Test Insects Research Articles

Moringa water extract promising additive to prolong the activity of baculovirus under field-sunlight conditions in Egypt.

Baculoviruses are considered as effective bio pesticides except of being not active under sunlight conditions. The aim of this study is to evaluate the capability of moringa extract to prolong virus activity under Egyptian field conditions especially that Moringa proved to be strong protective material under previous investigation under laboratory conditions the addition of moringa filters were tested on tomato plant foliage. Results are based on leaf bioassay using Spodoptera littoralis test insect and its nuclepolyhedrovirus (SpliNPV) as standard materials. The Original Activity Remaining (OAR) and Lethal Infectivity Time to 50% (LIT50) were estimated after exposure to natural sunlight. cacao and green tea were tested as comparative materials, which proved to be effective as virus protective agent in earlier investigations. The results showed that moringa additive at 10% sustained 50% of virus activity for 193.53 hours and 62.05 and 23.023 hours post application for cacao and green tea; respectively. While virus alone treatment lasts for only 17.551 hours. Moringa generally available, relatively cheap; it also has been tested and proved to be non-toxic, safe, and friendly to the environment. The obtained results showed the activity of moringa water extract in prolonging the virus activity under field application.

Preference of three scarab beetle species to floral cues

The role of floral visual cues was studied in both sexes of three nocturnal scarab beetle species (Holotrichia oblita, Holotrichia parallela, and Anomala corpulenta). Flower patterns were designed using n-petal rose curve and radial gradient tools. Bioassay of plain colored patterns showed that both sexes of H. oblita and H. parallela preferred yellow and white. In contrast, A. corpulenta showed sexual differentiation in preferences. Comparison between given radial gradient patterns and their color components indicated that a radial gradient was necessary in both sexes of H. oblita rather than both sexes of H. parallela to elicit the highest response. Sexual differentiation was found in A. corpulenta. Among 4-, 8-, and 12-petaled patterns, the 4-petaled patterns were most preferred by all of the test insects, regardless of species and sex. Choice assays that provided both odor and visual cues suggest that olfaction may be the primary sensory modality in the three scarab species.

Design and efficacy evaluation of a modern automated controlled atmosphere system for pest management in stored dates

The use of high-pressure carbon dioxide and heating applications has been more popular against stored product insect pests recently. We designed and constructed a modern automated controlled atmosphere system based on carbon dioxide under different pressures and temperature regimes for the management of the red flour beetle (Tribolium castaneum) (RFB) and saw-toothed grain beetle (Oryzaephilus surinamensis) (SGB) infesting stored dates (cv. Sagai). The findings of this study showed that the minimum exposure time that killed 100% of all developmental stages of the two beetles was 30 min at a pressure of 300 kPa and a temperature of 45 °C. This combination was optimal in the consumption of electrical energy and carbon dioxide. Based on the lethal time that killed 50% (LT50) and 95% (LT95) of the test insect population, RFB showed more susceptibility to the treatment than SGB. The optimal combinations of carbon dioxide concentration, pressure, and temperature at minimum exposure time that killed 100% of the test insects have no significant detrimental effects on the essential characteristics related to date quality. The designed prototype of the controlled atmosphere system, based on the pressure of carbon dioxide and heat, proved to be effective against the two target insects in stored dates. The findings encourage further studies for testing and evaluating the system under field conditions at a larger scale.

Host Specificity Tests Reveals New Host of a Global Biological Control Agent Psyllaephagus bliteus (Hymenoptera: Encyrtidae)

Glycaspis brimblecombei (Hemiptera: Aphalaridae) is an invasive, sap-sucking eucalypt pest in various parts of the world. Psyllaephagus bliteus (Hymenoptera: Encyrtidae) was first released as a biological control agent against this pest in California in 2000. Since then, P. bliteus has been found with its insect pest host, with no intentional introduction, in various South American, European and North African countries, and recently South Africa. Here we report on host specificity studies of P. bliteus in South Africa in order to determine potential risks to non-target hosts. Non-target test insects included the only native lerp-forming psyllid in South Africa, Retroacizzia mopani (Hemiptera: Psyllidae), as well as two free-living and one lerp-forming psyllid that are not native but also feed on Eucalyptus species. Psyllaephagus bliteus was monitored during no-choice tests for antennation, probing and oviposition behaviours towards the test insects. In addition, P. bliteus was enclosed on live plants infested with the test insects which were then monitored for offspring of P. bliteus. Retroacizzia mopani and the non-native free-living psyllids were not attacked, but P. bliteus did attack and develop on the non-native lerp psyllid, Spondyliaspis cf. plicatuloides (Hemiptera: Aphalaridae). Choice tests were then undertaken with G. brimblecombei and S. cf. plicatuloides, and G. brimblecombei was found to be the preferred host. The results indicate that the risk of P. bliteus to native insects is low, but that the host range of P. bliteus is not restricted to Glycaspis spp. and Creiis costatus (Hemiptera: Aphalaridae) as previously thought. The host range of P. bliteus may thus include other lerp-forming insects on eucalypts, especially those within the Spondyliaspidinae.

Biocidal Activities of Seed Oils of Jatropha curcas and Moringa oleifera on Development of African Maize Stalk borer, Busseola fusca Fuller (Lepdoptera: Pyralidae)

Laboratory experiment was conducted at the Department of Crop Protection Laboratory, Faculty of Agriculture, Bayero University, Kano, in order to assess the effect of oils obtained from the seeds of Jatropha curcas and Moringa oleifera on African Maize Stalk Borer (Busseola fusca Fuller). The effects of the plant seed oils on larvae mortality, pupae and adult emergence were tested on freshly cut leaves/stem of maize 3-4 cm long) and treated with the prepared plant oils at various concentrations (10, 20, and 30%) and control (0%). The experiment was laid out in a completely randomized design and replicated four times. The results showed that both plant seeds oils were lethal to the developmental stages of B. fusca, causing mortality (21%) to the larvae, and subsequently preventing and/or suppressing pupae (2.08) and adult emergence (1.95). Treatment at 30% concentration was found to be more lethal to all the developmental stages of the test insect. Based on the findings of this study, it is recommended that any of the plant seed oils at 30 % concentration could be used to manage B. fusca.

Development and evaluation of lepidopteran insect resistant jute expressing the fused Bt-Cry1Ab/Ac toxin driven by CaMV35S promoter

The global demand for jute fibres in industrial and commercial applications makes jute (Corchorus sp.) a popular cash crop. Jute is an ideal eco friendly material for packaging and product manufacturing owing to its long, shiny, non-toxic, biodegradable bast fibres and high yield of cellulosic biomass produced per acre in cultivation. In order to match the increasing global demand for jute fibres, sustainable protection of jute cultivation from insect pests is essential. Lepidopteran pest resistant Bt (Bacillus thuringiensis) jute lines were developed by expressing the fused Bt-cry1Ab/Ac gene, driven by the CaMV35S constitutive promoter in the white jute (C. capsularis) cultiver- JRC321 and named as CBT (CaMV35S Bt). Molecular analyses confirmed the single copy integration of the Bt-cry1Ab/Ac gene in the transgenic CBT lines and 0.25 ng/mg of Bt-Cry1Ab/Ac δ-endotoxin production in the leaf tissue. The study involved evaluation of the insect resistance and the level of Bt-cry1Ab/Ac gene expression in different parts (leaf, stem, seed coat, and root) of the CBT lines in comparison with the previously developed, actin1 promoter driven Bt-cry1Ab/Ac gene containing, ABT lines (actin1 Bt). The CBT and ABT (Bt jute) lines were tested against two major jute pests- hairy caterpillars (Spilarctia obliqua) and indigo caterpillars (Spodoptera exigua). The Abbott’s insect mortality was observed for hairy caterpillars and indigo caterpillars on CBT lines as 90.74 % and 76.37 % respectively and on ABT lines as 97.11 % and 80.74 % respectively. Progeny plants of both the CBT and ABT lines showed similar and significant effects of insect resistance on the test insects under bioassay. Quantification of the expression of Bt-cry1Ab/Ac gene transcripts was similar in the leaves of both CBT and ABT lines but for stems, seed coats, and roots, the expression was found to be higher in ABT lines. This study confirmed that ABT lines were superior and more promising than CBT lines for jute pest management. The progeny plants from both CBT and ABT lines were similar to WT plants in terms of agronomic parameters.

Evaluation of plant quality by Corythucha marmorata (Hemiptera: Tingidae) mothers: relationship between oviposition preference and nymphal performance on four sweet potato cultivars and goldenrod

In novel plant–insect relationships, oviposition preference and nymphal performance determine host range evolution. Corythucha marmorata, native to North America and specialist on asteraceous plants, has been reported to exploit sweet potato (Convolvulaceae) in Japan. Here we examined the capability of females to oviposit and of nymphs to grow on both a conventional host (goldenrod, Solidago altissima) and novel hosts (four sweet potato cultivars), of which the test insects had virtually no experience of contact at the population level. We then tested whether female preference and offspring performance were correlated. Nymphal survival and development time were always significantly greater on goldenrod, followed by sweet potato cultivars Caroline Lea, Benisengan, Narutokintoki, and Beniazuma in that order. Female oviposition preferences showed a similar order. On higher-ranked plants, the females accepted the plant faster and had higher fecundity. When goldenrod was included in the analysis, nymphal development time and survival rate were significantly related to preoviposition period. When goldenrod was excluded, nymphal survival rate was still significantly related to preoviposition period. These results support the theory that females lay their eggs on the most suitable host to maximize offspring fitness, even though C. marmorata had no experience with sweet potato cultivars. As C. marmorata is a hemimetabolous insect, in which adults and nymphs have a similar feeding habit and exploit the same habitat, this relationship seems plausible.

Fumigant effect of essential oils against pulse beetle (Callosobruchus chinensis L.) and rice weevil (Sitophilus oryzae L.) in stored products

Objectives: To develop a method to replace the usage of synthetic fumigants in stored product pest management. Methodology: For this purpose, we employed four plant based essential oils namely, Lantana camara (Lantana) oil, Citronella nardus (Citronella) oil, Cinnamomum zeylanicum (Cinnamon) oil and Trachyspermmum copicum (Ajwain) oil and evaluated against pulse beetle, Callosobruchus chinensis L., and rice weevil, Sitophilus oryzae L., for their fumigant toxicity and the weight loss caused by them. The oils of Lantana and Citronella were extracted from leaves, Cinnamon and Ajwain from barks and seeds respectively. Findings: Among the essential oils tested for fumigant toxicity, C. zeylanicum performed better with Lethal Concentration (LC50) of 23.16 and 21.91ml in minimal period of exposure i.e. at 12 h of treatment and found effective against adults of test insects viz., C. chinensis, and S. oryzae respectively. During the maximum period of exposure i.e. at 72 h. the fumigation efficacy of T. copicum was noticed to be the highest (3.43 ml) against adults of C. chinensis whereas C. zeylanicum was found better against S. oryzae (6.19ml). The minimum loss of pulse grains was observed in C. zeylanicum treated at 60 % of 24 h LC50 ; with 7.41 % weight loss. The minimum weight loss was noticed in C. zeylanicum about 60 % of 24 h LC50 with 9.68 per cent against S. oryzae. The fumigant toxicity bioassay revealed that as the exposure period increases, mortality of test insects also found increased i.e. exposure period directly proportional to mortality of insects. Keywords: Coleoptera; essential oils; fumigant toxicity; stored product pests; volatiles

Insecticidal activity of cashew nut shell liquid against sucking pests of cowpea, Vigna unguiculata subsp. sesquipedalis (L.) Verdc.

Cashew nut shell liquid (CNSL), an important agro waste from cashew nut processing factories, was emulsified in water and assayed for insecticidal activity at concentrations ranging from 0.05 to 0.2 % against aphid, Aphis craccivora and pod bug, Riptortus pedestris infesting cowpea, Vigna unguiculata sesquipedalis under laboratory conditions by topical application. CNSL at various concentrations was found to have insecticidal properties against A. craccivora and R. pedestris wherein the speed of kill and efficacy varied with concentration and test insect. CNSL @ 0.1 % with mortality ranging from 95.83 to 100 per cent at 48 hours after treatment (HAT) was found effective against A. craccivora whereas a concentration of 0.2% was required against R. pedestris to achieve similar mortality (96.67 to 100 %) at 72 HAT. CNSL derived from two cashew nut processing methods (drum roasting and steam boiling) did not differ significantly in their insecticidal action. At concentrations of 0.1 and 0.2 %, mortality produced by CNSL was comparable to that of chemical insecticide, thiamethoxam 0.03% and significantly superior to the widely used botanical neem oil @ 2% against A. craccivora and R. pedestris respectively. R. pedestris that survived exposure to CNSL treatments exhibited developmental abnormalities and formation of nymphal adult intermediary indicating its possible insect growth regulatory effect.

The toxicity of neem (Azadirachta indica), citronella (Cymbopogon nardus), castor (Ricinus communis), and clove (Syzygium aromaticum) oil against Spodoptera frugiferda

An important pest in corn plantation recently reported in Indonesia was Spodoptera frugiperda, a polyphagous pest that have a fast spread rate and caused high damage on young corn. One control that able to use is botanical insecticide. This experiment aims to determine the toxicity of neem, jatropha, clove, and citronella oil (concentrations of 0.1% and 0.05%) against S. frugiferda in corn. Tests carried out using the feeding assay or residue on corn leaves (size 5 x 5 cm). Then, the leaf treatment was given to 10 larvae of S. frugiferda (instars 2) for 48 hours. After that, the feed replaced with untreated feed. The test results showed that concentration neem oil of 0.1% caused the highest mortality of S. frugiferda. Neem oil exposure is also able to inhibit the time of larval development, reduce the percentage of feed consumption, and the weight of pupa the S. frugiferda. Other vegetable oils exposure gave lower mortality in the test insects and some treatments were not significantly different from the controls on the parameters of larval development, pupae weight, and percentage of feed consumption. Neem oils showed strong toxicity against S. frugiperda larvae with Lethal Concentration 50 (LC50) of 0.079 % (CI (95%) 0.066 – 0.095%) and LC95 of 0.338% (CI (95%) 0.024-0.567%).

Insecticidal activity of some plant essential oil extracts against Alphitobius diaperinus pest causing Avian influenza

Alphitobius diaperinusis a type of pest insects found in animal feed and chicken manure that the direct contact with chickens causes this pest to be used as a vector for various pathogens like Avian influenza virus. Alphitobius diaperinus control which still using chemical pesticides is dangerous for health and the environment. The study aims to examine the insecticidal activity of some plant essential oil extracts (Mentha piperita, Syzygium aromaticum, Melaleuca leucadendra and Cymbopogon citratus) against Alphitobius diaperinus. Test insects used were adult Alphitobius diaperinus propagated in the laboratory. Tests carried out are insecticidal tests. Observations were made every hour after treatment for seven days. The two-way ANOVA with the Tukey follow-up test were employed to analyze the data. The results revealed that Mentha piperita at the ninth hour and Syzygium aromaticum at the 10 hour showed against Alphitobius diaperinus insecticidal properties. Whereas Cymbopogon citratus and Melaleuca leucadendra did not give a mortality effect for four days. Thus, Mentha piperita and Syzygium aromaticum essential oil extracts can be an environmentally friendly natural pest control for Alphitobius diaperinus.

Potential uses of Lipopolysaccharide and Exopolysaccharide Isolated from Agrobacterium spp.

A gram-negative bacterium, Agrobacterium, synthesizes lipopolysaccharide and exopolysaccharide, both indispensable in establishing complex interactions with plant hosts. These polysaccharides have biocontrol applications. This study intended to determine: 1) LPS potential as insecticide; 2) EPS production capacity. LPSs obtained from Agrobacterium isolates were tested for insecticidal activity against test insects, damaging stored grains. Agrobacterial LPS elicits insect mortalities comparable to Permethrin (standard insecticide). Typical strains (At2, At3 At5, At6) incited 80% mortality of tested insects. EPS yield was quantified at regular intervals under varying physical parameters. Maximum EPS yield of 12.25 g/L was recorded for strain At1. Antibacterial activity of all isolates (before and after UV light exposure) was tested against Gram-positive and Gram-negative reference strains. Agrobacteria exposed to UV light exhibited antibacterial activity against Gram-positive reference strains. Therefore, agrobacterial LPS can be future candidate for biocontrol of insect pests in grain stocks. Moreover, agrobacteria can not only be prospective candidates for industrial scale EPS production but can also potentially help in treating infections by antibiotic resistant Gram-positive bacteria. Hence, same native isolates carry numerous benefits for the community.

Effect of Temperature and Relative Humidity on the Growth and Development of Acridid Grasshopper, Chrotogonus trachypterus Blanchard

Growth and development of acridid grasshopper, Chrotogonus trachypterus Blanchard was greatly influenced by different levels of temperature (20, 25, 30, 35 and 37oC) and relative humidity (40, 60 and 70%). A laboratory study was revealed that temperature between 30-35oC with 60% relative humidity is mostly suitable for life cycle of the test insect. Maximum oviposition period was 54.6±2.21 days at 25oC whereas, maximum hatching percent was recorded at 30oC (90.6±1.18). Average fecundity of a female increased with the increase in temperature up to 35oC (242.1±2.55) but decreased at 37oC. Developmental period of nymphs was longer at 20oC as 94.03±3.45 and 105.3±3.16 days for males and females whereas, nymphs quickly developed at 37oC within 50.3±0.55 and 60.2±2.44 days, respectively. Highest survivability was obtained at 25o and 30oC. Relative humidity ranged from 60-70% gave non-significant differences and found to be most suitable for insect growth. Study of interaction of ecological factors will be helpful in management strategy of the pest and future adaptation behavior and outbreak issues.

Toxicity of Bacillus thuringiensis Berl. KJ3P1 and DLM isolates towards pest of oil palm Oryctes rhinoceros [Coleoptera: Scarabaeidae

Oil palm plants are industrial plants that generate foreign exchange for Indonesia. Some obstacles are leading to production decrease. One of the important pests is Oryctes rhinoceros [Coleoptera: Scarabaeidae]. Both larval and imago stadia attack oil-palm in immature plants [IP] and mature plants [MP]. The method of controlling Oryctes often use chemical insecticides, in which continuously applications will cause residues in the environment and mortality of non-target insects. Therefore it is necessary to find an environmentally friendly control method that is easy, inexpensive and safe for the environment. The use of entomopathogenic bacteria Bacillus thuringiensis is an alternative. The study was aimed to study the toxicity of two B. thuringiensis isolates from the collection of Plant Protection Department, Faculty of Agriculture, Sriwijaya University [KJ3P1 and DLM isolate codes] on mortality of 3rd instar Oryctes larvae. Experiments were conducted at the Entomological Laboratory, Department of Plant Protection, Faculty of Agriculture, Sriwijaya University from March until May 2019. Bioinsecticide-based B. thuringiensis was made with 2 types of growth media, namely: 1] cow’s bio-urine enriched with 5% molasses, and 2]. Rice washing water enriched with 5% molasses. Treatments were included: 1] DLM5 isolate, 2] KJ3P1 isolate, 3] commercial B. thuringiensis and 4]. without treatment [as control]. The test insects used were 25 individuals of 1st instar Oryctes larvae in each treatment. The results showed KJ3PI isolate that propagated in bio-urine media showed the highest production of B. thuringiensis [5.69 x 106 spores/ml], the highest mortality [76% ] and the lowest LT50 value [5.28 days] as well. The use of agricultural and livestock waste as a medium to multiply B. thuringiensis bacteria may produce high cell and spore production and can be used as bioinsecticides to control O. rhinoceros.

Effectiveness of Beauveria bassiana Vuill. isolate on various culture media and its pathogenicity against Tribolium castaneum

One of the selected microbes that has been widely used for production of bioinsecticides is B. bassiana. The fungus is very effective in suppressing larvae of pest insects Lepidoptera and Coleoptera. However, data on the potential of B. bassiana as bioinsecticides against Coleoptera are not widely available in Indonesia. This study aims to determine the effectiveness of B. bassiana against warehouse pests from Coleoptera Tribolium castaneum. Culture of B. bassiana on Potato Dextrose Agar media was propagated on corn media, corn liquid media, PDA media, and rice media. Tribolium castaneum test insects are derived from the remains of rice mills and then kept until imago lay eggs and have a uniform age. Then B. Bassiana was applied to Tribolium castaneum. Observations were made every 24 hours on the mortality of Tribolium castaneum. The results showed that rice media is the best media used for propagation of Beauveria bassiana when viewed from spore density where the average spore density is 12.53 X 106. The fungus isolates that were propagated using liquid corn media, rice media, and corn media were the best isolates that could be used to kill T. castaneum pest in warehouse.

Effectiveness of Entomopathogenic Nematodes against the African White Rice Stem Borer Maliarpha separatella Rag

The efficacy of three entomopathogenic nematodes (EPN) species Steinernema carpocapsae Weiser, Steinernema karii Waturu, Hunt & Reid, Heterorhabdtids indica Poinar, Karunaka & David and two EPN isolates collected from Coastal Kenya (EX MOMBASA) and Rift valley (EX NAKURU) was evaluated against larvae of African white rice stem borer, Maliarpha separatella Rag. The experiment was carried out using no- choice modified filter paper bioassay at KARI-Mwea. Whatman filter paper was substituted with white cotton cloth discs. The activity of the biological agents under study was determined at 25℃ and 65% relative humidity, with concentrations of 50, 100 and 200 infective juveniles (IJs) per one M. separatella third instar larva. The larvae were confined in 60mm plastic petri dishes in darkness as the larvae spend their entire life inside the rice stems. The mortality rate was determined at 24, 48, 72 and 96 hours after application of the nematode suspension. Significant virulence was obtained with all the nematode species at 200 infective juveniles (IJs). There was low mortality at 50 and 100 concentration rates. All the EPNs significantly reduced M. separatella larvae after 48 hours in the following order H. indica> EX NAKURU> S. carpocapsae> EX MOMBASA >S. karii. The number of nematodes from the infected cadavers after 48 hours post infection was H. indica (553), EX –MSA (294), EX-NKU (242), S. karii (168) and S. carpocapsae (157). S. karii took the longest time (96 hours) to kill all the test insects. In conclusion, the study shows that EPNs are effective against M. separatella and could be used within an integrated pest management strategy for the pest. There is need to carry out further studies to determine effective dosages under field conditions.

Bioefficacy evaluation of buprofezin 15% + acephate 35% WP against brown planthopper and yellow stem borer in rice

Brown plant hopper and yellow stem borer emerged as the insect pests having potent adaptability to develop resistance against sole insecticides requesting a demand to formulate a mix formulation with different target specificity and mode of action. Field experiments were conducted during kharif season of 2013 and 2014 in experimental fields of Krishi Vigyan Kendra, Gangavathi to evaluate the efficacy of ready mixed insecticide (buprofezin 15% +acephate 35% WP) @ 1000, 1250 and 1500 ml per ha against BPH (Nilaparvata lugens) and rice yellow stem borer (Scirpophaga incertulas) of Rice. Buprofezin 15% + acephate 35% WP @ 1500 ml per ha was found as best effective insecticide against BPH and YSB during both experimental seasons with highest reduction against the test insects. It was found that buprofezin 15% + acephate 35% WP @ 1500 ml per ha showed significant control over other treatments and were also found to be on par safe with natural enemies and expressing no phytotoxicity.

POTENSI JAMUR ENTOMOPATOGEN Metarhizium anisopliae, Beauveria bassiana dan Streptomyces sp. TERHADAP MORTALITAS Lepidiota stigma PADA TANAMAN TEBU

Tebu merupakan salah satu tanaman yang hanya dapat tumbuh di iklim tropis. Hama dan penyakit tanaman dalam budidaya tidak pernah lepas. Salah satu hama penting tanaman tebu adalah hama uret perusak akar (Lepidiota stigma). Serangan hama tersebut dapat menurunkan hasil produksi tanaman mencapai 50%. Salah satu alternatif terbaik untuk pengendalian hama uret yang aman dan ramah lingkungan dengan menggunakan agensia hayati. Agensia hayati yang digunakan adalah Metarhizium anisopliae, Beauveria bassiana dan Streptomyces sp. Pengembangan agensia hayati untuk pengendali hama, mempunyai potensi dan prospek baik. Hal ini karena bersifat spesifik inang dan tidak berbahaya bagi manusia. Penelitian ini dilakukan untuk mengetahui efektivitas Metarhizium anisopliae, Beauveria bassiana dan Streptomyces sp. terhadap mortalitas Lepidiota stigma. Penelitian ini menggunakan 3 perlakuan dalam Rancangan Acak Lengkap (RAL) dengan masing-masing perlakuan diulang sebanyak 9 kali. Hasil penelitian menunjukkan bahwa selama empat kali pengamatan dengan interval tujuh hari pengamatan. Kemampuan dari ketiga agensia hayati berbeda-beda dalam mematikan serangga uji. Hal ini ditunjukkan dengan persentase mortalitas tertinggi M. anisopliae dengan total mortalitas yaitu 88,89%.

Lipophilic profiling of Sorghum bicolor (L.) Moench seedlings vis-à-vis Chilo partellus (Swinhoe) larvae reveals involvement of biomarkers in sorghum-stem borer interactions

Lipophilic metabolites play important role in the developmental process of insects, however, still there is no clarity on their involvement in plant resistance. Therefore, we carried out the lipophilic profile of host sorghum genotype seedlings and the Chilo partellus (Swinhoe) larvae, to understand the role and contribution of certain lipophilic metabolites in sorghum plant defense against the dreaded pest, spotted stem borer, C. partellus . There were variations in the form of presence or absence, along with significant differences in lipophilic metabolites across sorghum genotypes and the C. partellus larvae. The significantly higher contents of myristic acid, palmitic acid, linoleic acid, linolenic acid, eicosanoic acid and behenic acid in resistant sorghum genotypes; and linolenic acid, methyl 3-methoxytetradecanoate, myristic acid, oleic acid, palmitic acid, palmitoleic acid, lathosterol and squalene in C. partellus larvae were significantly lower than those fed on susceptible genotype, indicating their role in insect-plant biochemical disruptions. Myristic acid, methyl 3-methoxy-tetradecanoate, stearic acid, squalene, fucosterol, hexacontane, tetrapentacontane, palmitic acid, l-(+)-ascorbic acid 2,6-dihexa-decanoate, 2-pentadecanone, 6,10,14-trimethyl, lignoceric acid and stigmasterol in sorghum seedlings contributed to 60 to 100% variability in various biological and resistance parameters of C. partellus . However, myristic acid, linoleic acid, margaric acid, methyl 14-methylhexadecanoate, methyl 3-methoxytetradecanoate, stearic acid, palmitic acid, palmitoleic acid, eicosanoic acid, gamma-ergostenol, cholesterol, lathosterol, squalene, 1-triacontanol and n-pentadecanol in C. partellus larvae contributed to 64 to 100% variability in various biological and resistance parameters of C. partellus . The myristic acid, methyl 3-methoxytetradecanoate, palmitic acid, stearic acid and squalene present in both host plant and the test insect, contributed significantly to explain variability in resistance against C. partellus , thus could be used as biomarkers for sorghum-stem borer interactions.

Chemical composition and insecticidal activity of the essential oils of <i>Crateva Adansonii</i> dc. Leaf on <i>Sitophilus Zeamais</i> and <i>Callosobrunchus Maculatus</i>

This study was conducted to determine the insecticidal activity of essential oil of Crateva adansonii against adult S. zeamaise and C. maculatus. The essential oil was obtained from the leaves of the plant using a Clevenger apparatus and analyzed by gas chromatography and mass spectrometry (GC/MS). The experimental data generated from the insecticidal assay results were analysed using statistical tool (ANOVA). GC/MS analysis revealed the presence of 52 compounds but with a low total yield of volatile fractions (0.1%). The major constituents of the oil were n-hexadecanoic acid (palmitic acid) (14.68%), Phytol (14.21%), 9,12-octadecanoic acid (Z,Z)- (linoleic acid)(5.81%), linalool (5.75%). Insecticidal bioassays showed that Crateva adansonii oil had a strong insecticidal activity on adult test insects they were exposed to at different concentrations and periods. An increase in the exposure time from 24 h to 72 h caused increase in mortality from 35.5% to 100% in S. zeamais and 31.1% to 100% in C. maculatus, respectively. According to these results, Crateva adansonii essential oil can be useful as an alternative for beans and maize protection against C. maculatus and S. zeamais.Key words: Insecticidal Bioassays, C. maculatus, S. zeamais, Crateva adansonii, Essential Oil,