Carmine Spider Mite Tetranychus Cinnabarinus Research Articles

Carmine spider mite Tetranychus cinnabarinus control: Laboratory and field efficacy and biochemical characterization of 2, 4-di-tertbutylphenol and ethyl oleate

Natural pesticides are potential alternatives to conventional chemical pesticides. Recently, studies on pesticide–pest interactions have combined empirical biochemical measurements and practical field experiments. In this study, we performed laboratory and field efficacy analysis and biochemical characterization of two phytochemicals (2,4-di-tertbutylphenol (DTBP) and ethyl oleate (EO)) for carmine spider mite Tetranychus cinnabarinus control. DTBP and EO controlled mites by inhibiting egg hatchability and showed significant residual toxicity in laboratory tests. The control efficacy was confirmed in eggplant and cucumber field trials in three provinces in China. Oxidative stress induced by antioxidant enzymes (superoxide dismutase and peroxidase) and detoxification metabolism (involving carboxylesterase and/or mixed-function oxidase) may be involved in the response of mites to DTBP and EO. This study demonstrates the potential of DTBP and EO as effective acaricides for the control of spider mites and provides researchers a better understanding of acaricide–mite interactions.

LincRNA_Tc13743.2-miR-133-5p-TcGSTm02 regulation pathway mediates cyflumetofen resistance in Tetranychus cinnabarinus

Differential expression of metabolic detoxification enzymes is an important mechanism involved in pesticide/acaricide resistance of mite pests. The competing endogenous RNA hypothesis offers a new opportunity to investigate post-transcriptional regulation of those genes. In this study, 4454 long non-coding RNAs were identified in the carmine spider mite Tetranychus cinnabarinus by transcriptome sequencing. Software-based predictions indicated that a long intergenic non-coding RNA, (lincRNA)_Tc13743.2 and a detoxification enzyme gene, TcGSTm02, both contained a microRNA (miR-133-5p) response element. Over-expression of lincRNA_Tc13743.2 and TcGSTm02 were detected in a cyflumetofen-resistant T. cinnabarinus strain (CyR), whereas down-regulation of miR-133-5p was observed in this strain. Conversely, up-regulation of miR-133-5p could inhibit TcGSTm02 expression levels, and both lincRNA_Tc13743.2 and TcGSTm02 were significantly enriched in miR-133-5p biotin–avidin pull-down assays. RNA-binding protein immunoprecipitation assay showed that lincRNA_Tc13743.2 and TcGSTm02 bound to a silencing complex containing miR-133-5p. Moreover, a luciferase reporter assay based on a human cell line revealed that over-expression of lincRNA_Tc13743.2 could significantly reduce the inhibition exerted by miR-133-5p through the TcGSTm02 3′UTR. In addition, co-localization of lincRNA_Tc13743.2 and miR-133-5p was detected using fluorescence in situ hybridization, suggesting that lincRNA_Tc13743.2 interacts directly with miR-133-5p in spider mites. More importantly, silencing the expression of lincRNA_Tc13743.2 significantly reduced the expression levels of TcGSTm02 and increased the sensitivity of spider mites to cyflumetofen. Our data show that lincRNA_Tc13743.2 up-regulates TcGSTm02 expression by competing for miR-133-5p binding, demonstrating that a lincRNA_Tc13743.2–miR-133-5p–TcGSTm02 pathway mediates cyflumetofen resistance in mites.

Plant Defense Responses Induced by Two Herbivores and Consequences for Whitefly Bemisia tabaci.

Diverse herbivores are known to induce various plant defenses. The plant defenses may detrimentally affect the performance and preference to subsequent herbivores on the same plant, such as affecting another insect’s feeding, settling, growth or oviposition. Here, we report two herbivores (mealybug Phenacoccus solenopsis and carmine spider mite Tetranychus cinnabarinus) which were used to pre-infest the cucumber to explore the impact on the plants and the later-colonizing species, whitefly Bemisia tabaci. The results showed that the whiteflies tended to select the treatments pre-infested by the mites, rather than the uninfected treatments. However, the result of treatments pre-infested by the mealybugs was opposite. Total number of eggs laid of whiteflies was related to their feeding preference. The results also showed that T. cinnabarinus were more likely to activate plant jasmonic acid (JA) regulated genes, while mealybugs were more likely to activate key genes regulated by salicylic acid (SA). The different plant defense activities on cucumbers may be one of the essential factors that affects the preference of B. tabaci. Moreover, the digestive enzymes and protective enzymes of the whitefly might play a substantial regulatory role in its settling and oviposition ability.

Synthesis and insecticidal bioactivities of 2,3-dihydroimidazo[1,2-a]pyridin-5(1H)-one derivatives

A novel synthesis of 2,3-dihydroimidazo[1,2-a]pyridin-5(1H)-one 4 and its derivatives were described. Preliminary bioassays showed that some of the target compounds exhibited excellent insecticidal activities against brown planthopper (Nilaparvata lugens), cowpea aphids (Aphis craccivora) (4, 5a, 5c, 5g, 5h, 5j, 5r, 6b, 6e) and carmine spider mite (Tetranychus cinnabarinus (5f, 5s, 6a) at 500 mg/L. Among them, compound 4 was still active against brown planthopper and cowpea aphids at 4 mg/L. The insecticidal activities were influenced by the types and position of the substituents, which provided guidance for the structure modifications.

Acaricide-Mediated Competition Between the Sibling Species Tetranychus cinnabarinus and Tetranychus urticae.

The carmine spider mite (Tetranychus cinnabarinus [Acarifonnes: Tetranychidae]) and the two-spotted spider mite (Tetranychus urticae [Acarifonnes: Tetranychidae]) are two notorious pests of agricultural crops. Control of these pests has been dependent upon using different kinds of acaricides. The purpose of this study was to determine the differential responses of these two pest species collected from crops in the same field to acaricide treatments. Field trials have shown that without spraying acaricides, T. cinnabarinus will displace T. urticae. However, the application of abamectin has the potential to change the composition of spider mite complexes and facilitate the interspecific competition of T. urticae against T. cinnabarinus when both are fed on cowpeas and eggplants. Moreover, T. urticae is more prone to develop resistance than T. cinnabarinus when selected in the laboratory using cyflumetofen or fenpropathrin. After 20 generations of acaricide selection, the activities of detoxifying enzymes were considerably higher in T. urticae with more detoxifying enzymes upregulated after selection in this species. The results of this study demonstrate that differential responses to acaricide treatments have made it possible for T. urticae to overcome the competitive advantage present in T. cinnabarinus during the absence of acaricide application.

Acaricidal Activity and Synergistic Effect of Thyme Oil Constituents against Carmine Spider Mite (Tetranychus Cinnabarinus (Boisduval)).

Studies examining the use of essential oils as replacements for synthetic insecticides require an understanding of the contribution of each constituent present, interactions among these components, and how they relate to overall toxicity. In the present study, the chemical composition of commercial thyme oil was identified by gas chromatography-mass spectrometry. Thyme oil and blends of its major constituents were tested for their acaricidal activitities against carmine spider mites (Tetranychus cinnabarinus (Boisduval)) using a slide-dip bioassay. Natural thyme oil showed greater toxicity than any single constituent or blend of constituents. Thymol was the most abundant component (34.4%), and also possessed the strongest acaricidal activity compared with other single constituents. When tested individually, four constituents (linalool, terpinene, p-cymene and carvacrol) also had activity, while α-pinene, benzoic acid and ethyl gallate had almost no activity. The toxicity of blends of selected constituents indicated a synergistic effect among the putatively active and inactive constituents, with the presence of all constituents necessary to reach the highest toxicity. The results indicated that thyme oil and some of its major constituents have the potential to be developed into botanical acaricides.

Effect of the extract and compound from Solanum nigrum Linn on Tetranychus cinnabarinus

AbstractThe carmine spider mite Tetranychus cinnabarinus (Boisduval) is a serious pest affecting various glasshouse vegetables, fruits and crops and causes significant damage to crop yields and quality by piercing and sucking foliar tissues. The control of this mite primarily involves the application of synthetic chemical pesticides. In this study, a Solanum nigrum L. extract was evaluated for its potential acaricidal activity against adult female T. cinnabarinus in laboratory conditions, and the S. nigrum extract showed marked efficacy in controlling the carmine spider mite both in vitro and in potted seedlings. Furthermore, the active compound, a phytostanol ester (β‐sitosterol‐3‐O‐heptadeca‐8Z, 11Z‐dienoate), was isolated from the petroleum ether‐soluble fraction of S. nigrum extract via repeated column chromatography and identified based on its physiochemical properties and spectral data. At 7 days after treatment in a potted seedling experiment, the LC50 values of the S. nigrum extract and active compound were found to be 4.70 and 1.85 g/l, respectively. All of these results demonstrated that the S. nigrum extract and its active component exhibit the potential for use as new natural acaricides for controlling carmine spider mites.

The Acaricidal Activity of Venom from the Jellyfish Nemopilema nomurai against the Carmine Spider Mite Tetranychus cinnabarinus.

The carmine spider mite Tetranychus cinnabarinus (T. cinnabarinus) is a common polyphagous pest that attacks crops, vegetables, flowers, and so on. It is necessary to find lead compounds for developing novel, powerful, and environmentally-friendly acaricides as an alternative approach to controlling the carmine spider mite because of the serious resistance and residual agrochemicals in the environment. In addition, the study on the acaricidal activities of marine bioactive substances is comparatively deficient. In the present study, the acaricidal activity of venom (NnFV) from the jellyfish Nemopilema nomurai against the carmine spider mite T. cinnabarinus was determined for the first time. The venom had contact toxicity, and the 24-h LC50-value was 29.1 μg/mL. The mite body wall was affected by the venom, with the mite body having no luster and being seriously shrunken after 24 h. T. cinnabarinus was a potential target pest of NnFV, which had potential as a type of natural bioacaricide. The repellent activity and systemic toxicity of the venom against T. cinnabarinus were also studied. However, NnFV had no repellent activity and systemic toxicity against T. cinnabarinus.

Identification of Differentially Expressed microRNAs between the Fenpropathrin Resistant and Susceptible Strains in Tetranychus cinnabarinus.

The carmine spider mite (Tetranychus cinnabarinus) is one of the most serious pests on crops and its control mainly depends on chemical acaricides. The excessive and improper acaricides use has resulted in mite resistance to many acaricides, including fenpropathrin. Previous studies have indicated fenpropathrin resistance is a complex development process involving many genes, but information on resistance mechanism of post-transcription regulation is rare. Using Illumina sequencing, several categories of sRNAs were identified from susceptible (TS) and fenpropathrin-resistant strains (TR) of T. cinnabarinus, including 75 known microRNAs (miRNAs) and 64 novel miRNAs, whose target genes containing 78592 miRNA-target pairs were predicted by 6 algorithms. Also, 12 significantly differently expressed miRNAs were identified between the TS and TR libraries and RT-qPCR validation also performed a well consistency with sequencing. The targets of significantly differentially expressed miRNAs included 7 glutathione S-transferase, 7 cytochrome P450 and 16 carboxyl/choline esterase genes, their function in fenpropathrin resistance were further analyzed. The present study provides the firstly large-scale characterization of miRNAs in T. cinnabarinus and the comparison between TS and TR strains gives a clue on how miRNA involves in fenpropathrin resistance.

Synergistic inhibitory effect of scopoletin and bisdemethoxycurcumin on Tetranychus cinnabarinus (Boisduval) (Acari: Tetranychidae).

The study aimed to investigate the synergistic activity of scopoletin and bisdemethoxycurcumin (BDMC) against the carmine spider mite Tetranychus cinnabarinus. The acaricidal activities of mixtures of scopoletin and BDMC against T. cinnabarinus female adults were measured via slide dipping and leaf disc dipping. A mathematical model was established by SPSS software. Bioassays for multiple effects including contact, ovicidal, cowpea root intake, repellency and oviposition inhibitory activity were carried out. The optimal mass ratio of the mixture of scopoletin and BDMC (at their respective LC(50)), the median lethal concentration (LC(50)) and the co-toxicity coefficient were 7:6, 0.19 mg/mL and 129, respectively. LC(50) values of contact activities of the mixture at optimal ratio against adults, nymphs, larvae, and eggs were 0.19, 0.18, 0.06, and 1.52 mg/mL, respectively. LC(50) values of cowpea root intake activity against adults and nymphs were 5.62 and 6.52 mg/mL, respectively. The highest repellent rates against adults and nymphs were 69.5% and 72.5%, respectively. The mixture of scopoletin and BDMC at the optimal mass ratio possessed strong acaricidal activity against T. cinnabarinus at various developmental stages.

Acaricidal, repellent, and oviposition-deterrent activities of 2,4-di-tert-butylphenol and ethyl oleate against the carmine spider mite Tetranychus cinnabarinus

Tetranychus cinnabarinus (Boisduval) is highly polyphagous and is considered one of the most important crop pests, infesting over 100 crop species grown in field and greenhouse crops worldwide. The control of this mite is still based primarily on the use of synthetic chemical pesticides. In this study, 2,4-di-tert-butylphenol (DTBP) and ethyl oleate (EO) were investigated for their acaricidal, repellent, and oviposition-deterrent properties against T. cinnabarinus under laboratory conditions. Both DTBP and EO exhibited significantly adulticidal, larvicidal, and ovicidal activities against T. cinnabarinus in a concentration-dependent manner after treatment, with LC50 values of 1,256.51, 625.39, and 743.64 ppm for DTBP and 1,621.57, 859.25, and 987.26 ppm for EO, respectively. The mites exhibited the highest run-off rate on bean leaf surfaces sprayed with both DTBP and EO when applied at sub-lethal doses and moved toward surfaces that had not been sprayed with these compounds, according to Pearson’s χ 2 test. Furthermore, not only in a choice assay but also in a no-choice assay, a significant difference was found using an ANOVA between the numbers of eggs laid on bean leaves that were sprayed with DTBP and EO at sub-lethal doses compared to the number laid on unsprayed bean leaves. Additionally, stability assays revealed that EO was more sensitive to environmental factors than DTBP. These results demonstrate that the two compounds DTBP and EO have potential for development as new, natural acaricides for controlling carmine spider mites.

Molecular cloning and expression of glutathione S-transferases involved in propargite resistance of the carmine spider mite, Tetranychus cinnabarinus (Boisduval)

The carmine spider mite (CSM) Tetranychus cinnabarinus has become a serious pest in China and has developed resistance to acaricide propargite as it is used to control mites worldwide including T. cinnabarinus. In this study, a resistant colony of T. cinnabarinus, PRR34 (37.78-fold resistant ratio), was established after 34 generations of propargite selection, and cross-resistance patterns of 7 other acaricides were determined in comparison with a susceptible strain (SS). The contribution of detoxification enzymes to propargite tolerance were investigated using biological, biochemical and molecular approaches. Enzyme inhibitor synergist tests suggested glutathione S-transferases (GST) involvement in propargite-resistance of PRR34, and GST activity against 1-chloro-2,4-dinitrobenzene (CDNB) was correlated with the development of resistance. Eight novel GST genes (TcGSTd1, TcGSTd2, TcGSTm1, TcGSTm2, TcGSTm3, TcGSTm4 and TcGSTm5) were cloned, and phylogenetic analysis showed that the eight GST genes were most closely related to GST family delta and mu from Tetranychusurticae. Quantitative RT-PCR revealed that the expression level of GSTs in PPR34 strain increased in larvae, nymphs and adults, while decreased in eggs compared with that of SS. Collectively, these results support a role of GSTs in mediating resistance to propargite in the PRR34 strain. TcGSTd1,TcGSTd2 and TcGSTm2 genes might play significant roles in propargite resistance of CSM, especially at adult stage. This is the first attempt to define specific genes involved in GST mediated propargite resistance of T. cinnabarinus at the transcriptional level.

Comparing Abundance of Predacious and Phytophagous Mites (Acarina) in Conjunction with Resistance Identification between Bt and non-Bt Cotton Cultivars

Knowledge of the arthropod complex associated with any crop is essential for developing pest control strategies. Bt (GK-12, Lu-23 and SGK-321) and non-Bt (Zhong-12, Shiyuan-321 and Simian-3) cotton varieties were used for assessing differences in harbouring populations of the carmine spider mite Tetranychus cinnabarinus (Boisduval) and predatory mite Neoseiulus cucumeris (Oudemans). Two Bt cotton varieties GK-12 and Lu-23, and two non-Bt varieties Zhong-12 and Simian-3 appeared more supportive for maintaining T. cinnabarinus, whereas, SGK-321 (Bt) and Shiyuan-321 (non-Bt) clearly showed reduced pest susceptibility, but efficient in maintaining N. cucumeris population. Throughout the study period, the densities of T. cinnabarinus remained higher (1.77 and 1.40 per leaf) in Bt than non-Bt varieties following insecticides application against the cotton pest complex. The beneficial mite N. cucumeris remained active in both Bt and non-Bt varieties, but Bt cotton had slightly higher numbers of the predator (0.58 per leaf) than non-Bt cotton (0.40 per leaf). Consequently, there were no great impacts on the predatory natural enemy associated with Bt cotton and the predator population in Bt fields was not negatively affected in comparison with conventional cotton. All tested varieties of cotton significantly differed in relation to their morphological characteristics. Of the different factors found to affect the populations of predacious and phytophagous mites, in general, the trichome density on the lower surface of the leaf, leaf thickness and plant height had positive relations with arthropod abundance. Our results showed that SGK-321 (Bt) and Shiyuan-321 (non-Bt) could be recommended for use in creating new resistant cotton varieties as a component of an integrated pest management strategy. Hence, the differences in the response of pest and predator to host plant and leaf architectures should be considered to enhance their roles in biological control strategy.

Metabolism-based synthesis, biological evaluation and structure-activity relationship analysis of spirotetramat analogues as potential lipid biosynthesis inhibitors

In previous studies, scientists found that, when spirotetramat was introduced into plants or animals, it was mainly metabolised at positions C-4 and C-8. That is to say, these two functional positions potentially played an important role in spirotetramat's bioactivities. In order to develop novel insecticides or miticides, the present authors designed and synthesised 35 spirotetramat analogues based on metabolite structures. All of the analogues have been identified on the basis of (1)H NMR, ESI-MS and elemental analysis data. The activities of these analogues were evaluated against three organisms, and biological assays indicated that compounds 5f, 5h and 5u possessed better insecticidal activities against bean aphids (Aphis fabae) than the lead compound spirotetramat. The LC50 of 5f, 5h and 5u against bean aphids reached 0.42, 0.28 and 2.53 mg L(-1) respectively. Moreover, some compounds possessed comparable activities against carmine spider mite (Tetranychus cinnabarinus) and oriental armyworm (Mythimna sepatara) with spirotetramat. The structure-activity relationships (SARs) indicated that the flexible bridge at position C-4 of spirotetramat was important for its bioactivities, and the size of the group at position C-8 would have great influence on the activities. Furthermore, the log P values lower than 6.0 may be favourable for insecticidal activities. The present work demonstrates that some spirotetramat analogues can be used as potential lead compounds for developing novel insecticides, and preliminary SAR analysis would provide information for the utilisation of spirotetramat analogues as potential lipid biosynthesis inhibitors.

Synthesis and Bioactivity Study of 2-Acylamino-Substituted N′-Benzylbenzohydrazide Derivatives

The discovery of new safe and effective pesticides is one of the main means of providing eco-friendly agricultural agents for modern crop protection. To identify new biological molecules based of the anthranilic diamide skeleton of the novel pesticide chlorantraniliprole, which acts on the ryanodine receptor and functional groups in acyl hydrazine insect growth regulators, more than 40 new compounds of 2-acylamino-substituted N'-benzylbenzohydrazide derivatives were designed and synthesized. The structures of the new compounds were characterized using (1)H nuclear magnetic resonance (NMR), high-resolution mass spectrometry (HRMS), or electron impact mass spectrometry (EI-MS), and their biological activities at a concentration of 600 mg L(-1) were determined against cotton aphid (Aphis gossypii Glover), carmine spider mite (Tetranychus cinnabarinus), and diamondback moth (Plutella xylostella). The results of a preliminary assay showed that compounds 6a-I-2 and 6d-III-4 maintained the lethal activity of anthranilic diamide against P. xylostella; compounds 6c-II-4, 6d-I-7, 6d-II-1, and 6d-III-5 exhibited good lethal activity against A. gossypii; and compounds 6a-II-1, 6a-III-1, 6b-I-7, 6c-I-1, and 6c-III-5 retained promising larvicidal activities against T. cinnabarinus. In subsequent further tests against T. cinnabarinus, compounds 6a-II-1, 6a-III-1, 6c-I-1, and 6c-III-5 showed an LC(50) value of <90 mg L(-1); especially, the LC(50) of compound 6a-III-1 was only 27.9 mg L(-1). In conclusion, the introduction of the functional fragment-substituted acyl hydrazine improved the acaricidal activity of the anthranilic diamide skeleton, and the halogen atom at X position and the methyl group at R(1) play crucial roles in the biological activities of the compounds.

Design, Synthesis, and Analysis of the Quantitative Structure–Activity Relationships of 4-Phenyl-acyl-substituted 3-(2,5-Dimethylphenyl)-4-hydroxy-1-azaspiro[4.5]dec-3-ene-2,8-dione Derivatives

A series of 4-phenyl-acyl-substituted 3-(2,5-dimethylphenyl)-4-hydroxy-1-azaspiro[4.5]dec-3-ene-2,8-dione derivatives were designed and synthesized, and their structures were characterized using (1)H NMR (or (13)C NMR), mass spectrometry, and elemental analysis. The bioactivities of the new compounds were evaluated. These compounds exhibited good inhibition activities against bean aphids (Aphis fabae) and carmine spider mite (Tetranychus cinnabarinus), and 4-phenyl acyl esters showed stronger bioactivity than 4-arylesterases and alkyl esters. The results showed that compound 8-I-e, which contains a para-methoxy group on the phenyl acyl, and compound 8-I-m, which contains a para-trifluoromethyl group on the phenyl acyl, displayed potent insecticidal activity against A. fabae and T. cinnabarinus respectively. The insecticidal activity showed a clear structure-activity relationship, confirming the importance of the flexible bridge. The DFT/B3LYP/6-31(d) level method was used to calculate molecular geometries and electronic descriptors. These factors included total energy, charge distribution, and the linear orbital level of the title compounds. Quantitative structure-activity relationship studies were performed on these compounds using quantum-chemical and physicochemical parameters as independent variables and insecticidal activity as a dependent variable. Insecticidal activity was most closely correlated (r > 0.8) with quantum chemical and physicochemical parameters.

Transcription and induction profiles of two esterase genes in susceptible and acaricide-resistant Tetranychus cinnabarinus

The carmine spider mite Tetranychus cinnabarinus is the most serious of crop mite pests in China. Their ability to rapidly develop resistance to acaricides has caused difficulty in controlling this mite. In this study, the molecular mechanism of acaricide resistance associated with esterase genes TCE1 and TCE2 was investigated in susceptible and acaricide-resistant strains of T. cinnabarinus. The quantitative real-time PCR (qrtPCR) method was adopted to compare the expression level of two esterase genes TCE1 and TCE2 among four different strains (abamectin-resistant, AbR; fenpropathrin-resistant, FeR; omethoate-resistant, OmR and susceptible strains, S) of T. cinnabarinus. The relative expression level of TCE2 was 1.39–2.47 fold in the three resistant strains compared with the S strain. And after inducing with abamectin, fenpropathrin, and omethoate the highest expression level of TCE2 in the S was 1.64-, 2.92- and 2.24-fold compared with the control, respectively, and this difference was found to be significant. However, there was no obvious difference of the mRNA relative expression levels of TCE1 genes among the four strains, and those of TCE1 were not higher than the control throughout the study. Furthermore, the expression modes of TCE1 and TCE2 in AbR and FeR were similar with that in the S after being treated with abamectin and fenpropathrin, respectively. These results indicated that the enhanced expression of esterase gene TCE2 was associated with acaricide-resistance in T. cinnabarinus.

The potential of four mite species (Acari: Phytoseiidae) as predators of sucking pests on protected cucumber (Cucumis sativus L.) crop

Protected crop experiments were conducted to study the suitability and efficacy of Phytoseiid mite species as predators of western flower thrips Frankliniella occidentalis (Pergande), carmine spider mite Tetranychus cinnabarinus (Boisduval) and greenhouse whitefly Trialeurodes vaporariorum(Westwood) in cucumber (Cucumis sativus L.) under greenhouse conditions. In this study, predatory mites Neoseiulus pseudolongispinosus Euseius castaneae Euseius utilis and Euseius finlandicus (Oudemans) (Phytosiidae) were investigated for their potential as biological control agents in treated along with untreated check. The current findings to judge the biocontrol potential of predators showed that laboratory bred adults and nymph instars of all predators efficiently preyed upon sucking arthropods and pests populations were drastically reduced in treated plants than in untreated control where their intensities were numerous. Among all predators, N. pseudolongispinosus was the most proficient and steadfast predator in controlling thrips and whitefly populations, contrary to E. finlandicus that proved better in reducing spider mite density in treated crop. The current findings indicated the potential of Phytoseiid predators for their augmentative releases to give best control of sucking pests in protected cucumber plants. Keywords: Biological control, predaceous mite, greenhouse, cucumber, phytoseiidae.

Male age influences the strength of Cardinium-induced cytoplasmic incompatibility expression in the carmine spider mite Tetranychus cinnabarinus

‘Candidatus Cardinium’, a recently described bacterium from the Bacteroidetes group, causes diverse reproductive alterations of its arthropod hosts, including cytoplasmic incompatibility (CI), parthenogenesis and feminization. We detected severe CI expression induced by Cardinium in the carmine spider mite Tetranychus cinnabarinus (Boisduval). CI was expressed as a reduction in egg hatchability and a male-biased sex ratio in crosses between uninfected females and infected males. To determine whether male age affects Cardinium-induced CI expression, uninfected females were crossed with infected virgin males at different ages. Cardinium density in males, as measured by quantitative PCR using the 16S rDNA gene, declined rapidly with increasing age. The CI level also declined rapidly with increasing age. Cardinium lost the ability to induce CI by day 12, and the Cardinium density declined to 3.0×106 copies per ml. Cardinium density was positively correlated with the CI level, which is consistent with the bacterial density model of CI. Our results suggest that both male age and Cardinium density are key factors in Cardinium-induced CI expression in T. cinnabarinus, and a threshold level of Cardinium density may be required for induction of CI.

Biological parameters of Cydnodromus picanus and Phytoseiulus persimilis raised on the carmine spider mite, Tetranychus cinnabarinus (Acari: Phytoseiidae, Tetranychidae)

V. Tello, R. Vargas, J. Araya, and A. Cardemil. 2009. Biological parameters of Cydnodromus picanus and Phytoseiulus persimilis raised on the carmine spider mite Tetranychus cinnabarinus (Acari: Phytoseiidae, Tetranychidae). Cien. Inv. Agr. 36(2):277-290. The postembryonic development, consumption and life table parameters of Cydnodromus picanus Ragusa and Phytoseiulus persimilis (Athias-Henriot) were studied at 29.44 ± 1.47 °C and 42.35 ± 5.01% of RH with a photoperiod of 14:10 h (L:D) in order to evaluate the potential of these predators for feeding on the carmine spider mite Tetranychus cinnabarinus (Boisduval). Eggs, larvae and protonymphs of T. cinnabarinus may be optimal food for C. picanus, which obtained survival rates of 100%, 97% and 93%, respectively, on them. The survival of P. persimilis was around 6.7% with diets based on eggs, larvae and protonymphs, showing a high mortality level by dehydration when fed with eggs. The time of the postembryonic development was signifi cantly shorter (p < 0.05) for C. picanus than for P. persimilis when they were fed with eggs, larvae and deutonymphs of T. cinnabarinus. When fed with eggs and a combination of different stages of T. cinnabarinus, the intrinsic rate of growth (r m ) was signifi cantly higher (p < 0.05) for C. picanus (0.289 and 0.307, respectively) than for P. persimilis (0.019 and 0.025, respectively). The values of the fi nite rate of growth (λ) were also signifi cantly (p < 0.05) higher for C. picanus (1.34 and 1.36) than for P. persimilis (1.02 and 1.03) when they were nourished with eggs and a mixed diet, respectively. The high values of r m and λ found for C. picanus in the experimental conditions are indicators of the possible control that this phytoseiid mite, as a predator of T. cinnabarinus, would potentially offer under the conditions of lower relative humidity encountered in the arid zone of the desert of Chile.