Anti‐feeding and insecticidal efficacy of a topical administration of dinotefuran–pyriproxyfen–permethrin spot‐on (Vectra® 3D) on mice against Stegomyia albopicta (= Aedes albopictus)

An ectoparasiticide combining three active ingredients [dinotefuran, permethrin and pyriproxyfen (DPP)] was used in mice in an experiment designed to evaluate its anti‐feeding and insecticidal efficacy against Stegomyia albopicta (= Aedes albopictus) (Diptera: Culicidae) mosquitoes. Twenty‐two adult mice were randomly allocated into two groups consisting of an untreated control group and a DPP‐treated group. Mice were exposed individually for 1 h to a mean ± standard deviation of 27 ± 2 starved female mosquitoes on days 1, 7, 14, 21 and 28 post‐treatment. At the end of the exposure (1 h), mosquitoes were assessed for immediate survival and engorgement status. Additionally, live mosquitoes in both groups were incubated separately and observed for mortality at 24 h after the end of the exposure. The anti‐feeding efficacy of DPP after the 1‐h exposure period was 99.2, 100, 98.0, 89.3 and 87.4% at 1, 7, 14, 21 and 28 days, respectively. Levels of insecticidal efficacy evaluated at 1 h and 24 h after exposure on days 1, 7, 14, 21 and 28 were 36.7, 28.9, 30.8, 23.1 and 11.9%, and 68.4, 45.0, 43.3, 37.9 and 19.9%, respectively. Based on the mouse model, the present study demonstrates that the DPP combination has significant anti‐feeding and insecticidal efficacy against S. albopicta for at least 4 weeks.     

Insecticidal and antifeeding activity of Perilla frutescens‐derived material against the diamondback moth,Plutella xylostella L

Insecticidal and antifeeding activities against Plutella xylostella were observed using whole‐plant‐derived Perilla frutescens material. The active ingredient in P. frutescens was identified by spectroscopic analysis as the sesquiterpenoid α‐farnesene, which showed insecticidal activity against third‐instar larva of P. xylostella in a leaf‐dipping bioassay based on 24‐h LD₅₀ values (LD₅₀ = 53.7 ppm). The feeding inhibition rate of α‐farnesene was 82.98% against P. xylostella at 10 ppm, and the antifeeding responses were determined using an oscilloscope to detect electrophysiological responses. The electrophysiological responses of the medial styloconic sensillum (MSS) were approximately 7‐fold more sensitive at 100 ppm than those of the lateral styloconic sensillum (LSS). These results suggest that the insecticidal and antifeeding effect of α‐farnesene, which is a P. frutescens‐derived material, can be used as a potential control agent for P. xylostella.     

Comparison of insecticidal paint and deltamethrin against Triatoma infestans (Hemiptera: Reduviidae) feeding and mortality in simulated natural conditions

The vector of Chagas disease, Triatoma infestans, is largely controlled by the household application of pyrethroid insecticides. Because effective, large‐scale insecticide application is costly and necessitates numerous trained personnel, alternative control techniques are badly needed. We compared the residual effect of organophosphate‐based insecticidal paint (Inesfly 5A IGR? (I5A)) to standard deltamethrin, and a negative control, against T. infestans in a simulated natural environment. We evaluated mortality, knockdown, and ability to take a blood meal among 5^th instar nymphs. I5A paint caused significantly greater mortality at time points up to nine months compared to deltamethrin (Fisher's Exact Test, p < 0.01 in all instances). A year following application, mortality among nymphs in the I5A was similar to those in the deltamethrin (χ2 = 0.76, df=1, p < 0.76). At months 0 and 1 after application, fewer nymphs exposed to deltamethrin took a blood meal compared to insects exposed to paint (Fisher's Exact Tests, p < 0.01 and p < 0.01, respectively). Insecticidal paint may provide an easily‐applied means of protection against vectors of Chagas disease.     

Toxicity of Carum copticum essential oil‐loaded nanogel against Sitophilus granarius and Tribolium confusum

Myristic acid–chitosan (MA‐chitosan) nanogels were synthesized with the technique of self‐assembly and loaded with Carum copticum (L.) essential oil. Scanning electron microscopy (SEM) study indicated nanogels with smooth surfaces and near spherical appearance, and according to transmission electron microscopy (TEM) image, core–shell stricter of nanogels was reported. Subsequently, fumigant toxicity of C. copticum oil and oil‐loaded nanogels was assessed against Sitophilus granarius (L.) and Tribolium confusum Jacquelin du Val. Adults were exposed to different concentrations of the oil and oil‐loaded nanogels at 27 ± 1°C and 55 ± 5% r.h. in continuous darkness. The mortality was counted after 3, 6, 10, 24 and 48 h of exposure. Mortality increased with increasing concentration levels. Fumigant toxicity of oil‐loaded nanogels was significantly more than the oil even after 48 h. According to the findings, oil‐loaded nanogels were 8.9‐ and 3.7‐fold more toxic than the oil against S. granarius and T. confusum, respectively. The persistence of oil and oil‐loaded nanogels was also investigated over period of time. Oil‐loaded nanogels lost the insecticidal effectiveness after 21 days post‐application for S. granarius and 33 days in the case of T. confusum, while the efficacy of oil decreased in the early days of application. Chemical composition of C. copticum essential oil was measured, and six components were identified. Thymol, ρ‐cymene and γ‐terpinolene were the major components of the oil. The essential oil‐loaded nanogels may have potential to be used as an alternative to synthetic insecticides for stored products protection. However, more research is necessary to improve the findings.     

Feed‐through insecticides for the control of the sand fly Phlebotomus argentipes

Three rodent feed‐through studies were conducted to evaluate the efficacy of insecticides to control Phlebotomus argentipes (Diptera: Psychodidae). The initial test evaluated diflubenzuron, eprinomectin, fipronil and ivermectin as feed‐through treatments in Rattus rattus (Rodentia: Muridae). In the preliminary trial, all four insecticides yielded 100% mortality of P. argentipes larvae within 20 days of exposure to treated rodent faeces. Based upon the initial results, fipronil was evaluated further as a feed‐through utilizing Bandicota bengalensis (Rodentia: Muridae). The B. bengalensis trial evaluated fipronil against both adult and larval sandflies at 250 p.p.m., 100 p.p.m. and 50 p.p.m. The results showed the fipronil treatment to have 100% efficacy against larvae up to 20 days post‐treatment and over 74% efficacy against adult sandflies presented with B. bengalensis faeces up to 10 days post‐treatment at all three dosage levels. The results of the three studies suggest that all four insecticides may be useful tools with which to control Leishmania vector populations.     

Snowdrop and wheatgerm lectins and avidin as antimetabolites for the control of sugarcane whitegrubs

Snowdrop and wheatgerm lectins were found to be insecticidal and growth inhibiting dietary proteins for larvae of the sugarcane whitegrub Antitrogus parvulus. At concentrations as low as 0.5 mg of snowdrop lectin per gram of semi-artificial diet, growth was inhibited by 21 days of feeding and significant mortality was apparent by 28 days. Wheatgerm lectin was active at similar concentrations, although expression of the effects was slower. Avidin was found to be a growth inhibiting dietary protein for larvae of Antitrogus consanguineus. At levels as low as 0.01 mg g^-1 of diet, growth was inhibited by 28 days of feeding. Avidin caused no significant mortality after 35 days of feeding. Snowdrop and wheatgerm lectins and avidin are insect growth-inhibiting proteins whose genes potentially could be manipulated into sugarcane and improve host-plant resistance to whitegrubs.     

Effects of chronic exposures of selected heavy metals on the glutathione S-transferase activity of freshwater snails Lymnaea natalensis in Zimbabwe

The effect of the heavy metals (cadmium, copper, mercury and lead) on snail glutathione S-transferase (GST) was investigated in 2015. Groups of Lymnaea natalensis snails were exposed to heavy metals for 28 days at concentrations reportedly found in the Mguza Dam. Water and food were changed daily. Samples were collected at days 1, 7, 14, 21 and 28 post exposure. Inhibition of GST activity, following cadmium exposures, ranged between 58 and 60%, with a decrease of 30% on day 28. When snails were exposed to copper, inhibition significantly decreased by 16%, 29%, 49% and 72% inhibition when tested on days 1, 7, 14 and 21, respectively. Inhibition on day 28 was 44%. Mercury exposures resulted in significant increases in GST inhibition, namely, 47%, 62% and 79% inhibition on days 1, 7 and 14, respectively. Inhibition on day 21 was 82%, whereas on day 28 it was significantly lower, at 29%. Concerning lead exposures, inhibition levels on day 1, 7 and 21 had mean inhibition of 60%. Inhibition on days 14 and 28 was significantly lower, with a mean inhibition of 30%. These results suggest that chronic exposures could inhibit GST activity for a certain period, after which inhibition is reduced, possibly as a result of adaptation.     

Effects of palmitate and oleate on the respiratory quotient during acute feeding

Objective: Using tracers, we showed, over 9 hours, that palmitic acid (PA) is oxidized at a lower rate than oleic acid (OA). Our subsequent clinical trial showed that enriching the diet for 28 days with PA, relative to OA, lowered fatty acid (FA) oxidation. However, because this conclusion was based on indirect calorimetry for 7 hours after a test meal, transient differences in the kinetics of oxidation of OA and PA could explain these results. Thus, we hypothesized that increasing PA vs. OA would decrease FA oxidation during the first day of feeding the diets. Research Methods and Procedures: A double‐masked trial was conducted in 20 adults, who, after a baseline diet, were randomized to one of two experimental formula diets: high (HI) OA (PA = 1.7% kcal, OA = 31.4% kcal; N = 11) or HI PA (PA = 16.8% kcal, OA = 16.4% kcal; N = 9). Respiratory quotient (RQ) was measured over the first 14 hours of feeding the experimental diets (7:00 am to 9:00 pm ). To determine whether these subjects were representative of the subjects in the previous trial, we assessed RQ 28 days after beginning either diet. Results: During the first 14 hours of feeding the diets, time (p = 0.026) but not diet group had an effect on the difference between the RQ post‐feeding and the fasting pre‐value. However, RQ in the fed state was significantly higher in the HI PA group after 28 days of feeding. Discussion: Chronically increasing dietary PA for 28 days, but not acute meal feeding, lowers total FA oxidation.     

Insecticidal activity of garlic juice in two dipteran pests

Abstract

• 1 Botanical products excluding pyrethroids constitute a small, but growing portion of the U.K. pesticides market. With increasing legislative pressure upon chemical pesticides such as organophosphates, interest in this sector is increasing steadily.
• 2 Garlic Allium sativum L. juices and extracts form the basis of several commercially available pest control products, but the performance of these products is variable, possibly due to lack of quality control upon batches of materials in the manufacturing process.
• 3 Some garlic products designed for use in the food industry are subjected to rigorous batch‐control to ensure organoleptic consistency. We studied the insecticidal efficacy of a commercially produced food grade garlic juice using two target dipteran pests, Delia radicum (L.) and Musca domestica L.
• 4 Exposure of the two species to different concentrations of garlic juice revealed variability in insecticidal effect across life stages. LC₅₀ values recorded for D. radicum were: eggs (7‐day exposure) 0.8%; larvae (24‐h exposure) 26.4%; larvae (48‐h exposure) 6.8%; and adults (24‐h exposure) 0.4%. LC₅₀ values recorded for M. domestica were: eggs (7‐day exposure) 1.6%; larvae (24‐h exposure) 10.1%; larvae (24‐h exposure) 4.5%; and adults (24‐h exposure) 2.2%.
• 5 Mortality rates caused by the garlic juice were comparable with those obtained with the organophosphate pesticide Birlane^®, indicating parity of effect at various concentrations depending on life stage.
• 6 We conclude that this product may provide an effective, naturally‐derived insecticide for use in agricultural systems against dipteran pests.

     

Purification of the Cry1Ac protein of Bacillus thuringiensis and assessment against the Plutella xylostella and soil microbial community

The insecticidal toxin gene of Bacillus thuringiensis (Bt) is the most commonly used to develop insect‐resistant living modified organisms (LMOs). Insecticidal proteins produced in transgenic plants are released into the soil from the roots. In this study, possible effects of crystal 1Ac (Cry1Ac) protein on the soil microbial community in Korea were studied. To purify the insoluble Cry1Ac protein expressing Escherichia coli cells, we performed repeated sonication and PBS washing of the insoluble part and Cry1Ac protein was isolated in soluble form from the insoluble form using 100 mM Na₂CO₃ buffer (pH 9.6) without affinity bead. Also, size‐exclusion chromatography (SEC) was performed to increase the purity of the isolated Cry1Ac protein. The final protein product was identified as Cry1Ac protein through MALDI‐TOF. Insecticidal activity of Cry1Ac protein was demonstrated through the death of Plutella xylostella treated with Cry1Ac protein. Purely isolated Cry1Ac protein showed the same insecticidal activity as Cry1Ac expressed in LM crops. To investigate the change of soil microbial distribution using maize field soils treated with Cry1Ac protein, we isolated high quality metagenomic DNAs from buffer‐ and Cry1Ac protein‐treated soil groups, and analyzed the distribution of soil microorganisms through next‐generation sequencing (NGS) analysis. NGS results showed a similar microbial distribution in both buffer‐ and Cry1Ac protein‐treated samples. These results suggest a useful risk assessment method for domestic targeted insect and soil microorganisms using the Cry1Ac protein.     

Persistence of enterohaemorrhagic and nonpathogenic E. coli on spinach leaves and in rhizosphere soil*

Aims: Survival of Escherichia coli O157:H7 and nonpathogenic E. coli on spinach leaves and in organic soil while growing spinach in a growth chamber was investigated. Methods and Results: Spinach plants were maintained in the growth chamber at 20°C (14 h) and 18°C (10 h) settings at 60% relative humidity. Five separate inocula, each containing one strain of E. coli O157:H7 and one nonpathogenic E. coli isolate were applied to individual 4‐week‐old spinach plants (cultivar ‘Whale’) grown in sandy soil. Leaf and soil inocula consisted of 100 μl, in 5 μl droplets, on the upper side of leaves resulting in 6·5 log CFU plant^?1 and 1 ml in soil, resulting in 6·5 log CFU 200 g^?1 soil per plant. Four replicates of each plant shoot and soil sample per inoculum were analysed on day 1 and every 7 days for 28 days for E. coli O157:H7 and nonpathogenic E. coli (by MPN) and for heterotrophic plate counts (HPC). Escherichia coli O157:H7 was not detected on plant shoots after 7 days but did survive in soil for up to 28 days. Nonpathogenic E. coli survived up to 14 days on shoots and was detected at low concentrations for up to 28 days. In contrast, there were no significant differences in HPC from days 0 to 28 on plants, except one treatment on day 7. Conclusions: Escherichia coli O157:H7 persisted in soil for at least 28 days. Escherichia coli O157:H7 on spinach leaves survived for less than 14 days when co‐inoculated with nonpathogenic E. coli. There was no correlation between HPC and E. coli O157:H7 or nonpathogenic E. coli. Significance and Impact of the Study: The persistence of nonpathogenic E. coli isolates makes them possible candidates as surrogates for E. coli O157:H7 on spinach leaves in field trials.     

Selection of white-rot basidiomycetes for bioconversion of mustard (Brassica compestris) straw under solid-state fermentation into energy substrate for rumen micro-organism

Aims: Selection of white‐rot fungi of bio‐conversion of mustard straw (MS) into feed for ruminants. Methods and Results: Mustard straw was cultured with Ganoderma applanatum, Coriolus versicolor and Phanerochaete chrysosporium for solid‐state fermentation at 35°C from 7 to 63 days for dilignification and for 21 days to study dry matter digestibility and protein enrichment. Lignin loss in fungus cultured straw varied between 100 and 470 g kg^?1 lignin. Dilignification was higher between 7 and 28 days fermentation with C. versicolor. Among the three fungi P. chrysosporium was the most effective in degrading lignin for longer fermentation. In‐vitro dry matter digestibility (IVDMD) and crude protein content was higher in C. versicolor cultured straw. Large quantity of straw was cultured by C. versicolor for 21 days, for in vivo evaluation. Mean pH and metabolites of rumen fermentation were not different while, pH and volatile fatty acid increased at 6 h postfermentation on cultured straw feeding. Cultured straw fermentation increased (P = 0·001) small holotricks and reduced (P = 0·005) large holotricks population. Fungus cultures straw did not improve microbial enzyme concentration. Conclusions: Coriolus versicolor and P. chrysosporium were the promising fungus for MS bio‐dilignification. Significance and Impact of the Study: Coriolus versicolor treated MS improved dry matter digestibility and protein content.     

Isolation of <Emphasis Type="Italic">Beauveria bassiana</Emphasis> (Bals.) Vuill. (Deuteromycotina: Hyphomycetes) from the Chagas disease vector, <Emphasis Type="Italic">Triatoma infestans</Emphasis> (Hemiptera: Reduviidae) in Argentina

A survey for natural entomopathogenic fungi of the Chagas disease vector Triatoma infestans was conducted in five provinces of Argentina since 2001. Nymphs (1.5%) and adults (3.3%) infected with a strain of the fungus Beauveria bassiana were found at Dean Funes, Córdoba province, Argentina. Field collected insects that died in the laboratory were maintained in moist chambers and incubated at 22 °C. Beauveria bassiana from infected insects was cultured on SDAY media. Pathogenicity tests were conducted with a conidial suspension (1 × 10⁷ conidia/ml) of this isolate on T. infestans adults. A mortality rate of 100% was obtained at 15 days post-infection. This is the first record of natural infection of T. infestans by B. bassiana.     

Early‐Life Exposure to Pulsed LTE Radiofrequency Fields Causes Persistent Changes in Activity and Behavior in C57BL/6 J Mice

Despite much research, gaps remain in knowledge about the potential health effects of exposure to radiofrequency (RF) fields. This study investigated the effects of early‐life exposure to pulsed long term evolution (LTE) 1,846 MHz downlink signals on innate mouse behavior. Animals were exposed for 30 min/day, 5 days/week at a whole‐body average specific energy absorption rate (SAR) of 0.5 or 1 W/kg from late pregnancy (gestation day 13.5) to weaning (postnatal day 21). A behavioral tracking system measured locomotor, drinking, and feeding behavior in the home cage from 12 to 28 weeks of age. The exposure caused significant effects on both appetitive behaviors and activity of offspring that depended on the SAR. Compared with sham‐exposed controls, exposure at 0.5 W/kg significantly decreased drinking frequency (P ≤ 0.000) and significantly decreased distance moved (P ≤ 0.001). In contrast, exposure at 1 W/kg significantly increased drinking frequency (P ≤ 0.001) and significantly increased moving duration (P ≤ 0.005). In the absence of other plausible explanations, it is concluded that repeated exposure to low‐level RF fields in early life may have a persistent and long‐term effect on adult behavior. Bioelectromagnetics. 2019;40:498–511. © 2019 The Authors. Bioelectromagnetics Published by Wiley Periodicals, Inc.     

Temporal changes in olfactory and oviposition responses of the diamondback moth to herbivore‐induced host plants

Temporal changes in the pre‐ and post‐alighting responses of mated female diamondback moth, Plutella xylostella L. (Lepidoptera: Plutellidae), to two species of Brassica (Brassicaceae) host plants induced by larval feeding were studied using olfactometer and oviposition assays. Females displayed strong olfactory and oviposition preferences for herbivore‐induced common cabbage (Brassica oleracea var. capitata L. cv. sugarloaf) plants over intact plants; these preferences decreased with time and disappeared by the 7th day after induction. In herbivore‐induced common cabbage plants, eggs were clustered near feeding damage on the younger leaves (leaves 5–7), whereas in intact plants, eggs were clustered on the stem and lower leaves (leaves 1–4) . However, as the time interval between larval feeding and oviposition increased, more eggs were laid on the lower leaves of induced plants. This demonstrates a change in egg distribution from the pattern associated with induced plants to that associated with intact plants. In contrast, females displayed strong olfactory and oviposition preferences for intact Chinese cabbage [Brassica rapa ssp. pekinensis (Lour.) Hanelt cv. Wombok] plants over induced plants; these preferences decreased with time and disappeared by the 5th day after induction. More eggs were laid on the upper leaves (leaves 4–6) than on the lower leaves (leaves 1–3) of intact Chinese cabbage plants at first, but the distribution changed over time until there were no significant differences in the egg count between upper and lower leaves by the 4th day post induction. For both host plant species, pre‐alighting responses of moths were reliable indicators of post‐alighting responses on the first 2 days post induction. The results suggest that temporal changes in a plant's profile (chemical or otherwise) following herbivory may influence attractiveness to an insect herbivore and be accompanied by changes in olfactory and oviposition preferences.     

Cortisol stress response and histopathological alteration index in Clarias gariepinus exposed to sublethal concentrations of Qua Iboe crude oil and rig wash

The histological effect on and stress response of post juvenile Clarias gariepinus exposed to Qua Iboe crude oil and rig wash were investigated. Fish weighing 60–90 g and measuring 16–18 cm were exposed for 7–28 days to 8.00 ml^?1 Qua Iboe crude oil and 0.0018 ml^–1 rig wash, both being 0.1 of the 96 hr LC₅₀. Blood samples of C. gariepinus were collected every seven days and evaluated for stress by measuring cortisol concentration. The gills and liver were studied and scored for Gill Alteration Index (GAI) and Hepatic Alteration Index (HAI), respectively. There was an increase in cortisol level up to the 7th and 14th day among the group exposed to Qua Iboe crude oil, with a decrease on the 21st and 28th day. The rig wash group increased in cortisol level up to the 7th day and decreased slightly on the 14th day, after which the trend became irregular. The toxic effects of the Qua Iboe crude oil and rig wash were time dependent, as shown by the histopathological alteration index (HAI) of gill and liver. After 28 days of exposure, the gills had irreparable damage due to high frequency of cellular necrosis and degeneration, whereas the liver had from moderate to severe damage due to the high frequency of cellular degeneration and inflammation. Qua Iboe crude oil and rig wash are both toxic to C. gariepinus, therefore their indiscriminate discharge to the environment must be discouraged.     

Crystal structure of Bacillus thuringiensis Cry7Ca1 toxin active against Locusta migratoria manilensis

Insecticidal crystal (Cry) proteins produced by Bacillus thuringiensis (Bt) are widely used as environmentally friendly insecticides. As the only known Cry protein with insecticidal activity against Locusta migratoria manilensis, a locust subspecies that causes extensive destruction of crops, the Cry7Ca1 protein from Bt strain BTH‐13 identified in our previous study is of particular interest to locust prevention and control. However, the three‐dimensional structure of Cry7Ca1 toxin (the active form of the Cry7Ca1 protein) and the mechanisms of the Cry7Ca1 insecticidal specificity remain largely elusive. Here, we report a 2.3 Å crystal structure of the Cry7Ca1 toxin and carry out a systematic comparison of all available Cry toxins structures. A cluster of six loops in Cry toxin domain II, named Apex here, are the most variable structural elements and were documented to contribute in insecticidal specificity. The Cry7Ca1 toxin Apex loops are different from those of other Cry toxins in length, conformation, and sequence. Electrostatic potential analysis further revealed that Cry7Ca1 is the only structure‐available Cry toxin that does not have a high contrast of surface electrostatic potentials in the Apex. We further suggest that the L1/L2 loops in the center of the Cry7Ca1 Apex may be worthy of attention in future efforts to unravel the Cry7Ca1 insecticidal specificity as they exhibit unique features not found in the corresponding regions of other Cry toxins. Our work highlights the uniqueness of the Apex in the Cry7Ca1 toxin and may assist exploration of the insecticidal mechanism of the Cry7Ca1 against Locusta migratoria manilensis.     

Short‐term survival and movements of Atlantic sharpnose sharks captured by hook‐and‐line in the north‐east Gulf of Mexico

Ultrasonic telemetry was used to compare post‐release survival and movements of Atlantic sharpnose sharks Rhizoprionodon terraenovae in a coastal area of the north‐east Gulf of Mexico. Ten fish were caught with standardized hook‐and‐line gear during June to October 1999. Atlantic sharpnose sharks were continuously tracked after release for periods of 0·75 to 5·90 h and their positions recorded at a median interval of 9 min. Individual rate of movement was the mean of all distance and time measurements for each fish. Mean ± s.e . individual rate of movement was 0·45 ± 0·06 total lengths per second (L_T s^?1) and ranged from 0·28 to 0·92 L_T s^?1 over all fish. Movement patterns did not differ between jaw and internally hooked Atlantic sharpnose sharks. Individual rate of movement was inversely correlated with bottom water temperature at capture (r² = 0·52, P ≤ 0·05). No consistent direction in movement was detected for Atlantic sharpnose sharks after release, except that they avoided movement towards shallower areas. Capture‐release survival was high (90%), with only one fish not surviving, i.e. this particular fish stopped movement for a period of 10 min. Total rate of movement was total distance over total time (m min^?1) for each Atlantic sharpnose shark. Mean total rate of movement was significantly higher immediately after release at 21·5 m min^?1 over the first 1·5 h of tracking, then decreased to 11·2 m min^?1 over 1·5–6 h, and 7·7 m min^?1 over 3–6 h (P ≤ 0·002), which suggested initial post‐release stress but quick recovery from capture. Thus, high survival (90%) and quick recovery indicate that the practice of catch‐and‐release would be a viable method to reduce capture mortality for R. terraenovae.     

Phosphatidylinositol 3‐kinase‐mediated regulation of neuronal apoptosis and necrosis by insulin and IGF‐I

We examined effects of two insulin‐like growth factors, insulin and insulin‐like growth factor‐I (IGF‐I), against apoptosis, excitotoxicity, and free radical neurotoxicity in cortical cell cultures. Like IGF‐I, insulin attenuated serum deprivation‐induced neuronal apoptosis in a dose‐dependent manner at 10–100 ng/mL. The anti‐apoptosis effect of insulin against serum deprivation disappeared by addition of a broad protein kinase inhibitor, staurosporine, but not by calphostin C, a selective protein kinase C inhibitor. Addition of PD98059, a mitogen‐activated protein kinase kinase (MAPKK) inhibitor, blocked insulin‐induced activation of extracellular signal‐regulated protein kinases (ERK1/2) without altering the neuroprotective effect of insulin. Cortical neurons underwent activation of phosphatidylinositol (PI) 3‐kinase as early as 1 min after exposure to insulin. Inclusion of wortmannin or LY294002, selective inhibitors of PI 3‐K, reversed the insulin effect against apoptosis. In contrast to the anti‐apoptosis effect, neither insulin nor IGF‐I protected excitotoxic neuronal necrosis following continuous exposure to 15 μM N‐methyl‐d ‐aspartate or 40 μM kainate for 24 h. Surprisingly, concurrent inclusion of 50 ng/mL insulin or IGF‐I aggravated free radical‐induced neuronal necrosis over 24 h following continuous exposure to 10 μM Fe²⁺ or 100 μM buthionine sulfoximine. Wortmannin or LY294002 also reversed this potentiation effect of insulin. These results suggest that insulin‐ like growth factors act as anti‐apoptosis factor and pro‐oxidant depending uon the activation of PI 3‐kinase. © 1999 John Wiley & Sons, Inc. J Neurobiol 39: 536–546, 1999