The diamondback moth Plutella xylostella: ecological and biological aspects, harmfulness, population control

Data on prevalence, biological and physiological characteristics of the diamondback moth Plutella xylostella (Lepidoptera: Plutellidae) are presented. Pest damage is described. Reasons causing increase in harmfulness and economic importance of the insect are noted. An increase in the number of generations able to develop during growing season and earlier pest emergence are recorded under conditions of Siberian region. Factors contributing to the insect density dynamics, including plant species and variety, entomophagous arthropods and entomopathogenic microorganisms, have been considered. Range of chemical insecticides recommended for diamondback moth management in Russian Federation has been indicated. An increase in resistance to chemicals and certain entomopathogens in P. xylostella populations in different regions of the world has been recorded. Possibility of pheromone traps exploitation for efficient pest detection and monitoring has been established. Perspectives of novel efficient and safe means of pest density regulation have been defined.

Reproduction deep inside wood: a low O 2 and high CO 2 environment promotes egg production by termite queens

Extreme conditions are normal for animals living in harsh environments. These animals adapt to their habitats and can use difficult conditions by default. Organisms living in enclosed spaces, notably termites in decaying wood, experience low O 2 and high CO 2 gas conditions due to limited gas exchange and high insect density. Termite queens, in particular, reproduce in royal chambers deep inside the wood, wherein tens of thousands of individuals engage in social labour. Here, we demonstrate that royal chambers in termite nests have low O 2 and high CO 2 gas concentrations, which enhance egg production by queens. We identified a unique gas condition of royal chambers in the nest of the subterranean termite Reticulitermes speratus , which is characterized by low O 2 (15.75%) and high CO 2 (4.99%) concentrations. Queens showed significantly greater fecundity under the low O 2 and high CO 2 gas conditions in the royal chambers than under ambient gas conditions. Quantitative PCR analysis revealed that the royal chamber gas conditions significantly promoted the expression levels of the vitellogenin genes RsVg1 , RsVg2 and RsVg3 in queens compared with ambient gas conditions. This study highlights the adaptation of animals that live in closed habitats, which are hypoxic and hypercapnic as the result of their own metabolism, so as to have a high fitness in such environmental conditions.

Incidence of spiraling whiteflies Aleurodicus dspersus Russell (Hemiptera: Aleyrodidae) and its natural enemies on guava orchards

Population dynamics of spiraling whitefly and its natural enemies on guava orchards are essential for improvement of existing pest control methods. To find out the seasonal abundance of guava whitefly and its natural enemies and levels of infestations were studied on guava orchards severely infested by A. dispersus. Five guava plants were selected randomly. To determine each stage of the insect density, six leaves comprising upper, middle and lower part of each plant were randomly sampled. Sooty mould infested leaves and presence of natural enemies of A. dispersus were also recorded. The highest number of egg mass (5.0) and nymphs (10.0) per leave were found in the month of September. The highest (0.20%) ladybird beetle, Scymnus sp. (Coccinellidae: Coleoptera) and Encarsia sp. (0.15%) were found in the months of October and January, respectively. The number of leaves infested with sooty mould fungus was estimated highest (93%) during October to January. A. dispersus population was peak in the months of August to January and the associated natural enemies may successfully contribute to the existing pest control methods.J. bio-sci. 24: 67-74, 2016

Impact of Insect Densities Tribolium Castaneum on the Benzoquinone Secretions and Aflatoxins Levels in Wheat Flour During Storage Periods

Objectives: The present study was prepared to investigate the impact of insect density, adult emergence of Tribolium castaneum on the secretion of Benzoquinones (BQs) consist of methyl-1,4-benzoquinone(MBQ) and Ethyl-1,4-Benzoquinone (EBQ), and accumulation of Aflatoxins (AFs) in wheat flour stored at different periods. Methods: Forty grams of wheat flour were put into small glass jars (8 cm diameter and 12 cm length). Then T. castaneum was put in each jars at rates of 10, 20 and 30 unsexed pairs of insect adult. The jars were covered with muslin cloth and the rubber band was fixed to prevent insects to escape. A glass jar without any insects served as the control. The jars lifted on bench in the laboratory for two, three and four months of storage under laboratory temperature conditions (with average 28 ± 20C and 65±5 R.H). The previous design was replicated three times. At the end of each storage period, the jars containing the flour were sieved thoroughly by 40 wire mesh size to separate the insects. The insects have been counted on the other hand wheat flour was prepared to determine MBQ, EBQ and AFs by HPLC methods. Results: The results indicated the levels of EBQ higher than MBQ in all infested samples at all insect densities (No. of insect pairs). The concentrations of MBQ in wheat flour released by ten adult pairs (10P) with the three storage periods two, three and four months were 10.42 ± 0.56, 22.38 ± 3.67, 27.06 ± 6.71µg/g, respectively. These results increased with insect densities to (30p) were 39.67 ± 0.10, 63.58 ± 2.35 and 106.24 ± 7.4 µg/g after storage periods two, three and four months, respectively. In addition to the concentrations of EBQ with (10P) were 67.45 ± 3.64, 98.0 ± 6.1 204.66 ± 5.8 µg/g with storage periods two, three and four months, respectively. In case (30P) the levels of EBQ were 376.7 ± 0.87, 570.1 ± 2.11 and 1558.66 ± 10.88 (µg/g). The highest concentration of the BQs 1664.90 ± 11.43 (µg/g) released by T. castaneum achieved with the highest adult emergence (1021 insect adult) and the highest insect density (30p) at four months storage period. In general, AFs levels enhanced with a period of storage and insect densities. Conclusion: Levels of the BQs (MBQ and EBQ) increased with an increase of storage periods and insect densities. Therefore, the presence of this insect should be prevented in stored wheat flour reducing AFs contamination is possible by storage for short time and prohibit insects which causes an increase temperature of the flour and moisture, all of which promote production of AFs.

`INVENTARISASI JENIS-JENIS SERANGGA ORDO ORTHOPTERA PADA TANAMAN JAGUNG DI DESA KESIMAN-DENPASAR

In Indonesian national economics, maize is a second food source after rice. The production of maize in some aspect is affected by the presence of insect particularly Orthopteran Order. The information of advantage and disadvantage of insects is useful for farmers. This research aimed to determine the species of Orthopteran and it is role to maize plant in the Village Kesiman, Denpasar. This research was conducted from December 2015 to February 2016. Insect was collected using sweeping net accordingly in each plot of maize plants. The plot was square form with the size of 10 m x 25 m. The sample was collected from the maize plant in the Ve phase until physiological maturation phase. in each phase, from 07.00 am until 10.00 am Bali time. Sample was collected for 15 minutes per plot and repeated three times. The insects collected was identified, and the insect density was predicted following Krebs (1989). As many as 242 individual insect which belong to Orthopteran Order was collected. Those belong to 8 families and 25 species. The species were Atractomorpha sp., Orchelimum sp., Phlaeoba sp., Gastrimargus sp., Urnisiella sp., Metaleptea brevicornis, Xenocatantops sp., Scudderia sp., Calolampra sp., Eritettix sp., Platyzoteria sp., Conocephalus strictus, Morabine sp., Acrida sp., Tenodera sp., Stagmomantis sp., Blattela sp., Periplaneta sp., Tettigidea lateralis, Mantis sp., Gryllus sp., and Anaxipha exigua, Tettigidea sp. 2, Tettigidea sp. 1, and unidentified (species x). Families that act as omnivores are Family Blattidae and Grillidae, families that act as herbivores are Pyrgomorphidae, Acrididae, Tettigonidae, Eumastacidae, and Tetrigidae, while families that act as predators are Mantidae. Keyword : maize, orthopteran, insect species, insect role.

Distribution and trophic dynamics of riparian tetragnathid spiders in a large river system

Development and agriculture are increasingly encroaching into riparian areas, with largely unknown effects on nearshore arthropods, which are important components of linked aquatic–terrestrial food webs. To assess the environmental determinants of the distribution and trophic dynamics of riparian spiders of the family Tetragnathidae, we characterised riparian habitat, collected emergent aquatic insects, and surveyed spiders in developed and rural landscapes of the Scioto River system, Ohio, USA, which provided a range of riparian land cover, nearshore vegetation types and habitat complexity. We also estimated the trophic position (TP) of Tetragnathidae and the proportion of energetic and nutritional subsidies derived from benthic algae (EBA) using naturally abundant carbon (C) and nitrogen (N) stable isotopes. Model-selection results revealed that tetragnathid spider density (1.57–3.80individualsm–1) was more sensitive to differences in overhanging vegetation than to those in aquatic food resources (i.e. emergent aquatic insects). Tetragnathidae TP, which averaged 3.16 across all 12 study reaches (range: 2.35–3.98), was largely driven by canopy density, shoreline shape, percentage overhanging vegetation and emergent-insect density. Emergent-insect density was the strongest driver of tetragnathid spider EBA (0.04–0.54, µ=0.24). Our study reinforced the notion that riparian spiders ecologically link aquatic and terrestrial ecosystems. In particular, our results further current understanding of the mechanisms affecting riparian spider distribution and trophic dynamics, particularly in the context of larger stream and river systems, given that the propensity of related research has occurred in small streams.