Functional and numerical responses of the predatory mite Amblyseius aerialis (Acari: Phytoseiidae) to Aceria guerreronis (Acari: Eriophyidae)

The coconut mite, Aceria guerreronis Keifer, is one of the main pests of the coconut tree (Cocos nucifera L.) worldwide. Its control is mainly based on the use of acaricides. However, due to the habitat of this pest mite, which is protected by fruit bracts that act as a physical barrier, chemical control is often inefficient. Thus, natural enemies have been studied as an alternative to acaricides. We evaluated the functional and numerical responses of Amblyseius aerialis (Muma) to increasing densities of A. guerreronis (40, 80, 160, 240 and 360) and additionally the oviposition rates of the phytoseiid A. aerialis over 11 days on different food sources: coconut pollen, A. guerreronis and a mix of pollen and A. guerreronis. Our results showed that Amblyseius aerialis showed a type III functional response, where prey consumption increasing as the density of A. guerreronis increased, with a maximum consumption of up to 175 prey per predator. All the prey densities allowed female oviposition. The number of eggs laid by A. aerialis increased with increasing prey density and stabilized between 240 and 360 A. guerreronis individuals, with an average oviposition of 1.7 eggs/female. Furthermore, our results showed that all the food sources (coconut pollen, A. guerreronis and a mix of pollen and A. guerreronis) supported oviposition. The mean oviposition was approximately 1.5 eggs/female on all the food sources. Our study suggests that A. aerialis can be effective in the biological control of A. guerreronis. However, further studies are needed to investigate whether A. aerialis can explore the habitat of A. guerreronis and if that prey can support the development of immature stages and the reproduction of A. aerialis.

Acaricide-impaired functional and numerical responses of the predatory mite, Amblyseius largoensis (Acari: Phytoseiidae) to the pest mite Raoiella indica (Acari: Tenuipalpidae)

The suppression of pest populations by a predator depends on two basic components of the predator-prey interaction: the functional and the numerical responses of the predator. Such responses can be affected by exposure to acaricides. In the present study, the effects of acaricides (abamectin, azadirachtin, fenpyroximate, and chlorfenapyr) on the functional and numerical responses of the predatory mite, Amblyseius largoensis (Acari: Phytoseiidae) an important natural enemy of the pest mite, Raoiella indica (Acari: Tenuipalpidae), were investigated. The exposure of A. largoensis to acaricides occurred through contact with a surface contaminated with dried acaricide residue. Subsequently, A. largoensis exhibited a type II functional response, which was not altered by exposure of any acaricides. However, exposure to abamectin resulted in a decrease in the average mean numbers of prey consumed by a predator. Exposure to acaricides increased prey handling time by 67%, 25%, 38%, and 35% for abamectin, azadirachtin, fenpyroximate, and chlorfenapyr, respectively. Exposure to abamectin reduced the attack rate of A. largoensis by 52%. The numerical response of A. largoensis was only affected by exposure to abamectin, where just 60% of the females oviposited, and regardless of the prey density, the average mean numbers of eggs/female/day was always less than 0.4. The food conversion efficiency into biomass of A. largoensis eggs decreased with increasing prey density, and this trend was not altered by exposure to any acaricides. However, exposure to abamectin drastically compromised the oviposition of A. largoensis, showing no increase in egg production with increasing prey density.

Variability of infestation of rose varieties by the spider mite Tetranychus urticae under conditions of application of Phytoseiulus persimilis or acaricides

The two-spotted spider mite Tetranychus urticae is a dangerous polyphagous pest of agricultural and ornamental plants. In a commercial greenhouse treated with acaricides or biological control using predatory mite Phytoseiulus persimilis individual varieties of roses differed significantly in terms of the average annual infestation by the pest mite. On the poorly populated rose varieties, the biological control agent application was more effective as compared to the acaricides. To effectively control the pest, the required predatory mite rates were 4.6–8.7 times higher on varieties with a minimal spider mite infestation (Aqua and Deep Water) as compared to the maximal pest infestation (Heaven and Brazil).

Kepadatan populasi dan waktu efektif pelepasan tungau predator Neoseiulus longispinosus Evans untuk pengendalian Tetranychus kanzawai Kishida

Kanzawa spider mite, Tetranychus kanzawai Kishida (Tetranychidae) is one of the most important pest mite in Indonesia. This mite is known as the pest of many crops, including cassava. Neoseiulus longispinosus Evans (Phytoseiidae) is a predatory mite commonly found on plant infested by kanzawa spider mite. This predatory mite has high potential to be developed as biological control agent of T. kanzawai. The aim of this research is to elucidate the effective density and release time of N. longispinosus to control T. kanzawai on cassava. The research was conducted in the greenhouse, using cassava of Mentega cultivar. T. kanzawai were introduced into the cassava plants two weeks after planting, with density 5 female adults/plants. N. longispinosus were introduced 1, 2, and 3 weeks after T. kanzawai introduction with predator:prey ratio of 0:5, 1:5, 2:5, dan 3:5, respectively. Population of T. kanzawai and N. longispinosus, and also plant damage were observed at 6 weeks after planting. N. longispinosus could suppress T. kanzawai population and the highest suppression occurred at the interaction between 3:5 ratio and the release time at one week after T. kanzawai infestation. There was no significant effect of N. longispinosus release at various release ratio and time on attack intensity of T. kanzawai.

Characteristic and expression of Hsp70 and Hsp90 genes from Tyrophagus putrescentiae and their response to thermal stress

The development of insects is critically affected by temperature, which therefore plays an important role in the control of stored grain pests. Extreme temperature stress conditions lead to biological responses in mites, such as the synthesis of heat shock proteins. Tyrophagus putrescentiae (Tp) is a pest mite in stored grain that has negative effects on both economy and health. Since T. putrescentiae population dynamics are strongly influenced by temperature, in the present study we have cloned the cDNA of HSP70 and HSP90 (referred to as TpHSP70-1, TpHSP70-2 and TpHSP90) and determined their expression by fluorescence real time quantitative PCR. TpHSP70 and TpHSP90 showed high homology with similar genes in other species and the open reading frames of TpHSP70-1, TpHSP70-2 and TpHSP90 encoded proteins of 665, 661 and 718 amino acid residues, respectively. Under thermal stress, expression of TpHsp70-1 and TpHsp90 was up-regulated at higher temperatures, suggesting their role in the defense against thermal stress.

Characteristic and Expression of Hsp70 and Hsp90 Genes from Tyrophagus Putrescentiae and Their Response to Thermal Stress

Tyrophagus putrescentiae (T. putrescentiae) is a worldwide tored grain pest mite which has do great harm to human’s economy and health. Temperature has a great influence on the population dynamics of T. putrescentiae. In this study, the cDNA of T. putrescentiae HSP70 and HSP90 (designated TpHSP70-1, TpHSP70-2 and TpHSP90) were cloned, and their expression were determined by fluorescent real time quantitative PCR. Results indicate that TpHSP70-1, TpHSP70-2 and TpHSP90 contained an open reading frame of 1,998 bp, 1,984 bp and 2,157 bp that encoded 665, 661 and 718 amino acid residues, respectively. Sequences and phylogenetic analyses suggested that TpHSP70 and TpHSP90 showed high homology with other species. The RT-qPCR results indicated the relative expression level of TpHSP90 and TpHSP70 gene at different stages were different. Also thermal stress could increase its expression significantly. This study indicates that TpHSP70 and TpHSP90 are very important genes for T. putrescentiae to defend against thermal stress.

Effect of foundress population density and size on reproduction and population growth of a haplodiploid mite

Tetranychus ludeni Zacher (Acari: Tetranychidae) is an invasive polyphagous haplodiploid pest mite of many vegetable crops in many parts of the world. This study investigated the effects of simultaneous variations in the local foundress population density and size on the reproduction and population growth of T. ludeni. We show that negative population-density and -size dependency limited the reproduction of foundresses, where the effects of population size on population growth overweighed that of population density. We further demonstrate that ovipositing females could accelerate population growth rate (intrinsic rate of increase, rm) at higher population sizes by producing more daughters early during their lifespan, which can be an adaptive strategy to allow more daughters to complete development and disperse to reduce future food competition intensity. This study provided knowledge on population dynamics in response to foundress population density and size in general and T. ludeni population forecast and precise timing of pest management in particular.

PENYEBARAN HAMA KUTU PUTIH PEPAYA PARACOCCUS MARGINATUS Williams & Granara de Willink (Hemiptera : Pseudococcidae) PADA BERBAGAI TANAMAN INANG DI KABUPATEN ENDE

Papaya is one of the many horticultural commodities grown by farmers. In mid-2008, thousands of trees in the District Sukaraga papaya, Bogor Regency pest infestation papaya white and whole tree has been attacked. P. marginatus is a prolific insect that attack several host plants, including tropical fruit crops and ornamental plants. This research aims to determine the spread of lice infestation in White Paracoccus marginatus Ende and type of host plants are attacked by pest Mite White Paracoccus marginatus. This study is useful to obtain information about the spread of pest P. marginatus in the district of Ende as a step in taking control measures, information to relevant agencies and farmer about the existence pf pest P. marginatus in Ende district, and continued research on the existence of natural enemies and pest bioecology O. Marginatus. Sampling study conducted in 21 sub-district in NTT Propinsis Ende. The study was conducted from March-August 2011. Materials used in this study plant pest Paracoccus marginatus, Alcohol 95%. The tools used are a collection of bottles, brushes, a microscope, transparent plastic, paper labels, Thermo-Hygrometer, coo box, stationery and literature. The result showe that the spread of pest P. marginatus was observed in 21 sub-district in Ende found only in the District 2 District East Ende and Ndona. Papaya is attacked by P. marginatus have chlorotic leaves, young leaves to fall and prospective fruits and fruit and leaves are covered by this pest by stacking layers of wax until the drought ends up dead. The intensity of damage caused by pest P. marginatus in the District of East Ende of 33.33% and 16.67% for Ndona District. The spread of pest P. marginatus in the district of Ende found at two locations namely Ende District East and District Ndona. Types of host plants are attacked by pest P. marginatus is Papaya plants.

The establishment of an invasive pest mite, Raoiella indica, affects mite abundance and diversity on coconut plants

The introduction and establishment of an invasive species in a new habitat represents a major threat to biodiversity and ecosystem structure. A recent example of a mite that has become an invasive species is the red palm mite, Raoiella indica Hirst (Acari: Tenuipalpidae). After its introduction in the Americas, this species has considerably expanded the number of hosts and has been reported as a key pest of some of these. In the present study we investigated the possibility of mitefauna alteration on coconut leaflets (abundance and diversity) mediated by the introduction and establishment of R. indica. A survey was conducted over a period of 1 year in two areas of coconut cultivation: one infested and one free of R. indica. The results of the present study suggest that the introduction of R. indica modifies the mitefauna existing in coconut leaflets. Differences were detected in the abundance and diversity of mites at the level of the taxonomic categories (family and species) and at the level of the trophic groups (predators, herbivores and mites with undefined feeding mode). Additionally, in plants infested by the invasive species, a similar pattern was observed between the fluctuation of the phytoseiid mites and other tenuipalpid mites. In these plants, the density of the tenuipalpid mites (including R. indica) was also the variable that most contributed to explain the fluctuation of phytoseiid mites. This suggests that the invasive species, R. indica, acts as a keystone species, structuring the mitefauna in coconut plants.

Genetic analysis and screening of detoxification-related genes in an amitraz-resistant strain of Panonychus citri

Panonychus citri (McGregor) is the most common pest in citrus-producing regions. Special low-toxicity acaricides, such as spirocyclic tetronic acids and mite growth inhibitors, have been used for a long time in China. However, pesticide resistance in mites is a growing problem due to the lack of new acaricide development. Wide-spectrum insecticides, such as amitraz have gained acceptance among fruit growers. An amitraz-resistant strain of P. citri was obtained by indoor screening to examine field resistance monitoring of mites to acaricides and to explore the resistant mechanism of mites against amitraz. The amitraz-resistant strain of P. citri had an LC50 value of 2361.45 mg l−1. The resistance ratio was 81.35 times higher in the resistant strain of P. citri compared with the sensitive strain. Crossing experiments between the sensitive and resistant strains of P. citri were conducted, resulting in a D value of 0.11 for F1 SS♀×RS♂ and 0.06 for F1 RS♀×SS♂. Reciprocal cross experiments showed that the dose–mortality curves for the F1 generations coincided, indicating that the resistance trait was not affected by cytoplasmic inheritance. The dose–expected response relationship was evaluated in the backcross generation and a significant difference was observed compared with the actual value. The above results indicate that the inheritance of resistance trait was incompletely dominant, governed by polygenes on the chromosome. Synergism studies demonstrated that cytochrome P450s and esterase may play important roles in the detoxification of amitraz. Based on differential gene analysis, 23 metabolism-related genes of P. citri were identified, consistent with the results of synergism studies. Real-time PCR verification implied that P450s, ABC transporters, and acetylcholinesterase might influence the detoxification of amitraz by P. citri. These results provide the genetic and molecular foundation for the management of pest mite resistance.