Field Experiment Effect on Citrus Spider Mite Panonychus citri of Venom from Jellyfish Nemopilema nomurai: The Potential Use of Jellyfish in Agriculture.

Jellyfish are rich in resources and widely distributed along coastal areas. As a potential approach to respond to jellyfish blooms, the use of jellyfish-derived products is increasing. The citrus spider mite (Panonychus citri) is one of the key citrus pests, negatively impacting the quality and quantity of oranges. Due to the resistance and residue of chemical acaricides, it is important to seek natural substitutes that are environmentally friendly. The field efficacy of the venom from the jellyfish Nemopilema nomurai against P. citri was assayed in a citrus garden. The frozen N. nomurai tentacles were sonicated in different buffers to isolate the venom. The venom isolated by PBS buffer (10 mM, pH 6.0) had the strongest acaricidal activity of the four samples, and the corrected field efficacy 7 days after treatment was up to 95.21%. This study demonstrated that jellyfish has potential use in agriculture.

Lemon Terpenes Influence Behavior of the African Citrus Triozid Trioza erytreae (Hemiptera: Triozidae).

The African citrus triozid, Trioza erytreae Del Guercio (Hemiptera: Triozidae) is one of the primary vectors of the bacterium Candidatus Liberibacter spp. which causes citrus greening, a disease of global economic importance in citrus production. Despite its economic importance, little is known about its chemical ecology. Here, we used behavioral assays and chemical analysis to study the chemical basis of interaction between T. erytreae and one of its preferred host plants, Citrus jambhiri. In dual choice Y-tube olfactometer assays, lemon leaf odors attracted females but not males compared to plain air or solvent controls. However, in a petri dish arena assay, both sexes were arrested by lemon leaf odors. Coupled gas chromatography-mass spectrometry (GC/MS) analysis revealed quantitative differences in the odors of flushing and mature leaves, dominated by terpenes. Twenty-six terpenes were identified and quantified. In Petri dish arena assays, synthetic blends of the most abundant terpenes mimicking lemon flushing leaf odors elicited varying behavioral responses from both sexes of T. erytreae. A nine-component blend and a blend of the three most abundant terpenes; limonene, sabinene and ß-ocimene arrested both sexes of T. erytreae. In contrast, a six-component blend lacking in these three components elicited an avoidance response in both sexes. Furthermore, both sexes of T. erytreae preferred the three-component synthetic blend to lemon crude volatile extract. These results suggest that lemon terpenes might be used in the management of T. erytreae.

Developing Citrus Huanglongbing (HLB) Management Strategies Based on the Severity of Symptoms in HLB-Endemic Citrus-Producing Regions.

Citrus Huanglongbing (HLB), also known as greening, is a destructive disease caused by the fastidious, phloem-colonizing bacteria Candidatus Liberibacter spp.; 'Ca. Liberibacter asiaticus' (Las) is the most prevalent of the species causing HLB. The Asian citrus psyllid (ACP, Diaphorina citri) transmits Las. HLB is threatening citrus production worldwide, and there is no cure for infected trees. Management strategies targeting diseased trees at different stages of colonization by Las are needed for sustainable citrus production in HLB-endemic regions. We evaluated the effect of the combinations of plant defense elicitors, nitrogen (N) fertilizer, and compost on mildly diseased trees. We tested thermotherapy on severely diseased trees and assessed tree protectors to prevent feeding by ACP, thus preventing Las from being transmitted to new plantings that replaced HLB-moribund trees. After four applications over two consecutive growing seasons we found that the combination of compost, urea, and plant defense elicitors ß-aminobutyric acid, plus ascorbic acid and potassium phosphite with or without salicylic acid, slowed down the progression of HLB and reduced disease severity by approximately 18%, compared with the untreated control. Our data showed no decline in fruit yield, indeed treatment resulted in a higher yield compared with the untreated control. Thermotherapy treatment (55°C for 2 min) exhibited a suppressive effect on growth of Las and progress of HLB in severely diseased trees for 2 to 3 months after treatment. The tree protectors prevented feeding by ACP, and therefore young replant trees remained healthy and free from infection by Las over the 2-year duration of the experiment. Taken together, these results may contribute to a basis for developing a targeted approach to control HLB based on stage of host colonization, application of plant defense elicitors, N fertilizer, compost, thermotherapy, and tree protectors. There is potential to implement these strategies in conjunction with other disease control measures to contribute to sustainable citrus production in HLB-endemic regions.

Essential Oil Variation from Twenty Two Genotypes of Citrus in Brazil-Chemometric Approach and Repellency Against Diaphorina citri Kuwayama.

The chemical composition of volatile oils from 22 genotypes of Citrus and related genera was poorly differentiated, but chemometric techniques have clarified the relationships between the 22 genotypes, and allowed us to understand their resistance to D. citri. The most convincing similarities include the synthesis of (Z)-ß-ocimene and (E)-caryophyllene for all 11 genotypes of group A. Genotypes of group B are not uniformly characterized by essential oil compounds. When stimulated with odor sources of 22 genotypes in a Y-tube olfactometer D. citri preferentially entered the arm containing the volatile oils of Murraya paniculata, confirming orange jasmine as its best host. C. reticulata × C. sinensis was the least preferred genotype, and is characterized by the presence of phytol, (Z)-ß-ocimene, and ß-elemene, which were not found in the most preferred genotype. We speculate that these three compounds may act as a repellent, making these oils less attractive to D. citri.

[Screening for virulence strains of Metarhizium against Dorysthenes hydropicus pascoes].

OBJECTIVE: The aim of the present study was to screen the Metarhizium strains with high virulence against the larvae of Dorysthenes hydropicus, a serious pest of Citrus grandis. METHOD: Thirty six strains of Metarhiziums were isolated from the soil of C. grandis GAP base and collected from other institutions, and the pathogenicity of these strains against 1st instar larvae of D. hydropicus was detected at concentration of 1 x 10(8) conidia/g. The high violence strains against D. hydropicus were cultivated in sabouraud dextrose yeast medium at first, then transfer to rice grain. And the sporulations of these violent strains against D. hydropicus were detected. RESULT: Twenty-eight strains showed virulence against D. hydropicus by preliminary study, and 7 strains of them were collected for further study, 6 of the 7 showed high virulence, the highest cadaver rate was higher than 74%. The conidia production of strain 1 and strain 4 were 2.35 +/- 0. 25 (1 x 10(9) conidia/g), 2.21 +/- 0.27 (1 x 10(9) conidia/g), respectively, showed significantly higher than other strains. CONCLUSION: Strain 1 and strain 4 of the 36 Metarhiziums strains showed high virulence against D. hydropicus, and the highest sporulation ability, so they have a best application prospect.

[Isolation and identification of Metarhizium from Citrus grandis 'tomentosa' GAP base].

A type of entomopathogenic fungus of soil in Citrus grandis 'tomentosa' production base was isolated and identified with morphological and molecular biological methods, including pathogenesis, spore characteristic and ITS sequence analysis were conducted. The results showed that eighteen entomopathogenic fungi strains were isolated from the Tenebrio molitor infected in the soil samples, which were identified as Metarhizium anisopliae var. anisopliae. Based on results above, we concluded that there was quantity of Metarhizium resources in this area. These provided the useful information for controlling some pests of C. grandis by using these strains of fungus.

Subterranean, herbivore-induced plant volatile increases biological control activity of multiple beneficial nematode species in distinct habitats.

While the role of herbivore-induced volatiles in plant-herbivore-natural enemy interactions is well documented aboveground, new evidence suggests that belowground volatile emissions can protect plants by attracting entomopathogenic nematodes (EPNs). However, due to methodological limitations, no study has previously detected belowground herbivore-induced volatiles in the field or quantified their impact on attraction of diverse EPN species. Here we show how a belowground herbivore-induced volatile can enhance mortality of agriculturally significant root pests. First, in real time, we identified pregeijerene (1,5-dimethylcyclodeca-1,5,7-triene) from citrus roots 9-12 hours after initiation of larval Diaprepes abbreviatus feeding. This compound was also detected in the root zone of mature citrus trees in the field. Application of collected volatiles from weevil-damaged citrus roots attracted native EPNs and increased mortality of beetle larvae (D. abbreviatus) compared to controls in a citrus orchard. In addition, field applications of isolated pregeijerene caused similar results. Quantitative real-time PCR revealed that pregeijerene increased pest mortality by attracting four species of naturally occurring EPNs in the field. Finally, we tested the generality of this root-zone signal by application of pregeijerene in blueberry fields; mortality of larvae (Galleria mellonella and Anomala orientalis) again increased by attracting naturally occurring populations of an EPN. Thus, this specific belowground signal attracts natural enemies of widespread root pests in distinct agricultural systems and may have broad potential in biological control of root pests.

Impacts of horticultural mineral oils and two insecticide practices on population fluctuation of Diaphorina citri and spread of Huanglongbing in a citrus orchard in Sarawak.

Aspects of the incidence and spread of the citrus disease huanglongbing (HLB) in relation to the vector Diaphorina citri population fluctuation were studied from January 1999 to December 2001 seasons in a 0.8 ha citrus orchard at Jemukan (1° 33'N, 110° 41'E), Southwest Sarawak in Malaysia. In relation to insecticide and horticultural mineral oils (HMOs) use, levels of HLB infection rose quite rapidly over the next 3 years in the unsprayed control and less rapidly in the other treatments such as imidacloprid, nC24HMO, and triazophos/cypermethrin/chlorpyrifos. Levels of HLB as determined by Polymerase Chain Reaction (PCR) were 42.2%, 9.4%, 11.4%, and 22.7%, respectively. The effects of nC(24)HMO and conventional pesticides on the citrus psyllid population and parasitoids in citrus orchard were also determined.

Induced release of a plant-defense volatile 'deceptively' attracts insect vectors to plants infected with a bacterial pathogen.

Transmission of plant pathogens by insect vectors is a complex biological process involving interactions between the plant, insect, and pathogen. Pathogen-induced plant responses can include changes in volatile and nonvolatile secondary metabolites as well as major plant nutrients. Experiments were conducted to understand how a plant pathogenic bacterium, Candidatus Liberibacter asiaticus (Las), affects host preference behavior of its psyllid (Diaphorina citri Kuwayama) vector. D. citri were attracted to volatiles from pathogen-infected plants more than to those from non-infected counterparts. Las-infected plants were more attractive to D. citri adults than non-infected plants initially; however after feeding, psyllids subsequently dispersed to non-infected rather than infected plants as their preferred settling point. Experiments with Las-infected and non-infected plants under complete darkness yielded similar results to those recorded under light. The behavior of psyllids in response to infected versus non-infected plants was not influenced by whether or not they were carriers of the pathogen. Quantification of volatile release from non-infected and infected plants supported the hypothesis that odorants mediate psyllid preference. Significantly more methyl salicylate, yet less methyl anthranilate and D-limonene, was released by infected than non-infected plants. Methyl salicylate was attractive to psyllids, while methyl anthranilate did not affect their behavior. Feeding on citrus by D. citri adults also induced release of methyl salicylate, suggesting that it may be a cue revealing location of conspecifics on host plants. Infected plants were characterized by lower levels of nitrogen, phosphorus, sulfur, zinc, and iron, as well as, higher levels of potassium and boron than non-infected plants. Collectively, our results suggest that host selection behavior of D. citri may be modified by bacterial infection of plants, which alters release of specific headspace volatiles and plant nutritional contents. Furthermore, we show in a laboratory setting that this apparent pathogen-mediated manipulation of vector behavior may facilitate pathogen spread.

Larval feeding stimulants for a rutaceae-feeding swallowtail butterfly, Papilio xuthus L. in Citrus unshiu leaves.

Larvae of a swallowtail butterfly, Papilio xuthus L., feed exclusively on plants of the family Rutaceae, including various Citrus crops. Larvae were strongly stimulated to feed on paper strips impregnated with ethanolic extracts of host-plant leaves. Stimulation of feeding on extracts of Citrus unshiu leaves required a mixture of chemicals including sugars (D: -glucose, D: -fructose, and D: -sucrose), a betaine [(-)-stachydrine], a cyclic peptide (citrusin I), a polymethoxyflavone (isosinensetin), and the lipids 1-linolenoylglycerol, 1-linoleoylglycerol, 1-octadecenoylglycerol, 1-stearoylglycerol, and 1,2-dilinolenoyl-3-galactosyl-sn-glycerol. When these compounds were assayed individually, few larvae consumed test strips. However, larvae readily chewed the test strips treated with a mixture of all compounds, indicating that host recognition by P. xuthus larvae is mediated by a specific combination of both primary and secondary substances. Comparison of 11 stimulant components with 10 compounds from C. unshiu leaves previously reported as stimulant components for oviposition by P. xuthus adult females revealed only one compound, stachydrine, as an ingredient in common. While the larval feeding-stimulant mixture is dominated by nutrients and other compounds of general significance for primary metabolism, the component oviposition stimulants are mostly secondary substances, including flavonoid glycosides, protoalkaloids, a cyclitol, and a betaine, that have restricted distributions in plants. Reliance by adult females on unique profiles of secondary compounds presumably reflects the need to locate and recognize specific host-plant species within a diverse flora. Since the initial host choice for the larvae is made typically by the ovipositing female, however, unique secondary compounds may be less important for larval feeding than are compounds useful for indicating food and microhabitat quality once on the host plant.

Unreliable pesticide control of the vector psyllid Diaphorina citri (Hemiptera: Psyllidae) for the reduction of microorganism disease transmission.

Systemic insecticides and application methods were examined for the control of the vector psyllid of citrus greening disease, Diaphorina citri, on grown king mandarin trees in an orchard in southern Vietnam from May 2007 to September 2008. Leaf spraying of imidacloprid, thiamethoxam, and clothianidin attained about 50 % to 70 % mortality of the psyllid for one month after the application and showed decreased efficacy thereafter. Imidacloprid was more effective than the other two insecticides, but the efficacy on grown trees was still much lower than that following application to young seedlings. Trunk injection of these insecticides accomplished similar mortality, about 50 %, and the efficacy of the insecticides continued for one month. An adjuvant was used with the goal of protecting the insecticide applied on leaves from precipitation, and mineral oil was used for the same reason, as well as its potential to control the psyllid. Neither the adjuvant nor the mineral oil played an evident role in the increase of insecticide efficacy or longevity. Application of systemic insecticides at even 50 times the dose described above did not show an apparent increase in psyllid mortality. The insecticides commonly used for the control of the psyllid were not as effective on this insect on grown trees as we had expected they would be.

Subterranean herbivore-induced volatiles released by citrus roots upon feeding by Diaprepes abbreviatus recruit entomopathogenic nematodes.

Herbivore-induced volatile emissions benefit plant hosts by recruiting natural enemies of herbivorous insects. Such tritrophic interactions have been examined thoroughly in the above-ground terrestrial environment. Recently, similar signals have also been described in the subterranean environment, which may be of equal importance for indirect plant defense. The larvae of the root weevil, Diaprepes abbreviates, are a serious pest of citrus. Infestations can be controlled by the use of entomopathogenic nematodes, yet the interactions between the plant, insect and nematode are poorly understood and remain unpredictable. In bioassays that used a root zone six-arm olfactometer, citrus roots ('Swingle citrumelo' rootstock) recruited significantly more entomopathogenic nematodes (Steinernema diaprepesi) when infested with root weevil larvae than non-infested roots. Infested plants were more attractive to nematodes than larvae alone. Roots damaged by weevil larvae attracted more nematodes than mechanically damaged roots and sand controls. By dynamic in situ collection and GC-MS analysis of volatiles from soil, we determined that four major terpene compounds were produced by infested plant roots that were not found in samples from non-infested roots or soil that contained only larvae. Solvent extracts of weevil-infested roots attracted more nematodes than extracts of non-infested roots in a two choice sand-column bioassay. These findings suggest that Swingle citrus roots release induced volatiles as an indirect defense in response to herbivore feeding, and that some of these induced volatiles function as attractants for entomopathogenic nematodes.

[Primary studies on biological characteristics of Dorysthenes hydropicus].

OBJECTIVE: To study the biological characteristics of Dorysthenes hydropicus in the farm of Cirtus grandis, and offer scientific evidence for prevention and controlling of D. hydropicus. METHOD: Indoor-rearing and light trap were applied to study the biological characteristics, development course and harmful effect of D. hydropicus. RESULT: D. hydropicus reproduces one generation in 1-2 year in Guangdong province, and overwinters in the form of larvae. Its imago comes out of the earth mainly in late May after mature. The body length has great individual diversity normally ranged from 25-60 cm, It also shows strong phototaxy. One lamp can trap more than 2 000 of them per night. Female imago has a large egg load with the maximum amount of 543. The eggs hatching is in depth of 1-3 cm soil. The dominant hatching period of egg is from late June to early July, and hatchability is over 85%. The living space of larva ranges from 15-60 cm in soil. D. hydropicus has caused serious harm and lead to thousands of Cirtus grandis trees death every year. CONCLUSION: Dorysthenes hydropicus showed serious threat to the growth of Cirtus grandis and should be prevented and controlled.

A new concept for insect damage evaluation based on plant physiological variables.

The objective of this study was to determine the damage levels caused by Orthezia praelonga Douglas, 1891 and Leucoptera coffeella (Guérin-Mèneville 1842), on rangpur lime and Obatã coffee leaves, respectively. Measurements were based on a new concept for the evaluation of the following plant physiological parameters: photosynthesis, stomatal conductance, leaf temperature and transpiration, and internal concentration of CO2 (by infrared analyzer). A negative correlation between infestation level and photosynthesis was found, where the negative inflexion point of the curve was considered as a reference for damage levels. The control level for O. praelonga is below the 7-13% limit for damaged leaf area (40 to 70 scales per leaf), while for L. coffeella it is below the 26-36% limit for the same variable. Photosynthesis provided the best correlation for this type of analysis.

A new concept for insect damage evaluation based on plant physiological variables

The objective of this study was to determine the damage levels caused by Orthezia praelonga Douglas, 1891 and Leucoptera coffeella (Guérin-Mèneville 1842), on rangpur lime and Obatã coffee leaves, respectively. Measurements were based on a new concept for the evaluation of the following plant physiological parameters: photosynthesis, stomatal conductance, leaf temperature and transpiration, and internal concentration of CO2 (by infrared analyzer). A negative correlation between infestation level and photosynthesis was found, where the negative inflexion point of the curve was considered as a reference for damage levels. The control level for O. praelonga is below the 7-13 percent limit for damaged leaf area (40 to 70 scales per leaf), while for L. coffeella it is below the 26-36 percent limit for the same variable. Photosynthesis provided the best correlation for this type of analysis.

O objetivo deste trabalho foi estabelecer, baseado em um novo conceito de avaliação de parâmetros fisiológicos vegetais, o nível de dano causado por Orthezia praelonga Douglas 1891 e por Leucoptera coffeella (Guérin-Mèneville 1842) em folhas de limão cravo e cafeeiro 'Obatã', respectivamente. Foram feitas leituras de trocas gasosas por infravermelho, além da avaliação da condutância estomática, temperatura foliar, transpiração foliar e concentração interna de CO2. Os dados demonstraram uma correlação negativa entre o nível de infestação e a fotossíntese, sendo o ponto de inflexão negativa da curva tomado como referência de nível de dano, onde o nível de controle para O. praelonga encontra-se abaixo do limite de 7 a 13 por cento de área foliar lesionada (40 a 70 cochonilhas por folha), e o de L. coffeella encontra-se abaixo dos valores de 26 a 36 por cento de área foliar lesionada. Dentre os parâmetros avaliados a fotossíntese foi o que demonstrou melhor correlação para este tipo de análise.

Reproductive performance of the mite Brevipalpus phoenicis (Geijskes, 1939) on citrus and coffee, using life table parameters.

The flat-mite Brevipalpus phoenicis (Geijskes, 1939) (Acari: Tenuipalpidae) is considered important in citrus (Citrus spp.) and coffee plants (Coffea spp.) in Brazil, and is known as the leprosis and coffee ring spot mite, as being a vector of the Citrus Leprosis Rhabdovirus - CitLV and Coffee Ring Spot Virus - CoRSV. The objective of this work is to find out about the reproductive success of B. phoenicis on citric fruits and coffee leaves by fertility life table parameters and its biology. The experiments were carried out in laboratory conditions at 25 +/- 2 degrees C, 70 +/- 10% of relative humidity and 14 h of photophase. The lengths of embryonic and post-embryonic periods were different due to the host where the mite was reared. B. phoenicis showed better development and higher survival and fecundity in citric fruits than coffee leaves. The intrinsic rate of the population increase (r(m)) was 0.128 and 0.090 - females/female/day on citric fruits and coffee leaves, respectively. The citric fruits were more appropriate for the development of B. phoenicis than coffee leaves.

Reproductive performance of the mite Brevipalpus phoenicis (Geijskes, 1939) on citrus and coffee, using life table parameters / Desempenho reprodutivo do ácaro Brevipalpus phoenicis (Geijskes, 1939) em citros e em cafeeiro, utilizando parâmetros de tabela de vida

The flat-mite Brevipalpus phoenicis (Geijskes, 1939) (Acari: Tenuipalpidae) is considered important in citrus (Citrus spp.) and coffee plants (Coffea spp.) in Brazil, and is known as the leprosis and coffee ring spot mite, as being a vector of the Citrus Leprosis Rhabdovirus - CitLV and Coffee Ring Spot Virus - CoRSV. The objective of this work is to find out about the reproductive success of B. phoenicis on citric fruits and coffee leaves by fertility life table parameters and its biology. The experiments were carried out in laboratory conditions at 25 ± 2 °C, 70 ± 10 percent of relative humidity and 14 h of photophase. The lengths of embryonic and post-embryonic periods were different due to the host where the mite was reared. B. phoenicis showed better development and higher survival and fecundity in citric fruits than coffee leaves. The intrinsic rate of the population increase (r m) was 0.128 and 0.090 - females/female/day on citric fruits and coffee leaves, respectively. The citric fruits were more appropriate for the development of B. phoenicis than coffee leaves.

O ácaro Brevipalpus phoenicis (Geijskes, 1939) (Acari: Tenuipalpidae) é considerado importante em citros (Citrus spp.) e cafeeiro (Coffea spp.) no Brasil, sendo conhecido como ácaro da leprose e da mancha-anular, por ser vetor dos vírus causadores da leprose em citros,Citrus Leprosis Rhabdovirus - CitLV, e da mancha-anular em cafeeiro,Coffee Ring Spot Virus - CoRSV. O objetivo deste trabalho foi avaliar o sucesso reprodutivo de B. phoenicis, em frutos cítricos e em folhas de cafeeiro, por meio de parâmetros calculados a partir da tabela de vida,de fertilidade e da biologia. Os experimentos foram realizados em laboratório a 25 ± 2 °C, 70 ± 10 por cento de umidade relativa e 14 h de fotofase. Os períodos embrionário e pós-embrionário apresentaram diferenças em função do hospedeiro em que o ácaro foi criado.B. phoenicis teve melhor desenvolvimento, maior sobrevivência e maior fertilidade específica em frutos cítricos do que em folhas de cafeeiro. A taxa intrínseca de crescimento populacional (rm) foi de 0,128 e 0,090 fêmeas/fêmea/dia em frutos cítricos e em folhas de cafeeiro, respectivamente. Os frutos cítricos mostraram-se mais adequados ao desenvolvimento de B. phoenicis do que as folhas de cafeeiro.

Volatile allelochemicals in the Ageratum conyzoides intercropped citrus orchard and their effects on mites Amblyseius newsami and Panonychus citri.

Ageratum conyzoides L. weed often invades cultivated fields and reduces crop productivity in Southeast Asia and South China. However, intercropping this weed in citrus orchards may increase the population of predatory mite Amblyseius newsami, an effective natural enemy of citrus red mite Panonychus citri, and keep the population of P. citri at low and noninjurious levels. This study showed that A. conyzoides produced and released volatile allelochemicals into the air in the intercropped citrus orchard, and these volatiles influenced the olfactory responses of A. newsami and P. citri. At test temperature (25 degrees C), A. conyzoides fresh leaves, its essential oil, and major constituents, demethoxy-ageratochromene, beta-caryophyllene, alpha-bisabolene, and E-beta-farnesene, attracted A. newsami and slightly repelled P. citri. Field experiments demonstrated that spraying A. conyzoides essential oil emulsion in an A. conyzoides nonintercropped citrus orchard increased the population density of A. newsami from below 0.1 to over 0.3 individuals per leaf, reaching the same level as in an A. conyzoides intercropped citrus orchard. However, this effect could not be maintained beyond 48 hr because of the volatility of the essential oil. In contrast, in the A. conyzoides intercropped citrus orchard, A. conyzoides plants continuously produced and released volatile allelochemicals and maintained the A. newsami population for a long time. The results suggest that intercropping of A. conyzoides not only made the citrus orchard ecosystem more favorable for the predatory mite A. newsami, but also that the volatile allelochemicals released from A. conyzoides regulated the population of A. newsami and P. citri.

Biology of three species of Agistemus (Acari: Stigmaeidae): life table parameters using eggs of Panonychus citri or pollen of Malephora crocea as food.

The biology and life table parameters of Agistemus industani Gonzalez, A. cyprius Gonzalez, and A. floridanus Gonzalez (Acari: Stigmaeidae) were studied under laboratory conditions using two food sources: Panonychus citri (McGregor) eggs or ice plant, Malephora crocea (Jacquin) Schwantes pollen at 25 degrees C. The larval, protonymph, deutonymph, and adult stages of A. industani fed on citrus red mite eggs. All active stages of A. industani, except the larva, fed on all P. citri stages and the larval stage could not feed on P. citri adults. All immature stages of A. industani fed on M. crocea pollen. Agistemus cyprius larvae fed on P. citri eggs and larvae or ice plant pollen. The nymphal stages fed on P. citri eggs, larvae, and protonymphs but not deutonymphs or adults while A. cyprius deutonymphs and adults fed on all P. citri stages. Adult and nymphal stages of A. cyprius fed on ice plant pollen and successfully completed their development while A. floridanus did not. Agistemus floridanus larvae fed only on P. citri eggs, while the other stages fed on P. citri eggs, larvae, and protonymphs. The developmental times from egg to adult for A. industani and A. cyprius when fed M. crocea pollen were 11.3 and 13.4 days, respectively. Agistemus floridanus was unable to complete its life cycle on a diet of only M. crocea pollen. Agistemus industani, A. cyprius, and A. floridanus completed development from egg to adult in 11.7, 13.8, and 10.8 days, respectively, when fed P. citri eggs. The intrinsic rate of increase (r(m)) values for A. cyprius and A. industani were 0.0311 and 0.1201 per day on the pollen diet. The net reproductive rate (Ro) was 3.58 for A. cyprius and 10.07 for A. industani with generation times (T) of 45.2 and 35.1 days, respectively, on the ice plant pollen diet. The r(m) values for A. cyprius, A. floridanus, and A. industani on the P. citri egg only diet were: 0.0562, 0.1001, and 0.1031 per day, respectively. The Ro values for each species fed P. citri eggs only were: 6.36, 7.90, and 18.70 for A. cyprius, A. floridanus, and A. industani and the generation times (T) for each of the three species were: 35.2, 29.9 and 37.8 days, respectively.

[Bioassay on oviposition repellency of non-preferable plant extracts against citrus red mite Panonychus citri].

The oviposition repellency of the alcohol extracts from 50 species of non-preferable plants and azadirachtin against citrus red mite (Panonychus citri) was determined using laboratory bioassays. In choice tests, the extracts from 42 of the 50 plant species and 1% azadirachtin (2000 x) significantly reduced oviposition 1d after treatment. The repellency effect of the extracts from the 42 plant species was better than that of azadirachtin. Mikania micrantha extract had the best result, with an Interference Index of Population Control (IIPC) of 0.087 1 d after treatment, and significantly reduced oviposition for 9 d, while the extracts from Sesbania cannabina, Allium tuberosum, Paederia scandens, Duranta erecta and Dicranopteris pedata also had good effects, with an oviposition repellency of over 70% 1 d after treatment, and significantly reduced oviposition for 4-6 d. The effect became weaker as time went on. None of the extracts showed significant oviposition attraction.