Bamboo-Leaf Prickly Ash extract: A potential bio-pesticide against oriental leaf worm, Spodoptera litura (Fabricius) (Lepidoptera: Noctuidae).

Bamboo-Leaf Prickly Ash, Zanthoxylum armatum (Rutaceae) is a versatile and widely distributed plant species in nature. It is an edible plant species, commonly used in daily life for condiments and therapeutic remedies. Besides its bioactive and medicinal properties, different plant parts of the Z. armatum also have insecticidal potential. However, this potential has not been yet determined against many agricultural pests, including leaf worm, Spodoptera litura (Lepidoptera: Noctuidae). In this study, we demonstrated for the first time the contact and oral toxicity and sub-lethal effects (including antifeedent and ovicidal action) of various fractions of pericarp, leaf and seeds of Z. armatum against S. litura. Overall findings revealed that the n-hexane pericarp extract of Z. armatum has strong antifeedent, ovicidal and larvicidal properties against S. litura. Sub-lethal doses of pericarp extract can negatively alter the biology of S. litura. Since n-hexane extract of leaves also has better larvicidal properties, it could also be utilized for the S. litura management during period of unavailability of fruits (or pericarp). Accordingly, the Z. armatum pericarp and leaf extract has tremendous commercial utilization potential for the management of polyphagus pests like S. litura and other related species, which are quite difficult to manage even by chemical pesticides.

Alternating temperatures affect the performance of Trichogramma species.

The environmental compatibility of a biological control agent is an important aspect of successful reduction of agricultural pests. Temperature fluctuations during the day have a strong influence on the performance of laboratory-reared parasitoids. In field conditions, Trichogramma (Hymenoptera: Trichogrammatidae) wasps are exposed to variable temperatures during their development, which has a significant impact on their ability to control pest species. A simulation-based study was undertaken to evaluate the impact of variations in daily temperature on the pest-control abilities of female Trichogramma and their immature progenies. Considering the temperature variability of different agricultural zones of India, five temperature levels ranging from 20ºC to 40ºC were selected for daily short-term heat shocks to the immature progenies and egg-laying females of two major Trichogramma species. Intensity and frequency of thermal shocks showed inverse relationships with adult emergence, fecundity, and longevity of T. chilonis and T. poliae. Parasitoid pupae were found to be more tolerant to temperature variations than eggs and larvae. Fecundity and longevity of parasitoids were significantly reduced under high temperature shocks to egg-laying females. Sex ratio was significantly affected by high temperature shocks to the immature and adult stages. However, the effect was more severe in eggs. A female-biased sex ratio was apparent in both parasitoids throughout the experiment. Overall, daily short-term temperature shocks to different developmental stages of parasitoids showed radical effects on emergence, fecundity, longevity, and sex ratio of the progeny. Therefore, releases of parasitoids should be conducted when they are in their pupal stages during the morning and evening in order to achieve their highest effectiveness for pest management.

Bio-pesticide applications may impair the pollination services and survival of foragers of honey bee, Apis cerana Fabricius in oilseed brassica.

Honey bees and brassica plants are co-evolved and due to the peculiar floral characters, mustard (Brassica juncea) plants are strongly dependent on bees for survival. Mustard is one of the most important oilseeds across the world. Insect pests often cause huge economic losses in mustard and their management, especially during flowering stage is very crucial to achieve maximum yield, although this step often displays undesirable effects on the foraging bees. Effects of synthetic pesticides on bees are widely documented and extensively reported. Although the numbers of pesticides/bio-pesticides are widely used in oilseed brassica's, the reports are mostly focused on neonicotinoids. To identify the bee-friendly pesticides, the study was conducted in two tier approach (i.e. laboratory and field conditions) and determined the potential impacts of widely used biopesticides on Asiatic honey bees, Apis cerana Fabricius. The LC50, LC90 and LD50 were determined for four destructive pests and honey bees, to assess their risk against honey bees. In laboratory studies, LC50's of pesticides to the honey bee was in the order of Beauveria bassiana 1.5L (4.79%) > Bacillus thuriengiensis 8SP (1.67%) > Azadirachtin 0.03 EC (1.64%) > Annonin 1 EC (1.22%) > Spinosad 2.5 SC (0.006%) > Imidacloprid 17.8SL (0.005%). Based on three essential risk assessment criteria's (viz., Selectivity ratio, Probit substitution method (%) and Hazard Ratio/Risk quotient); the Azadirachtin, Anonnin, B. bassiana and Bt var. k were found selective, and slightly to moderately toxic to the honeybee; whereas Spinosad and Imidacloprid was found non-selective and dangerous to the bees. Entomopathogenic fungus, Nomuraea rileyi was found absolutely harmless to the bees. In field studies, the relative abundance, foraging rate and foraging speed of honey bees was significantly affected in different treatments even up to 2 days of spraying. Among bio-pesticides, deterrence/repellent effect was, however, strongly observed in Annonin and Spinosad treatments. Significantly higher yield was obtained in Azadirachtin (1.43 t/ha) and Anonin (1.22 t/ha) treated plots. Except Spinosad, remaining bio-pesticides were found selective to the foraging bees, nevertheless considering the efficiency in pest control and higher yield, Azadirachtin 0.03 EC and Annonin 1 EC could be efficiently used in Integrated Pest cum Pollinator Management Programme (IPPM) in oilseed brassica's. The spraying of Spinosad may be discouraged, especially at flowering time.

Assessing risks of pesticides targeting lepidopteran pests in cruciferous ecosystems to eggs parasitoid, Trichogramma brassicae (Bezdenko).

Lethal and sub lethal effects of fresh and old residues of azadirachtin, spinosad, Bacillus thuringiensis var. kurstaki (Bt var. k), and deltamethrin, were evaluated at their recommended field doses against adult and immature stages of Trichogramma brassicae under in vitro conditions. The experiments were carried out at the Entomology section of Division of Crop Protection, ICAR Research Complex for NEH region, Umiam, Meghalaya, in 2012-2013. The effects of different pesticides were determined by bioassays using the residual film method, the diet contamination method, the pupal dip method and the topical application technique. The four pesticides were found harmful to adult T. brassicae after ingestion, however surface contact bioassays revealed that Bt var. k was the least toxic pesticide. Except Bt var. k, other three pesticides were found harmful also to the immature stages of T. brassicae and significantly affected parasitism potential, adult emergence, longevity of adults, and sex ratio of the progeny. Deltamethrin and azadirachtin were the most harmful, even after 15 days of application. Spinosad was found to be relatively safe to T. brassicae after 15 days of application. As Bt appeared to be the least toxic pesticide for T. brassicae, it could be used for the management of severe infestations of lepidopteran pests in cruciferous ecosystems. If essential, spinosad may be used 15 days after parasitoid release, thus minimizing the chances of parasitoid exposure.

Genetic characterization of Bactrocera fruit flies (Diptera: Tephritidae) from Northeastern India based on DNA barcodes.

The Northeastern region of India, one of the mega biodiversity hot spots has enormous potential for the production of fruits and vegetables. Fruit flies of the genus Bactrocera Macquart are important pests of fruits and vegetables, and one of the limiting factors in successful production of these commodities. The relationship among some of the species is unclear due to their high molecular and morphological similarities. Moreover, due to the significant morphological resemblance between fruit fly species, reliable identification is very difficult task. We genetically characterized 10 fruit fly species of the genus Bactrocera by using standard DNA barcoding region of COI gene. The characterization and identification of eight species were straight forward. This study was unable to establish the molecular identity of Bactrocera sp. 2. Within the 547 bp region of partial COI gene, there were 157 variable sites of which 110 sites were parsimony informative, 153 were synonymous substitutions and 4 were non-synonymous substitutions. The estimate of genetic divergence among the ten species was in the range of 0-21.9% and the pairwise genetic distance of Bactrocera. (Bactrocera) dorsalis (Hendel) with B. (B.) carambolae was only 0.7%. Phylogenetic analysis formed separate clades for fruit and vegetable infesting fruit flies. B. (B.) aethriobasis Hardy, B. (B.) thailandica and B. (B.) tuberculata (Bezzi) have been reported for the first time from the Northeastern India. The information generated from this study would certainly have implications for pest management, taxonomy, quarantine and trade.

Eco-toxicological risk and impact of pesticides on important parasitoids of cabbage butterflies in cruciferous ecosystem.

Eco-toxicological risk and impact of pesticides was estimated on three important parasitoids of butterflies viz., Hyposoter ebeninus, Cotesia glomerata and Pteromalus puparum. Four commonly used pesticides were evaluated using standard protocol (of IOBC/WPRS-group). In laboratory tests, the survival of the female wasps decreased significantly on fresh contact and ingestion of deltamethrin, spinosad and azadirachtin; whereas Bacillus thuringiensis var kurstaki (Btk) was found harmless pesticide. Under semi-field conditions, parasitoid mortality decreased significantly on fresh contact with the pesticides. Although, at 72 h after treatment, spinosad and deltamethrin were found harmful (Class-IV) and azadirachtin was moderately harmful (Class-III), whereas Btk was harmless (Class-I). Furthermore, 15-day-old residues of pesticides (except deltamethrin) were harmless to all parasitoid species under semi-field conditions. Notably, adult emergence and pupal duration in pesticide-treated cocoons were not significantly affected; however, their survival decreased after emergence except in Btk. The contact and oral toxicity trends of the pesticides were almost similar for three species of parasitoid females and pupae; however little variability was observed in toxicity to the host caterpillars parasitized by H. ebeninus (HCPHE) and C. glomerata (HCPCG). In semi-field tests, fresh residues of all the pesticides were harmful to HCPHE and HCPCG. However, action of Btk was slightly delayed and toxicity was rather low for HCPCG. In 15-day-old residues, deltamethrin and azadirachtin were slightly harmful to the parasitized caterpillars, whereas those of Btk and spinosad were harmless. Since, Btk appeared to be safe for parasitoids; it could be used for managing cabbage butterflies in brassicaceous crops.

Complete mitochondrial genome sequence of a phytophagous ladybird beetle, Henosepilachna pusillanima (Mulsant) (Coleoptera: Coccinellidae).

Ladybird beetles are generally considered as agriculturally beneficial insects, but the ladybird beetles in the coleopteran subfamily Epilachninae are phytophagous and major plant feeding pest species which causes severe economic losses to cucurbitaceous and solanaceous crops. Henosepilachna pusillanima (Mulsant) is one of the important pest species of ladybird beetle. In this report, we sequenced and characterized the complete mitochondrial genome of H. pusillanima. For sequencing of the complete mitochondrial genome, we used the Ion Torrent sequencing platform. The complete circular mitochondrial genome of the H. pusillanima was determined to be 16,216 bp long. There were totally 13 protein coding genes, 22 transfer RNA, 2 ribosomal RNA and a control (A + T-rich) region estimated to be 1690 bp. The gene arrangement and orientations of assembled mitogenome were identical to the reported predatory ladybird beetle Coccinella septempunctata L. This is the first completely sequenced coleopteran mitochondrial genome from the beetle subfamily Epilachninae from India. Data generated in this study will benefit future comparative genomics studies for understanding the evolutionary relationships between predatory and phytophagous coccinellid beetles.