Residual toxicity of some insecticides on the predatory bugs Dicyphus tamaninii and Macrolophus caliginosus

Chlorpyrifos, formetanate, methamidophos, imidacloprid and endosulfan were tested in the laboratory for their effects upon the mirid bugs Dicyphus tamaninii and Macrolophus caliginosus, which are polyphagous predators used for IPM programs in some vegetable crops. The mortality of third-fourth instar nymphs was checked 24 and 48 hours and 7 days after exposure to 1-, 3-, 8-, 21- and 30-day residues of the treatments on tomato leaflets. The reproductive capacity of surviving females also was evaluated for 15 days and compared with females that had not been exposed to insecticides. Chlorpyrifos, formetanate and methamidophos are considered persistent because they remained toxic to both mirid species for 30 days. Imidacloprid is moderately persistent, becoming harmless by 21 days after treatment for M. caliginosus and by 30 days after treatment for D. tamaninii. Endosulfan is moderately persistent for M. caliginosus, becoming harmless by 21 days after treatment, and is short lived for D. tamaninii, becoming harmless by 3 days after treatment. There were no effects on the reproductive capacity of females that were exposed as nymphs to the insecticides tested. Of all the insecticides, only endosulfan is marginally compatible with the use of D. tamaninii.     

Toxicity of diflubenzuron, pyriproxyfen, imidacloprid and diafenthiuron to the predatory bugOrius laevigatus (Het.: Anthocoridae)

The susceptibility of the predatory bugOrius laevigatus (Fieber) to the insect growth regulators diflubenzuron, pyriproxyfen, the nitroguanidine insecticide imidacloprid and the thiourea compound diafenthiuron was investigated in the laboratory. Fifth-instar nymphs were exposed to formulated materials of each compound and adults were exposed to formulated materials of diafenthiuron and imidacloprid. In each case, exposure via ingestion and residual contact was tested. Pyriproxyfen was harmless toO. laevigatus nymphs by both ways of exposure. The respective LC₅₀-values of diflubenzuron via ingestion and residual contact were 229.9 and 391.1 mg a.i./l. Diafenthiuron did not cause significant mortality to fifth-instar nymphs and adults via ingestion but was toxic by residual contact with LC₅₀-values of 329.4 mg a.i./l and 125.9 mg a.i./l for nymphs and adults respectively. Imidacloprid proved to be the most toxic compound with LC₅₀-values of 1.1 and 0.04 mg a.i./l for nymphs and 2.1 and 0.3 mg a.i./l for adults, via ingestion and residual contact, respectively. The results suggest that use of pyriproxyfen in an integrated pest management programme will not cause any problems but that imidacloprid, and to a lesser extent, also diflubenzuron and diafenthiuron could be harmful to the predator.     

常用杀虫杀螨剂对腐食酪螨的毒力测定

采用药膜法和玻片浸渍法分别测定了14种常用杀虫杀螨剂对腐食酪螨雌成螨和卵的毒力。结果表明:各药剂对雌成螨都有一定作用,但对卵没有杀伤效果。其中,对雌成螨毒力最高的为杀螨多,LC50为0.2568 mg.L-1;毒力最低的为敌敌畏,LC50为320.4793 mg.L-1。     

Olfactory response of Trigonotylus caelestialium (Het.: Miridae) to rice plant and gramineous weeds

Abstract:  The olfactory response of Trigonotylus caelestialium , to rice, Oryza sativa L., and two species of gramineous weeds, Poa annua and Digitaria ciliaris , was investigated with an olfactometer to clarify the role of host-plant odours as olfactory cues in their host-finding behaviour. Third-instar nymphs and adult males were significantly attracted to whole plants (above ground parts) of P. annua . However, adult females were not significantly attracted to whole plants of P. annua . Attractancy of rice to T. caelestialium differed with the growth stage and part of the plant. Adult females were significantly attracted to stems and leaves in the panicle-formation stage, and panicles in the flowering stage. They were not attracted to stems and leaves in the fourth-leaf stage and flowering stage, or to panicles in the milk-and full-ripe stages. Although adult males were significantly attracted to stems and leaves in the panicle-formation stage, they were not attracted to the other rice structures tested. Both females and males were significantly attracted to stems and leaves, as well as panicles of D. ciliaris in the flowering stage. The findings suggest that T. caelestialium use host-plant volatiles as olfactory cues to find their host plants and their invasion to paddy fields were caused by olfactory responses to rice plant.     

Analysis of some morphological and biochemical characteristics of the egg of the predaceous bugMacrolophus caliginosus (Het.: Miridae) during embryogenesis

The predaceous bug,Macrolophus caliginosus Wagner (Heteroptera: Miridae) is a biological control agent used in greenhouses in the French Mediterranean region. The egg of this mirid is embedded in plant tissues and all embryonic development occurs in this environment. In order to define an artificial substrate for egg-laying, exchanges of chemical substances between the egg and the host plant were investigated by morphological and biochemical analyses. Egg wet weight doubled throughout embryonic development, while egg dry weight did not vary. The amino acid content of the egg remained stable during embryogenesis. Only aspartic acid, serine and alanine decreased during the first five days of development. It can be concluded that exchanges mainly involved uptake of water by the egg.     

Macrolophus caliginosus (Wagner) as an Intraguild Prey for the Zoophytophagous Dicyphus tamaninii Wagner (Heteroptera: Miridae)

The zoophytophagous predator Macrolophus caliginosus (Wagner) (Heteroptera: Miridae) has previously been identified as a potential prey for the intraguild zoophytophagous predator Dicyphus tamaninii Wagner. Its value as an intraguild prey was tested for D. tamaninii nymphal development and adult survival. In the laboratory, plant (red tomato fruit, green tomato fruit, tomato leaf) and animal (aphids, whiteflies, pyralid eggs) resources were compared to frozen nymphs of M. caliginosus as an intraguild resource for D. tamaninii. M. caliginosus nymphs allowed complete and rapid development of D. tamaninii nymphs and generated low mortality of nymphal and adult stages. Performances were higher with the intraguild M. caliginosus resource than with plant resources. Tomato leaves did not allow the complete nymphal development of D. tamaninii. Tomato fruit generated lighter adults and doubled the nymphal developmental time compared with the M. caliginosus resource. In the animal resource group, there were no differences between the M. caliginosus and the other treatments (aphids, whiteflies, pyralid eggs) for nymphal mortality, average number of molts, nymphal developmental time, adult weight, and adult survival. M. caliginosus should be considered a high-quality resource for D. tamaninii.     

Susceptibility of two bulb mites,Rhizoglyphus robini andR. setosus (Acarina: Acaridae), to some acaricides and insecticides

The susceptibility of two field-collected bulb mites,Rhizoglyphus robini andR. setosus to some organophosphorus, carbamates, pyrethroids and other compounds with acaricidal activity was evaluated. In general,R. setosus was more tolerant to these compounds thanR. robini. Among the 58 commercially formulated compounds tested,R. robini was susceptible to chlorpyrifos 22.5% EC, EPN 45% EC, ethion 46.5% EC, fenitrothion 50% EC, methamidophos 50% S, methidathion 40% EC, mevinphos 25.3% EC, omethoate 25% EC, parathion 47% EC, phosmet 50% WP, profenofos 43% EC, prothiophos 50% EC, benfuracarb 20% EC, carbofuran 40.64% F, carbosulfan 48.34% EC, formetanate 50% SP, methiocarb 50% WP, azocyclotin 25% WP and cyhexatin 50% WP. Demeton-S-methyl 25% EC, methidathion 40% EC, phosmet 50% WP, profenofos 43% EC, prothiophos 50% EC, azocyclotin 25% WP and cyhexatin 50% WP gave good toxicity toR. setosus. Both species were tolerant to avermectin 1.8% EC and some newly developed synthetic pyrethroids, which were proved to have acaricidal activity. In addition, two bioassay methods were also evaluated for these two mites.Contribution No. 1354 from Taiwan Agricultural Research Institute     

Microbial community of predatory bugs of the genus Macrolophus(Hemiptera: Miridae)

Background

The predatory mirids of the genus Macrolophus are key natural enemies of various economically important agricultural pests. Both M. caliginosus and M. pygmaeus are commercially available for the augmentative biological control of arthropod pests in European greenhouses. The latter species is known to be infected with Wolbachia -inducing cytoplasmic incompatibility in its host- but the presence of other endosymbionts has not been demonstrated. In the present study, the microbial diversity was examined in various populations of M. caliginosus and M. pygmaeus by 16S rRNA sequencing and denaturing gradient gel electrophoresis.

Results

Besides Wolbachia, a co-infection of 2 Rickettsia species was detected in all M. pygmaeus populations. Based on a concatenated alignment of the 16S rRNA gene, the gltA gene and the coxA gene, the first is phylogenetically related to Rickettsia bellii, whereas the other is closely related to Rickettsia limoniae. All M. caliginosus populations were infected with the same Wolbachia and limoniae-like Rickettsia strain as M. pygmaeus, but did not harbour the bellii-like Rickettsia strain. Interestingly, individuals with a single infection were not found. A PCR assay on the ovaries of M. pygmaeus and M. caliginosus indicated that all endosymbionts are vertically transmitted. The presence of Wolbachia and Rickettsia in oocytes was confirmed by a fluorescence in situ hybridisation. A bio-assay comparing an infected and an uninfected M. pygmaeus population suggested that the endosymbionts had minor effects on nymphal development of their insect host and did not influence its fecundity.

Conclusion

Two species of the palaearctic mirid genus Macrolophus are infected with multiple endosymbionts, including Wolbachia and Rickettsia. Independent of the origin, all tested populations of both M. pygmaeus and M. caliginosus were infected with three and two endosymbionts, respectively. There was no indication that infection with endosymbiotic bacteria had a fitness cost in terms of development and fecundity of the predators.

     

Impact of Macrolophus caliginosus presence on damage production by Dicyphus tamaninii (Heteroptera: Miridae) on tomato fruits

In northeast Spain, the most common predators found in tomato fields and greenhouses are the mirids Macrolophus caliginosus Wagner and Dicyphus tamaninii Wagner. Natural colonization occurs during the growing season and both species prey on whiteflies. Because D. tamaninii can damage tomato fruits during periods of prey scarcity, a semifield experiment was carried out to evaluate whether the presence of M. caliginosus affects damage produced by D. tamaninii. In a tomato greenhouse, 60 plants were individually caged and distinct predator treatments were introduced: D. tamaninii, D. tamaninii + eggs of Ephestia kuehniella Zeller, D. tamaninii + M. caliginosus, M. caliginosus alone, and a control without any insect. Damage to tomato fruits was recorded (>25% of the fruit) in all the treatments with D. tamaninii, whereas no significant damage was detected with M. caliginosus alone. Finally, no intraguild predation was detected between both mirid species.     

Oviposition preference of Lygocoris pabulinus (Het., Miridae) in relation to plants and conspecifics

Abstract: To predict possible locations of Lygocoris pabulinus (L) in the field during the summer, we determined their oviposition preference under summer conditions. With L. pabulinus reared on potato, oviposition preference was determined for potato, tomato or green bean. As preference may depend on larval or early adult experience, the oviposition preference of bugs reared on green bean for three generations, and of bugs captured from the field 12 h prior to the experiment was also determined. All females showed a strong preference for potato plants, on which fecundity was higher. Hence, although L. pabulinus is a generalist in its feeding habits, the summer generation seems to be an oviposition specialist. Aggregation of ovipositing females does not seem to occur; similar amounts of eggs were oviposited in plants with clip cages containing conspecifics as in plants without conspecifics. More eggs were oviposited in damaged plants than in undamaged plants. Plant volatiles released upon damage may aid L. pabulinus females in finding suitable oviposition sites.     

河南省绿盲蝽对有机磷类杀虫剂的抗药性监测

【目的】全面了解河南省绿盲蝽Apolygus lucorum(Meyer-Dür)对有机磷杀虫剂的敏感性变化,可为该虫的有效防治提供科学依据。【方法】采用瓶膜法于2010—2013年系统监测了河南新乡、周口、南阳地区绿盲蝽田间种群对毒死蜱、马拉硫磷、辛硫磷和乙酰甲胺磷4种常用有机磷杀虫剂的敏感性。【结果】相对于室内敏感种群,2010—2013年河南省各地绿盲蝽种群对不同有机磷杀虫剂表现出不同程度的敏感性变化,但相对毒力比值均小于5倍。其中对毒死蜱、马拉硫磷、辛硫磷和乙酰甲胺磷的敏感性均未降低,且3个种群对马拉硫磷表现为敏感性增强。【结论】毒死蜱、马拉硫磷、辛硫磷和乙酰甲胺磷仍是河南省防治绿盲蝽的有效药剂。     

Effect of insecticides,acaricides and fungicides onMormoniella vitripennis walker (Hym. Pteromalidae)

Zusammenfassung In Versuchen über die Anf?lligkeit von Schlupfwespen für Bek?mpfungsmittel wurdeMormoniella vitripennis benutzt. Eine Spritzbelagmethode wurde angewandt. Die Ergebnisse in Tabellen I, II und III zeigen eine sehr geringe Giftwirkung von Captan, Karathane, Thiram und die Sauerstoffanalogon von Eradex, dagegen gaben Thiodan und Sevin eine sehr hohe Mortalit?t. Ryanicide, Chlorbenside und Isolan waren in den angewandten Konzentrationen nicht gef?hrlich für diesen Parasit.      

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.     

氯虫苯甲酰胺对黑肩绿盲蝽捕食功能的影响

为协调褐飞虱Nilaparvata lugens (Stal) 的化学防治和生物防治提供参考, 本研究采用稻茎浸渍法研究了氯虫苯甲酰胺对黑肩绿盲蝽Cyrtorhinus lividipennis (Reuter) 捕食褐飞虱功能反应的影响。结果表明: 在氯虫苯甲酰胺的推荐剂量下, 黑肩绿盲蝽功能反应模型的结构没有改变, 但影响到了模型的各项参数。在推荐剂量下, 氯虫苯甲酰胺可降低黑肩绿盲蝽的瞬时攻击率(a′); 药剂处理后黑肩绿盲蝽若虫对褐飞虱卵、1龄若虫和2龄若虫的处理时间(Th)比对照分别增加163.03%, 104.21%和95.11%, 而黑肩绿盲蝽成虫对它们的处理时间则分别增加81.97%, 102.45%和99.52%; 药剂处理后黑肩绿盲蝽日最大捕食量(Na*)降低, 其寻找效应(S)也减弱。研究表明氯虫苯甲酰胺对黑肩绿盲蝽捕食作用存在着不良影响。     

Toxicity of seventeen insecticides to Camponotus sericeus (Hymenoptera: Formicidae)

The success of chemical control depends on toxicity of insecticides against insect pests. Camponotus sericeus is an important urban pest with the ability to cause substantial damage to wooden structures, but there is a lack of information on toxicity of insecticides against C. sericeus. To determine the insecticide toxicity, workers of C. sericeus were exposed to 17 insecticides from different classes: carbamate (methomyl, bendiocarb), organophosphate (chlorpyrifos, profenofos, temephos), pyrethroid (bifenthrin, deltamethrin, permethrin), neonicotinoid (acetamiprid, imidacloprid, thiamethoxam), avermectin (abamectin, emamectin), pyrrole (chlorfenapyr), phenylpyrazole (fipronil), and spinosyn (spinosad and spinetoram), via residual bioassay method. The LC₅₀ ranged from: 0.15 to 0.20 µg/vial for carbamates, 0.09 to 0.27 µg/vial for organophosphates, 0.09 to 0.44 µg/vial for pyrethroids, 0.02 to 0.67 µg/vial for neonicotinoids, 0.54 to 0.82 µg/vial for avermectins, 0.78 µg/vial for pyrrole, 0.62 µg/vial for phenylpyrazole, and 1.96 to 2.05 µg/vial for spinosyns. Overall, acetamiprid was the most toxic one among the tested insecticides followed by permethrin, temephos, profenofos, bendiocarb and methomyl, while spinosad and spinetoram were the least toxic insecticides. Considering the potential toxicity of different insecticides against C. sericeus, future studies could investigate the practical application of these insecticides in order to design an effective management plan.     

Thermal effects on the biological parameters of the predatory mirid Pilophorus gallicus (Hemiptera: Miridae)

Pilophorus gallicus Remane (Hemiptera: Miridae) is a predatory mirid reported in deciduous trees in the western Mediterranean area. This work aimed to determine the biological and demographic parameters for this species at different temperatures (15, 20, 25 and 30°C). Egg hatching times shortened from 57.8 days at 15°C to 9.2 days at 30°C, and nymphal development times declined from 62.8 days at 15°C to 11.1 days at 30°C. The hatching and nymphal survival rates were low at 15 and 30°C. The lower thermal thresholds for the egg and nymphal development were 12.4 and 12.0°C, respectively. These high thermal thresholds could be a safety mechanism to avoid the emergence of nymphs in the unfavorable winter period. Female weight increased between 15 and 25°C and decreased at 30°C. The fecundity increased from 70.2 eggs per female at 15°C to 212.4 eggs per female at 25°C, and decreased to 88.5 eggs per female at 30°C. Fertility ranged from 9.4% at 15°C to 40.9% at 25°C, being 24.9% at 30°C. The intrinsic rate of natural increase (r_m) rose from 0.001 to 0.081 between 15 and 25°C and decreased to 0.05 at 30°C. In summary, this species performs poorly at low temperatures and has a relative tolerance of high temperatures (30°C); its performance was best at 25°C. Knowledge of the variation in the biological parameters with temperature may be very useful for the understanding of its ecology and population dynamics.     

Influence of host plant and prey availability on developmental time and surviorship of Nesidiocoris tenius (Het.: Miridae)

Nesidiocoris tenuis is a zoophytophagous mirid with biological control potential. However, the relative importance of predation and herbivory for survival and development has not been clear. The bugs survived longer on tomato than on eggplant and especially sweet pepper, but could not complete development in the absence of supplemental food. Tomato also proved to be a more favorable substrate than pepper when eggs of Ephestia kuehniella were added as a food supplement. These results demonstrated that animal prey is a required dietary component for N. tenuis, and also that survival time on a strict plant diet is host plant dependent.     

Gut content analysis to study predatory efficacy of Nesidiocoris tenuis (Reuter) (Hemiptera: Miridae) by molecular methods

Nesidiocoris tenuis is considered to make significant contributions to the control of greenhouse pests such as whiteflies, thrips, leafminers, lepidopterans, and spider mites, although there is little information based on direct observation of the predation of N. tenuis on these target pests. We developed a method to perform gut content analysis of N. tenuis based on DNA in which specific PCR primers were designed to detect the DNA of target pests. By means of gut‐content analysis, we found that the percentage of N. tenuis preying on Bemisia tabaci and Thrips palmi was approximately 40% in the field.     

Comparative toxicity of some acaricides to the predatory mite, Phytoseiulus persimilis and the twospotted spider mite, Tetranychus urticae

The relative toxicity of someacaricides to the predatory mite, Phytoseiulus persimilis and the twospottedspider mite, Tetranychus urticae (Acari: Phytoseiidae, Tetranychidae) wasevaluated in laboratory. Five of theacaricides tested, including bifenazate,acequinocyl, chlorfenapyr, flufenoxuron andfenbutatin oxide, were much less toxic to adultfemales and immatures of P. persimilisthan to those of T. urticae, and adultfemale predators treated with these fiveacaricides produced 84±96% as many eggs as didcontrol females. Etoxazole did not seriouslyaffect the survival and reproduction of adultfemale predators but caused high mortalityrates in eggs and larvae of P.persimilis. Milbemectin and fenazaquin werevery toxic to adult females and immatures ofP. persimilis. Adult female predatorssurvived on a diet of spider mites treated withbifenazate, acequinocyl, chlorfenapyr,flufenoxuron and fenbutatin oxide, and theirfecundity, prey consumption and the sex ratioof the progeny were not substantially affected. Based on the results, bifenazate, acequinocyl,chlorfenapyr, flufenoxuron and fenbutatin oxideappeared to be the promising candidates for usein integrated mite management programs whereP. persimilis is the major naturalenemy.     

Toxicity and efficacy of selected pesticides and new acaricides to stored product mites (Acari: Acaridida)

Stored product mites can often infest stored products, but currently there is little information regarding the efficacy of pesticides that can be used for control. In this study we evaluated several common pesticides formulated from single active ingredients (a.i.) or commercially available mixtures (chlorpyrifos, deltamethrin, beta-cyfluthrin, and a combination of deltamethrin and S-bioallethrin), plus an acaricide composed of permethrin, pyriproxyfen and benzyl benzolate, for efficacy against Acarus siro, Tyrophagus putrescentiae, and Aleuroglyphus ovatus. The pesticides were incorporated into the mite diets in a dose range of 10–1000 μg a.i. g⁻¹ diet. Concentrations for suppression of 50 and 90% population growth and eradication (rC₀) of mites were fit to linear regression models. None of the tested pesticides gave complete eradication of A. siro, which was the most tolerant of the three mite species tested. The most effective pesticide Allergoff 175 CS was a combination product (a nano-capsule suspension of permethrin, pyriproxyfen and benzyl benzolate) labeled for dust mites, with rC₀ range of 463–2453 μg a.i. (permethrin) g⁻¹ diet depending on the species. Least effective were chlorpyrifos and deltamethrin.