Phospholipase A2 in Salivary Glands Isolated from Tobacco Hornworms, \u3ci\u3eManduca sexta\u3c/i\u3e

We describe a phospholipase A2 (PLA2) associated with the salivary glands of tobacco hornworms, Manduca sexta. This enzyme is able to hydrolyze arachidonic acid from the sn-2 position of PLs. Addition of the calcium chelator, EGTA, or calcium, to the Tris reaction buffer impaired the PLA2 activity, from which we infer the enzyme requires very low concentrations of calcium or perhaps other ions for optimal activity. PLA2 activity was sensitive to protein concentration (highest activity at 25 μg protein per μl), reaction time (optimal at 30 min), buffer pH (optimal at pH 8–10), and reaction temperature (optimal range 18–38°C). The salivary gland PLA2 was sensitive to the site-specific inhibitor, oleyloxyethylphosphorylcholine and stable to freezing at –80°C, but not –20°C. The biological significance of this enzyme may relate to hydrolysis of fatty acid moieties from dietary PLs for absorption by midgut epithelia. This salivary gland enzyme may also be responsible for killing food-borne bacteria

Lethal effect of Turkish diatomaceous earth (Bgn-1 ) agaınst adults of German cockroaches (Blatella germanıca L.): Presentation

In this study, mortality effects of BGN-1 which is local diatomaceous earths, were investigated against adults of German cockroach (Blatella gemanica (L.)) on concrete, ceramic floor tile and laminate flooring. On these three different surfaces, B. germanica adults were exposed to BGN-1 diatomaceous earth at the doses of 2.5, 5, 10, 20 g/m2 along 6 days. In all surface applications of BGN-1 diatomaceous earth, exposure time and dose caused significant effect on mortality rates of B. germanica adults. It was determined that BGN-1 coded Turkish diatomaceous earth has the lowest mortality effect on all application surfaces at the dose of 2.5 g/m2. 2.5 g/m2 BGN-1 caused 100 % mortality after 6 days concrete surface and caused 100 % mortality at the end of the fourth day on ceramic floor tile and laminate flooring. On the other hand, doses of 5 and 10 g/m2 of BGN-1 caused 100% B. germanica mortality on all surfaces at the end of the second day, while the highest dose of 20 g /m2 of BGN-1 reached 100% B. germanica mortality at the end of the first day on all application surfaces. In general, the mortality activity of BGN-1 diatomites against B. germanica adults was found to be similar on all three surfaces. At the end of this study, local diatomaceous earth coded BGN-1 was found to be good alternatives for controlling B. germanica which is a medical pest insect

Naturally existing Beauveria on the surface of stored wheat kernels, and their pathogenicity on Rhyzopertha dominica and Sitophilus oryzae adults: Poster

Entomopathogenic fungi have been investigated to control stored product pests, as an alternative strategy to chemical insecticides. Although many studies evaluated isolates from various sources, few studies surveyed fungi naturally infecting stored product pests, revealing predominantly Beauveria isolates. This study aimed to reveal the amount of Beauveria carried on the surface of stored wheat kernels, and their pathogenicity against Rhyzopertha dominica and Sitophilus oryzae adults. Sixteen wheat samples from different storage facilities in four cities were examined for existence of Beauveria. One-hundred g of wheat was washed in 100 mL of 2% Tween80 solution. After increasing concentration of possible fungi by centrifugation, the liquid was spread on medium with dodine and monitored at 25±2°C. Nine of the isolates were tested for pathogenicity at 500 ppm (w/w) at 25±2°C, 65±5% r.h. in darkness with five replicates. While only four samples did not have Beauveria, others had 17-2992 cfu/100 g wheat. Six samples had 17-50, four samples 150-858, one sample 1625 and one had 2992 cfu/100 g wheat. Mortalities against R. dominica adults ranged between 5-86% and 32-100% in 7 and 14 days, respectively. Mortality of S. oryzae ranged from 3-45% and 8-83% in 7 and 14 days, respectively. This study demonstrated that wheat kernels can naturally carry Beauveria with various levels of pathogenicity. Potential naturally occurring entomopathogenic fungi can be isolated directly from stored commodities to be evaluated as biological control agents for stored product pest control.Entomopathogenic fungi have been investigated to control stored product pests, as an alternative strategy to chemical insecticides. Although many studies evaluated isolates from various sources, few studies surveyed fungi naturally infecting stored product pests, revealing predominantly Beauveria isolates. This study aimed to reveal the amount of Beauveria carried on the surface of stored wheat kernels, and their pathogenicity against Rhyzopertha dominica and Sitophilus oryzae adults. Sixteen wheat samples from different storage facilities in four cities were examined for existence of Beauveria. One-hundred g of wheat was washed in 100 mL of 2% Tween80 solution. After increasing concentration of possible fungi by centrifugation, the liquid was spread on medium with dodine and monitored at 25±2°C. Nine of the isolates were tested for pathogenicity at 500 ppm (w/w) at 25±2°C, 65±5% r.h. in darkness with five replicates. While only four samples did not have Beauveria, others had 17-2992 cfu/100 g wheat. Six samples had 17-50, four samples 150-858, one sample 1625 and one had 2992 cfu/100 g wheat. Mortalities against R. dominica adults ranged between 5-86% and 32-100% in 7 and 14 days, respectively. Mortality of S. oryzae ranged from 3-45% and 8-83% in 7 and 14 days, respectively. This study demonstrated that wheat kernels can naturally carry Beauveria with various levels of pathogenicity. Potential naturally occurring entomopathogenic fungi can be isolated directly from stored commodities to be evaluated as biological control agents for stored product pest control

Efficiency of ozone gas treatment against Plodia interpunctella (Hübner) (Lepidoptera:Pyralidae) (Indianmeal Moth) in hazelnut: Poster

In this study, ozone gas at different concentrations (16.7, 33.3 and 66.6 mg/L) were exposed to all biological stages (egg, larva, pupa and adult) placed at top and bottom of the hazelnut for various exposure periods (2, 4 and 6 hours). In biological tests conducted in presence of hazelnuts, 100% mortalities of all biological stages of P. interpunctella placed at top of the commodity were obtained at tested ozone concentrations and exposure periods while it was easier to kill the adult and pupa stages that the larva and egg stages. While it was possible to kill 100% of the adults and pupae placed at bottom of the commodity at tested ozone concentrations and exposure periods, 100% mortality of the larvae and eggs were not obtained at any of the ozone treatments. Generally, the mortalities of all life stages of P. interpunctella placed at bottom of the commodity for ozone treatments were lower than those placed at top of the commodity. It was easy to kill the pupae and adults of P. interpunctella placed at bottom of the commodity while the ozone treatments resulted in low mortalities of the egg and larvae placed at bottom of the commodity. Just as 100% mortalities of the larva and adult stages were not obtained even at the highest ozone concentration for the longest exposure period. In conclusion, in this study, it was observed that ozone gas only at high concentrations can control all biological stages of P. interpunctella in hazelnut and therefore could have an alternative potential for methyl bromide in quarantine applications in short application period.In this study, ozone gas at different concentrations (16.7, 33.3 and 66.6 mg/L) were exposed to all biological stages (egg, larva, pupa and adult) placed at top and bottom of the hazelnut for various exposure periods (2, 4 and 6 hours). In biological tests conducted in presence of hazelnuts, 100% mortalities of all biological stages of P. interpunctella placed at top of the commodity were obtained at tested ozone concentrations and exposure periods while it was easier to kill the adult and pupa stages that the larva and egg stages. While it was possible to kill 100% of the adults and pupae placed at bottom of the commodity at tested ozone concentrations and exposure periods, 100% mortality of the larvae and eggs were not obtained at any of the ozone treatments. Generally, the mortalities of all life stages of P. interpunctella placed at bottom of the commodity for ozone treatments were lower than those placed at top of the commodity. It was easy to kill the pupae and adults of P. interpunctella placed at bottom of the commodity while the ozone treatments resulted in low mortalities of the egg and larvae placed at bottom of the commodity. Just as 100% mortalities of the larva and adult stages were not obtained even at the highest ozone concentration for the longest exposure period. In conclusion, in this study, it was observed that ozone gas only at high concentrations can control all biological stages of P. interpunctella in hazelnut and therefore could have an alternative potential for methyl bromide in quarantine applications in short application period

Preliminary Checking of Some Turkish Diatomaceous Earth Similarities with Commercial Diatomaceous Earths under Scanning Electron Microscope (SEM)

Diatoms are dead bodies of unicellular algae’s and made up of fossilized diatoms in aquatic ecosystems. Diatomaceous earth (DE) is a dust varying in color depending on composition, from white-grey to yellow to red and active ingredient is amorphous silicon dioxide. DEs are commonly used for purification of water, the purification of juices, separation of various oils and chemicals and also used as an insecticide. Mode of action as insecticide which damage occurs to the insects protective wax coat on the cuticle, mostly by sorption and to a lesser degree by abrasion, or both. The result is the loss of water from the insect's body through desiccation resulting in death. The efficacy of DE against insects depends on different physical and morphological characteristics of the diatoms. In present study, image properties of 10 different Turkish DE samples under Scanning Electron Microscope (SEM) were checked and compared similarities with commercial DEs, namely Protector, SilicoSec, Insecto and Pyrisec. SEM image analysis indicated that there were variations in shape and size of dead bodies of diatoms in Turkish and commercial DEs. The shapes of dead bodies of diatoms in Turkish local DE’s named as CBN and BGN were found very similar with those in commercial DE, Silicosec. Local DE coded as DC has a round shape and looks similar to commercial DE of Pyrisec while local DE coded as CAN has triangle shape and its shape was different from those of all other DE samples

The biosynthesis and actions of prostaglandins in insect immune tissues

I report on the biosynthesis and actions of prostaglandins (PGs) in insect immune tissues. PGs, oxygenated metabolites of arachidonic acid, are important mediators of insect cellular defense reactions to infections. While PGs and PG biosynthesis have been recorded in a few insect tissues, there remains a large lacuna in our understanding of PG biosynthesis in insect tissues. Chapters 2 and 3 add new data on PG biosynthesis by fat body (a major immune tissue) from larvae of true armyworm, Pseudaletia unipuncta, and the tenebrionid beetle, Zophobas atratus. Fat bodies from both species produced four PGs, PGA2, PGD2, PGE 2 and PGF2α. PGA2 and PGE2 were the predominant products in true armyworm fat body whereas PGA2 and PGF2α were predominant products in beetle fat body. Indomethacin and naproxin effectively inhibited PG biosynthesis in both fat body preparations. Unlike the tenebrionid beetle and other invertebrates (as well as mammalian systems) studied to date, the true armyworm fat body did not require the presence of the usual exogenous co-factors (reduced glutathione and hemoglobin) for optimal PG biosynthesis. I infer that, as seen in most animals, these two insect species are competent to biosynthesize PGs, although we can not yet outline the general principles of PG biosynthesis in insects. In mammalian systems, PGs influence cells through their interactions with specific PG receptor sites. Here, I also report the first biochemical characterization of an insect PG receptor in hemocytes prepared from tobacco hornworms, Manduca sexta. The binding of (3H)PGE 2 was saturable and specific. Mathematical analysis indicate the presence of a single population of PGE2 binding sites with a KD approximately 35 pmol/mg protein and Bmax approximately 7.5 fmol/mg protein. The influence of purine nucleotides on binding suggests these are functional G protein coupled binding sites. I infer from these results that the mechanism of PG action in insect cellular immune physiology involves specific G protein couple PG receptors. This research marks a meaningful advance in our understanding of PG biosynthesis and actions in insect immunity

Zararlı böceklerin mücadelesinde böcek büyüme düzenleyicileri

Büyüme düzenleyici özellikleri olan insektisitler, biyokimyasal yollarla büyüme ve gelişme için gerekli olan sistemleri düzenliyerek veya önleyerek böceklerde etkili olurlar. Bu maddeler hücrelerin ve organların gelişiminde etkili olan hormonların anormal çalışmasına neden olurlar ve böylece, hedef alınan böcekleri öldürürler. Diğer bazı böceklerde de, gelişme dönemlerinin uzaması sonucu doğal düşmanlar ve çevre koşulları gibi diğer ölüm faktörleri nedeniyle ölümler meydana gelir. Böcek büyüme düzenleyicileri ya sentetik kimyasalların karışımından ya da değişik bitkilerden doğal olarak elde edilmektedir. Günümüzde, böcekler üzerinde etkili olan ve böcek hormonlarını taklit eden bu maddelerin kimyasal yapıları çalışılmakta ve zararlı böceklere karşı yeni maddelerin geliştirilmesinde kullanılmaktadır. Ancak, omurgalılar ve omurgasızlar arasındaki biyokimyasal benzerlikler bu maddelerin geliştirilmesini sınırlandırmaktadır. Zararlı böcek mücadelesinde kullanılan kimyasal bileşimlerin meydana getirdiği çevre kirliliği bu maddeleri üreten sanayiyi engellemekte ve dolayısıyla çevre açısından daha az zararlı kimyasal bileşimlerin üretin çalışmalarına geçilmesine neden olmaktadır.Insecticides with growth regulating properties (IGR) may adversely affect insects by regulating or inhibiting specific biochemical pathways or processes essential for insect growth and development. Some insects exposed to such compounds may die due to abnormal regulation of hormone-mediated cell or organ development. Other insects may die either from a prolonged exposure at the developmental stage to other mortality factors (susceptibility to natural enemies, environmental conditions etc) or from an abnormal termination of a developmental stage itself. Insect growth regulators may come from a blend of synthetic chemicals or from other natural sources, such as plants. The chemical composition of hormones indigenous to insects is now being studied and used as a basis for developing analogs or mimics against insects. The similarities, however, in certain aspects of biochemistry among vertebrates and invertebrates may result in the limited development of IGRs. Environmental contamination also creates a hurdle as well as a challenge for industries to develop compounds that provide a more environmentally or ecologically sound insect pest control

An Entomopathogenic Bacterium, \u3ci\u3eXenorhabdus nematophila\u3c/i\u3e, Inhibits Hemocytic Phospholipase A2 (PLA2) in Tobacco Hornworms, \u3ci\u3eManduca sexta\u3c/i\u3e

The entomopathogenic bacterium, Xenorhabdus nematophila, induces immunodepression in target insects and finally leads to lethal septicemia of the infected hosts. A hypothesis has been raised that the bacteria inhibit eicosanoid-biosynthesis pathway to interrupt immune signaling of the infected hosts. Here, we show direct evidence that X. nematophila inhibits the activity of phospholipase A2 (PLA2), the initial step in the eicosanoid-biosynthesis pathway. Inhibition of PLA2 was dependent on both incubation time with X. nematophila and the bacterial concentration in in vitro PLA2 preparations of Manduca sexta hemocytes. While living bacteria inhibited PLA2 activity, heat-killed X. nematophila rather increased PLA2 activity. X. nematophila secreted PLA2 inhibitor(s), which were detected in the organic, but not aqueous, extract of the bacterial culture medium. The PLA2 inhibitory activity of the organic extract was lost after heat treatment. These results clearly indicate that X. nematophila inhibits PLA2 activity and thereby inhibits eicosanoid biosynthesis, which leads to immunodepression of the infected hosts