Seletividade de acaricidas a insetos e ácaros predadores em citros

Estudou-se a seletividade de acaricidas a insetos e ácaros predadores em pomares citrícolas localizados em Monte Alto e Vista Alegre do Alto, SP, em 1993 e 1994. Os acaricidas nas dosagens testadas (em g.i.a/1001) foram: em 1993, pyridaben 20 CE, 20 PM e 75 PM (10 e 15), óxido fenbutatin (40) e testemunha; em 1994, pyridaben 20 CE e pyridaben 75 PM (10 e 20), óxido fenbutatin (40), cyhexatin (25) e testemunha. Larvas e adultos de Pentilia egena Muls. e Coccidophilus citricola Bréthes, adultos de Cycloneda sanguinea L., Azya sp. e Calloeneis sp. e larvas de crisopídeos foram observados nas plantas, previamente e a 1, 3, 7, 10, 14 e 21 dias após a aplicação. Para contagem de Euseius sp. e Iphiseiodes zuluagai Denmark & Muma, 10 folhas do interior da planta foram coletadas e observadas. Os produtos foram classificados em: seletivo (até 25% de mortalidade); levemente tóxico (25 a 50%; moderadamente tóxico (51 a 75%) e tóxico (> 75% de mortalidade). Os resultados indicaram que todos os produtos foram seletivos a adultos de P. egena, porém, pyridaben causou de 25 a 50% e cyhexatin de 51 a 75% de mortalidade de larvas. Pyridaben 20 CE e 75 PM reduziram em 25 a 50% e 51 a 75% respectivamente o número de adultos de C. citricola; já cyhexatin foi tóxico e fenbutatin seletivo a adultos desta espécie. em relação a larvas de C. citricola mortalidade de 51 a 75% foi causada por pyridaben 20 CE e 75 PM, maior que 75% por cyhexatin e entre 25 e 50% no caso de fenbutatin. Todos os acaricidas foram tóxicos aos ácaros predadores por mais de 21 dias, no entanto, fenbutatin apresentou efeito residual menor (14 dias).

Tests to determine LC50 and discriminating doses for macrocyclic lactones against the cattle tick, Boophilus microplus

Laboratory tests were carried out on larvae and adults of the cattle tick Boophilus microplus to determine the toxicity of macrocyclic lactone acaricides (MLs). Technical and commercial MLs were used in larval packet test (LPT), larval immersion test (LIT) and adult immersion test (AIT). Tn LIT and AIT the toxicity of MLs was much higher than for LPT. In the AIT, diluting the injectable formulation of MLs in water was as effective as dilution in ethanol + Triton X-100. LC50, LC99.9 and 95% confidence limits were determined so that a discriminating dose (DD) could be set for larval and adult tests in order to diagnose potential resistance to MLs in field samples of the tick. These DDs are for Australian strains of B. microplus and may not be suitable for other strains until further work is carried out.The value of these diagnostic tests can only be verified if or when resistance to MLs emerges in ticks. (C) 2001 Elsevier B.V. B.V. All rights reserved.

Efeito da lavagem artificial na eficiência de acaricidas-ovicidas no controle de Brevipalpus phoenicis (Geijskes, 1939) (Acari: Tenuipalpidae) em citros

The objective of this research was to test the control of Brevipalpus phoenicis (Geijskes, 1939) by the hexythiazox and quinometionato products in citrus crop with and without adhesive spread and when submitted to artificial rain. The plants were sprayed at 2, 4, 8, 24 and 48 hours. When dried, the fruits were collected (eight/plants) and half of them were washed in laboratory with artificial rainfall on the basis of 30 mm/h during 15 minutes establishing the following treatments: T1 - hexythiazox + washing; T2 - hexythiazox + agral + washing; T3 - quinometionato + washing; T4 - quinometionato + agral + washing; T5 - control + agral + washing; T6 - hexythiazox; T7 - hexythiazox + agral; T8 - quinometionato; T9 - quinometionato + agral; T10 - control + agral. Thus, all the fruits were inoculated with ten females of B. phoenicis and five days later the mites alive were counted and eliminated. Approximately 15 days later the number of larvae alive were also counted. The results obtained allowed the following conclusions: a) the acaricides were efficient to control B. phoenicis; b) the rainfall (washing) did not alter the efficiency; c) the agral did not change the results.

Efficacy of the Bm86 antigen against immature instars and adults of the dog tick Rhipicephalus sanguineus (Latreille, 1806) (Acari: Ixodidae)

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Ação de pesticidas em Metarhizium anisopliae no solo

The present study aimed to analyze the action of some acaricides, fungicides, insecticides and herbicides containing different active ingredients on Metarhizium anisopliae Metsch. (Sorokin) inoculated into autoclaved soil. The action of the pesticides was evaluated based on the fungal respiratory activity. The first assessment was done at 48h after inoculation. The pesticides were then added and respiratory activity was determined nine times every 48h and an additional five times every 4 days. Except for the fungicides, no significant effect (P > 0.05) of the pesticides on M. anisopliae was observed. A reduction in CO2 production was observed for the mancozeb treatment from day 4 to day 6 of incubation, and for tebuconazol between days 4 and 6, 8 and 10, and 32 and 36. The same was observed for copper oxychloride between days 10 and 12 and 32 and 36, and for chlorothalonyl between 8 and 10, 10 and 12, and 32 and 36 days of incubation. Identical effect occurred for the acaricides abamectin and fenbutatin oxide, with a reduction in CO2 production between 20 and 24 days of incubation. The herbicides glyphosate, trifluralin and ametrin reduced the respiratory activity of the fungus between days 10 and 12, while the insecticide trichlorfon reduced respiratory activity only from 32 to 40 days of incubation. The results indicate that the toxic action of pesticides on the fungus in soil is small, suggesting that this pest control bioagent can be used in combination with pesticides without compromising its activity.

Fluazuron-induced morphophysiological changes in the cuticle formation and midgut of Rhipicephalus sanguineus Latreille, 1806 (Acari: Ixodidae) nymphs

The present study demonstrated the effects of the arthropod growth regulator, fluazuron (Acatak®), in the formation of the integument and digestive processes of Rhipicephalus sanguineus nymphs fed on rabbits treated with different doses of this chemical acaricide. For this, three different doses of fluazuron (20, 40, or 80 mg/kg) were applied pour on to the hosts (groups II, III, and IV), as well as distilled water to the control group. On the first day after treatment (24 h), the hosts were artificially infested with R. sanguineus nymphs. After full engorgement (7 days), the nymphs were removed, placed on labeled Petri dishes, and kept in biochemical oxygen demand incubator for 7 days. The engorged nymphs were then taken for morphological, histochemical, and histological analyses. The results showed the occurrence of cytological, morphohistological, and histochemical alterations in the integument and midgut of nymphs from all the different treated groups. These alterations occurred at cuticular level in the subdivisions of the cuticle, related to the size of the digestive cells, amount of accumulated blood elements, and digestive residues, as well as the presence of vacuoles in the cytoplasm of the digestive cells. Thus, this study demonstrated that fluazuron acts on the integument and midgut cells of R. sanguineus nymphs fed on treated rabbits and pointed out the possibility of the use of this chemical - which is more specific, less toxic, and less harmful to the environment and nontarget organisms - in the control of R. sanguineus, at least in the nymphal stage of its biological cycle. © 2012 Springer-Verlag.

Rhipicephalus sanguineus (Acari: Ixodidae) female ticks exposed to castor oil (Ricinus communis): An ultrastructural overview

Tick control has been accomplished through the use of synthetic acaricides, which has created resistant individuals, as well as contaminating the environment and nontarget organisms. Substances of plant origin, such as oils and extracts of eucalyptus and neem leaves, have been researched as an alternative to replace the synthetic acaricides. Ricinoleic acid esters from castor oil have recently been shown as a promising alternative in eliminating bacterial contamination during ethanol fermentation, by acting as an effective biocide. The same positive results have been observed when these esters are added to the food given to tick-infested rabbits. This study tested the effect of these substance on the reproductive system of Rhipicephalus sanguineus females, added to rabbit food, more specifically on oogenesis. For this, four groups were established: four control groups (CG1, CG2, CG3, and CG4) and four treatment groups (TG1, TG2, TG3, and TG4) with one rabbit in each (New Zealand White), used as hosts. After full 4 days feeding (semi-engorgement), the females were collected and had their ovaries extracted. In this study, it was observed that R. sanguineus females exposed to esters had their ovaries modified, which was demonstrated through transmission electron microscopy techniques. The addition of ricinoleic esters to the diet of tick-infested rabbits revealed how toxic such substances are for the cytoplasmic organelles of oocytes and pedicel cells. These compounds can change the morphophysiology of germ and somatic cells, consequently influencing their viability and, therefore, confirming that the ricinoleic acid esters from castor oil are a promising substance in the control of R. sanguineus. © 2012 Springer-Verlag Berlin Heidelberg.

Aspectos técnicos e econômicos da poda e do controle químico de Brevipalpus phoenicis no manejo da leprose dos citros

The objective of this study was to evaluate different citrus leprosis management tactics during seven seasons, based in pruning and acaricide applications, considering technical and economic aspects of each tactic. The trial was conducted from October 2003 to August 2010 in an orange plantation of Pera cv. located in the municipality of Reginópolis-SP, Brazil. The plants of citrus used were12 years old and grafted onto Cleopatra tangerine. The experimental design used was randomized blocks, in a factorial scheme, made up of factors type of pruning (A), with six levels: (1) drastic pruning, (2) intermediate pruning without leprosis lesions, (3) intermediate pruning with leprosis lesions (4) light pruning, (5) without pruning and (6) replant; acaricide applications factor (B), with three levels: (1) without acaricides applications, (2) with lime sulfur applications and (3) spirodiclofen or cyhexatin applied in rotation; pruning factor to remove leprosis symptomatic branches (C), with two levels: (1) with pruning for removal, (2) without removal pruning. The combination of factors, with respective levels (6 x 3 x 2), resulted in 36 treatments that were repeated four times, with each parcel being made up of three plants in a row. After seven years, it was observed that the types of the pruning and remove of leprosis symptomatic branches used as single management tactic, is not sufficient to leprosis control. Therefore, the results demonstrated that for leprosis management, it is essential the association between tactics, especially the control mite vector. For ensuring the citrus production economically, the use of acaricides highly efficient is essential in B. phoenicis control. The recommendation of the type of pruning should be in function of the leprosis incidence and severity in the orchard. In orchards with low leprosis incidence and severity the light pruning is more appropriate, because it is efficient and ensures greater financial balance. However, in orchards with high leprosis incidence and severity it is indicated the severe pruning for reducing or eliminating inoculum source. Between the severe prunings, the intermediate pruning with leprosis lesions is the most relevant, because the financial return will be faster. Replant is indicated only for young orchards, because does not imply in changes onto cultural practices.

Morphological and cytochemical changes in synganglion of Rhipicephalus sanguineus (Latreille, 1806) (Acari: Ixodidae) female ticks from exposure of andiroba oil (Carapa guianensis)

Actually, the most used method to control ticks is synthetic acaricides with neurotoxic action. However, the use of these methods presents inconveniences, such as the contamination of the environment and risks to the host's health due to the residual effects. Thus, several studies have been developed aiming to find alternative ways to control these ectoparasites, such as the use of natural compounds with active ingredients, which act controlling some species of plagues in addition to presenting medicinal properties that are beneficial to humans. The present study aimed to analyze the action of andiroba oil (Carapa guianensis) on the synganglion of Rhipicephalus sanguineus semiengorged females through morphological and cytochemical techniques aiming to verify if this natural product have neurotoxic action as the numerous synthetic acaricides. The results showed that andiroba oil interferes in the synganglion through structural and enzymatic changes, which lead the nervous tissue to apoptotic death involving autophagy. Among these changes was observed the emergence of large empty spaces between the perineurium and the cortical region, vacuolated cortex cells and with cell swelling, neural cells with picnotic nuclei or in initial stage of chromatin margination and neuropile with high structural disorganization. Considering these data, it can be concluded that andiroba seed oil can be used as an alternative method in the control of R. sanguineus ticks due to its neurotoxic action. © 2013 Wiley Periodicals, Inc.

In vitro activity of pineapple extracts (Ananas comosus, Bromeliaceae) on Rhipicephalus (Boophilus) microplus (Acari: Ixodidae)

Measures to control the cattle tick, Rhipicephalus (Boophilus) microplus, based only on chemical products are becoming unsustainable, mainly because of the development of resistance. The objective of this study was to test the effect of the aqueous extract of pineapple skin (AEPS) and bromelain extracted from the stem (Sigma-Aldrich®, B4882) on engorged females and larvae of R. (B.) microplus in vitro. These substances were diluted in water and evaluated at eight concentrations. Engorged females were collected and distributed in groups of 10, with three repetitions for each treatment. After immersion in the solutions, the females were placed in an incubator for observation of survival, oviposition and larval hatching. The larval packet method was used, also with three repetitions with about 100 larvae each. The packets were incubated and the readings were performed after 24h. The estimated reproduction and efficacy of the solutions were calculated. The LC50 and LC90 were estimated using the Probit procedure of the SAS program. The eight concentrations were compared within each treatment by the Tukey test. For the experiment with engorged females, the most effective concentrations were 125, 250 and 500mg/mL: 33%, 48% and 59% for the AEPS and 27%, 51% and 55% for the bromelain. The LC50 and LC90 values were, respectively, 276 and 8691mg/mL for AEPS and 373 and 5172mg/mL for bromelain. None of the dilutions tested was effective against the larvae of R. (B.) microplus. This is the first report of the action of pineapple extracts or their constituents on cattle ticks. The results demonstrate that further studies regarding composition of tick cuticle, with evaluation of other solvents and formulations, should be conducted seeking to enhance the effect of pineapple extracts and compounds against this ectoparasite. © 2013 Elsevier Inc.

Neurotoxic action of permethrin in Rhipicephalus sanguineus (Latreille, 1806) (Acari: Ixodidae) female ticks. Morphological and cytochemical evaluation of the central nervous system

Studies on the molecular bases of the neurotoxic action of acaricides are found in the literature; but there are no studies of this action on the nervous system of ticks at the cellular level. The present study describes the morphological and cytochemical changes in the synganglion of Rhipicephalus sanguineus semi-engorged females exposed to different concentrations of permethrin, a pyrethroid with recognized neurotoxic action. Permethrin induced the degeneration of the synganglion through a process of apoptosis involving autophagy, characterized by the condensation and margination of the chromatin, formation of blebs in the nuclear envelope and fragmentation of the nucleus, loss of shape of neural cells and integrity of cellular membrane, cytoplasmic shrinkage, and lower levels of acid phosphatase in the nervous tissue as the concentration of permethrin increased. This study provided further evidence of the neurotoxic action of permethrin, which impairs the metabolism of R. sanguineus nervous systems, and consequently the physiology of other systems, dependent on the neural control. These results provide cytochemical and histological confirmation of the neurotoxic action of permethrin, previously inferred from molecular and tick behavioral evidence. © 2013 Elsevier B.V.

Action of andiroba oil and permethrin on the central nervous and reproductive systems of Rhipicephalus sanguineus (Latreille, 1806) (Acari: Ixodidae) ticks females. A confocal study

Research for acaricides with lower toxicity and impact on the environment has been intensified. An alternative would be the use of natural compounds or of synthetic products in lower concentrations than the ones sold commercially. Thus, this study describes the action of andiroba seed oil on the nuclei of the ovary and synganglion cells of Rhipicephalus sanguineus, and presents an analysis of the nuclear morphology of the nervous system cells of this tick species when exposed to permethrin. The results obtained showed that, although no changes have been observed in the genetic material of the ovary cells exposed to the andiroba oil, this compound, as well as permethrin, has neurotoxic action on the females of this species. The damages caused to the physiology of the synganglion, due to the loss of integrity of the genetic material, would result in the impairment of the metabolism of other systems of R. sanguineus ticks. © 2013 Elsevier Ltd.

Alterações morfofisiológicas do tegumento de coelhos infestados por carrapatos Rhipicephalus sanguineus (Acari: Ixodidae) e expostos à selamectina (princípio ativo do acaricida Revolution®, Pfizer)

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Efeito de diferentes águas e fertilizantes foliares em caldas acaricidas no controle do ácaro Brevipalpus phoenicis (Geijskes, 1939) (Acari: Tenuipalpidae) em citros

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Fatores socioeconômicos e percepção de risco de produtores de leite no uso de produtos veterinários

Pós-graduação em Medicina Veterinária - FCAV