Laboratory test method to evaluate the effect of 31 pesticides on the predatory bug,Orius laevigatus (Het: Anthocoridae)

A laboratory test method was developed to evaluate the pesticide toxicity on the predatory bugOrius laevigatus (Fieber). Newly hatched first-instar nymphs ofO. laevigatus were exposed to spray deposits of pesticides that were sprayed on the glass plates of a drum cell at the manufacturer’s recommended maximum dosage. Nymphal mortality and oviposition of surviving adults were recorded. Test results of various (31) commonly used pesticides (insecticides, insecticides/acaricides, acaricides and fungicides) are presented and discussed in accord with the classification of the IOBC/WPRS Working Group ”Pesticides and Beneficial Organisms”. Most fungicides had no toxic effect on nymphal development and egg-laying of surviving adults. The acaricides tested had variable toxicity on the predatory bug, while some insect growth regulators, such as the benzoylphenyl urea were very toxic. Otherwise, the ecdysone agonist tebufenozide and azadirachtin were not harmful for nymphal development and oviposition     

Bionomics of a polyphagous predator:Orius laevigatus (Het.: Anthocoridae)

The main characteristics of the imaginal and preimaginal development and the reproduction ofOrius laevigatus were studied at 15, 20, 25 and 30°C. Temperature greatly influences the developmental and reproductive biology of this species. The lowest developmental threshold is 10,6°C. Reproduction is greatly reduced at 15°C relative to the higher temperatures tested. O. laevigatus is well adapted to relatively high temperature conditions. The best development and reproduction rates are observed between 20 and 30°C with a theoretical optimum at 26°C.

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Résumé Les principales caractéristiques du développement pré-imaginal et imaginal ainsi que la reproduction d'Orius laevigatus sont étudiées à des températures de 15, 20, 25 et 30°C. La température influence considérablement le développement embryonnaire et post-embryoannaire de cette espèce. Le zéro théorique de développement se situe à 10,5°C. Les capacités reproductrices sont fortement perturbées à des températures inférieures à 15°C. Les résultats montrent queO. laevigatus est une espèce adaptée à des conditions thermiques relativement élevées. C'est entre 20 et 30°C, avec un optimum de 26°C, que s'expriment le mieux les capacités de développement et de reproduction de ce prédateur.

     

Side-effects of pesticides on the predatory bug Orius laevigatus (Heteroptera: Anthocoridae) in the laboratory

Laboratory trials were carried out in order to test the effects of 29 pesticides on the predatory bug, Orius laevigatus. To evaluate residual contact activity, newly moulted fourth instar nymphs of O. laevigatus were placed on treated Petri dishes and their mortality was checked after 7 days. The fecundity of surviving females was tested for 14 days. Young O. laevigatus adults were fed with eggs of Ephestia kuehniella, treated with the (above-mentioned) pesticides, to assess the effect of pesticides by ingestion. Adult mortality, female fecundity and egg hatching were recorded. Azadirachtin, granulosis virus products, mineral oil, pirimicarb, tebufenozide, clofentezine, hexythiazox and copper oxychloride had no significant effect on the survival and fecundity of O. laevigatus when predators were exposed to pesticide residues by contact or by ingestion. Triflumuron and diflubenzuron appeared to be harmless by contact, but diflubenzuron was slightly toxic when ingested. Buprofezin and teflubenzuron were slightly to moderately toxic, while hexaflumuron, flufenoxuron, and lufenuron showed a marked toxicity by contact as well as by ingestion. A number of organophosphates, endosulfan and deltamethrin were detrimental especially by contact. Imidacloprid was very toxic by contact but only slightly toxic when ingested. Indoxacarb and methoxyfenozide were less toxic than imidacloprid. These findings should be considered when releases of O. laevigatus are used in greenhouses or on outdoor crops.     

Toxicity of some insecticides and acaricides to the predatory bugDicyphus tamaninii (Het.: Miridae)

Several pesticides were tested in the laboratory for their side-effects upon the mirid bugDicyphus tamaninii, a polyphagous predator used for IPM programmes in some vegetable crops. Residual toxicity to 3rd -4th instar nymphs on tomato leaflets was checked 24, 48 hours and seven days after treatment. The acaricides bromopropylate, dicofol+tetradifon and fenpyroximate were harmless to the nymphs. The insect growth regulators azadirachtin, buprofezin, lufenuron and pyriproxyfen were also harmless to nymphs and teflubenzuron was slightly harmful seven days after treatment. Among the conventional insecticides tested, only pirimicarb and tau-fluvalinate were harmless toD. tamaninii nymphs     

Development and survival ofOrius albidipennis andO. levigatus (Het.: Anthocoridae) on various diets

The effect of various diets on nymphal development and survival of two predaceous anthocorid bugs,Orius albidipennis (Reuter) andO. laevigatus (Fieber) was investigated in the laboratory. Five different diets were compared: eggs ofEphestia kuehniella Zeller; eggs ofE. kuehniella plus mixed flower pollen; only mixed flower pollen; pollen from sweet pepper (Capsicum annuum L. cv. Mazurka) flowers; and sweet pepper plants. A high percentage of predators successfully completed nymphal development on those diets containing lepidopterous eggs. When fed on sweet pepper pollen, the survival percentages were 65% forO. laevigatus and 38% forO. albidipennis. No nymphs of either species completed the nymphal stage on mixed flower pollen or on sweet pepper plants. Development was significantly faster on diets containing eggs ofE. kuehniella. Results are discussed in relation to the capability of the bugs to survive periods of prey scarcity and to the optimization of release strategies for these predators in the greenhouse.     

Supplemental food affects thrips predation and movement of Orius laevigatus (Hemiptera: Anthocoridae) and Neoseiulus cucumeris (Acari: Phytoseiidae)

Two experiments were done to examine the predation of thrips, and the movement of Orius laevigatus Fieber and Neoseiulus cucumeris (Oudemans) in the presence and absence of two supplemental food sources, pollen and the fungus Trichoderma viride. The presence of pollen led to a 55% reduction in predation of the thrips by N. cucumeris and a 40% reduction in thrips predation by O. laevigatus, in experiments using single predators. The presence of fungus had no significant effect on thrips predation by either of the natural enemy species. Movement of the natural enemies was examined in a multiple predator experiment, and this showed that O. laevigatus was more likely to remain on the plant in the presence of thrips and when supplemental food, either pollen or fungus, was present. For N. cucumeris, there was no association between the presence of thrips and the mite, with the majority of the mites being found on the leaves where pollen was present. Although the single and multiple predator experiments were done at different times, the indications are that the predation rates of the N. cucumeris do not differ greatly between the two experiments, suggesting that there may be a potential interference effect between the mites, which is not present for O. laevigatus. The significance of these results for the use of supplemental food sources in biological control is discussed.     

Developmental and reproductive fitness of Orius laevigatus (Hemiptera: Anthocoridae) reared on factitious and artificial diets

The developmental and reproductive fitness of the polyphagous predator Orius laevigatus (Fieber) (Hemiptera: Anthocoridae) was compared on two factitious foods and four artificial diets. Adults fed factitious foods (Ephestia kuehniella Zeller eggs and Artemia franciscana Kellogg cysts) performed better than those fed artificial diets. Among the artificial diets, a diet composed of liver and ground beef scored better than meridic diets based on egg yolk. Within the egg yolk-based artificial diets, the developmental fitness varied proportionally with the amount of egg yolk present in the diet. A food switching experiment, in which nymphs and adults of the predator were fed either E. kuehniella eggs or an egg yolk-based artificial diet, showed that the impact of adult food on reproductive capacity was greater than that of nymphal food. An optimal adult food was able to wholly compensate for deficiencies incurred by an inferior artificial diet in the nymphal stage. A strong correlation was found between oocyte counts, lifetime oviposition, and the number of eggs laid after 8 d. A rapid dissection assay may thus be effective to reliably and economically assess the fitness of O. laevigatus as a function of the diet. This method also may prove useful as part of quality assurance procedure for commercially produced predators.     

Temperature effect on the predation rate of Anthocoris nemorum (Het.: Anthocoridae) on cabbage aphids (Hom.: Aphididae)

The temperature‐dependent predation by Anthocoris nemorum L. (Het.: Anthocoridae) on second instar Brevicoryne brassicae L. (Hom.: Aphididae) at constant temperatures of 12, 15 and 20°C increased linearly with temperature with a mean (±SE) consumption of 6.9 (±0.8), 9.28 (±1) and 15.9 (±0.8) respectively. The estimated lower temperature threshold for predation (T₀) was 6.4°C.     

Nutritional value of brine shrimp cysts as a factitious food for Orius laevigatus (Heteroptera: Anthocoridae)

Decapsulated cysts of the brine shrimp Artemia franciscana were assessed as a factitious food for rearing the anthocorid predator Orius laevigatus. Developmental and reproductive traits of O. laevigatus reared for a single generation on A. franciscana from three geographical locations or on gamma-irradiated eggs of the Mediterranean flour moth Ephestia kuehniella were compared. There was no effect of diet on nymphal survival but nymphal period on E. kuehniella eggs (12.2 days) was 0.7-1.6 days shorter than on the Artemia diets. The predator developed 0.5-1 day faster on cysts from San Francisco Bay (USA) than on cysts from Great Salt Lake (USA) or Macau (Brazil). Fecundity on brine shrimp cysts from different locations was similar to that on flour moth eggs (142-187 eggs/female). The biochemical composition of decapsulated cysts from San Francisco Bay was compared with that of E. kuehniella eggs. Depending on the type of analysis, Artemia cysts contained higher or similar amounts of protein as compared with E. kuehniella eggs, but amino acid patterns were generally similar. Flour moth eggs were almost three times richer in fatty acids than brine shrimp cysts, with some marked differences in fatty acid profiles. Because nutrient imbalances in a diet may be expressed only after several generations of rearing, the predator was cultured for three consecutive generations on A. franciscana cysts from San Francisco Bay. In the third generation on brine shrimp cysts, nymphs took 18% longer to develop, and adults were shorted-lived and about 60% less fecund than those maintained on E. kuehniella eggs. Brine shrimp cysts may be used as a supplement in the mass production of O. laevigatus but may not be a suitable food for long-term culturing of the predator.     

Effectiveness of Orius laevigatus (Hem.: Anthocoridae) for the control of Frankliniella occidentalis on cucumber and pepper in the UK

Biological control of Western Flower Thrips was sought by the use of Orius laevigatus, an anthocorid bug indigenous to the UK. Rearing methods were successfully devised for this species and glasshouse trials on cucumbers and peppers were conducted. It was not possible to obtain full establishment of O. laevigatus on a cucumber crop, but breeding populations established satisfactorily in the flowers of sweet peppers. On peppers, releases totalling one to two Orius per plant resulted in good thrips control over several months providing that initial thrips numbers were low. Early season supplementary lighting using tungsten bulbs to extend the photoperiod ensured good control of thrips on peppers in February and March by promoting Orius breeding on the crop.     

Toxicity of three acaricides to Tetranychus urticae (Tetranychidae: Acari) and Orius insidiosus (Anthocoridae: Hemiptera)

Management for twospotted spider mite, Tetranychus urticae Koch, populations in peanut, Arachis hypogaea L., relies on acaricides. The outcomes of acaricide applications are most predictable when complete information on their toxicity and specificity is available. Specifically, the degrees to which acaricides impact different stages of T. urticae and natural enemies combined determine the overall efficacy of an acaricide application. The objectives of this study were to determine stage-specific direct and residual efficacies of three acaricides (fenpropathrin, etoxazole, and propargite) against T. urticae, and the direct and residual toxicity of the acaricides to Orius insidiosus (Say) adults. Direct toxicity of acaricides to T. urticae was measured on peanut cuttings. All acaricide treatments caused significant mortality to a mixed stage population of T. urticae, and mortality did not differ among the acaricides 7 d after treatment. When toxicity to eggs was tested, the proportion of eggs that hatched for all acaricide treatments was significantly lower than the control, with etoxazole and propargite causing 100% mortality. Exposure to acaricide residues caused < 30% mortality of T. urticae adults 1 and 2 d after treatment and was not significantly different from the control. Fenpropathrin and propargite caused 100% mortality and etoxazole caused > 50% mortality of O. insidious adults after direct exposure to the acaricides. Residual toxicity of acaricides to O. insidiosus adults varied but remained toxic to O. insidiosus longer than to T. urticae. Fenpropathrin had the longest residual effect on O. insidiosus adults, causing > 95% mortality after 14 d; etoxazole and propargite caused < 30% mortality after 14 d.     

Temperature effects on development ofOrius tantillus (Het.: Anthocoridae), A predator ofThrips palmi (Thys.: Thripidae)

To explore the possibility of usingOrius tantillus (Motschulsky) as a control agent againstThrips palmi Karny in greenhouses in Japan during the winter months, the effects of temperature on the development of eggs and nymphs of this predator were determined by rearing individuals under eight constant temperatures ranging from 17.5–35.0°C. Estimates of lower developmental threshold temperatures for eggs, male nymphs and female nymphs were 13.7°C, 11.9°C and 13.4°C, respectively. These estimates were lower than the average winter temperature at night in greenhouses in Japan, suggesting thatO. tantillus could possibly be used for the control ofT. palmi in such greenhouses. Thermal constants were estimated at 52.6, 185.2 and 153.8 degree days for eggs, male nymphs and female nymphs, respectively. Egg survival at temperatures between 20°C and 30°C was higher (p=0.05) than at 17.5°C.     

Test of the RAPD-PCR method to evaluate the efficacy of augmentative biological control withOrius (Het., Anthocoridae)

Bugs from the genusOrius (Heteroptera, Anthocoridae) are used as biological control predators against acari and homopteran pests. This augmentative biological control method consists of massive field releases where ever indigenous populations may be present. Identification of the released predators along with the indigenous ones is a prerequisite to estimate the efficiency of the biological control agent. We have tested whether strain-specific molecular markers can be used to discriminate strains of predators. The RAPD-PCR method was used. Species are easily distinguishable by this technique, but, differentiation of strains from distinct geographic origins was impossible due to the high level of polymorphism observed. Reduction of this polymorphism by inbreeding lines and selection of rare alleles may allow to overcome this problem.     

Modelling population dynamics of Orius laevigatus and O. albidipennis (Hemiptera: Anthocoridae) to optimize their use as biological control agents of Frankliniella occidentalis (Thysanoptera: Thripidae)

ORIUS LAEVIGATUS: (Fieber) and O. albidipennis (Reuter) play an important role in the control of Frankliniella occidentalis (Pergande) in crops and natural vegetation in the Mediterranean area. The biological parameters of the two anthocorids were studied and modelled in relation to temperature to optimize their use in thrips control programmes. Development times and reproductive parameters of O. laevigatus and O. albidipennis were determined at 20, 25, 30 and 35 degrees C. Pre-imaginal development times ranged from 34.6 and 37.2 days at 20 degrees C to 12.3 and 10.2 days at 35 degrees C in O. laevigatus and O. albidipennis, respectively. The lower thermal development threshold was significantly higher for O. albidipennis (14.2 +/- 0.9 degrees C) than for O. laevigatus (11.3 +/- 0.7 degrees C). No significant differences in fecundities between the two anthocorids were observed at 20, 25 and 30 degrees C. At 35 degrees C, O. albidipennis had a significantly higher fecundity than O. laevigatus. Non-linear models were used to explain reproduction and female survivorship in relation to temperature. The upper reproductive thresholds were estimated at 40.9 +/- 0.3 and 35.5 +/- 0.1 degrees C for O. albidipennis and O. laevigatus, respectively. The different optimum temperatures may explain, at least in part, the different distributions of the two species in the Palaeartic region and their population dynamics in greenhouses and natural vegetation in the south of Spain. The estimation of rm as a function of temperature showed high variability between years. Three release rates of 0.75-0.25 Orius per plant are recommended from early March to mid May to deal with thrips outbreaks in pepper crops.     

Effects of starvation on the search path characteristics of Orius majusculus (Reuter) (Het., Anthocoridae)

Abstract: Orius majusculus (Reuter) is a polyphagous predator bug used to control western flower thrips Frankliniella occidentalis (Pergande). As physiological factors may be highly influential upon the predatory behaviour of Orius spp. we studied the possible impact of starvation on the search path of this bug. Orius majusculus was maintained on a diet of Ephestia kuehniella Zeller (Lep., Pyralidae) eggs in laboratory. Adults were collected immediately after the imaginal moult and were individually placed in Petri dishes with abundant food. Each adult was randomly assigned to one of the following five treatments: immediate observation or starved for 2, 6, 9 or 12 h prior to observation. The observation procedure consisted of placing a single O. majusculus adult at the centre of an empty arena. The displacement of each insect was recorded with a video camera until it had reached the limits of the arena. The recorded paths were digitized and the digitized search path was used to calculate the mean walking speed, the number of stops per second, the duration of stops and the diffusion rate. The results clearly show that, in comparison with unstarved bugs, insects that experienced 6 h of prey deprivation walked more slowly, stopped more frequently and for longer periods, and had a lower rate of diffusion away from the release point. In contrast, all search path variables returned to the levels measured in unstarved bugs in the group that experienced the longest period of starvation (12 h), whereas groups of O. majusculus that had experienced 2 or 9 h of prey deprivation presented intermediate values for all the variables tested. Starvation produced evident changes in the search path characteristics that we assume to be related to physiological states of hunger and energy availability. These behavioural changes related to physiological state could have consequences for the use of this pirate bug in biological control.     

Light intensity and wavelength influence development, reproduction and locomotor activity in the predatory flower bug Orius sauteri (Poppius) (Hemiptera: Anthocoridae)

Light wavelength and intensity are physical factors that can affect arthropod development and reproduction. The present study examined the development, reproduction and locomotor activity of the predatory flower bug, Orius sauteri (Poppius) (Hemiptera: Anthocoridae), under five light intensities (1000, 2000, 3000, 4000 and 5000 lux) and five wavelengths [red (678.5 nm), green (620.0 nm), yellow (581.7 nm), blue (478. 1 nm) and white (all wavelengths)] at constant temperature (25 °C) and RH (70 %). The duration of nymphal development was extended at lower light intensities, primarily due to effects on the first three instars. Under white, yellow and green light, O. sauteri completed development in 18.0 days, but blue light extended development by 3.2 days and red light extended it by 7.4 days. Although lower light intensities extended the preoviposition period and reduced fecundity, they improved egg fertility. Both red and blue light negatively affected preoviposition period, fecundity and egg fertility. Whereas adult female mean walking speed over a five min period was reduced at lower light intensities, longer wavelengths (yellow and red) increased it, ostensibly reflecting an avoidance response. The respiration quotient of adult O. sauteri females was also elevated under red light conditions. These findings are informative for optimizing O. sauteri mass-rearing procedures and maximizing its efficacy as a biological control agent in greenhouse cultures.     

Toxicity of pesticides used in chrysanthemum crops to eggs and nymphs of Orius insidiosus (Say) (Hemiptera: Anthocoridae)

The objective of this study was to evaluate the toxicity of some pesticides used in chrysanthemum crops to eggs and nymphs of Orius insidiosus (Say). The bioassays were carried out at 25 +/- 2 degrees C, 70 +/- 10% RH and 12h photophase. For the tests with eggs, stems of Bidens pilosa L. previously exposed to predator oviposition were dipped for five seconds in aqueous dilution of the pesticides, using 40 eggs per treatment. The pesticides were applied on nymphs using a Potter's tower. Forty first-instar and twenty second-instar nymphs of O. insidiosus were used per treatment in the tests with nymphs. The adults from eggs and nymphs treated were grouped in couples to study the pesticides effects on its reproductive parameters. None tested pesticide affected the viability of treated eggs. Azoxystrobin, benomyl, imibenconazole, iprodione, metalaxyl + mancozeb and triforine were harmless to first- and second-instar nymphs of O. insidiosus, whereas abamectin, acephate and chlorfenapyr were shown to be harmful to nymphs of both first and second instars. The pre-oviposition period, the daily number of eggs, number of eggs in ten days, and egg viability were not affected by azoxystrobin, benomyl, imibenconazole, iprodione, metalaxyl + mancozeb and triforine. These pesticides, for showing low toxicity to the predator, can be recommended in disease management programs for chrysanthemum crops, in association with O. insidiosus.     

Influence of weed management on the abundance of thrips species (Thysanoptera) and the predatory bug,Orius niger (Hemiptera: Anthocoridae) in citrus mandarin

Applied Entomology and Zoology - Field trials were carried out in 2014 and 2015 in fields of Çukurova University Research and Implementation Area, Adana province, Turkey. The experiment was...     

Analysis of the activity rhythm of the predatory bug Orius sauteri (Poppius) (Heteroptera: Anthocoridae) for optimizing its selective light attraction

Applied Entomology and Zoology - The minute pirate bug Orius sauteri (Poppius) (Heteroptera: Anthocoridae) is a major natural enemy of micro-pests and is expected to be an effective pest-control...