Reduced egg viability in codling moth Cydia pomonella (L.) (Lepidoptera: Tortricidae) following adult exposure to novaluron

BACKGROUND: The codling moth, Cydia pomonella (L.), is one of the principal pests of pome fruits in the world. The effects of novaluron, a benzoylurea chitin synthesis inhibitor insecticide registered for use on apples in the USA, on fecundity and egg viability in codling moth were studied under laboratory conditions. Three different exposure methods were investigated: ingestion, contact and topical spray. Additionally, the duration of novaluron sublethal effects was measured subsequent to the three modes of exposure. RESULTS: The fecundity of codling moth adults was not significantly affected by novaluron with any of the exposure methods. However, novaluron did cause significant reductions in the proportion of egg hatch with all three exposure methods. The duration of sublethal effects was 9 days or more for all modes of exposure, but with the topical spray these effects began to diminish after 6 days. CONCLUSION: Novaluron does not affect fecundity in codling moth, but has significant sublethal activity by reducing egg viability subsequent to adult exposure. The topical, contact and ingestion exposures all induce sublethal effects after exposure, and these persist to various degrees throughout codling moth oviposition. A more complete understanding of novaluron's lethal and sublethal activities will help IPM practitioners optimize its use for management of the codling moth. Copyright © 2008 Society of Chemical Industry     

Reduced viability of Colorado potato beetle, Leptinotarsa decemlineata, eggs exposed to novaluron

BACKGROUND: Novaluron is a benzoylphenyl urea chitin synthesis inhibitor that combines good activity against larval stages of the Colorado potato beetle, Leptinotarsa decemlineata (Say) (Coleoptera: Chrysomelidae), with low mammalian toxicity. Previous studies suggest that it has deleterious sublethal effects on adults. RESULTS: Continuous exposure of adult Colorado potato beetles to novaluron-treated foliage as both ovipositional and feeding substrate did not affect their survivorship or the number of eggs produced, but viable larvae hatched only from the eggs that were laid on the first day of the experiment. Viability was restored after adult beetles spent 48-96 hours on untreated leaves. In a separate experiment, direct exposure to novaluron of eggs laid by unexposed beetles also reduced the number of larvae hatching. CONCLUSIONS: Results confirm a negative effect of novaluron on the number of progeny produced by the Colorado potato beetle. Direct toxicity did not explain all of the reduction in egg hatch observed, suggesting that novaluron probably acted on reproductive adults as well as on eggs after they were deposited.     

Effect of Buprofezin onIcerya Purchasi andPlanococcus Citri

The effectiveness of buprofezin (aqueous suspensions from 25% wettable powder) on cumulative nymph mortality and reproduction of two homopterous pests,Icerya purchasi Maskell (Margarodidae) andPlanococcus citri (Risso) (Pseudococcidae), was investigated under laboratory conditions. Buprofezin was very effective against crawlers of both species. Dipping in concentrations of 0.002%, 0.01% and 0.05% (a. i.) resulted in 91–99% nymph mortality ofP. citri, whereas 100% mortality was recorded whenI. purchasi was treated at 0.05% (a. i.); the 3rd-instar nymphs ofI. purchasi were less susceptible to the chemical. Death of the larval stages occurred mainly during the molting process to the 2nd-instar nymphs. At 0.05%, buprofezin sprayed on adults slightly reduced fecundity and decreased egg hatch to 31% forI. purchasi and, depending on the exposure period of the females, to 49-7% forP. citri. Buprofezin at 0.05% exhibited strong ovicidal activity onP. citri, resulting in inhibition of over 80% egg hatch.     

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.     

Effect of methoprene on the progeny production of Tribolium castaneum (Coleoptera: Tenebrionidae)

BACKGROUND: Tribolium castaneum (red flour beetle) is a serious insect pest of stored products around the world. Current control measures for this species have several limitations: loss of registration of insecticides, insecticide resistance and consumer concerns about chemical residues in food. The objective of this study was to determine whether methoprene affects progeny production of T. castaneum. Late‐instar larvae or young adults were exposed to methoprene‐treated wheat, and progeny production was determined. The pairing of male and female adults was performed as untreated × untreated, treated × untreated or treated × treated, to study sex‐based effects. RESULTS: There were three outcomes to late‐instar larvae held on methoprene‐treated wheat kernels (0.001 and 0.0165 ppm): (1) failure to emerge as an adult; (2) emergence as an adult, and almost no offspring produced; (3) emergence as an adult and normal production of offspring. Male larvae were more susceptible to methoprene than female larvae. In contrast, young adults exposed to methoprene (1.67–66.6 ppm) showed no reduction in offspring production. CONCLUSION: Methoprene concentrations will decline with time following its application. However, this research indicates that methoprene can still reduce populations of T. castaneum by reducing their progeny production, even if adults emerge. Copyright © 2011 Society of Chemical Industry     

Effect of buprofezin on adult life span,oviposition, egg hatch and progeny production of the cotton whitefly,Bemisia Tabaci

The 50% survival ofBemisia tabaci Genn. females was reduced to 5.9 days by exposure to bean seedlings treated with 1000 ppm buprofezinvs 8.9 days in the control. At lower concentrations ranging from 50 to 500 ppm, survival was extended to 11.8–14.2 days. Mean fecundity was significantly reduced on plants treated with 1000 ppm as compared with the control, whereas at 50 to 500 ppm the oviposition period was extended with a considerable increase in mean fecundity, irrespective of concentrations. Overall mean percent hatch dropped gradually from 25.8 to 12.9 with increase of concentration from 50 to 1000 ppm, as against 96.9% in the control. The survival of hatched nymphs was greatly affected at all buprofezin concentrations. No immature stages survived at 50, 100, 250 and 500 ppm; nymphal survival was 13.8, 7.0, 1.9 and 1.2%, respectively, as against 81.6% in the control.     

Effects of temperature and yeast supplementation on the development ofTribolium castaneum (Herbst) in wholemeal and polished flour derived from four cereals in Maiduguri, Nigeria

The effects of temperature, yeast and polishing (removal of bran) on the development ofTribolium castaneurn (Herbst) in flour derived from millet, sorghum, maize and wheat were investigated for one generation in Maiduguri, Nigeria. Significantly moreT. castaneurn adults and larvae developed in flour stored at 35 °C than in flour stored at 30 °C or 40 °C; mortality of adult beetles in flour stored at 40 °C was 95 % in sorghum and maize and 100 % in millet and wheat. Addition of three levels (2.5, 5.0 and 10.0 %, w/w) of yeast to cereal flour, on average, significantly increased the population of adult and larval progenies relative to the population in yeast-free flour. Considerably higher number of adult beetles developed in wholemeal than in polished flour derived from millet.     

Effects of temperature and yeast supplementation on the development ofTribolium castaneum (Herbst) in wholemeal and polished flour derived from four cereals in Maiduguri, Nigeria

The effects of temperature, yeast and polishing (removal of bran) on the development ofTribolium castaneurn (Herbst) in flour derived from millet, sorghum, maize and wheat were investigated for one generation in Maiduguri, Nigeria. Significantly moreT. castaneurn adults and larvae developed in flour stored at 35 °C than in flour stored at 30 °C or 40 °C; mortality of adult beetles in flour stored at 40 °C was 95 % in sorghum and maize and 100 % in millet and wheat. Addition of three levels (2.5, 5.0 and 10.0 %, w/w) of yeast to cereal flour, on average, significantly increased the population of adult and larval progenies relative to the population in yeast-free flour. Considerably higher number of adult beetles developed in wholemeal than in polished flour derived from millet.     

The effect of IKI-7899, a new chitin synthesis inhibitor,on larvae ofTribolium castaneum andSpodoptera littoralis

The effect of IKI-7899 and diflubenzuron on larval development and emergence ofTribolium castaneum and ofSpodoptera littoralis was determined. The LC₅₀ of IKI-7899 at adult emergence ofT. castaneum larvae fed the compound in their diet and the ED₅₀ of S.littoralis larvae treated topically were approximately one-sixth those of diflubenzuron.     

Effect of temperature on the egg viability and duration of egg development of<Emphasis Type="Italic">Parahypopta caestrum</Emphasis>

The thermal requirements of the egg ofParahypopta caestrum (Hübner) (Lepidoptera: Cossidae) for predicting egg hatch and the effect of temperature on viability were examined. Egg duration was directly related to temperature, ranging from 19 days at 30° to 40 days at 17°C. Egg hatch did not occur at 35°C. Egg hatch percentage (viability) was also related to temperature, ranging from 28% at 30° to 98% at 25°C. The results of the study showed that viability increases with temperature up to 25°C. However, above 25°C, viability decreases significantly. These data can be used to predict egg hatch in the field and develop a control strategy. http://www.phytoparasitica.org posting July 14, 2004.     

Laboratory evaluation of natural pyrethrins, pymetrozine and triflumuron as alternatives to controlCeratitis capitata adults

Three insecticides, pyrethrins + piperonil butoxide (PBO), pymetrozine and triflumuron, were tested as potential alternatives for controlling the Mediterranean fruit flyCeratitis capitata (Wiedemann) (Diptera: Tephritidae). The compounds were administered to adult flies in the laboratory by different uptake methods at the recommended rates currently used in fruit crops in Spain. Pyrethrins + PBO (80 + 320 ppm a.i.) exhibited a comparable knock-down effect to malathion (1,500 ppm a.i.) in the laboratory, irrespective of the method of application used. After these results were obtained, the number of concentrations tested was increased to carry out a dose-response analysis. Pymetrozine (300 ppm a.i.) and triflumuron (150 ppm a.i.) did not kill adults at the concentrations tested. However, pymetrozine diminished the fecundity, especially when adults were fed the insecticide; egg hatch was decreased by 59.3% compared with controls. Further experiments showed that increased period of ingestion and higher concentrations had a clear effect in reducing both fecundity and fertility. The possible use of pyrethrins + PBO and pymetrozine to reduce populations ofC. capitata is discussed. http://www.phytoparasitica.org posting July 22, 2006. Corresponding author     

Influence of temperature on toxicity of propylene oxide at low pressure against<Emphasis Type="Italic">Tribolium castaneum</Emphasis>

Toxicity of propylene oxide (PPO) at low pressure against the most common stored-product insect,Tribolium castaneum (Herbst), over a short exposure time, was tested at three different temperatures (16°, 22° and 30°C). Toxicities of PPO at 100 mm Hg were strongly influenced by ambient temperature. LD₅₀ and LD₉₉ toxicities ranged from 4.7 to 28.9 mgl ⁻¹ and from 10.5 to 72.6 mgl ⁻¹ respectively, showing that susceptibility was positively correlated to the temperature. The LD₉₉ values for all life stages (except the larval stage) were significantly lower at 30° than those at 16° and 22°C. However, the LD₉₉ values for all life stages (except the pupal stage) at 16° were not significantly different from those at 22°C. A concentration × time (Ct) product of 291, 171 and 98 mg h/l was required to obtain complete mortality (99%) ofT. castaneum at 16°, 22° and 30°C, respectively. Thus, the efficacy of PPO at 100 mm Hg to all life stages ofT. castaneum also decreased as the temperature decreased from 30° to 16°C. http://www.phytoparasitica.org posting Sept. 28, 2004.     

The effects of low oxygen tensions on three stored-product insect pests

The relationship between different oxygen tensions and exposure times producing 95% mortality, and loss in weight of three stored-product insects at 54% R.H. and 26°C, was determined.Ephestia cautella (Wlk.) pupae andTribolium castaneum (Herbst) adults reacted in a similar pattern: the lower the oxygen concentration, the shorter the exposure time needed to produce 95% mortality, and the higher the rate of loss in weight. The response ofSitophilus oryzae (L.) adults was different: there was greater sensitivity at 1% oxygen than at the lower or higher levels of oxygen tested. A relationship was demonstrated between low oxygen tensions (0–5%) and the relative humidity of the environment for producing a lethal atmosphere forE. cautella pupae andT. castaneum adults.     

Spirodiclofen and spirotetramat bioassays for monitoring resistance in citrus red mite, Panonychus citri (Acari: Tetranychidae)

BACKGROUND: Citrus red mite, Panonychus citri (McGregor), is a key pest of San Joaquin Valley California citrus. Spirodiclofen was registered for mite control in 2007, and spirotetramat for scale control in 2008. Because of the potential for resistance to spirodiclofen to develop in spider mites, and cross‐resistance to spirotetramat used for other citrus pests, bioassay methods for resistance monitoring were developed. RESULTS: The responses of four populations of adult female, egg and larval stages of P. citri to spirodiclofen were compared to determine the most robust bioassay method for this pesticide. Adult females responded with a higher LC₉₉ and larval stages exhibited higher control mortality and a lower slope of response compared with the egg stage. Thus, the egg stage was found to be the most suitable stage for testing. Egg production and egg shape were significantly affected by spirodiclofen treatment of adult female mites. Bioassays with the related compound spirotetramat revealed that P. citri egg hatch was less affected by this compound, requiring the assessment of mortality to be extended to 11 days after treatment when the hatched larvae succumbed to the pesticide. Discriminating concentrations of 10 ppm for spirodiclofen and 31.6 ppm for spirotetramat in an 11 day bioassay were tested against eight field populations of P. citri, and 99–100% mortality resulted. CONCLUSION: These results provide a baseline for the response of P. citri to spirodiclofen and spirotetramat that will aid resistance management in California citrus. Copyright © 2011 Society of Chemical Industry     

Development and reproduction of Adalia bipunctata (Coleoptera: Coccinellidae) on eggs of Ephestia kuehniella (Lepidoptera: Phycitidae) and pollen

Due to growing criticism over the use of non-indigenous coccinellids, the two-spot ladybird, Adalia bipunctata (L.), has enjoyed increasing attention for aphid biocontrol in Europe. In the current study, eggs of the Mediterranean flour moth, Ephestia kuehniella Zeller, whether or not supplemented with bee pollen, were evaluated as a factitious food for larvae and adults of A. bipunctata. The predator showed slower larval development and lower survival when reared on live pea aphids, Acyrthosiphon pisum (Harris), than on E. kuehniella eggs. Survival on gamma-irradiated eggs of E. kuehniella was superior to that on frozen flour moth eggs, but other developmental characteristics were similar. Adults of A. bipunctata reared on Ac. pisum were only half as fecund as those offered irradiated or frozen E. kuehniella eggs, but egg hatch was markedly better on live aphids than on flour moth eggs (61 versus 20-27%, respectively). However, when a diet of flour moth eggs was supplemented with frozen moist bee pollen, egg hatch of A. bipunctata was equally as good as on live aphids. Supplementing flour moth eggs with dry pollen did not yield satisfactory results. Only 10% of larvae reached adulthood on moist bee pollen alone and resulting adults weighed less than half as much as those obtained on flour moth eggs. Our findings indicate that A. bipunctata is able to compensate for a suboptimal diet of animal prey by supplementary feeding on flower pollen. It is concluded that pollinivory may be a crucial trait for both the rearing of this natural enemy and its use in biological control programmes.     

Fumigant toxicity of essential oils fromLaurus nobilis andRosmarinus officinalis against all life stages ofTribolium confusum

The essential oils from rosemary (Rosmarinus officinalis L.) and laurel (Laurus nobilis L.) obtained from Mersin Province in Turkey, were tested for their fumigant toxicity against all life stages of confused flour beetle (Tribolium confusum du Val.). GC-MS analysis showed that 1,8-cineole was found to be the major component of both rosemary and laurel essential oils. Vapors of rosemary and laurel essential oils were toxic to all life stages ofT. confusum. Only 65% mortality of the eggs was achieved when exposed to a dose of 172.6 mgl ⁻¹ air of rosemary essential oil at the longest exposure period (144 h); at the same dose, the pupae were the most resistant stage, with LT₉₀ (lethal time) value of 120.2 h. The adults were the most resistant stage to laurel essential oil, with LT₉₀ value of 77.2 h. On the basis of LT₉₀ values, tolerance of the life stages ofT. confusum to rosemary and laurel essential oils was, in descending order: pupa < larva < adult, and larva < adult < egg < pupa, respectively. Based on the concentration × time (Ct) products (g hl ⁻¹), rosemary essential oil was more toxic than laurel to the adults and larvae ofT. confusum. However, laurel essential oil was more toxic than rosemary to the eggs and pupae. Since these essential oils need such high Ct products to obtain complete mortality ofT. confusum compared with the most commonly used commercial fumigants, it would be impossible to use them on their own as a commercial fumigant against stored-product insects.     

Composition and toxic, repellent and feeding deterrent activity of essential oils against the stored-grain pests Tribolium castaneum (Coleoptera: Tenebrionidae) and Sitophilus oryzae (Coleoptera: Curculionidae)

BACKGROUND: The composition and bioactivity of essential oils from Tagetes terniflora Kunth, Cymbopogon citratus Stapf. and Elyonurus muticus (Spreng) Kuntz were evaluated against stored‐grain pests. RESULTS: Fumigant and contact toxicities were observed with T. terniflora on adults of both pests. In contact toxicity, this oil was less toxic to Tribolium castaneum (Herbst). Essential oils from C. citratus and E. muticus showed contact toxicity on S. oryzae. All essential oils produced: (a) repellency on larvae and adults of T. castaneum and adults of Sitophilus oryzae (L.); (b) post‐ingestive toxicity on T. castaneum larvae and S. oryzae adults and alteration of nutritional index on T. castaneum and S. oryzae adults. Cymbopogon citratus reduced the relative growth rate and the efficiency of conversion of ingested food in T. castaneum larvae. Tagetes terniflora produced a feeding stimulant effect in T. castaneum adults. In addition, they had a feeding deterrent action against S. oryzae adults. The composition of essential oils from C. citratus and E. muticus varied only in one component. CONCLUSION: These results showed that the essential oils from T. terniflora, C. citratus and E. muticus should be studied further for their use in integrated pest management programmes for T. castaneum and S. oryzae control. Copyright © 2011 Society of Chemical Industry     

Metabolism of a synthetic insect juvenile hormone (JH-I) during the development of Tribolium castaneum (herbst) (coleoptera,tenebrionidae)

Metabolites produced from ¹⁴C-labelled C-18 juvenile hormone (JH-I) topically applied to the flour beetle Tribolium castaneum were measured in larvae aged 21 and 28 days, pupae at four stages of development, and newly emerged and mature adults. The hormone was metabolized rapidly, in all stages examined, to form the corresponding diol-ester, acid-epoxide, and acid-diol derivatives, the diol-ester derivative being the major metabolite produced. The metabolism of JH-I was most rapid at the times of the larval/pupal and pupal/adult transformations. The differences in the rate of metabolism appeared to be correlated with changes in the production of the diol-ester derivative. Similar metabolic changes may regulate the levels of endogenous juvenile hormones during development in this species.     

Development,fecundity and prey consumption ofExochomus nigromaculatus feeding onHyalopterus pruni

Development, survival and reproduction ofExochomus nigromaculatus (Goeze) were studied in the laboratory at four constant temperatures from 20°C to 35±1°C in 5°C increments, 60±5% r.h. and 16 h of artificial light (5000 lux). Development time from egg to adult ranged from 22.4 days at 20°C to 10.6 days at 35°C, and required 278 degree-days above a threshold estimated to be 9.11°C. Survival was highest at 25°C and lowest at 35°C. Longevity of females declined significantly with increasing temperatures, ranging from 120.7 days at 20°C to 46.6 days at 35°C. Mean generation time became shorter with increasing temperatures. The intrinsic rate of increase of individuals kept at 30°C was significantly greater than that of individuals kept at the other temperatures tested. Fourth larval instars and adults ofE. nigromaculatus displayed a Type II functional response toHyalopterus pruni densities. Searching rate of fourth instar larvae and adults was similar, but handling time was shorter for female adults. Results obtained in this study showed that the optimal temperature for population growth ofE. nigromaculatus was 30°C and this coccinellid predator may have potential as a biological control agent forH. pruni because of its feeding capacity. http://www.phytoparasitica.org posting Aug. 22, 2002.     

Lethal doses of ozone for control of all stages of internal and external feeders in stored products

BACKGROUND: Gaseous ozone (O₃) has potential for control of insects in stored grain. Previous studies have focused on freely exposed insects. Immatures of internal pests (e.g. Sitophilus spp. and most stages of Rhyzopertha dominica F.) are protected within kernels and probably require higher doses and/or longer treatment times for full control. A laboratory study determined the doses of ozone necessary for full control of freely exposed and internal stages of eleven stored‐product pest species. Test insects were three species of Sitophilus, R. dominica, Tribolium confusum Jacquelin du Val, T. castaneum Herbst, Plodia interpunctella Hübner, Sitotroga cerealella Olivier, Oryzaephilus surinamensis L., Ephestia kuehniella Zeller and Stegobium paniceum L. Insects were exposed to continuous flows of ozone in doses of 10–135 ppm and exposure times of 5–8 days. Dose‐mortality bioassays were conducted on three species of Sitophilus and P. interpunctella. RESULTS: Freely exposed stages (with a few exceptions) were controlled with 35 ppm of ozone for 6 days. Full mortality of internal stages within kernels required exposure to 135 ppm for 8 days. CONCLUSION: This study confirms that higher doses and/or longer treatment times are necessary for control of internal stages of stored‐product pests. Copyright © 2012 Society of Chemical Industry