Toxoptera Aurantii Research Articles

Physiological and metabolomic analyses reveal the resistance response mechanism to tea aphid infestation in new shoots of tea plants (Camellia sinensis)

The tea plant (Camellia sinensis (L.) O. Kuntze) is an important woody economic crop and often attacked by various insect pests such as tea aphids (Toxoptera aurantii Boyer de Fonscolombe). To reveal tea plant responses to tea aphid infestation, tea aphid-resistant cultivar ‘Taicha13’ and -susceptible one ‘Jingfeng’ were first screened, and then widely targeted metabolomics profiling, biochemical parameter and RT-qPCR analyses were performed in three samples, TCN (tea aphid non-infested ‘Taicha13’), JFN (tea aphid non-infested ‘Jingfeng’) and JFA (tea aphid-infested ‘Jingfeng’). The results showed amnio acid (plus proline) and protein content, and amnio acid: sucrose ratio were significantly less abundant in TCN relative to JFN, suggesting TCN is low nutritional quality for tea aphids. Metabolite profiling revealed that flavonoids and JA-isoleucine (JA-Ile) were more enriched in TCN and JFA compared to JFN, proposing effective roles of flavonoids and JA-Ile in tea plant defense against tea aphid infestation. RT-qPCR results demonstrated that five JA biosynthesis genes (CsLOX2, CsLOX3, CsOPR, CsAOC and CsJAR) in exception of CsAOS, and six flavonoid biosynthesis genes (CsPAL, CsC4H, CsCHS1, CsCHS2, CsFL and CsDFR) shared similarly higher abundance in TCN than in JFN, and exhibited elevated expression levels in JFA relative to JFN, further suggesting flavonoids and JA confer tea plant resistance against tea aphid feeding. Overall, our findings uncovered that tea aphid-infestation activated defensive responses and highlighted involvement of nutritional quality, flavonoids and JA-Ile in tea plant resistance against tea aphid infestation.

Role of chitinase expression in the virulence of Lecanicillium lecanii against citrus black aphid (Toxoptera aurantii)

Chitinase plays a vital role in the virulence of entomopathogenic fungi (EPF) when it infects host insects. We used gene recombination technology to express chitinase of three strains of Lecanicillium lecanii: Vl6063, V3450, and Vp28. The ORF of ChitVl6063, ChitV3450 and ChitVp28 were inserted into the fungal expression vector pBARGPE-1, which contained strong promoter and terminator, respectively, to construct a chitinase overpressing plasmid, then transformed the wild-type strain with blastospore transformation method. The virulence of the three recombinant strains against Toxoptera aurantii was improved by overproduction of ChitVl6063, ChitV3450, and ChitVp28, as demonstrated by significantly lower 3.43 %, 1.72 %, and 1.23 % fatal doses, respectively, according to an insect bioassay. Similarly, lethal times of recombinants (ChitVl6063, ChitV3450 and ChitVp28) were also decreased up to 29.51 %, 30.46 % and 33.90 %, respectively, compared to the wild-type strains. Improving the expression of chitinase is considered as an effective method for the enhancement of the EPF value. The efficacy could be enhanced using recombinant technology, which provides a prospecting view for future insecticidal applications.

Aphid species found on citrus in Ogan Komering Ilir District, South Sumatra, Indonesia

Citrus is an economically valuable plantation crop and has high market opportunities. In Southeast Asia, Indonesia is the second largest citrus importer after Malaysia, with an import volume of 160,254 tons; however, various obstacles limiting the cultivation of citrus plants cannot be separated from pests that can affect citrus quality and reduce citrus production. One of the obstacles is insect attacks such as aphids. Therefore, this study aims to determine the species of aphids in citrus. This research was conducted from May to June 2023 in Ogan Komering Ilir Regency using a direct observation method in the field. Observations were made on the parts attacked by aphids and symptoms of attack. The results showed that three species from 1 family of aphids were found. The species found were Toxoptera aurantii, Toxoptera citricidus, and Toxoptera citricola from the Aphididae family. The highest species found in the study was T. aurantii, with 861 individuals, and the lowest species found was T. citricola, with 29 individuals. Aphid species were found mainly on Citrus microcarpa and least on Citrus grandis.

Exogenous salicylic acid induces defense responses in tea plants against Toxoptera aurantii (Hemiptera: Aphididae).

Toxoptera aurantii is one of the most destructive pests, threatening the yield and quality of tea plantations. The salicylic acid (SA)-mediated signaling pathway is vital for the induction of plant defense responses; however, its role in tea plant resistance to T. aurantii remains unclear. Thus, this study used and electrical penetration graph and monitoring of population dynamics to evaluate the effects of exogenous SA application on T. aurantii feeding behavior and population growth in tea seedlings. Moreover, the effects of SA treatment on the activities of defense-related enzymes were analyzed. Probe counts and the duration of xylem sap ingestion were significantly higher in SA-treated plants than those in the control group. The total duration of passive phloem ingestion was significantly decreased in 0.5 mmol/l SA-treated plants, and the application of 0.5, 1, and 4 mmol/l SA significantly inhibited T. aurantii population growth. In addition, the activities of polyphenol oxidase, peroxidase, and superoxide dismutase were significantly increased in the 0.5 mmol/l SA-treated plants. Overall, this study demonstrates the capacity of exogenous SA to activate defense responses against T. aurantii. These results have crucial implications for understanding the mechanisms of enhanced resistance, thereby providing a sustainable approach for managing T. aurantii.

Adaptability of Toxoptera aurantii (Hemiptera: Aphididae) to Different Tea Cultivars

The adaptability of phytophagous insects to different host plants is a key determinant of their population propagation. Understanding the feeding behaviour and population dynamics of insects is crucial for elucidating host adaptability and screening for insect-resistant germplasms. Here, we investigated Toxoptera aurantii (Hemiptera: Aphididae) adaptability using electropenetrography and assessed its population growth on seven tea cultivars: Huangjinya (HJY), Qianmei601 (QM601), Fudingdabaicha (FD), Longjing43 (LJ43), Qiancha1 (QC1), Qiancha8 (QC8) and Qiancha10 (QC10). The results showed that the feeding behaviour of T. aurantii differed significantly depending on the tea cultivars. The initial probing of T. aurantii on HJY was the earliest among the seven host plants. Aphids on QC1 and QC10 displayed an increased duration of stylet probing and decreased ingestion of phloem sap, whereas a contrasting trend was observed for aphids on HJY. In addition, the mechanical resistance of T. aurantii fed on HJY and QM601 during the probing phase was significantly lower than that of aphids fed on other cultivars. Population dynamic parameters revealed that the growth rate of T. aurantii reared on HJY was the fastest, and its population quantity within 15 days was markedly higher than that of aphids fed on other cultivars. These findings demonstrate that HJY is the most suitable host plant, whereas QC1 and QC10 are less suitable hosts for T. aurantii, although the aphids successfully survived on all the selected tea cultivars. Our results provide valuable information for the biological control of T. aurantii using resistant tea varieties.

Different Tea Germplasms Distinctly Influence the Adaptability of Toxoptera aurantii (Hemiptera: Aphididae).

Aphids are typical phloem-sucking insect pests. A good understanding regarding their feeding behavior and population dynamics are critical for evaluating host adaptation and screening of aphid-resistant resources. Herein, the adaptability of Toxoptera aurantii (Boyer) (Hemiptera: Aphididae) to different hosts was evaluated via electropenetrography and an age-stage, two-sex life table on six tea germplasms: Zikui (ZK), Zhongcha108 (ZC108), Zhongcha111 (ZC111), Qianmei419 (QM419), Meitan5 (MT5), and Fudingdabaicha (FD). Our findings revealed that the feeding activities of T. aurantii differed considerably among the host plants. T. aurantii exhibited significantly more pathway activities on ZK and FD than on the other hosts. However, the duration of feeding of T. aurantii on ZK phloem considerably decreased compared with those of the other germplasms. Life parameters indicated that T. aurantii exhibited the highest intrinsic rate of increase (r), net reproductive rate (R0), and finite rate of increase (λ) on MT5, and the maximum values of total longevity and oviposition period were recorded on FD; these variables were reduced significantly on ZK. The results of our study demonstrate that T. aurantii can successfully survive on the six tea germplasms; however, ZK was less suitable for T. aurantii and should be considered as a potential source of resistance in breeding and Integrated Pest Management.

IDENTIFICACIÓN MORFOLÓGICA Y CRÍA DEL ÁFIDO Toxoptera aurantii BOYER DE FONSCOLOMBE (HEMIPTERA: APHIDIDAE) EN INVERNADERO

<p><strong>Background. </strong>Aphids are one of the insect groups with the greatest impact on agricultural production. They affect a wide range of hosts, including fruit trees such as citrus. <strong>Objective. </strong> Identify the main morphological characters and evaluate a rearing protocol for the aphid <em>Toxoptera aurantii</em> Boyer de Fonscolombe, 1841 (Hemiptera: Aphididae) in a room-temperature in protected environment. <strong>Methodology. </strong>Specimens were collected from citrus trees in production in the province of Coclé, infested branches were cut and placed in plastic containers for transport. Insects were separated for identification through micro slides, observed under a microscope and identified using taxonomic reference keys. Four treatments were established with mucuna (<em>Mucuna pruriens</em> [L.] DC.), canavalia (<em>Canavalia ensiformis</em> [L.] DC.), bean (<em>Phaseolus vulgaris</em> L.) and orange jasmine (<em>Murraya paniculata</em> [L.] Jack) as host plants. Abundance was evaluated at 2 and 14 DAI. Data were analyzed by analysis of variance. For each treatment, 30 plants were used, and five aphids of different stages (two adults and three nymphs) were released on each plant. Plants were evaluated from 0 to 14 DAI (Days after infestation). Insect abundance was evaluated at 2 and 14 DAI. Data were analyzed by analysis of variance.<strong> Results. </strong>The morphological determinant characters of the species <em>T. aurantii</em> were identified. Statistically significant differences were observed between treatments (p<0.05) at 2 and 14 DAI, where the host plant that highlighted was the orange jasmine with an average of 51.5 ± 55.95 specimens per plant at 14 DAI. <strong>Implications. </strong>This research implies the importance of identifying the aphid species and determining a plant that meets feeding preferences for aphid breeding. <strong>Conclusions.</strong> The use of orange jasmine at room temperature in greenhouses allows the establishment of offspring of the aphid <em>T. aurantii</em> 10.3 times greater than the initial population in periods of 14 DAI.</p>

The genetic adaptations of Toxoptera aurantii facilitated its rapid multiple plant hosts dispersal and invasion

Toxoptera aurantii Boyer de Fonscolombe (Hemiptera: Aphididae) can attack many plant hosts, including tea (Camellia sinensis L.), citrus (Citrus spp.), lychee (Litchi chinensis Sonn.), banana (Musa spp.), and pineapple (Ananas comasus L.) among others. It is a widely distributed hexapod and one of the most destructive pests in tea plantations, causing enormous economic losses in tea production each year. A high-quality reference genome is important to study the phylogenetics and evolution of T. aurantii because its genome is highly heterozygous and repetitive. We obtained a de novo genome assembly of T. aurantii at the chromosome level using a combination of long Nanopore reads from sequencing with high-throughput chromosome conformation capture technology. When finally assembled, the genome was 318.95 Mb on four chromosomes with a 15.19 Mb scaffold N50. A total of 12,162 genes encoded proteins, while there were 22.01% repetitive sequences that totaled 67.73 Mb. Phylogenetic analyses revealed that T. aurantii and Aphis gossypii parted ways approximately 7.6 million years ago (Mya). We used a combination of long-read single-molecule sequencing with Hi-C–based chromatin interaction maps that resulted in a reference chromosomal level reference genome of T. aurantii that was high quality. Our results will enable the exploration of the genetics behind the special biological features of T. aurantii and also provide a source of data that should be useful to compare the compare genome among the Hemiptera.

Control of tea aphids via attracting the parasitic wasp, Aphelinus sp. with synthetic semiochemicals

The tea aphid (Toxoptera aurantii Boyer de Fonscolombe) is an important tea plant pest insect worldwide. The parasitoid wasp, Aphelinus sp., is one of the most important natural enemies of the tea aphid in China. Unfortunately, Aphelinus sp. alone cannot effectively control the outbreaks of the aphid under natural conditions. In this study, 27 volatile compounds from tea aphid-injured tea shoots, tea flowers, aphid sex pheromones, or body rinses were selected and tested in Y-tube olfactometer assays to find potential attractants of the parasitoid wasp, Aphelinus sp. Based on the Y-tube assay results, the following three attractant mixtures were formulated and further tested in the field. Attractant-1 (HIPV-based) included trans-2-hexenal (10−6 g/ml), β-ionone (10−6 g/ml), allyl isothiocyanate (10−4 g/ml), trans-2-pentenal (10−2 g/ml), and jasmone (10−2 g/ml) at equal loading volume of their solutions. Attractant-2 (with aphid sex-pheromone and body rinse compounds) included nepetalactone (10−6 g/ml), 2,5-hexanedione (10−4 g/ml), benzaldehyde (10−2 g/ml), eicosane (10−2 g/ml), and heptadecane (10−2 g/ml) at equal loading volume of their solutions. Attractant-3 (partial combination of Attractant-1 and Attractant-2) included nepetalactone (10−4 g/ml), benzaldehyde (10−2 g/ml), jasmone (10−2 g/ml), trans-2-hexenal (10−6 g/ml), eicosane (10−2 g/ml), and heptadecane (10−2 g/ml) at equal loading volume of their solutions. Field trials showed that Attractant-3 was much more attractive to the parasitic wasps than Attractant-1 and Attractant-2. From late August to late September the controlled release of Attractant-3 effectively attracted Aphelinus sp. to parasitize and colonize the aphid populations in the treated tea plantations, resulting in a progressive decrease of the tea aphid abundances/populations in the fall. The continued enhanced parasitism of overwintered aphids by Aphelinus sp. further reduced this population during the next spring tea harvest season. This approach may present an environmentally sound, non-insecticidal control tactic against tea aphids using synthetic semiochemicals.

A preliminary study of the biodiversity and bio-ecological parameters related to aphid’s species in an organic citrus orchard in Northeastern Tunisia

The Aphididae family contains many polyphagous species. Four species were identified in an organic Citrus orchard in Northeastern Tunisia in the current study. These species are Aphis gossypii, A. spiraecola, Macrosiphum euphorbiae, and Toxoptera aurantii. The most important and abundant species was A. gossypii followed respectively by A. spiraecola, M. euphorbiae, and T. aurantii. Monitoring species dynamic population showed that aphids began to occur in February and reached then high levels from March to May. Various structure and beta diversity indexes were calculated. The obtained results demonstrated that there was a high dominance of a few or one species. The evenness index was high and had a significant positive correlation with the Berger-Parker index. The Equitability index was low. The richness index had a strong positive correlation with Margalef’s richness index and the number of species. However, Menhinick's diversity index had a weak positive relationship with the Specific richness.

Check list of piercing-sucking insects in North-eastern Tunisia in the region of Cap-Bon and their host plants

The study of the biodiversity of piercing-sucking insects on various crops and weeds in North-eastern Tunisia in the region of Cap-Bon, permitted to identify several pest species. In the different investigated regions and sampled crops, aphids were the most dominant and abundant compared to the others. Twelve aphid species were identified; Aphis gossypii, A. craccivora, A. spiraecola, A. punicae, A. fabae, A. illinoisensis, Toxoptera aurantii, Myzus persicae, Sitobion avenae, Pterocholorides persicae, Rhopalosiphum maidis and Schizaphis graminum. Regarding thrips, seven species were identified; Thrips angusticeps, T. tabaci, Bregmatothrips dimorphus, Anaphothrips sudanensis, Limothrips cerealium, Liothrips oleae and Frankliniella occidentalis, which was the most polyphagous thrips species. Five scale-insect species were recorded in the different investigated locations; Parlatoria ziziphi, Aonidiella aurantii, Icerya purchasi, S. oleae, and Planococcus citri. One species of Psyllidae was registered: Euphyllura olivina in all visited olive stations. One leafhopper species Empoasca vitis in grapevine orchards and finally two species of whiteflies that were reported; Dialeurodes citri in citrus orchard and Bemisia tabaci on pepper crops.

Clustering Analysis of Volatile Components from the Tea Plants Infested by Tea Aphid (Toxoptera aurantii)

Clustering Analysis of Volatile Components from the Tea Plants Infested by Tea Aphid (Toxoptera aurantii)

PENYEBAB DAN SERANGGA VEKTOR PENYAKIT KERITING PADA TANAMAN LADA

The cause of stunting disease of black pepper (Piper nigrum) in Indonesia has not yet been confirmed cither due o a virus or mycoplaam. However, similar disease found on black pepper plants in the Southeast Asia is caused by Piper yellow mottle virus (PYMV) which is transmitted by Planococcus citri. This expeiments was aimed o examine the cause of the stunting disease and its insect vectors. The expeiment were conducted from October 1998 to May 2001. Diseased vegetative materials of black pepper plants showing stunting disease were collected from Sukamulya, Sukabumi. The potential insect vectors were collected from black pepper plants in Bogor, IP Sukamulya (Sukabumi), Lampung and Bangka. The insects were fed on the diseased plants obtained from Lampung, Bogor and IP Sukamulya, then transferred o the healthy plants. The healthy plants were produced rom true seeds and cutings oiginated rom Bogor and IP Sukamulya. The tested plants were incubated at the green house and examined for disease development. Diseased leaf samples collected rom black pepper plant rom IP. Sukamulya and the transmitted plants were sent to the University of Minnesota, USA for Ihe virus (PYMV) by using ISEM (immunosorbent electron microscope). The result snowed that the leaves samples rom IP. Sukamulya were infected by PYMV. The morphology and size of the virus were similar to those caused stunting disease in the South East Asia. Potential insects vectors found on the diseased black <br /><br />pepper plants were two mealybugs, P. minor and Ferrisia virgata (Hemiptera; Coccoidca: PaaidbcoccidaeX aa well as an aphid Toxoptera aurantii (Hemiptera: Aphidoidea: Aphididae). The first tial on disease transmission by using P. minor, previously reared on the potato tubers, showed one out of ten tested plants produced disease sympom. The subsequent trial using P minor, bred on healthy black pepper seedlings, showed thee out often tested plants developed disease symptoms. None of the aphid transmitted plants developed Ihe disease. This study confirmed thai PYMV b the cause of stunting disease on black pepper in IP Sukamulya and Lampung and P. minor as the insect vecor of the disease.<br /><br />

Penyebab Dan Serangga Vektor Penyakit Keriting Pada Tanaman Lada

The cause of stunting disease of black pepper (Piper nigrum) in Indonesia has not yet been confirmed cither due o a virus or mycoplaam. However, similar disease found on black pepper plants in the Southeast Asia is caused by Piper yellow mottle virus (PYMV) which is transmitted by Planococcus citri. This expeiments was aimed o examine the cause of the stunting disease and its insect vectors. The expeiment were conducted from October 1998 to May 2001. Diseased vegetative materials of black pepper plants showing stunting disease were collected from Sukamulya, Sukabumi. The potential insect vectors were collected from black pepper plants in Bogor, IP Sukamulya (Sukabumi), Lampung and Bangka. The insects were fed on the diseased plants obtained from Lampung, Bogor and IP Sukamulya, then transferred o the healthy plants. The healthy plants were produced rom true seeds and cutings oiginated rom Bogor and IP Sukamulya. The tested plants were incubated at the green house and examined for disease development. Diseased leaf samples collected rom black pepper plant rom IP. Sukamulya and the transmitted plants were sent to the University of Minnesota, USA for Ihe virus (PYMV) by using ISEM (immunosorbent electron microscope). The result snowed that the leaves samples rom IP. Sukamulya were infected by PYMV. The morphology and size of the virus were similar to those caused stunting disease in the South East Asia. Potential insects vectors found on the diseased black pepper plants were two mealybugs, P. minor and Ferrisia virgata (Hemiptera; Coccoidca: PaaidbcoccidaeX aa well as an aphid Toxoptera aurantii (Hemiptera: Aphidoidea: Aphididae). The first tial on disease transmission by using P. minor, previously reared on the potato tubers, showed one out of ten tested plants produced disease sympom. The subsequent trial using P minor, bred on healthy black pepper seedlings, showed thee out often tested plants developed disease symptoms. None of the aphid transmitted plants developed Ihe disease. This study confirmed thai PYMV b the cause of stunting disease on black pepper in IP Sukamulya and Lampung and P. minor as the insect vecor of the disease.

The effect of biorational insecticides on the citrus aphids and their predator, Coccinella septempunctata L.

To determine selective effectiveness for specific pesticides on biological control species, we evaluated the contact toxicity of different treatments including 10 ml l-1 dishwashing liquid, Dayabon 5, 6, 7, 8, 9 and 10 ml l-1, Palizin 1.5, 2.5 and 2.5 ml l-1, Palizin 1.5, 2 and 2.5­+­Citrol oil 5 ml l-1, Tondoxir 2 and 3­+­Bartar soap 1 ml l-1, Malathion 2 ml l-1 and control (water) on the adult aphids of the most important citrus gardens and their predator, Coccinella septempunctata L. in the laboratory conditions. The results revealed that the Palizin treatment 2.5­+­Citrol oil 5 ml l-1, caused the highest rate of the mortality of the citrus green aphid, Aphis spiraecola Patch, 1914 in 36 hours. Concentrations of 7 to 10 ml l-1, Dayabon and Palizin 2.5­+­Citrol oil 5 ml l-1, as well as 3 ml-1 Tondexir + Bartar soap 1 ml-1 had the highest mortality of the citrus brown aphid, Aphis citricidus (Kirkaldy, 1907), 36 hours after treatment (100 %). In addition, the treatments of Palizin 2 ml-1­+ Citrol oil of 5 ml-1, as well as 2 ml l-1 Tondexir­+­Bartar soap 1 ml l-1 and concentrations of 5 ml l-1 and 6 ml-1 of Dayabon produced the same amount of the mortality of the citrus black aphid, Toxoptera aurantii (Boyer de Fonscolombe, 1841). Tondexir 3 ml l-1­+­Bartar soap 1 ml l-1 in 24 hours after treatment caused the highest rate of the mortality of the cotton aphids, Aphis gossypii Glover, 1877 (83.88 %). Malathion treatment caused a 100 % mortality of the predator ladybird 36 hours after treatment, while the lowest amount was observed in the Dayabon at 10 ml l-1 with 33.34 % mortality.

Effects of elevated CO2 on foliar soluble nutrients and functional components of tea, and population dynamics of tea aphid, Toxoptera aurantii

The rising atmospheric CO2 concentration has shown to affect plant physiology and chemistry by altering plant primary and secondary metabolisms. Nevertheless, the impacts of elevated CO2 on plant nutrients and functional components of tea remain largely unknown, which will likely affect tea quality and taste under climate change scenario. Being sources of nutrients and secondary chemicals/metabolites for herbivorous insects, the variation in foliar soluble nutrients and functional components of tea plants resulting from CO2 enrichment will further affect the herbivorous insects' occurrence and feeding ecology. In this study, the tea aphid, Toxoptera aurantii was selected as the phloem-feeding herbivore to study the effects of elevated CO2 on foliar soluble nutrients and functional components of tea seedlings, and the population dynamics of T. aurantii. The results indicated that elevated CO2 enhanced the photosynthetic ability and improved the plant growth of tea seedlings compared with ambient CO2, with significant increases in net photosynthetic rate (+20%), intercellular CO2 concentration (+15.74%), leaf biomass (+15.04%) and root-to-shoot ratio (+8.08%), and significant decreases in stomatal conductance (−5.52%) and transpiration rate (−9.40%) of tea seedlings. Moreover, elevated CO2 significantly increased the foliar content of soluble sugars (+4.74%), theanine (+3.66%) and polyphenols (+12.01%) and reduced the foliar content of free amino acids (−9.09%) and caffeine (−3.38%) of tea seedlings compared with ambient CO2. Furthermore, the relative transcript levels of the genes of theanine synthetase (+18.64%), phenylalanine ammonia lyase (+49.50%), s’-adenosine methionine synthetase (+143.03%) and chalcone synthase (+61.86%) were up-regulated, and that of caffeine synthase (−56.91%) was down-regulated for the tea seedlings grown under elevated CO2 relative to ambient CO2. In addition, the foliar contents of jasmonic acid (+98.6%) and salicylic acid (+155.6%) also increased for the tea seedlings grown under elevated CO2 in contrast to ambient CO2. Also, significant increases in the population abundance of T. aurantii (+4.24%–41.17%) were observed when they fed on tea seedlings grown under elevated CO2 compared to ambient CO2. It is presumed that the tea quality and taste will be improved owing to the enhanced foliar soluble nutrients and functional components of tea seedlings under the climate change scenario, especially on account of the rising atmospheric CO2 concentration, while the climate change may exacerbate the occurrence of tea aphid, T. aurantii, despite the enhanced secondary defensive chemicals manifested by the CO2 enrichment.

Sublethal Effects of Four Insecticides on the Seven-Spotted Lady Beetle (Coleoptera: Coccinellidae).

To further develop integrated pest management (IPM) strategies against two sucking insect pests, Aleurocanthus spiniferus (Quaintanca) (Hemiptera: Aleyrodidae) and Toxoptera aurantii Boyer (Hemiptera: Aphididae), in Chinese tea plantations, it is important to evaluate the effects of insecticides on biological control agents, such as the seven-spot lady beetle, Coccinella septempunctata L. (Coleoptera: Coccinellidae). Therefore, we tested the toxicity and sublethal effects of spirotetramat, clothianidin, lambda-cyhalothrin, and bifenthrin on C. septempunctata. The side effects of the active ingredients of the insecticides were evaluated with residual contact tests on the larvae of C. septempunctata in the laboratory. Spirotetramat and clothianidin exhibited lower lethality to C. septempunctata as shown by the higher LC50 values and had higher selectivity for A. spiniferus and T. aurantii based on the selective toxicity ratios being superior to other tested insecticides. Spirotetramat also did not affect survival, longevity, fecundity, and egg hatching of C. septempunctata. Clothianidin and bifenthrin prolonged the duration of larval development stages of C. septempunctata obviously. Clothianidin at >2.5 mg/liter, lambda-cyhalothrin at >0.03 mg/liter, and bifenthrin at >0.125 mg/liter significantly reduced the survival and pupation rates of C. septempunctata larvae. Furthermore, spirotetramat at 3.125 mg/liter was harmless (IOBC class 1) to larvae of this coccinellid species. Based on the results, spirotetramat was innocuous to C. septempunctata larvae compared with clothianidin, lambda-cyhalothrin, and bifenthrin. Therefore, spirotetramat might be incorporated into IPM programs in combination with C. septempunctata for control of A. spiniferus and T. aurantii in the tea plantations.

Important predaceous insects of citrus aphids (Hemiptera: Aphididae) in the north of Iran

ABSTRACT- Several species of aphids cause severe damage to citrus in the north of Iran. Predatory insects play an important role in biological control of the pests in citrus orchards. In this study, potential predatory insects of citrus aphids, Aphis spiraecola, A. gossypii and Toxoptera aurantii, were identified and their seasonal population dynamics on Citrus unshiu and C. sinensis were investigated during 2016-2017. Overall, four species were identified as dominant predatory insects of citrus aphids in Mazandaran province including Xanthogramma pedissequum (Syrphidae), Scymnus subvillosus, Coccinella septempunctata (Coccinellidae), and Aphidoletes aphidomyza (Cecidomyiidae). Among these species, X. pedissequum and S. subvillossus were more abundant predators in the C. sinensis and C. unshiu orchards compared to the two other species. The predatory insects were observed when means of environmental temperature was about 15-20oC. Population fluctuations, population densities and presence periods of the predatory insects were different on the two host plants. Results of this study can be used in integrated pest management programs of citrus aphids in citrus orchards in the north of Iran.

Phytophagous insects in tamarind crop (Tamarindus indica L.), with emphasis on the greatest damage to the fruit, in five farms from the nearby Western of Antioquia

El tamarindo es un fruto importante para los pequeños productores del occidente cercano antioqueño, en cuanto a que se ofrece en diversas presentaciones a los turistas que visitan esta región. Sin embargo, algunos problemas de calidad, relacionados con la presencia de insectos en este fruto generan dificultades para su comercialización. El objetivo de este trabajo fue determinar los insectos fitófagos de los árboles de tamarindo, con énfasis en los que causan mayor daño al fruto. En cinco fincas de Santa Fe de Antioquia y Sopetrán, se recolectaron los insectos asociados a cada órgano, de seis árboles por finca, se describió su daño y se identificaron hasta el nivel más detallado posible. Tres insectos causantes del mayor daño en el fruto tuvieron prioridad, determinándose su porcentaje de infestación (PI). Para ello, se diseñó una escala de daño y se evaluaron 30 frutos por árbol. Se encontraron once insectos fitófagos asociados al tamarindo, de los cuales cinco registros son nuevos para el tamarindo en Colombia: H. obscurus, Toxoptera aurantii, Trigona sp., Ectomyelois ceratoniae y Acromyrmex octospinosus. Cinco insectos atacan al fruto: Caryedon serratus, dos polillas Phycitinae, Sitophilus linearis e Hypothenemus obscurus. El PI promedio para C. serratus, las dos polillas Phycitinae y S. linearis fue de 19,5%, 8% y 2,5%, respectivamente. Los tres primeros afectan la pulpa y S. linearis ataca a la semilla. El daño más frecuente (43% - 52%) fue de grado 1 y los grados 4 y 5 se presentaron en menores porcentajes (0% - 4%).

Potencial de Aclepias curassavica L. (Apocynaceae) en el control biológico de plagas


 
 
 Para conocer el potencial de Asclepias curassavica L. en el manejo de plagas, del 01 de enero al 28 de diciembre de 2012, se estableció un estudio en una plantación de limón “persa” Citrus latifolia en Emiliano Zapata, Villamar, Michoacán, México. Una sección (tratamiento) incluyó la planta A. curassavica y la otra se mantuvo sin esa especie (testigo). Muestreos semanales documentaron especies y número de depredadores, fitófagos, parasitoides, y niveles de parasitismo en áfidos. Toxoptera aurantii, Aphis spiraecola, Diaphorina citri y Phyllocnistis citrella, fueron las principales plagas. Sus mayores poblaciones ocurrieron en el segundo semestre del año y coincidieron con los principales periodos de brotación del cultivo. Los principales enemigos naturales observados en A. curassavica fueron las familias Coccinellidae, Syrphidae, Chamaemyiidae, Chrysopidae y el parasitoide Lysiphlebus testaceipes. Los Coccinellidos predominaron durante el primer semestre del año, mientras que los otros grupos fueron frecuentes durante todo el año. Los resultados muestran una reducción de 46.3% en las poblaciones de áfidos de los cítricos donde se establecieron Asclepias; sin embargo, las poblaciones de D. citri se incrementaron 77%. Probablemente el mayor biocontrol de áfidos favoreció la disponibilidad de nichos vacíos (brotes vegetativos) y consecuentemente las poblaciones del psílido. La amplia diversidad de enemigos naturales registrados en A. curassavica sugiere un alto potencial de la planta para utilizarse en la regulación y estabilidad de la entomofauna de los agroecosistemas, más que en el control de plagas específicas.