Effect of triflumuron on two species of nitidulid beetles,Carpophilus hemipterus andUrophorus humeralis

Egg hatch of two nitidulids,Carpophilus hemipterus L. andUrophorus humeralis F., was affected by the chitin synthesis inhibitor triflumuron (Alsystin; BAY SIR 8514)via the adult stage of the beetle. This occurred by exposure to treated diets, by a brief dip of the adults in aqueous dilutions of the toxicant, or by contact with a treated plastic netting cage. Exposure of adults ofC. hemipterus for 24 h to 0.0125%, 0.00125%, 0.00025% or 0.000125% and ofU. humeralis to 0.0125% a.i.-treated diets completely prevented hatch of eggs laid during the subsequent 48 h on an untreated diet. Although at first sterile eggs were obtained with adults of either nitidulid species transferred to an untreated diet after 24 h exposure to the 0.0125%-treated diet, egg viability gradually recovered. The speed of recovery and the course of mortality of larvae that hatched from eggs laid by treated adults, indicated thatC. hemipterus was more susceptible thanU. humeralis to triflumuron. DippingC. hemipterus adults — males or females — in 0.0125% a.i. triflumuron also resulted in complete prevention of egg hatch. Similar results were obtained by a 1-h contact of adults with treated cages. Triflumuron had no direct ovicidal activity against the two species at the concentrations used but was very effective against larvae of both species. At 0.0125% a.i., 3-5-mm-long larvae ofU. humeralis were more tolerant than newly hatched larvae and than 3-5-mm-long larvae ofC. hemipterus. Application of 0.0125% a.i. triflumuron in a date palm grove did not prevent fruit infestation by nitidulid adults but, due to prevention of egg hatch, almost no larval development was observed.     

Effects of variable temperatures on responses ofAphytis melinus andA. lingnanensis to host density

The effects of three variable temperature regimes (18–24, 24–29, and 29–35°C) on the responses of two species of the genusAphytis Howard (Hymenoptera: Aphelinidae), parasitic upon the California red scale, were studied, and a test to analyze parasite behavior was developed.Aphytis lingnanensis Compere was generally more efficient thanA. melinus DeBach; however, whereas a high temperature regime (29–35°C) had a negative effect on the responses ofA. lingnanensis, it improved those ofA. melinus. The two species distributed their eggs in clumps, but were able to respond to increasing host density by reducing the number of eggs laid per encounter. The combined effects of numerical, and functional responses of the two species on host population were considered, with special reference to the mechanism of competitive displacement.     

The effect of diflubenzuron on Eggs and larvae ofEarias Insulana (Boisd.)

Diflubenzuron was tested for its efficacy against the eggs and larvae ofEarias insulana Boisd. in laboratory experiments. The toxicity obtained on dipping the eggs was only moderate and, moreover, the results were highly inconsistent. The mortality of larvae on an artificial diet into which the wettable powder had been incorporated, was relatively high.     

Comparative toxicity of several insecticides to eggs,larvae and adults of the Egyptian cottonworm,Spodoptera littoralis,in laboratory trials

Insecticides commonly used in cotton fields in Israel against lepidopterous pests were tested against eggs, as well as against 2nd-instar larvae and adults raised from eggs ofSpodoptera littoralis (Boisduval) collected in cotton fields in the Bet She’an Valley. Methomyl, chlorpyrifos, methidathion, monocrotophos, ethyl parathion, and methyl parathion were effective against eggs even at low doses, profenofos and phosfolan were less active, and azinphos-methyl was ineffective. The doses needed for 90% kill (LD ₉₀ ) of the 2nd-instar larvae were 8.5, 35, 280, 1300 and 3400 g a.i./1000 m ² for chlorpyrifos, methomyl, profenofos, methyl parathion and ethyl parathion, respectively; monocrotophos was inactive against 2nd-instar larvae even at relatively high doses. The LD ₉₀ of adults was reached with 16, 32, 1700 and 6100 ga.i./l000 m² of chlorpyrifos, methomyl, ethyl parathion and profenofos, respectively. Only chlorpyrifos and methomyl gave successful control of all three stages of the insect tested, at doses close to those generally used with aerial applications.     

Inhibitory effects of some insect growth regulators on developmental stages,fecundity and fertility of the Florida wax scale,Ceroplastes floridensis

Four juvenile hormone analogs (JHAs), fenoxycarb. Pro-drone, R-20458 and dofenapyn, and three benzoylphenyl urea molt-inhibiting compounds (MICs), teflubenzuron, triflumuron and hexaflumuron, were evaluated in the laboratory at two concentrations (5 and 50 ppm) as to their effect on the Florida wax scale,Ceroplastes floridensis Comstock. In general, when the first nymphal stages were treated, the number of adults on treated guava plants at the end of the first generation was clearly reduced in comparison with that observed on untreated plants. The JHAs fenoxycarb and R-20458 arrested the development of the insect and no adults emerged at the end of the first generation. With 50 ppm of the JHA Pro-drone only 5.2% of the nymphs developed and transformed into adults. Triflumuron was superior to the other insect MICs in hampering development, as was dofenapyn. The adults emerging at the end of the first generation were used as parental scales for the next generation. Delayed adverse effects were observed on female fecundity and egg hatchability. There was a significant difference between the egg numbers laid by the females in the treatments and the control, and also between the different IGRs. No eggs hatched with dofenapyn and egg hatchability was 46% for teflubenzuronvs 88% for the control. Furthermore, in contradistinction to the control, insects on treated plants deposited only small amounts of wax in an irregular formation.     

A method for monitoringBemisia tabaci and timing spray applications against the pest in cotton fields in israel

A method for monitoring tobacco whitefly [Bemisia tabaci (Gennadius) (Homoptera: Aleyrodidae)] populations was developed and used for timing spray applications against this pest in cotton. It was found to be successful in tests in eight commercial cotton fields. A trap composed of a yellow plastic plate (15 × 20 cm) smeared on the upper side with a thin layer of glue, was attached to an iron pole which held the plate in a horizontal position above the plants. The traps were placed 400 m apart along the periphery of the field. The sticky plates were changed weekly and the adult whiteflies were counted. When the mean weekly catch per trap reached ~ 100–200 adults, spray applications were carried out. Following this treatment,B. tabaci populations remained low and sooty mould did not develop on the lint.     

基于性诱剂监测的梨小食心虫防治指标

为明确梨小食心虫性诱剂水盆诱捕器诱蛾量与梨果着卵量的关系,建立一种简单实用,基于梨小食心虫成虫发生量的防治指标,于2010和2011年在陕西蒲城梨园调查了梨小食心虫在早酥梨上的着卵情况及其与性诱剂水盆诱捕器诱蛾量之间的关系.结果显示,梨小食心虫在梨果胴部的着卵量显著高于其它部位,占总卵量的92.00％;百果卵数、卵果率随果实的增大而增加,直径70mm以上果实的百果卵数和卵果率均显著高于直径65 mm以下的果实.据此建立了诱蛾量与卵果率、百果卵量的回归方程,分析得出当以卵果率1％和百果卵量1粒为防治指标时,基于性诱剂监测的梨小食心虫的防治指标分别为每天每诱捕器2.27和2.32头;以卵果率2％和百果卵量2粒为防治指标时,则分别为每天每诱捕器2.61和2.58头.     

Some characteristics of an avocado strain of Tobacco mosaic Virus

An isolate of tobacco mosaic virus (TMV-A) was obtained from healthy and sunblotch-infected avocado (Persea americana) seedlings. TMV-A resembled common TMV in particle morphology, RNA size and coat protein molecular weight. TMV-A coat protein differed from common TMV coat by a minimum of 22 amino acid exchanges including the presence of one methionine, and by the absence of cysteine. Spur formation between the precipitation lines of TMV, TMV-A and a TMV antiserum indicates certain differences among the antigenic determinants of these two strains.     

Honeydew staining to evaluate survival of tobacco whitefly nymphs after insecticide application

A method was developed for estimating the number of surviving tobacco whitefly (TWF),Bemisia tabaci (Gennadius) (Homoptera: Aleyrodidae), nymphs after insecticide applications, based on the number of honeydew droplets ejected by TWF nymphs in 30 minutes. Honeydew droplets excreted by live TWF nymphs on a water-sensitive paper (Ciba-Geigy) stained blue and could easily be observed and counted. To estimate the number of live nymphs on an infested cotton leaf, the number of droplets ejected during 30 min was divided by a factor of 1.29.     

Screening insecticides against the tobacco whitefly (Bemisia tabaci) on cotton,using a leaf cage laboratory method

Over 20 insecticides were screened against the tobacco whitefly,Bemisia tabaci (Gennadius) (Homoptera: Aleyrodidae), on cotton. AsB. tabaci feeds only on live plants, a suitable laboratory test method incorporating young cotton plants was developed. Both cover sprays and systemic insecticides applied to the soil were tested. Triazophos, pyridaphenthion, azinphos-methyl, bendiocarb and flucythrinate were found to be effective and persistent. The best of the systemic insecticides was aldicarb, followed by butocarboxim.     

<Emphasis Type="Italic">Aphelenchoides gorganensis</Emphasis> n. sp. (Nematoda: Aphelenchoididae)<Emphasis Type="Italic">,</Emphasis> a new species from Iran

Phytophthora capsici infection of chili pepper seedlings can cause substantial losses due to damping-off and collar rot diseases. Chemical control is no longer effective due to reported resistance development, on top of the related environmental concerns and the consumer demands for reduced use of fungicides. Biological control is a sustainable option, with several agents having been reported to be effective against this pathogen. This research focused on optimizing the application of strain THSW13 of Trichoderma hamatum and a bacterial isolate BJ10–86 with the objectives of improving chili pepper seed germination, reduce damping-off disease incidence, and improve the growth of the seedlings. Bacterial isolate BJ10–86 was subjected to molecular identification and found to be Pseudomonas aeruginosa. Chili pepper seeds treated with the biocontrol agents, individually or in combination, were seeded into commercial nursery media that had been pre-inoculated with P. capsici zoospores. Over a period of 35 days the chili pepper seed treatments significantly (P = 0.008) reduced the disease incidence of seedlings damping-off. Combined application of T. hamatum and P. aeruginosa was the best biocontrol treatment with an area under disease curve of only 36.61 units compared to 92.87 units for the control treatment. Similar results were observed in vitro where T. hamatum and P. aeruginosa synergistically inhibited P. capsici growth by 73.2 %. The inhibition activity of this treatment was similar to mefenoxam treatment, which implies that it is an effective and sustainable alternative for chili pepper seed treatment. The biocontrol seed treatment had no effect on seed germination and seedling growth.     

Effect of some benzoylphenyl ureas onearias insulana eggs of different age

Diflubenzuron, PH 60–43, PH 60–45, penfluron(PH 60–44) and triflumuron were assayed by a dipping technique for their toxicity toEarias insulana (Boisd ) eggs of different age Testing at a screening concentration of 0 1% a 1 showed that diflubenzuron, triflumuron and PH 60–43 were highly active, whereas PH 60–44 and PH 60–45 were nearly inactive With triflumuron the mortality of 0-1-day-old eggs was >90% even at 0 005%, at 0 001% it was 50% In 1-2-day-old eggs, a >90% kill was obtained even at 0 0005%, whereas at 0 00025% it was 86% PH 60–43 was also highly active, at 0 01% the kill of 0-1-day-old eggs was >90% Again, this rate of kill was obtained with 1-2-day-old eggs at a still lower concentration, 0 005% Both compounds were inactive against 2-3-day-old eggs, even at 0 1%     

Honeydew staining techniques for estimating the live tobacco whitefly nymph population on cotton leaves

Techniques of staining the honeydew droplets excreted by nymphs of the tobacco whitefly,Bemisia tabaci (Gennadius) (Homoptera: Aleyrodidae), were screened to select an effective means of estimating the number of nymphs on an infested cotton leaf. Indicators of pH and redox potential, absorbed on a cellulose acetate strip and on a water-sensitive paper (Ciba-Geigy), were used to stain the droplets. The water-sensitive paper provided the most practical means for rapid counting of the stained droplets for nymph estimation.     

A Laboratory method for estimating survival of tobacco whitefly nymphs after insecticide treatment,based on honeydew excretion

A quick and easy method for estimating the number of surviving nymphs of the tobacco whitefly (TWF),Bemisia tabaci (Gennadius) (Homoptera: Aleyrodidae), after spray applications was developed in the laboratory. The method is based on the number of honeydew droplets ejected by TWF immatures during 30 minutes. Since the nymphs ofB. tabaci feed on the lower leaf surfaces, the honeydew excreted falls downward. In this study infested cotton leaves were placed with their lower side up, forcing the nymphs to eject the honeydew droplet upwards. Inverted plastic petri dish covers were placed over infested cotton leaves and after 30 minutes the droplets deposited on the inner side of each cover were counted and the average number of droplets per nymph was calculated. To estimate the number of live nymphs on an infested cotton leaf, the number of droplets ejected during 30 minutes was divided by the average number of droplets per nymph (factor of 1.23).     

Development of <Emphasis Type="Italic">Tetranychus ludeni</Emphasis> (Acari: Tetranychidae) on transgenic soybean cultivars

The aim of this study was to assess the influence of transgenic soybean [Glycine max L. (Fabaceae)] cultivars on the biological cycle of Tetranychus ludeni Zacher (Acari: Tetranychidae) in laboratory conditions. We used three cultivars: a conventional soybean (CO), a glyphosate-resistant with insertion of genes of Agrobacterium sp., Roundup Ready (RR), and a glyphosate-resistant with insertion of genes of Bacillus thuringiensis var. israelensis (BT). Duration of developmental stage, mite viability, number of laid eggs, and female longevity of T. ludeni were evaluated. The duration of the deutonymph phase was shorter in RR (2.1?±?0.12 days) than in CO (2.6?±?0.12) and BT (2.5?±?0.08). The duration of egg, larval, and protonymph phases were similar for T. ludeni on the three cultivars. The mean duration of each generation (T), net reproduction rate (R_o), intrinsic rate of natural increase (r_m), and doubling time (DT) were similar on the three cultivars. Results showed that population growth are not influenced by transgenesis at the laboratory level. Females died without a post-oviposition period on all soybean cultivars. The intrinsic rate of natural increase of T. ludeni on soybean cultivars was low (between 0.15 and 0.17).     

Plant oils as oviposition deterrents against winterform females of pear psylla, <Emphasis Type="Italic">Cacopsylla pyri</Emphasis> (L.) (Hemiptera: Psyllidae)

Oviposition deterrents have potential to prevent arthropod pest infestations making the crop habitat less or no favorable for pests to lay eggs and even to settle. In this study, seed oils of maize, safflower, rapeseed and castor oil plant were evaluated in the field between years of 2015 and 2016 for their oviposition deterrent activity against winterform females of pear psylla, Cacopsylla pyri (L.) (Hemiptera: Psyllidae), the most important insect pest of pears in Turkey. All the oils were used at three different concentrations, 1, 1.5 and 2 L/100 L water including 0.01% Tween-20 for a good mixture and applied at the dormant period (just before the first eggs were deposited by overwintered females). Only one application was made each year. Oviposition deterrency was evaluated by counts of eggs deposited by overwintered females of the pest on treated dormant shoots during the sampling times 3, 7, 14, 21 and 28 days after application. The results showed that significant reductions in total numbers of eggs laid by winterform females were observed in all the oil-treated plots compared with the controls sprayed with tap water including Tween-20 (0.01%). Safflower and castor oils exhibited 100% oviposition deterrent activity at all the concentrations during the 3 weeks period in both years. Even after 4 weeks, the deterrency of these oils was higher than 70%. In the control plots, the first eggs were deposited by overwintered females within 3 days after application in both years. These findings suggest that these oils are promising oviposition deterrents against winterform females of C. pyri.     

Development of conventional and real-time PCR protocols for specific and sensitive detection of Colletotrichum capsici in chilli (Capsicum annuum L.)

Anthracnose, caused by Colletotrichum capsici, is a major disease of chilli (Capsicum annuum L.) affecting both fruit and seed quality. The pathogen is both internally and externally seedborne. However, a rapid and sensitive method for detection of this pathogen in seeds is currently limited. In this study, a polymerase chain reaction (PCR) method based on sequence characterized amplified region (SCAR) marker was developed for specific and sensitive detection of C. capsici in chilli seeds and fruits. The developed SCAR primers were highly specific to C. capsici and resulted in the amplification of an expected 250-bp fragment from genomic DNA of all seven of the C. capsici isolates tested. No amplification occurred when the SCAR primers were tested with genomic DNA from three other fungal isolates and four other Colletotrichum species. The SCAR primers successfully amplified similar sized fragments from DNA derived from C. capsici-infected chilli fruits. The molecular detection sensitivity of C. capsici was 1 pg of purified C. capsici DNA template and 25 ng of DNA from C. capsici-infected chilli fruits. A real-time PCR assay was also developed using SYBR Green chemistry for detection of C. capsici in chilli fruits and seeds. The standard curve obtained showed a linear correlation between copy number of the cloned target DNA sequence of C. capsici and cycle threshold (Ct) values, with R² of 0.98. These PCR-based assays may be highly useful in detection of this important pathogen in chilli seeds and fruits in plant quarantine laboratories.     

Effect of Cotton leaf curl virus infected plants on the biology of the whitefly,Bemisia tabaci (Hemiptera: Aleyrodidae): Vector–virus mutualism

Cotton leaf curl virus (CLCuV) (Geminiviridae : Begomovirus), the causative agent of leaf curl disease in cotton plants (Gossypium hirsutum), is exclusively transmitted by whitefly species Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae). CLCuV transmission occurs in Sriganganagar (Rajasthan), an area endemic with cotton leaf curl disease. The relationships between plant viruses, their herbivore vectors and host plants can be beneficial, neutral, or antagonistic, depending on the species involved. To further understand these relationships, fecundity and life history parameters of an indigenous non- b (Asia II genetic group) biotype whitefly, B. tabaci, were compared on 10, 25, and 40 days post-inoculation (DPI), in CLCuV-infected and healthy cotton plants to determine the effect of virus on its vector. The development time of the immature stages of whiteflies was significantly reduced on CLCuV-infected plants. The development time of the immature stages did not change with severity of symptoms at 25 and 40 DPI (45- and 60-d-old plants). Cotton leaf curl virus infection increased percent egg viability of B. tabaci. Whiteflies deposited significantly fewer eggs on virus-infected plants than on healthy plants. Whiteflies had better egg viability on younger plants than older plants, whereas plant age did not affect the fecundity. Male and female whiteflies had shorter longevity on CLCuV-infected plants than on healthy plants.     

Influence of feeding-damaged plants on the oviposition responses within a community of female moths

Competitive or facilitative interactions characterise phytophagous insect communities that utilise the same resources. These interactions are often mediated by the host plant. Plant mediation influences the oviposition choices that a community of insects, sharing the same host plant make. In this context, the oviposition choices of females within a community of lepidopteran cereal stemborers namely Busseola fusca, Sesamia calamistis and Chilo partellus were studied in plant choice-experiments under laboratory and field conditions. Gravid females of each species were presented with a choice between maize plants infested by conspecific or heterospecific larvae and uninfested maize plants. The number of eggs and egg batches laid on plants were used to quantify oviposition. Results showed that none of the three stemborer species avoided oviposition on infested maize plants. In some cases a significant preference for infested maize plants were observed. Similarly, data from field trials under natural stemborer infestation, with B. fusca as the only species, showed that the wild ovipositing moths were not avoiding infested plants. Host plant mediation may influence the incidence of multi-species infestations by stemborer species often found in the field. The potential roles of herbivore-induced and egg-deposited-induced plant volatiles in this mechanism are discussed.     

不同食料对黄地老虎生长发育和繁殖的影响

幼虫在不同食料饲养中,以灰藜最好,苘麻最差。前者幼虫期平均23～30.9天,脱皮4～5次,自然死亡率4.3～8.0％;后者则各为46.1～47.1天、6～7次、45％。各种食料饲养的蛹重,以白菜和灰藜较重,马铃薯较轻。蛹重不是决定成虫产卵高低的主要因子,而与幼虫取食食料种类关系较为密切。如幼虫取食白菜、棉花及玉米、马铃薯混杂草者,较取食旋花、马铃薯及玉米者产卵量高0.15～2.23倍,产卵期和寿命亦较长。取食混合食料的幼虫,发育速度和成虫产卵量,一般均较取食单纯一种食料为高。在成虫取食各种花蜜饲养中,以供食蜂蜜红糖水、马蔺花和向日葵花者产卵率和产卵量最高,白菜花、苜蓿花和清水者最低,前者为后者产卵量的1.99～14.06倍,雌蛾产卵率高11.1～35.7％,产卵期和寿命亦以前者为长。从幼虫和成虫取食不同营养对产卵量的对比来看,成虫期补充营养较幼虫期营养更为重要。因而某一地区蜜源植物的种类、分布密度以及蜜源植物花期与成虫发生期的符合程度,是决定某地区黄地老虎种群密度高低、为害轻重的最主要因素之一。