chemicals. The efficacy of spinetoram against numerous insect pest species in a variety of field crops has been well demonstrated. However, there are no data available for the effectiveness of spinetoram against stored grain insects. In the present study, we evaluated spinetoram as a grain protectant, against six stored-product Coleoptera. The species tested were: the rice weevil, Sitophilus oryzae, the lesser grain borer, Rhyzopertha dominica, the larger grain borer, Prostephanus truncatus, the confused flour beetle, Tribolium confusum, the granary weevil, Sitophilus granarius and the sawtoothed grain beetle, Oryzaephilus surinamensis. All species were tested at the adult stage, on wheat (or maize in the case of P. truncatus) treated to achieve spinetoram concentrations of 0.01, 0.1, 0.5, 1, 2, 5 and 10 ppm. Mortality was recorded after 1, 2, 7, 14 and 21 d of exposure, and 65 d later the wheat and maize were examined for offspring emergence. Among the species examined, P. truncatus and R. dominica were by far the most susceptible, given that mortality was close to 100% after 7 d on wheat treated or maize with 0.1 ppm of spinetoram. At this concentration, progeny production of P. truncatus and R. dominica was negligible. On the other hand, T. confusum was the least susceptible; mortality reached 95% only at 10 ppm, and only after 14 d of exposure. Similarly, O. surinamensis was of limited susceptibility to spinetoram; mortality reached 95% only after 14 d of exposure on wheat treated with 5 ppm. Nevertheless, offspring emergence of these species was extremely low. For S. granarius and S. oryzae, complete (100%) mortality was recorded after 14 d of exposure, at 0.5 and 1 ppm, respectively. At these concentrations or higher, progeny production was notably reduced. The results of the present study demonstrate that spinetoram is effective as a grain protectant, but its efficacy varies according to the target species, concentration and exposure interval.

Field infestation of Faidherbia (Acacia) albida (Del.) A. Chew. pods by stored product Coleoptera in the Nigerian savanna and effect of infestation on nutrient quality

A 6-month survey of the insect pest complex infesting the pods of the leguminous tree,Faidherbia (Acacia) albida, as well as their natural enemies, was conducted in Maiduguri located in the Sudan savanna and in Magumeri located in the Sahel savanna areas of north-eastern Nigeria, from January to June, 1999. The effect of infestation on the nutrient quality of the pods which are used as animal feed by livestock farmers was also evaluated. A total of 791 adult pest beetles, all belonging to the families Bruchidae and Tenebrionidae, were collected during the study. Of these,Bruchidius atrolineatus (55·1%), Acanthoscelides obtectus (29·2%) and Caryedon serratus (7·8%) belonging to the family Bruchidae, together, were the more dominant species. Tribolium castaneum (7·8%) was the only representative of the family Tenebrionidae. The proportion of the pods collected from the Sudan savanna (Maiduguri) that were infested with beetles (91·6%) was significantly higher than that collected from the Sahel savanna (Magumeri)(85·9%). Of the 87 adult parasitic wasps collected during the study,Hyposoter sp. belonging to the family Ichneumonidae was the most dominant (67·8%), and the family Braconidae comprising Bracon hebetor (17·24%) and Iphiaulax sp. (14·94%) constituted 32·2% of the total number of parasitic wasps. The parasitoids were unable to keep the populations of the pest beetles in check. Results of the proximate analysis showed that the crude protein, ether extract and crude fibre decreased significantly (p<0·05) with increasing severity of infestation while the nitrogen-free extract increased with increasing severity of infestation. The ash content was significantly higher in the heavily infested pods than in the moderately/mildly infested pods or in the uninfested pods. To enhance the utilization of acacia pods for livestock feeding during the dry season, it is concluded that more studies are needed to develop effective ways of protecting pods in the field and preserving them in storage against infestation by pest beetles.

A survey of beetles in store-rooms containing barley and maize for animal feed, on the Island of Lefkas, Greece: Abundance and population fluctuation of the most significant species

During an 18-month survey on stored barley and maize intended for animal feed conducted in store-rooms on the island of Lefkas, Greece, 21 different taxa of stored product Coleoptera belonging to 12 families were represented in a total of 6027 individuals. The most abundant species were Sitophilus oryzae (L.) and S. granarius (L.). The abundance of each taxon in both products is presented, while their presence in different parts of the stores is commented upon. Finally, the population fluctuations of the 5 most numerically significant taxa are described.

The efficacy of linalool, a major component of freshly-milled Ocimum canum Sims (Lamiaceae), for protection against postharvest damage by certain stored product Coleoptera

Linalool was present at 8.6 ± 0.9 mg/g in the dried leaves of Ocimum canum Sims, an annual mint used in Rwanda to protect against postharvest insect damage. Direct exposure of adults of Zabrotes subfasciatus (Bohem.) to milled, dried O. canum leaves resulted in 100% mortality of males and 50% mortality of females after 48 hr. Dose-response curves for linalool were completed with adult Z. subfasciatus, Acanthoscelides obtectus (Say), Rhyzopertha dominica (F.), and Sitophilus oryzae (L.) using a filter paper bioassay. The LC 50 values were: 428 μg/cm 2 for Z. subfasciatus; 405 μg/cm 2 for A. obtectus; 428 μg/cm 2 for R. dominica; 427 μg/cm 2 for S. oryzae. Knockdown was occasionally followed by recovery at doses less than the LC 50 for all species. There are significant differences in the LC 50 and LT 50 values for male and female Z. subfasciatus. At the lower dosages hyperactivity rarely preceded moribundity and mortality where these occurred, while at higher dosages hyperactivity occurred soon after initial exposure and preceded imminent death. A concentration increase from 250 to 750 μg/cm 2, representing a tripling of dosage, spanned th 10–100% response mortality for all species at 24 hr. Air-exposure of linalool-treated papers (500 μg/cm 2) for up to 24 hr significantly decreased toxicity to both sexes of Z. subfasciatus. Quantitative analysis showed the only significant decrease in the amount of linalool to occur after 0.25 hr, and this did not fully correlate with the resulting decrease in efficacy against both sexes of Z. subfasciatus. The results are discussed in terms of the efficacy of using O. canum for the protection against loss due to insects in the traditional food storage systems of Rwanda.

Stored product Coleoptera in New Zealand

The records of 106 species of stored-product infesting Coleoptera from 8 New Zealand collections and recent literature have been compiled into 3 lists: a list of pest records, a product/pest list, and a plant/pest list. There are 50 species listed as intercepted, 45 as established, and the status of 11 is in doubt. Based on data from these records the distribution within New Zealand of each of the established species is detailed.

Variation in tolerance of seven species of stored product Coleoptera to methyl bromide and phosphine in strains from twenty-nine countries

AbstractThe toxicities at 25°C and 70% RH of methyl bromide at about 4 mg/litre and phosphine at about 0·24 mg/litre were determined for large populations, including all developmental stages, of a number of strains of seven species of stored product beetles from 29 countries for a range of exposure periods. The species tested were Oryzaephilus surmamensis (L.), Rhyzopertha dominica (F.), Sitophilus granarius (L.), S. oryzae (L.), S. zeamais Motsch., Tribolium castaneum (Hbst.) and T. confusum Duv. With both fumigants, some individuals of certain strains of S. oryzae and T. castaneum survived a concentration × time product twice that sufficient to kill every individual of other strains of these species, and this was also true for R. dominica with methyl bromide and T. confusum with phosphine. With methyl bromide, some individuals of six species survived the longest exposure used. For the two species of Tribolium, this was 48 h, and for the three of Sitophilus and R. dominica it was 32 h. With phosphine, individuals in many strains of S. granarius, S. oryzae and S. zeamais survived for 8 days. In several of the species, there was some correlation between the tolerances of immature stages and of adults for both fumigants. Many strains were tolerant to both fumigants.

Radiosensitivity of the Slenderhorned Flour Beetle, Gnathocerus maxillosus (Coleoptera: Tenebrionidae)

Ten krad of gamma irradiation to eggs and larvae of the slenderhorned flour beetle, Gnathocerus maxillosus (F.), prevented development of adults. Exposure of pupae to 5-100 krad allowed some emergence, but longevity was greatly reduced except at 5 krad. The dose required to sterilize adults was about the same as that for other species of stored-product tenebrionids: 20 krad was sterilizing to both sexes, and fecundity was greatly reduced by lesser amounts. Also, adult longevity was significantly reduced since none survived 3 weeks after exposure to 10 krad. Adults and pupae of G. maxillosus would require the same dose of irradiation for effective control as would most other stored-product Coleoptera.

Depressed Flour Beetle: Sensitivity to Gamma Irradiation1

Ten krad of gamma irradiation to eggs and larvae of Palorus subdepressus (Wollaston) prevented the development of adults. Exposure of pupae to 5, 10, 20, 30, or 50 krad (but not 100) allowed some emergence, but longevity was greatly reduced. Adults were resistant to sterilizing effects of the radiation compared with other species of stored-product beetles: 30 krad was not completely sterilizing to either males or females, but the dose did greatly reduce fecundity, and longevity was significantly reduced: none survived for 3 weeks after a 20-krad exposure. Adults and pupae of this species would require higher doses of irradiation for effective control than would most other stored-product Coleoptera. (auth)

GAMMA RADIATION SENSITIVITY OF THE SPIDER BEETLE, GIBBIUM PSYLLOIDES (COLEOPTERA: PTINIDAE)

AbstractThe effects of seven gamma radiation dosages from 5 to 100 krad on all metamorphic stages of the spider beetle, Gibbium psylloides (Czenpinski), were studied. Five kilorads prevented development of adults from treated eggs and larvae. Some adults emerged from the pupal cocoon at all treatment levels except 50 and 100 krad, but their longevity was greatly reduced. Adults were fairly resistant to sterilizing effects of the radiation. Twenty kilokrads was not completely sterilizing to either males or females, but fecundity was greatly reduced. The longevity of treated adults was significantly reduced, but some survived for 20 weeks after a 20-krad exposure. Adults and pupae of this species were more radiation resistant than were most other stored-product Coleoptera.

Some mutants of stored product Coleoptera

Some mutants of stored product Coleoptera