F1 Adult Emergence Research Articles

INVESTIGATION OF COMBINED EFFECT OF THREE PLANT POWDERS WITH DIATOMACEOUS EARTH AGAINST CALLOSOBRUCHUS MACULATUS

The study was conducted to investigate the combined effects of various plant powders and Silico-sec, a diatomaceous earth, on Callosobruchus maculatus at the research laboratory of the Department of Crop Pest and Soil Management, the Federal University of Technology, Akure. The study included three replications. The treatments consisted of three (3) plant materials derived from the dry flower buds of Eugenia aromatica, seeds of Piper guineense, and leaves of Nicotiana tabacum and their combination with Silico-sec. In one experiment, 0.4g of each plant material was added to 20 C. maculatus adults (10 couples, aged 1-2 days) in 20g of Ife Brown cowpea seeds, all contained within an air-tight plastic container. Another experiment involved the addition of 0.4g mixtures of Silico-sec and each plant powder (E. aromatica, P. guineense, and N. tabacum) in various ratios (1:5, 5:1, 1:10, 10:1, and 1:1) to the same number of C. maculatus adults in 20g of cowpea seeds, also in separate air-tight plastic containers. All the treatments and their combination were laid out in a completely randomized design (CRD) repeated three times. Data were collected at 12, 24, and 48 at p,0hours post-treatment. Oviposition, adult emergence, and seed weight loss were evaluated. The results demonstrated that both the plant powders and Silico-sec were effective in controlling C. maculatus infestation on cowpea by causing significant adult mortality at p< 0.05, reducing oviposition, suppressing F1 adult emergence, and minimizing seed damage. Among single applications, Silico-sec and E. aromatica powder provided the best protection for stored cowpea, yielding the highest adult mortality, lowest oviposition, most suppressed F1 adult emergence, and minimal seed damage. However, the mixture of Silico-sec and P. guineense at ratios of 5:1 and 10:1 offered the best protection, exhibiting significantly higher mortality, lower oviposition rates, suppressed F1 adult emergence, and reduced seed damage compared to other treatments. This study suggests that combination of P. guineense and Silico-sec is particularly effective in controlling cowpea storage pests and could serve as a viable alternative to synthetic insecticides for protecting stored cowpea against C. maculatus.

Microcapsules of mesoporous silica and cyclodextrin modified loaded with nonanal and decanal for effective control of Sitotroga cerealella in grain storage environments.

The Angoumois grain moth, Sitotroga cerealella, is a destructive pest of maize, wheat, and rice, causing economic losses and threatening food security. This study aimed to develop and characterize microcapsules of mesoporous silica nanospheres (MSN) and cyclodextrin-modified mesoporous silica nanospheres (CDMSN) containing two aldehydes, nonanal and decanal, found in plant essential oils, to assess their attractiveness to S. cerealella populations. Microcapsules with 2:1 ratio of nonanal and decanal exhibited an average encapsulation efficiency of 39.82% for MSN loaded with nonanal and decanal (MSN-ND) and 46.10% for CDMSN loaded with nonanal and decanal (CDMSN-ND). They have an elliptical shape with particle sizes of 115 nm for MSN and 175 nm for CDMSN. Gas chromatography-mass spectrometry analysis revealed in vitro release of nonanal in MSN at 96.24% and decanal at 96.42% by the 36th day. CDMSN showed releases of 93.83% for nonanal and 93.74% for decanal by the 50th day. CDMSN-ND attracted adult S. cerealella for 43 days, while MSN-ND remained effective for 29 days. In mass trapping assays in simulated grain warehouse, both MSN-ND and CDMSN-ND trapped over 50% of the adult population within 7 days, significantly reducing grain infestation rates below 10% by inhibiting F1 adult emergence. At temperatures ranging from 20 °C to 35 °C, both microcapsules exhibited significant and effective attraction rates for S. cerealella. Stored wheat seeds treated with CDMSN and CDMSN-ND over 1 year showed no significant differences in key germination parameters. Microencapsulated nonanal and decanal offer a promising, sustainable approach for controlling S. cerealella infestation in stored grains, contributing to global food security. © 2024 Society of Chemical Industry.

Studies on Efficacy of Botanical Oils and Leaf Powders Against Lesser Grain Borer, <i>Rhyzopertha dominica</i> (F.) in Stored Wheat

The experiment on biological activity of botanical oils and leaf powders against R. dominica was conducted under laboratory condition. The results revealed that among the botanical oils and leaf powder, the castor oil 2.0% and neem leaf powder 1% achieved maximum adult mortality at 72 hr after treatment (91.67% and 81.67%) and revealed as the best grain protectants with least seed damage (4.33% and 3.67%), weight loss (2.01% and 1.04%), F1 adult emergence (3.67 and 4.33) and high inhibition rate (97.25% and 97.34%). This is due to their high viscosity of oils and asphyxiation effect by leaf powders. The finding also revealed that the botanical oils and leaf powders do not affect the germination of wheat seed.

The aptness of entompathogenic bacteria against sawtoothed grain beetle (Oryzaephilus surinamensis [L.]) (Coleoptera: Silvanidae) in dates under laboratory conditions

ObjectiveThe sawtoothed grain beetle, Oryzaephilus surinamensis (L). is known as one of the most devastating insect pests in stored date fruits, infrequently found in newly harvested date fruits and raisins but developed a high plenty in dry fruits particularly after long storage. Indiscriminate use of pesticides and fumigants to control insects have resulted in insecticide resistance, environmental hazards, residual toxicity, and pest resurgence so the control trends have been changed and particularly biological control agents like entomopathogenic bacteria Photorhabdus temperata and Xenorhabdus nematophila being used to manage sawtoothed grain beetle. MethodsDuring present study, the pathogenicity of P. temperata and X. nematophila was evaluated against this crucial pest of stored grains. The bacterial concentrations, 1 × 104, 1 × 105, 1 × 106, 1 × 107 and 1 × 108 cells/ml of both bacteria were prepared and used for the experiments. The prepared solutions were applied directly to the date fruits infested with sawtoothed grain beetles and data were recorded. ResultsSignificant results were observed for both bacterial treatments as the highest concentration of 108 cells/ml showed to be very effective against the beetle in terms of fecundity, adult emergence, and mortality. In terms of fecundity, 8.66 to 4.33 mean number of eggs were produced at bacterial P. temperata concentrations of 1 × 104 and 1 × 108 cells/ml, respectively. Similarly, the F1 adult emergence for P. temperata was recorded 15.33 and 9 adults at concentrations of 1 × 104 and 1 × 108 cells/ml, respectively. Results showed a similar trend for the X. nematophila species. ConclusionsThese results indicate that utilizing bacteria as biological control agents can be advantageous for reducing insect populations in storage facilities and preventing the loss of grains and date fruits that have been stored in storage.

Rhyzopertha dominica (Coleoptera: Bostrychidae): Studies on screening techniques of wheat genotypes/varieties for resistance

Lesser grain borer, R. dominica (Coleoptera: Bostrychidae) is a notorious insect pest of wheat and it can cause both quantitative and qualitative losses and also decrease the sustenance of stored wheat. The host preference of R. dominica were studied in twenty five wheat genotypes/varieties with both free and force choice test. Free choice screening provided prefatory information which was antixenosis usually measured. In force choice’s per cent weight loss, F1 adult emergence and susceptibility index demonstrated the rapid increases in the R. dominica population in wheat variety GW 190 compared than wheat genotypes/varieties VD18-12, VD18-13, VD18-14 and LOK1. Based on per cent weight loss, the genotype/varieties were graded by arbitary categorization as resistant (9), moderately resistant (6), less susceptible (5), moderately susceptible (3), and susceptible (2). Correlation done between the weight loss and all other growth parameters revealed that the weight loss has positive and significant correlation with mean developmental period and highly significant and positive correlation with F1 adult emergence and susceptibility index. The wheat genotypes/varieties resistant to R. dominica VD18-12, VD18-13, VD18-14 and LOK1 have the potential to reducing the loss of wheat during storage condition and it can also used as donor lines for future breeding purpose.

Efficacy of binary combinations of powders from selected botanicals against Callosobruchus maculatus Fabricius damage in stored cowpea seeds

The efficacy of powder mixes of two different insecticidal plants against Callosobruchus maculatus Fabricius was determined at the Entomology Research Laboratory, Department of Crop, Soil and Pest Management of the Federal University of Technology, Akure, Ondo State, Nigeria, under ambient laboratory conditions of 26 ± 4° C and 65 ± 10% RH. The powder combinations were made from Azadirachta indica leaf Thaumatococcous daniellii rhizome Eugenia aromatica dry flower buds, seeds of Piper guineense and rhizome of Zingiber officinale in a 1:1 ratio. The binary combinations were assessed at the dosages of 0.0, 0.2, 0.4, 0.6, 0.8, 1.0 and 2.0 g per 20 g of cowpea seeds in separate 250 ml plastic containers with lids, against five pairs of newly emerged C. maculatus adults. Insect mortality was recorded 24, 48 and 72 hours post treatment and the number of F1 adult emergence was recorded after up to 35 days post treatment. The combination of E. aromatica and T. daniellii, and E. aromatica and Z. officinale produced 60% and 53% mortality respectively, of adults of C. maculatus at the lowest tested dosage (0.2 g/20 g of grain), and 100% and 83% mortality respectively, at the highest tested dosage (2.0 g/20 g of grain). Oviposition and progeny production of C. maculatus were also significantly lower in treatments involving the use of these two combinations; significantly fewer seeds bore beetle eggs and adult exit holes. The combination of E. aromatica and T. daniellii, and E. aromatica and Z. officinale may be included in pest management strategies for mitigating C. maculatus damage to stored cowpea.

Toxic and repellent impacts of botanical oils against Callosobruchus maculatus (Bruchidae: Coleoptera) in stored cowpea [Vigna unguiculata (L.) Walp.

Cowpea (Vigna unguiculata) is an important legume which is consumed globally for protein intake, particularly in Asian states. It is a well-known source of dietary fiber, protein, minerals, and vitamins. The cowpea grains are stored after harvest and used till the next harvest. However, the grains are infested by storage pests, primarily Callosobruchus maculatus. Hence, effective management strategies are needed to protect the stored grains form the pests. This study assessed the efficacy of some edible oils in suppressing C. maculatus infestation in stored cowpea grains. Four different botanical oils (i.e., mustard, neem, poppy, and pumpkin) at four different concentrations (i.e., 0.5, 1.0, 1.5 and 2.0 ml per 100 g grain) were included in the study. A control treatment without any botanical oil was also included for comparison. The relevant concentrations of botanical oils were poured into plastic containers containing 100 g cowpea grains and ten C. maculatus adults were released. The jars were sealed and placed at room temperature. Data relating to mortality, oviposition, F1 adult emergence, and seed weight loss were recorded. The tested botanical oils and their concentrations significantly affected mortality after one day. Mortality after 2nd and 3rd days remained unaffected by botanical oils and their different concentrations. The highest mortality was recorded in neem oil-treated grains followed by poppy, pumpkin, and mustard oils. Increased oviposition rate was observed in the grains treated with mustard and pumpkin oils, while those treated with neem and poppy oil recorded decreased oviposition. The control treatment had increased oviposition rate compared to tested botanical oils. All botanical oils significantly inhibited egg laying percentage. The highest germination was recorded for the grains treated with mustard oil followed by pumpkin, poppy, and neem oils, respectively. The lowest germination was recorded for control treatment. Significant differences were noted for C. maculatus repellency among botanical oils. No emergence of adults (F1 progeny) was recorded in all tested botanical oils; thus, F1 progeny was inhibited by 100%. Weight loss, damage percentage, and holes in the grains were not recorded since F1 progeny did not emerge. It is concluded that tested botanical oils are promising and could be utilized to control C. maculatus in cowpea grains during storage.

FUNCTIONAL RESPONSE, HOST STAGE PREFERENCE AND DEVELOPMENT OF RHYNOCORIS FUSCIPES (FAB.) (HETEROPTERA: REDUVIIDAE) FOR TWO COTTON PESTS

The rice weevil, Sitophilus oryzae is a major stored grain insect pest that causes both quantitative and qualitative damage to cereals. Hence, the study was conducted to evaluate the insecticidal efficacy of Clerodendrum multiflorum, Clerodendrum viscosum, Vitex negundo, Argemone mexicana and Withania somnifera leaves essential oil against S. oryzae in laboratory conditions. The essential oil isolated from V. negundo and A. mexicana at 2.0 μL/gm of wheat was found to be toxic, causing 100% mortality as compared to other plant essential oils. The percentage of oviposition deterrence increased from 20% to 90% by increasing the concentrations of essential oils. Interestingly, all plant essential oils were inhibited F1 adult emergence at lower dose. Essential oils of V. negundo and A. mexicana revealed significant toxicity, oviposition deterrence and inhibition of F1 adult emergence of S. oryzae at lower concentrations. Thus, these plant essential oils may be suggested as admixtures in the integrated management of rice weevil during the storage of grains.

A Phenology Model for Simulating Oobius agrili (Hymenoptera: Encyrtidae) Seasonal Voltinism and Synchrony With Emerald Ash Borer Oviposition.

In North America, the emerald ash borer, Agrilus planipennis Fairmaire (Coleoptera: Buprestidae), continues to spread, and its egg parasitoid, Oobius agrili Zhang and Huang (Hymenoptera: Encyrtidae), is being released for emerald ash borer biocontrol well beyond their endemic climatic ranges in China. We developed a multiple cohort rate summation model to simulate O. agrili F0, F1, and F2 generations, and emerald ash borer oviposition for examining host-parasitoid synchrony across a north-south gradient from Duluth, MN (latitude 46.8369, longitude -92.1833) to Shreveport, LA (latitude 32.4469, longitude -93.8242). Temporal occurrences of critical day length for O. agrili diapause induction were integrated into the model. We used O. agrili and emerald ash borer trapping data from south central and northwestern Lower Michigan for model validation. Simulations demonstrated that 1) F0 adult emergence consistently occurred 2-5 d before emerald ash borer oviposition began; 2) F1 adult emergence was most synchronized with peak emerald ash borer oviposition compared with other generations; and 3) emerald ash borer oviposition was complete, or near so, when F2 adult emergence was predicted across the north-south gradient. Comparison of O. agrili trap captures with model simulations demonstrated that primarily two adult O. agrili generations (F0 and F1) emerged per year in Michigan and almost all F2 larvae entered diapause despite day lengths longer than critical day length in south central Michigan. Critical day length varied temporally across the north-south gradient during emergence of O. agrili generations. Determining day lengths perceived by O. agrili larvae in the field should improve model realism for examining spatiotemporal variation in O. agrili population dynamics.

Effect of high-temperature extracted plant material fume against southern cowpea weevil (Callosobruchus chinensis L.) (Coleoptera: Bruchidae) as a non-chemical novel fumigation technique

BackgroundFumes from high-temperature heated plant leaves containing volatile phytochemicals generated from Lantana camara, Cinnamomum zeylanicum, Azadirachta indica and Ocimum sanctum were tested for their insecticidal activity against adult southern cowpea weevil (Callosobruchus chinensis L.) and their F1 progeny production/emergence. Volatile phytochemicals containing fume was generated using a flameless dry heat extraction method similar to pyrolysis combustion without air supplement at 180 ± 5 °C. Insect mortalities were assessed up to 72 h after exposure to the different treatments of fumigation by plant-fume and control.ResultsAll volatile plant-fume samples contained average of 16.3 ± 1.5% O2 and 5.8 ± 0.5% CO2 in the test jars. The F1 progeny emergence was estimated 30 days after treatment. After 36 h of exposure, L. camara showed the highest toxicity against C. chinensis, followed by O. sanctum, A. indica and C. zeylanicum, with LT50 values of 7.3, 9.4, 14.7 and 20.6 h, respectively. The volatile phytochemical containing plant-fume generated by A. indica and C. zeylanicum produced LT99 values that were not significantly different (P > 0.05) from each other. The F1 adult emergence from treated mungbean (Vigna radiata L.) samples was significantly inhibited by L. camara and A. indica volatile plant-fume compared to C. zeylanicum fume. However, plant-fume generated from all four plants exhibited effective direct toxicity and F1 progeny inhibition of more than 86%.ConclusionFrom the study, it can be concluded that volatile plant-fume treatment was highly lethal to C. chinensis and significantly reduced F1 progeny emergence. Therefore, phytochemicals obtained from thermal extraction technique can be used as an alternative technique to chemical fumigation of stored mungbean.

Insecticidal Potency of Three Selected Tropical Wood Dusts in the Control of Maize Weevil (<i>Sitophilus zeamais</i>) on Stored Maize

The insecticidal properties of wood dust obtained from three tropical plant species (Khaya ivoreinsis, Azadirachta indica and Moringa oleifera) were evaluated against 10 newly emerged adult Sitophilus zeamais at 1.0g, 1.5g and 2.0g treatment doses on 20g of maize grain in a 300cm3 rearing jars. Daily mortality count was observed for seven days, followed oviposition count with the aid of acid fuschin staining method. F1 adult emergence was also noted as well as grain damage and subsequent weight loss before the grain viability was tested. Data collected was subjected to ANOVA and the treatment means were compared using LSD at 5% probability level (P>0.05). The results revealed the 3 tropical wood dusts from effective in preventing the activities of S. zeamais in all the parameters measured. K. ivoreinsis wood dust recorded the highest (8.00) total mortality, and recorded the lowest F1 generation (0.50), number of grain damage (11.0) and weight loss (0.23). While, A. indica recorded highest number of seed viability (4.75). Therefore, sustainable use of these tropical wood dusts as biopesticides especially K. ivorensis in the control of insect pests like S. zeamais on stored maize is very much encouraged, since they are safe, cheap, and readily available for farmers.Key-words: Insecticidal, Maize, Sitophilus zeamais, Wood dust.

Influence of abiotic factors on the efficacy of insect growth regulators against Trogoderma granarium (Everts)(Coleoptera: Dermestidae): Presentation

Present study was designed to investigate the effects of different combinations of three temperatures (20, 25 and 30?) and three relative humidity levels (55, 65 and 75%) on the efficacy of three synthetic IGRs i.e., pyriproxyfen, lufenuron and buprofezin at concentrations of 1, 5 and 10ppm on fecundity and adult emergence inhibition of T. granarium under controlled laboratory conditions. This study was conducted at Grain Research Training and Storage management Cell, Department of Entomology, University of Agriculture, Faisalabad, Pakistan. All the treatments were replicated three times using Completely Randomized Design. Larvae of T. granarium were exposed to IGRs at different levels of temperature and relative humidity. F1 adult emergence results showed that at temperature 20°C, the highest percent reduction in adult emergence (84.38, 70.65 and 79.94%) was recorded after exposure to lufenuron, buprofezin and pyriproxyfen treated diet, respectively. At 75% relative humidity, lufenuron, buprofezin and pyriproxyfen caused 77.53, 80.00 and 80.32% reduction in adult emergence, respectively. Adults were exposed to IGRs at different temperature and relative humidity to evaluate the oviposition inhibition. The results revealed that at temperature 20°C, maximum percent reduction in fecundity (87.95, 80.45 and 70.55%) was recorded after exposure to buprofezin, pyriproxyfen and lufenuron treated diet, respectively. At 75% relative humidity buprofezin, pyriproxyfen and lufenuron caused 86.73, 83.72 and 69.11% reduction in fecundity, respectively. It is concluded that temperature and relative humidity play an important role in the effectiveness of insect growth regulators.

Bioefficacy of Three Selected Plant Species against the Cowpea Bruchid (Callosobruchus maculatus F.): A Green Paradigm for Post-Harvest Pest Management

Callosobruchus maculatus (Coleoptera: Bruchidae) is the most damaging insect pest of storage legumes and pulses. Control of this insect pest infestation primarily relies upon the extensive use of synthetic insecticides. However, the increasing serious problems associated with these chemical compounds have led to the need for more effective biodegradable natural products. In this context, plants appear to play a much greater role as a new class of eco-friendly products for the controlling of populations of this post-harvest insect pest. Therefore, three plants, Pimenta dioica (allspice), Ruta graveolens (garden rue) and Piper betle (betel) were evaluated with the intention of finding the most effective plant species as a desirable alternative to synthetic insecticides in suppressing C. maculatus populations in storage. Potential contact and fumigation repellent properties of leaf powders were assessed using a modified single-choice cup bio assay technique. Twenty laboratory reared one day old adult insects were exposed to 1, 3, 5, 7, and 9 g doses of the three leaf powders separately. All the repelled insects were counted after a three hour exposure period. Observations on both contact and fumigation repellency, for P. dioica leaf powder revealed an exceptionally high effect of 99% whereas P. betle and R. graveolens exhibited only 41% and 42.% repellent effects respectively for the highest dose (9 g). When three doses (1, 5, and 9 g) of P. dioica leaf powder were tested separately to evaluate its effect on F1 progeny production and duration for adult emergence, the highest dose produced extremely high reduction (p<0.05) in F1 adult emergence (6.78±3.25) compared with that of the control (55.60±8.16). Time duration for adult emergence showed that the two higher doses significantly differed with that of the control (21.90±1.24 days) indicating significantly high toxic effect of the powder. With the highest dose, 37.45±3.02 days were required for adult emergence, which was indicative of a growth regulatory effect. Following standard procedures, phytochemical constituents of aqueous, methanol, ethyl acetate and n-hexane extracts of P. dioica leaf powder were determined and the highest number of constituents (Alkaloids, saponins, flavonoids, tannins, and phenols) was obtained with methanolic extract. It can be suggested that one or many of these constituents may be responsible for its very high repellent, toxic and growth regulatory properties. The overall results of the present study clearly indicate that P. dioica leaf powder could be utilized quite successfully to suppress C. maculatus populations with the longstanding objective of developing an eco-friendly green pesticide. Keywords: Callosobruchus maculatus, Pimenta dioica, Ruta graveolance, Piper betle, Repellency

Larvicidal efficacy of some indigenous plant extracts against epilachna beetle, epilachna vigintioctopunctata (FAB.) (coleoptera: coccinellidae)

The study was carried out to assess the larvicidal efficacies of some indigenous plant seed extracts against epilachna beetle, Epilachna vigintioctopunctata in the laboratory of the Department of Entomology, HSTU, Dinajpur, Bangladesh. Petroleum ether and methanol solvent extracts of ata (Annona squamosa), neem (Azadirachta indica), dhutura (Datura metel) and castor (Ricinus communis) seeds were evaluated for their larvicidal properties against the larval stage of E. vigintioctopunctata. The result revealed that all the tested plant extracts had more or less insecticidal effect against the larvae and their progeny. Among the plant extracts, ata seed extract in methanol solvent performed the highest toxicity (LD50 value 0.031 mg/insect) in larval stage after 72 hours exposure time. The effects of the extracts on fecundity, fertility and F1 adult emergence of the epilachna beetle at doses 4.0, 2.0 and 1.0 ml/l of water including untreated control were also evaluated. The result indicated that, among the extracts, ata seed extract at maximum dose (4.0 ml/l water) showed the highest efficacy with the inhibition of total eggs (74.1%), viable eggs (80.4%) and number of emergent adult progeny (87.3%). The result also revealed that the number of eggs, number of viable eggs and F1 progeny production decreased with the increase of doses. All the treated doses effectively reduced the epilachna beetle as compared to untreated control.Bangladesh J. Agril. Res. 40(3): 451-463, September 2015

Influence of grain type on the efficacy of spinetoram for the control of Rhyzopertha dominica, Sitophilus granarius and Sitophilus oryzae

The efficacy of spinetoram against adults of three major stored grain beetle species, the lesser grain borer, Rhyzopertha dominica (F.) (Coleoptera: Bostrychidae), the granary weevil, Sitophilus granarius (L.) (Coleoptera: Curculionidae) and the rice weevil, Sitophilus oryzae (L.) (Coleoptera: Curculionidae) in seven grain commodities was evaluated under laboratory conditions. Spinetoram residues in each grain were quantified using high-performance liquid chromatography (HPLC) with UV detection. The tested grains were hard wheat, soft wheat, oats, rye, triticale, paddy rice and maize. Spinetoram was applied at three dose rates: 0.1, 1 and 10 ppm (mg of active ingredient per kg of grain) and bioassays were carried out at 25 °C and 60% r.h. Mortality of the exposed adults was assessed after 7 and 14 d of exposure while progeny emergence was recorded 65 d after the last exposure interval (14 d). Among the tested species, R. dominica was highly susceptible to spinetoram for all commodities tested, since 100% mortality was noted after 14 d of exposure at 1 and 10 ppm. From the two Sitophilus species, S. granarius was more susceptible to spinetoram than S. oryzae, while for both species 0.1 ppm was not effective. For these two species, spinetoram efficacy differed among the tested commodities. In general, mortality was higher in hard wheat for both Sitophilus species in comparison with the other grains, while the lowest mortality levels were recorded in oats and soft wheat for S. granarius and in maize and soft wheat for S. oryzae. Progeny production was low in the case of R. dominica, and F1 adult emergence was recorded mostly at 0.1 ppm. For both S. granarius and S. oryzae, the highest progeny production was noted in soft wheat. Spinetoram residue determination in each grain at the dose rate of 10 ppm, did not show any differences among the treated commodities.

Observations on the Biology of Callosobruchus maculatus (Fab.) (Coleoptera: Bruchidae) under Ambient Laboratory Conditions

Observations on the biology of Callosobruchus maculatus( Fab.) were carried out under ambient laboratory conditions. Pattern of oviposition, female adult longevity and F1 progeny emergence in Callosobruchus maculatus ( Fab. ) were observed. The results showed that over 60% of the total number of eggs was laid during the first 72 hours of the commencement of oviposition; however, oviposition rate and F1 adult emergence of the bruchids decreased with time thereafter. The maximum adult C. maculatus survival period was about ten days.Keywords: Callosobruchus maculatus, pattern of oviposition, female adult longevity and F1 adult progeny emergence

Relative Susceptibility and Proximate Composition of Some Imported and Local Rice Varieties to Infestation and Damage by &lt;i&gt;Sitophilus oryzae&lt;/i&gt; L. (Coleoptera: Curculionidae)

Ten rice varieties were assessed for their comparative susceptibility and proximate composition to post harvest infestation and damage by Sitophilus oryzae L. (Coleoptera: Curculionidae). The damage parameters used to compare the susceptibility of the rice varieties to S. oryzae were; percentage mortality 4 weeks after adult insects infestation, number of F1 progeny, percentage grains weight loss and F2 adult emergence. Four weeks post infestation (WPI), almost all the adults introduced to ITA 315 had died (95% mortality rate) which was significantly (P 0.05) in the weight loss of Igbemo, Ofada and Erio varieties. Highest and lowest weight loss was obtained for Isan and ITA 315, at week 8 and 12 respectively. The extent of damage done by the introduced adult S. oryzae were observed to be reduced in ITA 315, Caprice, ITA 257 and Cisadene varieties, as they may have found it hard to puncture into or oviposit in the grains, resulting in reduced weight loss, and low F1 progeny and F2 adult emergence. Grain hardness, moisture content and anti-nutrient compositions of the selected varieties were investigated whether it may be used as indicators of resistance. Only moisture content could be established as an indicator of resistance, as the grain moisture content was significantly positively correlated with both F1 and F2 adult emergence. The imported varieties which recorded higher resistance had lower moisture content compared to the local varieties. Grain hardness and anti-nutrient composition did not affect susceptibility of the rice varieties to infestation and damage of S. oryzae because there was no significant (P>0.05) correlation between the two variables and susceptibility to the weevil.

Chemical analysis of three herbal extracts and observation of their activity against adults of Acanthoscelides obtectus and Leptinotarsa decemlineata using a video tracking system

Ethanol extracts of Rosmarinus officinalis, Lavandula angus-tifolia and Ruta graveolens were tested against adults of Acanthoscelides obtectus and Leptinotarsa decemlineata. Using a newly developed computer tracking system, a choice test revealed that all of the extracts have a repellent action. The highest repellent activity against the bean weevils adults was the ethanol extract of rue, whereas the highest repellent activity against the Colorado potato beetle adults was the lavender extract. We suggest that a cocktail of volatile components in the ethanol extracts was responsible for the observed repellent action. All three of the extracts have insecticidal effects on bean weevils, reducing F1 adult emergence, with no side effects on the germination of the bean plants. In contrast, the extracts did not demonstrate an insecticidal effect on Colorado potato beetles.

Control of stored grain pest, Callosobruchus maculatus (F.) (Coleoptera: Bruchidae) using the essential oil isolated from Plectranthus zeylanicus

The bruchid, Callosobruchus maculatus (F.) causes major losses during the storage of cowpea seeds [Vigna unguiculata (L.)Walp.] in Sri Lanka. Essential oil isolated from Plectranthus zeylanicus plant was tested for potential insecticidal activity against C. maculatus. The gas chromatography studies of the essential oil of P. zeylanicus showed that ρ-cymene (3.5%), β-caryophyllene (0.2%), geranyl acetate (9.3%) and geraniol (7.2%) were the major constituents. The adults of C. maculatus were susceptible to both fumigant and contact toxicity of P. zeylanicus plant oil. LC50 values of 0.927 and 0.010 g L−1 were obtained for fumigant toxicity and contact toxicity assays, respectively. Oviposition and F1 adult emergence were significantly inhibited by P. zeylanicus plant oil at a concentration higher than 0.001 g L−1 in both fumigant and contact toxicities. The analysis of olfactometer and choice camber bioassays revealed the repellent effects of the oil of P. zeylanicus plant.

Orange peel powder and its extracts as preservative against &lt;i&gt;Callosobruchus maculates&lt;/i&gt; (&lt;i&gt;Coleoptera:Bruchidae&lt;/i&gt;) attack in cowpea

Ethanolic crude extract, volatile oil and the peel powder of sweet orange (Citrus sinensis) were evaluated for their efficacy against the bean weevil (Callosobruchus maculatus Fab.). The peel powder was evaluated at concentrations of 5.0 g, 7.5 g, and 10.0 g /50 g of cowpea seeds. Ethanoliccrude extract and volatile oil were evaluated at concentrations of 0.1 ml, 0.2 ml and 0.3 ml / 50 g of cowpea seeds. Mortality count was recorded at 24, 48, and 72 hours post treatment. F1 adult emergence was also counted after 4 weeks of storage. All treatments exhibited significantly (p < 0.05) higher mortalities and lower F1 adult emergence than the untreated control.Ethanolic crude extract gave the least F1 adult emergence compared with other treatments and control. At the concentration of 0.3 ml/ 50 g of Ethanolic crude extract, there was no F1 adult emergence. Ethanolic crude extract at this concentration gave adequate protection to stored cowpea seeds.