Effect of ivermectin on larval mortality and reproductive potential of <Emphasis Type="Italic">Albizia</Emphasis> foliage feeder, <Emphasis Type="Italic">Spirama retorta</Emphasis> Cramer (Lepidoptera: Noctuidae)

Toxicity of ivermectin (Ivecop-12), a derivative of avermectin B, produced by a soil actinomycete, Streptomyces avermitilis, was evaluated in laboratory against the larvae of Spirama retorta Cramer (Lepidoptera: Noctuidae), a major stenophagous insect defoliator of Albizia spp. (family Leguminosae) in nurseries and young plantations. The study was conducted with eight treatment concentrations of lethal and sub-lethal doses. Results revealed that ivermectin is highly toxic and induce larval mortality when applied separately on host plant leaves and larvae, and on leaves and larvae of the insect pest together. The nature of treatment affects the larval mortality. Treatment of host plant leaves alone as well as leaves together with larvae showed 100% mortality by the treatment of 0.075% concentration whereas only 95% larval mortality was recorded due to larval treatment by the concentration of 1.2%. The LC₅₀ value of the tested product was worked out to be 0.014, 0.170 and 0.012% for leaf and larval treatments separately and leaf and larval treatments together, respectively, against the insect pest. This clearly shows that ivermectin is more effective in larval killing when ingested through food. Further, the adults developed from treatments of sub-lethal concentrations and subsequently, when mated laid significantly (P < 0.05–0.01) less number of eggs and also showed significant (P < 0.05–0.01) reduction in hatching percentage compared to control. These observations suggest that the tested bioproduct, ivermectin, interfere physiological programming of larvae thereby causing alteration in fecundity and fertility of the target insect pest.     

Antifeedant and toxic effects of acetogenins from <Emphasis Type="Italic">Annona montana</Emphasis> on <Emphasis Type="Italic">Spodoptera frugiperda</Emphasis>

Several species of the large family of tropical plants Annonaceae have been intensely investigated over the last 20 years, mainly because of the discovery of annonaceous acetogenins. These compounds are powerful cytotoxics, with potential applications as insecticides, antiparasitics, acaricides, fungicides, and antitumor drugs. Annona montana Macfad. (Annonaceae) grows in Santa Cruz de la Sierra, Bolivia, where an infusion of leaves is used for the treatment of lice, influenza, and insomnia. The major acetogenins from a Bolivian collection of A. montana, annonacin (1), cis-annonacin-10-one (2), densicomacin-1 (3), gigantetronenin (4), murihexocin-B (5), and tucupentol (6), were evaluated for their antifeedant and toxic effects on Spodoptera frugiperda Smith (Lepidoptera: Noctuidae), a serious pest affecting corn crops in Argentina. All the acetogenins produced 100% mortality during the larval or pupal stages at 100 μg of treatment per gram of diet. In addition, compounds 2, 3, and 4 deterred more than 80% feeding at the same dose. Relative toxicity values of LD₅₀ for the strongest larvicidal compounds 1, 2, and 4 were determined, indicating that the three compounds are effective natural insecticides. This is the first report on the antifeedant and toxic effects produced by the particular type of acetogenins, the mono-THF acetogenins, on the lepidopteran S. frugiperda. No correlation was detected between the toxicity of the mentioned compounds to larvae and the known capacity of the acetogenins 1, 2, and 4 to inhibit the NADH oxidase, indicating that the inhibition of the mitochondrial complex I is not the only cause for larval mortality of S. frugiperda.     

Parasitism of different <Emphasis Type="Italic">Trichogramma</Emphasis> species and strains on <Emphasis Type="Italic">Plutella xylostella</Emphasis> L. on greenhouse cauliflower

The diamondback moth, Plutella xylostella (L.) (Lepidoptera: Plutellidae), is the most important pest of cultivated Brassica worldwide, including those grown in greenhouses like cauliflower. In this article, we evaluate the potential of various species (and various strains of some species) of Trichogrammatidae (Hymenoptera: Chalcidoidea) to control this pest on cauliflower in greenhouse in France. We assessed the parasitism levels on P. xylostella of 17 Trichogrammatidae strains, belonging to 12 different species (2 indigenous strains from France), under greenhouse conditions. Parasitism levels for each of the Trichogrammatidae species and strains were determined on cauliflower leaves (Brassica oleracea botrytis L., Brassicaceae) infested with P. xylostella eggs. Nine strains parasitized 60% (or more) of the P. xylostella eggs. Compared to previous results in laboratory conditions, climatic conditions of the greenhouse did not influence parasitism levels. The presence of the cauliflower plants may have a positive effect on eight strains, a negative effect on four strains and no effect on five strains. Our study points out the importance of including the host plant of P. xylostella when conducting studies aiming to select the most efficient parasitoid against this pest.     

Acaricidal,repellent and oviposition deterrent activities of <Emphasis Type="Italic">Datura stramonium</Emphasis> L. against adult <Emphasis Type="Italic">Tetranychus urticae</Emphasis> (Koch)

The ethanol extracts obtained from both leaf and seed in the Thorn apple (Datura stramonium L.) (Solanaceae) were investigated for acaricidal, repellent and oviposition deterrent properties against adult two-spotted spider mites (Tetranychus urticae Koch) (Acari: Tetranychidae) under laboratory conditions. Leaf and seed extracts, which were applied in 167,250 and 145,750 mg/l concentrations, respectively (using a Petri leaf disc-spray tower method), caused 98 and 25% mortality among spider mite adults after 48 h. The simple logistic regression analysis showed that the independent variable, an increase in the dose of leaf extract was associated with a significant increase in the death rate of T. urticae females, but an increase in the dosage of seed extracts did not have a significant effect. Using probit analysis and estimating the parameters with a confidence limit of 95%, we determined the LC₅₀ values of leaf extract to be 70,593 mg/l. According to Pearson’s χ² test, mites showed the strongest run off to bean leaf surfaces sprayed with both leaf and seed extracts (in sub-lethal doses: <7,500 mg/l and <25,000 mg/l, respectively) and moved towards surfaces that had not been sprayed with extracts. Furthermore, repeated measures ANOVA indicated a significant difference between the number of eggs laid on unsprayed bean leaves compared to bean leaves that were sprayed with leaf and seed extracts at sub-lethal doses, 2,500 and 25,000 mg/l concentrations, respectively. These results suggest that D. stramonium extracts could be used to manage the two-spotted spider mite.     

Controlling the sugar beet beetle <Emphasis Type="Italic">Cassida vittata</Emphasis> with entomopathogenic nematodes

Sugar beet, Beta vulgaris L. is a strategic crop of sugar industry in Egypt. It is threatened by several insect pests among most important of them is the beet beetle Cassida vittata. This work deals with the biological control of this insect using four Egyptian and imported entomopathogenic nematodes (EPNs). The nematodes included Steinernema carpocapsae S2, Heterorhabditis bacteriophora S1, S. feltiae and H. bacteriophora (1-3). Daily mortality of larvae, pupae and adults of C. vittata were recorded after treatment with serial concentrations (from 500 to 4,000 infective juveniles/ml) of each of four studied EPNs. Development of nematodes in insect bodies was followed up. S. carpocapsae S2 was chosen for the application against different stages of the pest in a sugar beet field. In the field, single application of S. carpocapsae S2 killed 65% of the larvae, 92% of the pupae and 57.3% of the adults of C. vittata within a week. This work is the first report on using the EPNs to control sugar beet beetle.     

Aphidicidal activity of some indigenous plant extracts against bean aphid <Emphasis Type="Italic">Aphis </Emphasis><Emphasis Type="Italic">craccivora</Emphasis> Koch (Homoptera: Aphididae)

Aphidicidal activity of hot and cold water extracts of some indigenous plants, Azadirachta indica A. Juss (neem), Calotropis procera (Aiton) W.T. Aiton (akanda), Polygonum hydropiper L. (biskatali) and Ipomoea sepiaria J. Koenig ex Roxb. (bankalmi), were tested against the bean aphid, Aphis craccivora Koch. Hot water extract of P. hydropiper and A. indica was found to be the most effective (87.6–94.5 and 80.47–89.6% mortality respectively, P < 0.01) among all the extracts. Other hot and cold water extracts also appeared to be useful (59.5–87.5% mortality) as pesticides for A. craccivora. The highest yield (3.25 kg per plant) was obtained using hot water extract of P. hydropiper followed by hot water extract of A. indica (3.15 kg per plant). The lowest yield (0.32 kg per plant) was recorded from the control block. All the phytoproduct treatments had significantly (P < 0.01) better yield than the control block.     

Feeding performance of <Emphasis Type="Italic">Clostera fulgurita</Emphasis> on three clones of <Emphasis Type="Italic">Populus deltoides</Emphasis>

Poplar leaf defoliator, Clostera fulgurita (Walker) larvae were reared on three Populus deltoides clones (PL1, PL5 and PL7) in the laboratory. The nutritional indices were computed for working out the relationship between food consumption and growth rate of 3rd, 4th and 5th instar larvae on three clones. The result showed that the consumption index (CI), approximate digestibility (AD), growth rate (GR), relative growth rate (RGR) and efficiency of conversion of ingested food (ECI) decreased with the increase in the age of the larvae. Efficiency of conversion of digested food (ECD) increased with increase in age of the larvae. GR and RGR varied significantly, indicating that larval development was enhanced on PL1 as compared to PL5 & PL7. The values of AD, ECI and ECD were not affected by the different clones. Feeding and growth indices could be useful to define a defoliation prediction model.     

Insecticidal activity of synthetic antioxidants,natural phytochemicals,and essential oils against an <Emphasis Type="Italic">Aspergillus</Emphasis> section <Emphasis Type="Italic">Flavi</Emphasis> vector (<Emphasis Type="Italic">Oryzaephilus surinamensis</Emphasis> L.) in microcosm

The purpose of this study is to investigate the insecticidal activity of two benzoic acids 2(3)-tert-butyl-4 hydroxyanisole (BHA) and 2,6-di(tert-butyl)-p-cresol (BHT); two phenolic acids 3-phenyl-2-propenoic acid (CA) and trans-4-hydroxy-3-methoxycinnamic acid (FA); and two essential oils of Eugenia caryophyllata (clove tree) and Thymus vulgaris (thyme) against Oryzaephilus surinamensis (L.) vector carrier of aflatoxigenic fungi on stored peanut. The weight loss of peanut, susceptibility of insects, Aspergillus isolation frequency from insects and peanut, and aflatoxin B₁ analyses from peanut were determined. BHA, BHT, and BHA/BHT mixture were highly effective against O. surinamensis, these chemical agents give 100% mortality at the doses assayed. Essential oil of thyme at 2,000 and 3,000 ppm were highly effective against O. surinamensis, these concentrations gave 100% mortality. No Aspergillus section Flavi contamination was observed in dead insects collected from peanut treated with BHA/BHT mixture. No differences were observed in the fresh weight of pods peanut among treatments with and without chemical agents. All samples of treated peanut pods showed complete inhibition of this toxin after 120 days of storage. Our results indicate that these substances could be evaluated further for the control of pest vectors of aflatoxigenic fungi of stored peanut.     

Potential of Nepalese entomopathogenic nematodes as biocontrol agents against <Emphasis Type="Italic">Holotrichia longipennis</Emphasis> Blanch. (Coleoptera: Scarabaeidae)

Holotrichia longipennis Blanch. (Coleoptera: Scarabaeidae) is a serious pest of commercial crops in Siduwa, Dhankuta, Nepal. Seven indigenous isolates of entomopathogenic nematodes (Steinernema lamjungense LMT5, S. lamjungense SS4, S. everestense DKP4, S. abbasi CS1, S. sp. KL1, Heterorhabditis indica CK2 and H. indica CK6) were used in a series of bioassays against the insect. All isolates showed an increased dispersal in response to H. longipennis. Nematodes were more attracted towards third instar larvae than to second instars. Differences in penetration and multiplication in the insect were observed amongst the seven isolates. Steinernema lamjungense LMT5, S. everestense DKP4 and S. abbasi CS1 caused greater mortality than other isolates to different developmental stages. Pupae and second instar larvae were more susceptible than third instar larvae. Significant differences were observed in LT₅₀ values of the isolates against different stages of H. longipennis. Three isolates (S. lamjungense LMT5, S. everestense DKP4 and S. abbasi CS1) along with a commonly used insecticide (chlorpyrifos) were tested against this insect in pot and field experiments. In pot experiments using maize and cabbage as a host crop, S. lamjungense LMT5 and S. everestense DKP4 performed better than S. abbasi CS1 and yielded a mortality comparable with chlorpyrifos. Similar results were observed in field experiments 3 weeks after nematode application. These experiments overall suggest S. lamjungense LMT5 to be a promising biocontrol agent against H. longipennis followed by S. everestense DKP4 and S. abbasi CS1.     

Bioinsecticidal effect of the flavonoids pinocembrin and quercetin against <Emphasis Type="Italic">Spodoptera frugiperda</Emphasis>

Flavonoids function in many aspects of plant–insect interactions, but the responses of insects to these compounds vary greatly. In this study, we determined the effects of two widely distributed flavonoids, pinocembrin and quercetin, on the feeding behavior, survival, and development of the fall armyworm Spodoptera frugiperda J.E. (Smith) (Lepidoptera: Noctuidae). In a choice test, S. frugiperda larvae strongly rejected leaves treated with pinocembrin at concentrations of 10, 50, or 100 μg/cm². Larvae fed normally on leaves treated with quercetin at 10 and 50 μg/cm², but showed 57 % deterrence when fed on leaves treated with 100 μg/cm² quercetin. At concentrations of 0.01–1 µg/cm², pinocembrin and quercetin functioned as phagostimulants for S. frugiperda. In a multiple-choice experiment, S. frugiperda larvae preferred to consume untreated leaves or those treated with 0.1 µg/cm² pinocembrin, but rejected leaves treated with 5–50 µg/cm² pinocembrin. In a no-choice feeding experiment, larvae fed on leaves treated with 5 and 50 μg/cm² pinocembrin consumed less than those fed on leaves treated with 0.1 and 1 μg/cm² pinocembrin or untreated leaves. Pinocembrin at 1–50 μg/cm² negatively affected larval weight and survival, thus showing a toxic effect. In contrast, leaf consumption and larval weight were not significantly affected by quercetin at 0.1, 1, 5, and 50 μg/cm², and mortality rates only slightly increased. Because of its dual activity, pinocembrin could be used for insect control in a stimulo-deterrent diversionary strategy: the same compound could promote both stimulate (low doses) and deter insect activity (high doses).     

Contact and ingestion toxicities of plant extracts to <Emphasis Type="Italic">Thaumetopoea solitaria</Emphasis> Frey. (Lepidoptera: Thaumetopoeidae)

Thaumetopoea solitaria is a serious pest of pistachio throughout the Mediterranean and the surrounding region. In this study, contact and ingestion toxicities of Bifora radians, Fumaria officinalis, Humulus lupulus and Rhododendron ponticum extracts against T. solitaria larvae were examined under laboratory conditions. Dimethoate was used as a positive control. In the contact toxicity bioassays B. radians extract was the most toxic, causing 32% mortality. In the ingestion toxicity bioassays H. lupulus extract was the most active, causing 83% mortality after 48 h. This shows that H. lupulus is acting as a stomach poison. The LC₅₀ and LC₉₀ values for H. lupulus ingestion toxicity bioassays were 1.7 and 8.7%, respectively. The LT₅₀ value was 29.3 h. Since H. lupulus extract caused >50% mortality even 6 days after application, its long lasting residual effect promises fewer applications. These results imply that H. lupulus has potential for use as a crop protectant against T. solitaria.     

Attack and defense movements involved in the interaction of <Emphasis Type="Italic">Spodoptera frugiperda</Emphasis> and <Emphasis Type="Italic">Helicoverpa zea</Emphasis> (Lepidoptera: Noctuidae)

The fall armyworm, Spodoptera frugiperda (J. E. Smith) and the corn earworm, Helicoverpa zea (Boddie) are among the main pests of maize. Both species exhibit cannibalistic behavior and quite often share the same feeding guild in maize (maize ears), which can result in several interspecific and intraspecific interactions. Paired interaction scenarios of intraspecific and interspecific larvae were assessed in arenas in the presence and absence of food to characterize movements resulting from interactions of these insects. There was a difference in the frequency of behavioral movements in all the interactions, except for S. frugiperda in the presence of food. Head touching and recoiling were the predominant movements in most of the interaction scenarios. Spodoptera frugiperda exhibited a predominance of defensive movements when competing against H. zea in the same instars. Cannibalism and predation occurred frequently in interactions involving 6th instar of H. zea against opponents in 4th instar. Larvae of H. zea show a higher aggressive movement than S. frugiperda. The larvae of S. frugiperda take advantage during the interactions, although they present more defensive movements compared to H. zea. This study provides relevant information regarding the interaction of these species and intraguild interaction, which might influence the population dynamics and the competitive displacement of pest species that share the same ecological niche.     

Leaves from grafted Meliaceae species affect survival and performance of <Emphasis Type="Italic">Hypsipyla grandella</Emphasis> (Zeller) (Lepidoptera: Pyralidae) larvae

In order to determine their effects on growth and mortality of instar II Hypsipyla grandella (Zeller), larvae were fed with leaf disks taken from shoots of susceptible species (Cedrela odorata L. and Swietenia macrophylla King) scions grafted onto resistant ones (Khaya senegalensis Desr. A. Juss and Toona ciliata M. Roem.), from their reciprocal grafts, and from both intact and autografted plants. In addition, crude leaf extracts from the susceptible and resistant plants, as well as from C. odorata grafted onto T. ciliata plants, were tested on C. odorata leaf disks. Mortality was evaluated 2, 10, and 25 days after starting the bioassay. Leaf area consumed and weight gain per larva were assessed 2 days after starting bioassay. Time to reach pupation, pupal weight and length 1 day after pupation, and time to adult stage and appearance of wings were determined at the end of the bioassay. Plant species significantly affected mortality (P ≤ 0.04) throughout the test. Eighty to 100% of larvae fed leaf disks from intact T. ciliata and its autograft, or C. odorata onto T. ciliata and its reciprocal graft died in the first 2 days of evaluation. All other factors measured, except pupal weight and length, were also affected (P ≤ 0.01) by the leaf disks. Intact resistant plants and reciprocal grafted plants reduced leaf consumption and caused larval weight loss. Larvae fed on K. senegalensis grafted onto S. macrophylla extended by 8 days the time to pupa and to adult stages and induced abnormal wing formation compared to larvae fed intact leaves of C. odorata. Crude extracts from resistant plants equally affected larval survival and performance compared to crude extract from C. odorata grafted onto T. ciliata plants, and these extracts were more detrimental to larvae than those from susceptible species. This study demonstrated that grafting borer-susceptible species on resistant rootstocks can affect the survival and performance of instar II H. grandella larvae.     

Control of a new turf pest, <Emphasis Type="Italic">Dorcadion pseudopreissi</Emphasis> (Coleoptera: Cerambycidae), with the entomopathogenic nematode <Emphasis Type="Italic">Heterorhabditis bacteriophora</Emphasis>

The use of biological control in turf has increased to avoid possible negative effects on humans. Entomopathogenic nematodes (EPNs) belonging to the families Steinernematidae and Heterorhabditidae have control potential against many economically important insect pests. In the present study, the efficacy of Heterorhabditis bacteriophora against a new pest on turf, Dorcadion pseudopreissi, was examined in the field. Cages (1 × 1 × 1 m) with female and male D. pseudopreissi were placed on two kinds of turf: Lolium perenne and Festuca arundinacea. After beetles had deposited eggs into the moist soil surface, the cages were removed and H. bacteriophora was applied at 0.5 million infective juveniles/m² to half the plots. Application of H. bacteriophora caused a statistically significant reduction in numbers of beetle larvae in L. perenne plots and a non-significant reduction in F. arundinacea plots. The area damaged by D. pseudopreissi was significantly reduced by nematode application in both turf species. The number of nematodes declined after application, but small numbers could still be detected after 6 months.     

Direct and admixture toxicity of diatomaceous earth and monoterpenoids against the storage pests <Emphasis Type="Italic">Callosobruchus</Emphasis><Emphasis Type="Italic">maculatus</Emphasis> (F.) and <Emphasis Type="Italic">Sitophilus oryzae</Emphasis> (L.)

We investigated the effects of two commercial diatomaceous earth based insecticides (DE), Protect-It^® and SilicoSec^®, the nano-structured silica product AL06, developed by the section for Urban Plant Ecophysiology at Humboldt University Berlin, and the monoterpenoids, eugenol, and cinnamaldehyde on two stored product pests, Callosobruchus maculatus and Sitophilus oryzae. Protect-It^® was more effective than SilicoSec^® against C. maculatus while the reverse was true for S. oryzae. Generally C. maculatus was more sensitive towards DE and silica treatment than S. oryzae. Mortality rate of both pest species increased when DE’s were applied to food commodities previously treated with a monoterpenoid. In admixture experiments, the toxicity of SilicoSec^® + cinnamaldehyde (LD₅₀ = 42.73 ppm), SilicoSec^® + eugenol (LD₅₀ = 24.30 ppm), and Protect-It^® + eugenol (LD₅₀ = 2.60 ppm) was increased over DE alone against S. oryzae. Both substances showed a synergistic effect considering their co-toxicity coefficient relative to the LD₅₀-value. In contrast, we could not find any synergistic effects in experiments with C. maculatus. Here only Protect-It^® + cinnamaldehyde (LD₅₀ = 20.84 ppm) showed an additive effect while all other combinations of monoterpenoid and DE indicated antagonistic effects. In addition to contact insecticidal effects both monoterpenoids showed a strong fumigant action. The presented results indicate that the natural product DE has great potential to replace synthetic pesticides commonly used in stored product pest management. Efficacy of DE can be improved by adding certain monoterpenoids against certain insect pests.     

Laboratory and field evaluations of some botanical pesticides against the cedar leaf moth, <Emphasis Type="Italic">Acleris undulana</Emphasis>

The cedar leaf moth (CLM), Acleris undulana Walsingham, has recently become an important pest in the cedar forests in southwestern Turkey. Control has focussed on the use of synthetic chemical pesticides, with little research having been conducted on alternative control methods. In this study, four botanical pesticides (two commercial neem products, Neemazal-T/S^® and Greeneem^® oil, and two hot water plant extracts, Origanum onites L. and Pimpinella anisum L.) were evaluated for their effects against young (first–second) and older (third–fifth) instar larvae of CLM under laboratory and field conditions. The results of larval dip bioassay in the laboratory showed that all the botanical pesticides tested had significant larvicidal activity against both young and older instars of CLM compared to the water-treated control. Of the botanical pesticides tested, Neemazal was the most larvicidal botanical, causing mortalities ranging from 84 to 100%, the least effective was the P. anisum extract, but at high concentrations this extract still caused significant mortality. Results from field trials also revealed that the botanical pesticides had larvicidal activity against CLM. Neemazal was the most larvicidal botanical, followed by Greeneem oil then by O. onites and finally by P. anisum. Our overall results suggest that all the botanical pesticides tested are promising as larvicides against CLM, and may provide an alternative control method that is more compatible with Integrated Pest Management programs than the use of synthetic chemical pesticides.     

Fumigant activity of <Emphasis Type="Italic">Illicium verum</Emphasis> fruit extracts and their effects on the acetylcholinesterase and glutathione<Emphasis Type="Italic"> S</Emphasis>-transferase activities in adult <Emphasis Type="Italic">Sitophilus zeamais</Emphasis>

The insecticidal activity of Illicium verum Hook. f. against Sitophilus zeamais Motschulsky adults were identified, and the underlying mechanisms were studied. Extracts from I. verum fruits in methyl alcohol (MA), ethyl acetate (EA), and petroleum ether (PE) were tested by fumigation in a hermetic container to determine their toxicity. The effects of the three extracts on the activity of acetylcholinesterase (AChE) and glutathione S-transferases (GSTs) of S. zeamais were determined in vivo. All extracts showed strong fumigant activity. The fumigant effects were enhanced with increased dosage and prolonged exposure time. 1.25, 2.50, 5.00, 10.00, and 20.0 mg/l doses of the MA, EA, and PE extracts caused the mortalities from 8.37 to 90.26 %, 21.81 to 95.89 %, and 15.84 to 92.57 %, respectively, at 72 h after treatment. Consequently, the most effective dose of the MA, EA, and PE extracts is the 20.0 mg/l. The LD₅₀ of the MA, EA, and PE extracts at 72 h after treatment were 7.10, 3.93, and 4.55 mg/l, respectively. The activities of AChE and GSTs were notably inhibited by the three extracts, as compared with the control, with strong dose- and time-dependent effects. The inhibition strength of the three extracts on AChE and GSTs activities were in the following order: EA extract > PE extract ≥ MA extract. Therefore, I. verum extracts could be explored as novel natural fumigants for the future control of stored-product insect pests.     

Laboratory evaluation of five novel pyrrole derivatives as grain protectants against <Emphasis Type="Italic">Tribolium confusum</Emphasis> and <Emphasis Type="Italic">Ephestia kuehniella</Emphasis> larvae

Several naturally discovered or laboratory-synthesized pyrrole compounds have insecticidal, acaricidal and microbial properties. The novel sulfanyl 5H-dihydro-pyrrole derivatives exhibit certain antioxidant activities. However, there is a knowledge gap whether these substances are potent grain protectants against stored-product insect pest species. In this context, we evaluated the insecticidal activity of five novel pyrrole derivatives (under the trivial names 3a, 3g, 3l, 3m, 3h), against larvae of Tribolium confusum Jaquelin du Val and Ephestia kuehniella Zeller at different doses (0.1, 1 and 10 ppm), exposure intervals (7, 14 and 21 days or 1, 2, 7, 14, 21 days), temperatures (20, 25 and 30 °C), relative humidity (RH) (55 and 75 %) levels and commodities (wheat, maize, barley). The pyrrole derivative 3a exhibited the highest insecticidal activity, while 3g, 3l, 3m and 3h caused similar mortality against larvae of T. confusum. Apart of the level of efficacy, all tested pyrrole derivatives performed similarly according temperature. We found that increase in temperature increased mortality in the majority of the tested combinations. Generally, the pyrrole derivatives caused the highest mortality levels at 30 °C. The pyrrole derivatives 3a, 3g, 3l and 3m were affected by relative humidity at almost all combinations tested. The 75 % level of RH moderated the efficacy of the pyrrole derivatives, while the 55 % enhanced it. Mortality of T. confusum and E. kuehniella on maize was much lower on treated maize than barley or wheat. However, 100 % control of both species was recorded only on treated barley. The results of the present study indicate that the pyrrole derivatives tested could serve as grain protectants against noxious stored-product insects under certain biotic and abiotic conditions.     

Heartwood extractives from the Amazonian trees <Emphasis Type="Italic">Dipteryx odorata,Hymenaea courbaril</Emphasis>, and <Emphasis Type="Italic">Astronium lecointei</Emphasis> and their antioxidant activities

Heartwood extracts from Amazonian trees cumaru-ferro (Dipteryx odorata), jatoba (Hymenaea courbaril), and guarita (Astronium lecointei) exhibit antioxidant activities comparable with that of α-tocopherol, a well-known antioxidant. This article reports the characterization of the antioxidant compounds in the extracts of the three heartwoods. Silica gel column chromatography of the cumaru-ferro EtOAc extract yielded (−)-(3R)-7,2′,3′-trihydroxy-4′-methoxyisoflavan and (+)-(3R)-8,2′,3′-trihydroxy-7,4′-dimethoxyisoflavan. Silica gel column chromatography followed by preparative high-performance liquid chromatography of the jatoba EtOAc extract yielded (−)-fisetinidol and (+)-trans-taxifolin. Chemical structures were assigned using electron-ionization mass spectrometry, ¹H and ¹³C nuclear magnetic resonance (NMR) spectroscopy including nuclear Overhauser effect spectroscopy (NOESY), as well as optical rotation and circular dichroism. Gas chromatography-mass spectrometry demonstrated that the isolated compounds were predominant in the EtOAc extracts. In the guarita EtOAc extract, catechin and gallic acid were identified by comparing their retention times and mass fragmentation patterns with those of authentic samples. Antioxidant activity determined by the 1,1-diphenyl-2-picrylhydrazyl assay demonstrated that all these compounds had activities comparable with that of α-tocopherol. Part of this report was presented at the 57th Annual Meeting of the Japan Wood Research Society, Hiroshima, August 2007     

Allelopathic effects of <Emphasis Type="Italic">Pinus halepensis</Emphasis> and <Emphasis Type="Italic">Quercus coccifera</Emphasis> on the germination of Mediterranean crop seeds

Agroforestry is a leading alternative for food security and forest conservation. A full understanding of positive and negative, i.e. allelopathic, interactions between crops and forest trees is necessary for producing crops and conserving forests especially within the threatened Mediterranean forest ecosystems. The present study explored the allelopathic effects of green and senescent leaf and soil extracts of two agroforestry trees—Pinus halepensis and Quercus coccifera—on the germination of wheat, barley, lentil, chickpea, and fababean as the major grain crops of Jordan. Results revealed that allelopathic effects reduced seed germination of these crops. Germination reduction reached a maximum of 75% in fababean treated with green extracts of Q. coccifera and differed among crops and extract sources, but not between tree species. Comparing between green and senescent leaf and soil extract, regarding their effect on germination percentage, it was noticed that these effects were similar in some crops and were different in others. Germination responses were generally different between cereals and legumes where cereals tend to be less affected by allelopathic influences than legumes, especially fababean. We suggest using cereals such as wheat and barley in agroforestry practices in the Mediterranean region of Jordan.