Biocidal potential of clove oils against Aedes albopictus – A comparative study

The first phase of the study involved evaluation of leaf and bud oils of clove, Syzygium aromaticum for their biocidal (i.e. ovicidal and larvicidal) activity against Aedes albopictus. Eggs and fourth instar larvae were exposed to different concentrations of the oils to investigate their comparative efficacy against the target mosquito species. In the second phase of the study, biocidal activity of ‘test formulation’ derived from the leaf oil and commercial mosquitocide, Prallethrin were estimated by thesame method to compare the efficacy of the former with popular mosquitocides. Mortality data were analyzed by a computerized Log-Probit analysis (StatsDirect). Ovicidal assay of the oil samples recorded EC50 values of 0.37 and 2.0 mg/ml respectively for leaf and bud oil. Larvicidal assay showed LC50 and LC95 values of leaf oil as 5.3 and 7.03 mg/ml respectively, while bud oil recorded LC50 and LC95 values of 17.84 and 23.99 mg/ml, respectively. The ‘test formulation’ recorded EC50 value of 1.63 mg/ml, LC50 of 3.67 mg/ml and LC95 of 13.49 mg/ml respectively, indicating levels comparable to that of prallethrin. Third phase of the study involved chemical characterization of the oil samples using GC-MS.Eugenol constituted the major component of both the oils. The study demonstrated the potential of clove oil as a biocide against A. albopictus and warrants further standardization of the ‘test formulation

Incidence of cetonid beetles, Protaetia alboguttata (Vigors) on karonda, Carissa carandas

Severe infestation of cetonid beetles, Protaetia alboguttata (Vigors) has been noticed on karonda at the experimental station of Indian Institute of Horticultural Research, Bengaluru during the year 2013. The mean damage on the ripe fruits was found to be 22.40+2.50% with a range of 15.00 – 30.00%. Considering the polyphagy of cetoniids, these beetles can pose direct threat to the cultivation of karonda

A novel protein-based fruit fly trap in melon flies Bactrocera cucurbitae for effective pest control management

ACKNOWLE DGE MENTSThis study was carried out in collaboration with the Indian Gherkin Export Association (IGEA). We would like to thank anonymous re-viewers and the editors for useful comments on the manuscript. NN conducted this work during her NERC QUADRAT REP program (NE/S007377/1) in JM's lab. JM and AWM are supported by a BBSRC grant (BB/V015249/1).Peer reviewedPublisher PD

Overlooked Scents: Chemical Profile of Soma, Volatile Emissions and Trails of the Green Tree Ant, Oecophylla smaragdina

The green tree ant, Oecophylla smaragdina, is one of only two recognized species of weaver ants. While the identity and functions of chemicals produced and emitted by its congener O. longinoda have been studied quite extensively and serve as a valuable model in chemical ecology research, little comparable information is available about O. smaragdina. Although some analyses of chemicals produced and emitted by O. smaragdina have been reported, the literature is fragmentary and incomplete for this species. To address this knowledge gap, and to enable comparisons in the chemical ecology of the two weaver ant species, we here describe diverse chemicals from the cuticle, Dufour’s glands, poison glands, head, headspace volatiles, and trails of O. smaragdina

Computational reverse chemical ecology: Virtual screening and predicting behaviorally active semiochemicals for Bactrocera dorsalis

BACKGROUND: Semiochemical is a generic term used for a chemical substance that influences the behaviour of an organism. It is a common term used in the field of chemical ecology to encompass pheromones, allomones, kairomones, attractants and repellents. Insects have mastered the art of using semiochemicals as communication signals and rely on them to find mates, host or habitat. This dependency of insects on semiochemicals has allowed chemical ecologists to develop environment friendly pest management strategies. However, discovering semiochemicals is a laborious process that involves a plethora of behavioural and analytical techniques, making it expansively time consuming. Recently, reverse chemical ecology approach using odorant binding proteins (OBPs) as target for elucidating behaviourally active compounds is gaining eminence. In this scenario, we describe a “computational reverse chemical ecology” approach for rapid screening of potential semiochemicals. RESULTS: We illustrate the high prediction accuracy of our computational method. We screened 25 semiochemicals for their binding potential to a GOBP of B. dorsalis using molecular docking (in silico) and molecular dynamics. Parallely, compounds were subjected to fluorescent quenching assays (Experimental). The correlation between in silico and experimental data were significant (r(2) = 0.9408; P < 0.0001). Further, predicted compounds were subjected to behavioral bioassays and were found to be highly attractive to insects. CONCLUSIONS: The present study provides a unique methodology for rapid screening and predicting behaviorally active semiochemicals. This methodology may be developed as a viable approach for prospecting active semiochemicals for pest control, which otherwise is a laborious process

Ovicidal and larvicidal activities of <i>Cyperus giganteus</i> Vahl and <i>Cyperus rotundus</i> Linn. essential oils against <i>Aedes albopictus</i> (Skuse)

416-419The ovicidal and larvicidal efficacy of essential oils extracted from the tubers of Cyperus giganteus Vahl and Cyperus rotundus Linn. was studied on eggs and fourth instar larvae of Aedes albopictus (Skuse). The eggs and larvae were exposed to serial concentration of the oils ranging from 5-150 ppm and kept under observation for 24 h. Both the oils showed remarkable ovicidal and larvicidal activities indicated by EC50 values of 50 and LC90 values of . The results obtained suggest that the essential oils of these Cyperus species can serve as a potential source of natural mosquitocidal agents.</span

Bacteriostatic potential of <i style="">Argemone mexicana</i> Linn. against enteropathogenic bacteria

338-341Bacteriostatic efficacy of 16 crude extracts derived from different parts of Argemone mexicana Linn. (Papaveraceae) has been analyzed on enteropathogenic bacteria such as Klebsiella oxytoca, Vibrio damsella, Enterobacter aerogenes and Escherichia coli. The bacteriostatic efficacy was elucidated using single disc diffusion method. The minimum inhibitory concentration (MIC) of the extracts showing higher efficacy against the test organisms was determined. The MICs of acetone extract of seed and aqueous extract of leaf on different bacteria tested were found to be between 0.005-0.02 mg/disc

Evaluation of synthetic oviposition stimulants to enhance egg collection of the oriental fruit fly, Bactrocera dorsalis (Diptera: Tephritidae)

Tephritid flies are pests of horticultural importance throughout the globe. The oriental fruit fly, Bactrocera dorsalis (Hendel), is particularly feared because it attacks many commercial fruits and vegetables causing huge economic losses. The sterile insect technique (SIT) can be an effective, target-specific and economically feasible control method. However, implementation of SIT depends on mass production of high-quality insects. Production of superior quality eggs is of foremost importance in insect mass production. However, present protocols make use of fruit juices or fruit domes that attract saprophytic insects or microorganisms, reducing the quality of eggs. Furthermore, fermentation of juices is known to decrease oviposition efficiency, and daily sanitation of oviposition devices is required. Here, in a laboratory-scale study, we evaluate the effectiveness of four synthetic oviposition stimulants (OS) of B. dorsalis for egg production in dual choice tests, using oviposition devices similar to those used in mass rearing. Results indicated that γ-octalactone, benzothiazole, octen-3-ol and ethyl tiglate significantly increased egg laying compared to controls (water). Of these, γ-octalactone was particularly effective and elicited a 263-fold increase in oviposition on treated oviposition devices compared to control. Our findings demonstrate the potential of using OSs to improve the efficiency and cost effectiveness of mass production of B. dorsalis