Management of the American cockroach's oothecae: The potential of entomopathogenic fungi control.

The Periplaneta americana species is an annoyance to man, causing allergies and damage to clothes and documents. It has the ability to spread pathogens and requires control measures. Control with natural enemies is less aggressive and can currently be applied with less risk than other techniques, such as chemical control, which is the main method used worldwide to control its post-embryonic stages. The potential microbial control of nymphs and adults of this pest has been shown, but little is known about its oothecae. There are isolates of fungal species that can be used to achieve this aim, but they may have innate differences in their virulence and ability to spread. This study aimed to identify fungal isolates JAB 68 and IBCB 35 through genetic sequencing of the ITS1-5.8S-ITS2 region, analyze their ability to synthesize chitinase, and investigate and compare their aggressiveness against P. americana oothecae and their influence on nymph eclosion. Fungal suspensions were inoculated into minimal medium containing glucose (control) as the sole carbon source and 1% colloidal chitin to determine the chitinolytic activity on the 4th, 7th and 10th days and sporulation on the 10th day. To obtain mortality, extrusion and the compiled number of hatched nymphs, oothecae were sprayed with suspensions of the isolates as follows: T1 - no application; T2 - aqueous solution of Tween 80® 0.1% (vehicle suspension for treatments T3 to T8); T3 - 2 × 109 conidia/mL of the JAB 68 isolate; T4 - 2 × 108 con./mL of the JAB 68 isolate; T5 - 2 × 107 con./mL of the JAB 68 isolate; T6 - 2 × 109 con./mL of the IBCB 35 isolate; T7 - 2 × 108 con./mL of the IBCB 35 isolate; T8 - 2 × 107 con./mL of the IBCB 35 isolate. The JAB 68 and IBCB 35 isolates were identified as belonging to the species Metarhizium anisopliae and Beauveria bassiana, respectively. Chitinolytic activity and extrusion were good parameters for evaluating the fungi's action on oothecal control. The most aggressive entomopathogen was M. anisopliae isolate JAB 68, with shorter time for fungus extrusion at a concentration of 2 × 107 con./mL. B. bassiana reduced the number of hatched nymphs at a concentration of 2 × 108 con./mL. Both fungi are capable of infecting and killing P. americana's oothecae and reducing the number of nymphs hatched.

Ovicidal and larvicidal activity and possible mode of action of phenylpropanoids and ketone identified in Syzygium aromaticum bud against Bradysia procera.

Bradysia procera is a serious insect pest of Panax ginseng plants. This study was conducted to determine the toxicity and mechanism of action of three phenylpropanoids, three terpenoids, and a ketone from Syzygium aromaticum bud methanol extract and hydrodistillate against third-instar larvae and eggs of B. procera. In a filter-paper mortality bioassay, methyl salicylate (LC50, 5.26µg/cm2) was the most toxic compound, followed by 2-nonanone, eugenol, and eugenyl acetate (8.77-15.40µg/cm2). These compounds were significantly less toxic than either thiamethoxam, clothianidin, or cypermethrin. Egg hatching was inhibited by 97, 85, and 40% at 11.7µg/cm2 of methyl salicylate, 2-nonanone, and eugenol, respectively. The egg-hatching inhibition of these insecticides was between 90 and 94% at 0.09µg/cm2. These constituents were consistently more toxic in closed versus open containers, indicating that toxicity was achieved mainly through the action of vapor. The mechanism of larvicidal action of methyl salicylate, eugenol, and eugenyl acetate might be primarily due to interference with the octopaminergic system. 2-Heptyl acetate and 2-nonanone might act on both acetylcholinesterase and the octopaminergic receptor. 2-Heptanone might act primarily on acetylcholinesterase. Further studies will warrant possible applications of S. aromaticum bud-derived products as potential larvicides and ovicides for the control of B. procera.

Characterization of Tolypocladium cylindrosporum (Hypocreales: Ophiocordycipitaceae) and Its Impact Against Aedes aegypti and Aedes albopictus Eggs at Low Temperature.

We examined the growth characteristics of Tolypocladium cylindrosporum IBT 41712 and its potential to infect eggs of Aedes aegypti and Ae. albopictus at a low temperature (15°C). When grown on Sabouraud dextrose agar supplemented with yeast extract, the IBT 41712 formed white colonies turning to a slightly darker, off-white color when mature. The mycelia bore swollen conidiophores producing smooth-walled, oblong to cylindrical conidia with varying sizes, ranging from 1.5 to 3.5 µm long. To determine the optimum temperature for the fungus, we cultured the fungus at eight temperatures (4°C, 12°C, 15°C, 21°C, 28°C, 33°C, 37°C, and 40°C) and measured the diametric growth. The optimum temperature for growth was 28°C since it had the highest diametric growth rate (2.1 ± 0.05 mm/day) and the fastest sporulation period (within 8-10 days of incubation). There was no fungal growth at the 3 highest temperatures (33°C, 37°C, and 40°C) but plates incubated at 33°C, when shifted to optimal temperature (28°C), showed visible growth indicating that following incubation at 33°C, the fungus remained viable. The IBT 41712 successfully infected mosquito eggs at 15°C. Fungal treatment induced egg hatch on moist seed-germination paper and this effect was more pronounced in Ae. aegypti compared to Ae. albopictus. When treated eggs were immersed in dH2O 21 days posttreatment, larval hatch of both Ae. aegypti (control = 91%, 1 × 107 conidia/ml, fungal treatment = 0%) and Ae. albopictus (control = 85%, fungal treatment = 28%) was significantly lower in fungal treatment compared to the controls. The ability of the strain to grow in a wide temperature range, and effectively infect mosquito eggs and induce egg hatch at a low temperature warrants further investigation for its potential as a mosquito control agent targeting eggs that overwinter or undergo long diapause.

Evaluation of Household Bleach as an Ovicide for the Control of Aedes aegypti.

Accumulations of dormant eggs in container habitats allow Aedes aegypti populations to survive harsh environmental conditions and may frustrate control interventions directed at larval and adult life stages. While sodium hypochlorite solutions (NaOCl) have long been recognized as ovicides for use against dengue vectors, the susceptibility of eggs to spray applications has not been robustly evaluated on substrate materials representative of the most frequently utilized artificial container habitats. Experiments were performed under controlled and natural conditions by applying dilutions of household bleach (52.5 ppt NaOCl) as a spray to eggs on plastic, rubber, and concrete surfaces, with and without a smectite clay thickener. Laboratory assays identified the minimum NaOCl concentrations required to eliminate eggs on plastic (10 ppt), rubber (20 ppt) and concrete (20 ppt) surfaces. Addition of smectite clay reduced the minimum effective concentration to 10 ppt NaOCl for all 3 substrates. A minimum exposure period of 24 h was required to completely eliminate egg viability on concrete surfaces, even at the highest NaOCl concentration (52.5 ppt). Field experiments verified that spray application of a 1∶3 dilution of household bleach mixed with smectite clay can reduce egg hatching by ≥ 99% in shaded and sun-exposed plastic containers. Similarly, 4∶1 dilution of household bleach (with or without smectite clay) eliminated ≥ 98% of eggs from concrete surfaces in outdoor, water-filled drums. In this study, we propose a practical, effective and safe strategy for using household bleach to eliminate Ae. aegypti eggs in a range of artificial container habitats.

Approach to surveying egg masses of the invasive spotted lanternfly (Hemiptera: Fulgoridae).

For the invasive planthopper Lycorma delicatula, eggs are an attractive target for surveys and management because they can persist from September through May before hatching, and remnants may be retained for years after hatching. Efforts to control this invasive species, though, are hampered by imperfect detection, which impedes early detection and rapid response, obscures management impacts, and reduces the fraction of egg masses that can be managed. To estimate egg mass detectability, we conducted 75 duplicate surveys of 20 × 5 m plots located in forest edges and disturbed areas frequently used by L. delicatula. We fit binomial mixture models and investigated the effects of weather, height (above or below 3 m), season (winter or spring), and basal area of trees within plots, finding no evidence that these factors affected detection rate, which averaged 52.2%. We additionally estimated the fraction of L. delicatula eggs that were laid above 3 m, putting them outside of easy reach for management by scraping or targeted ovicide application. This proportion varied with basal area of trees within plots, and the estimated mean was greater than 50% across the range of basal areas in study plots. Finally, we found that counts of old egg masses correlated with counts of new egg masses laid the year prior, but the ability to infer prior years' egg mass counts was limited. Together, these findings inform managers delimiting L. delicatula populations in mixed habitats and those treating egg masses to slow population growth and spread of this pest.

Effects of a solid formulation containing lectin-rich fraction of Moringa oleifera seeds on egg hatching and development of Aedes aegypti larvae.

The measures currently used to minimize the spread of arboviruses, comprising dengue, Chikungunya, and Zika virus, involve controlling the size of population of the mosquito Aedes aegypti. However, the search for formulations containing new insecticides is gaining pace due to reports of mosquito populations showing resistance to commonly used compounds. In this study, tablets containing a protein fraction of Moringa oleifera seeds enriched in the WSMoL lectin, known to show larvicidal and ovicidal activities against A. aegypti, were developed. The compatibility between the fraction and the excipients used in obtaining the tablets was evaluated by thermogravimetry (TG), differential scanning calorimetry (DSC), and Fourier transform infrared (FTIR) absorption spectroscopy. The larvicidal and ovicidal activities of the resulting tablets [5%, 10%, and 15% (w/w) of the fraction] were evaluated, as well as their effect on mosquito oviposition. Assays were also performed using a placebo tablet. According to the TG, DSC, and FTIR results, the protein composition of the fraction did not change when mixed with the components of the formulation. Tablets containing 10% and 15% WSMoL-rich fraction caused mortality of 42.5% and 95% of the larvae after 48 h, respectively, with larvae incubated with these tablets showing reduced acetylcholinesterase activity. All tablets inhibited egg hatching after 72 h (36-74%), and tablets containing 15% fraction were found to exert a repellent effect on oviposition. Our results show that the formulation developed in this study interfered with the life cycle of A. aegypti, and thus show potential for use in the control of this mosquito.

Ecdysone Receptor (EcR) and Ultraspiracle Protein (USP) Genes From Conopomorpha sinensis Bradley Eggs: Identification and Expression in Response to Insecticides.

Conopomorpha sinensis Bradley (Lepidoptera: Gracilariidae) is the dominant insect pest of litchi (chinensis Sonn.) and longan (Euphoria longan Lour.) fruit trees. Management of this pest species is a challenging task due to its cryptic borer behavior. Controlling C. sinensis at the egg stage is the best alternative strategy to chemical control of C. sinensis adults. However, thorough studies regarding the indirect and sublethal effects of chemicals on the different developmental stages of C. sinensis are insufficient. In this study, the effect of some insecticides was evaluated on C. sinensis eggs. The ovicidal activity of chlorbenzuron, abamectin, chlorantraniliprole, and λ-cyhalothrin was confirmed by morphological observation of the defects in C. sinensis eggs. Moreover, we characterized four essential ecdysone receptor proteins in insects [i.e., two isoform ecdysone receptors (EcR: CsEcRA. CsEcRB) and two isoform ultraspiracle proteins (USP: CsUSP1, CsUSP2)] from C. sinensis eggs. The CsEcRA, CsEcRB, CsUSP1, and CsUSP2 genes consisted of 1521-, 1614-, 1410-, and 1236-bp open reading frames which encoded proteins of 506, 527, 469, and 413 amino acid residues, respectively. Furthermore, the embryonic differential responses of CsEcRs, CsUSPs, and vitellogenin receptor (VgR: CsVgR) to insecticides were evaluated by qRT-PCR. Among the five tested genes, CsVgR and CsUSP1 were the most sensitive to all the tested insecticides, with fold change of the expression diminished by 4.27-8.70 times compared with untreated control insects. The data suggests that these insecticidal compounds regulate the expression of these specific proteins, which might eventually lead to reduced viability of C. sinensis eggs. We present here the first data providing molecular elucidation of ecdysone receptor genes and their differential responses to insecticides in C. sinensis eggs. Together with our previous report of insecticide sublethal effects on two reproduction-related genes in C. sinensis adults, CsVgR and CsUSP1 seem to be appropriate molecular parameters for the evaluation of insecticide impact on C. sinensis. This study exemplifies the potential utility of transcriptional measurement of nuclear receptors as the molecular biomarkers for ecotoxicological evaluations of ovicidal impact of insecticides.

S-Methyl-(2-Methoxycarbonylamino-Benzimidazole-5) Thiosulfonate as a Potential Antiparasitic Agent-Its Action on the Development of Ascaris suum Eggs In Vitro.

Ascaris suum is a soil-transmitted parasite causing ascariasis in pigs, largely limiting livestock production globally. Searching for new drugs affecting all stages of nematode development is necessary and widely postulated. The in vitro activity of S-methyl-(2-methoxycarbonylamino-benzoimidasole-5) thiosulfonate on A. suum developing eggs was studied. Five concentrations of the drug were used-0.625, 1.25, 2.5, 5 and 10 mM during 24, 48 and 72 h of exposure. After drug treatment, the eggs were washed and cultured in 0.05 M HCl at 27 °C for 20 days. Both the concentration and duration of the drug exposure had an inhibitory impact on the percentage of L2 larvae developed. The best effect was obtained after 72 h of incubation in 5 mM drug solution, only 1.9 ± 3.3% of the larvae developed to the L2 stage. Moreover, no SNP was detected at codon 167, which is correlated with benzimidazole resistance, in the tested samples. For the first time, it has been demonstrated that S-M-(2-MKA-BZ-5)TS seems to be a potential ovicidal anti-helminthic agent. It may lead to the elimination of parasites and reduce environmental contamination from roundworm eggs. The ovicidal effects of the drug should be additionally confirmed by further infection studies using experimental animals.

Influence of Insect Growth Regulators on Stephanitis pyrioides (Hemiptera: Tingidae) Eggs and Nymphs.

The azalea lace bug, Stephanitis pyrioides (Scott) (Hemiptera: Tingidae), is an important insect pest of azaleas (Rhododendron L. spp.) in the USA. Stephanitis pyrioides feeds on azalea foliage and causes extensive chlorosis, which reduces the aesthetic value and marketability of these plants. Because the use of neonicotinoid insecticides has been dramatically reduced or discontinued, growers and landscape managers are seeking alternative tools or strategies to control this insect. Although insect growth regulators (IGRs) are known for their activity against immature insect stages, their activity against egg hatching has not been addressed thoroughly, specifically against S. pyrioides. Thus, a series of experiments was conducted to understand the ovicidal activity of IGRs using novaluron, azadirachtin, pyriproxyfen, and buprofezin against S. pyrioides. The number of newly emerged young instars was significantly lower when leaves implanted with eggs were sprayed on both sides with novaluron, azadirachtin, and buprofezin compared to nontreated and pyriproxyfen treatments. When IGRs plus adjuvant were applied to the adaxial surface of the leaves, the densities of the newly emerged nymphs were significantly lower under the novaluron treatment compared to the nontreated leaves. However, there was no significant difference in the number of nymphs that emerged in the absence of adjuvant. Furthermore, close monitoring revealed reduced levels of egg hatching in the presence of adjuvant with novaluron compared to its absence. The data show that the survival of S. pyrioides first instars was not affected by exposure to dried IGR residues.

Biosurfactants produced by Bacillus subtilis A1 and Pseudomonas stutzeri NA3 reduce longevity and fecundity of Anopheles stephensi and show high toxicity against young instars.

Anopheles stephensi acts as vector of Plasmodium parasites, which are responsible for malaria in tropical and subtropical areas worldwide. Currently, malaria management is a big challenge due to the presence of insecticide-resistant strains as well as to the development of Plasmodium species highly resistant to major antimalarial drugs. Therefore, the present study focused on biosurfactant produced by two bacteria Bacillus subtilis A1 and Pseudomonas stutzeri NA3, evaluating them for insecticidal applications against malaria mosquitoes. The produced biosurfactants were characterized using FT-IR spectroscopy and gas chromatography-mass spectrometry (GC-MS), which confirmed that biosurfactants had a lipopeptidic nature. Both biosurfactants were tested against larvae and pupae of A. stephensi. LC50 values were 3.58 (larva I), 4.92 (II), 5.73 (III), 7.10 (IV), and 7.99 (pupae) and 2.61 (I), 3.68 (II), 4.48 (III), 5.55 (IV), and 6.99 (pupa) for biosurfactants produced by B. subtilis A1 and P. stutzeri NA3, respectively. Treatments with bacterial surfactants led to various physiological changes including longer pupal duration, shorter adult oviposition period, and reduced longevity and fecundity. To the best of our knowledge, there are really limited reports on the mosquitocidal and physiological effects due to biosurfactant produced by bacterial strains. Overall, the toxic activity of these biosurfactant on all young instars of A. stephensi, as well as their major impact on adult longevity and fecundity, allows their further consideration for the development of insecticides in the fight against malaria mosquitoes.

Efficacy of a new spot-on formulation of selamectin plus sarolaner for cats against adult Ctenocephalides felis, flea egg production and adult flea emergence.

A new spot-on formulation of selamectin plus sarolaner was evaluated against fleas for adulticidal efficacy, and for the effect on egg production and hatching when applied to flea-infested cats. Ten male and ten female adult domestic shorthair cats were randomly assigned to one of two treatment groups based on pre-treatment flea counts. Cats received topical treatment on Day 0 in a single spot to the dorsal scapular area with either a placebo formulation or with the combination formulation at the minimal dose of 6.0mg selamectin plus 1.0mg sarolaner per kg bodyweight. On Days -1, 5, 12, 19, 26 and 33, cats were infested with approximately 100 (±5) unfed Ctenocephalides felis fleas. At 24h after treatment or 48h after subsequent flea infestation, cats were housed for a 20-h period in a cage to allow collection of flea eggs. At the end of this period, flea eggs were collected from the cages and cats were combed to remove and count live fleas. Emerged viable larvae and emerged adult fleas were counted 3days and 35days, respectively, after egg collection. The new spot-on formulation of selamectin plus sarolaner provided 100% efficacy against adult fleas up to Day 36 following a single application. Fleas on placebo-treated cats produced large numbers of eggs throughout the study, with individual counts ranging from 110 to 1256 eggs. Following treatment, four flea eggs were collected from a single selamectin/sarolaner-treated cat on Day 29, but there were no eggs collected from any other selamectin/sarolaner-treated animal during the study. No larvae or adult fleas developed from these four eggs. From the eggs collected from the placebo-treated cats, the mean percentage of live larvae and adults that emerged ranged from 67.3% to 84.2% and from 50.7% to 81.8%, respectively. A single topical treatment with a new spot-on formulation of selamectin plus sarolaner at the minimum label dose thus controlled fleas on cats and was 100% effective in preventing flea reproduction for over one month after treatment.

Ovicidal Efficacy of Abametapir Against Eggs of Human Head and Body Lice (Anoplura: Pediculidae).

Studies were undertaken to determine the ovicidal efficacy of 5,5'-dimethyl-2,2'-bipyridyl (abametapir) against eggs of both human head and body lice. Head lice eggs of different ages (0-2, 3-5, and 6-8-d-old eggs) were exposed to varying concentrations of abametapir in isopropanol and concentration-dependent response relationships established based on egg hatch. One hundred percent of all abametapir-treated eggs failed to hatch at the 0.74 and 0.55% concentrations, whereas 100% of 6-8-d-old head louse eggs failed to hatch only at the 0.74% concentration. The LC50 value for abametapir varied, depending on the age of the head lice eggs, from ∼0.10% recorded for 0-2-d-old eggs and increasing to ∼0.15% for 6-8-d-old eggs. Abametapir was also evaluated once formulated into a lotion referred to as Xeglyze (0.74% abametapir) and serial dilutions made. Ovicidal efficacies were determined against head lice eggs 0-8-d-old. Results indicated 100% ovicidal activity at the 0.74, 0.55, 0.37, and 0.18% concentrations. Additional studies undertaken using body lice eggs also demonstrated that abametapir was 100% ovicidal against eggs of all ages when evaluated at a concentration of 0.37 and 0.55%. Given that ovicidal activity is a critical component of any effective treatment regime for louse control, the data presented in this study clearly demonstrate the ability of abametapir to inhibit hatching of both head and body louse eggs as assessed in vitro.

An anti-mosquito mixture for domestic use, combining a fertiliser and a chemical or biological larvicide.

BACKGROUND: Plant saucers are an important larval habitat for Aedes aegypti and Ae. albopictus in peridomestic situations. Because NPK fertilisers in plant containers tend to enhance the oviposition of these species, we investigated the effects of Bacillus thuringiensis var. israelensis, spinosad, pyriproxyfen and diflubenzuron larvicides in combination with fertiliser on the adult emergence and fecundity of the mosquitoes coming from plant saucers in controlled greenhouse experiments. NPK + larvicide (NPK-LAV) treatments were tested on Ae. aegypti. Each treatment was compared with water and with fertiliser alone on a total of five houseplants and their saucers. The fertilising treatment was renewed every 30-45 days. RESULTS: With less than 5% imaginal emergence, the NPK + spinosad 0.5% treatment remained effective for 30 days. Both NPK + pyriproxyfen 0.1% and NPK + diflubenzuron 0.25% were effective for 45 days. The average number of eggs laid in the three treatments was similar to the NPK treatment, indicating that spinosad, pyriproxyfen and diflubenzuron did not alter the attraction effect of the fertiliser on egg laying. NPK + pyriproxyfen and NPK + diflubenzuron also had ovicidal activity and an important impact on the fecundity of the Ae. aegypti female imagos and the fertility of their eggs. CONCLUSION: The addition of NPK fertiliser to insecticides can increase larval control of Aedes mosquitoes. This innovative measure for personal protection, which is harmless for both humans and animals, would be an additional support for the community-based actions led by the institutional services for vector control. © 2015 Society of Chemical Industry.

Larvicidal, ovicidal and repellent activities of marine sponge Cliona celata (Grant) extracts against Anopheles stephensi Liston (Diptera: Culicidae).

OBJECTIVE: To evaluate the larvicidal, ovicidal and repellent properties of solvent extracts of marine sponge Cliona celata (C. celata) (Grant) against the malarial vector Anopheles stephensi (An. stephensi) Liston. METHODS: Marine sponge C. celata was thoroughly washed with distilled water and shade dried for 48 h. Then the sponges were homogenized and extracted sequentially with hexane, ethyl acetate and methanol. Larvicidal and ovicidal activities were tested at four different concentrations viz., 62.5, 125.0, 250.0 and 500.0 ppm. For repellent study extracts were taken in three different concentrations viz., 5.0, 2.5, 1.0 mg/cm at. RESULTS: Among the three solvent extracts of C. celata, methanol extract showed the highest larvicidal activity at 500 ppm against the fourth instar larvae of An. stephensi. The LC50 and LC90 values of C. celata methanol extract were recorded as 80.61 and 220.81 ppm against An. stephensi larvae respectively. High ovicidal activity of 91.2% was recorded at 500 ppm concentration of methanol extract. The haxane extract was found to be the most effective protectant against the adult female mosquitoes of An. stephensi. The mean protection time recorded in hexane extract was up to 245 min at 5 mg/cm(2) dosage against An. stephensi adults. CONCLUSIONS: The screening results suggest that the hexane and methanol extracts of C. celata are promising in mosquito control. Considering these bioactivities, C. celata could be probed further to obtain some novel pesticidal molecules.

Development of Thelastoma bulhoesi (Oxyurata: Thelastomatida) and the Effect of Thiabendazole on the Unembryonated Egg.

The embryological and postembryological development of Thelastoma bulhoesi was determined. Initial cleavage was into unequal cells and occurred within 1-2 hours at 25 C. Cell division was holoblastic but no true morula is formed. Gastrulation occurred at approximately 48 hours by epibolic synectic mechanisms. First-stage larvae were fully developed at 96 hours. The molt to second-stage larvae was initiated in the egg and was completed at hatching. Second-stage larvae were first observed in the host at 11 hours postinfection, third-stage larvae at 18 hours, and fourth-stage larvae at 192 hours. Adult female worms were observed at 32 days. Thiabendazole, in even the lowest concentrations, inhibited the developmem of unembryonated ova.

Self-/conspecific discrimination and superparasitism strategy in the ovicidal parasitoid Echthrodelphax fairchildii (Hymenoptera: Dryinidae).

Superparasitism in solitary parasitoids results in fatal competition between the immature parasitoids, and consequently only one individual can emerge. In the semisolitary ovicidal parasitoid Echthrodelphax fairchildii (Hymenoptera: Dryinidae), 2 adults can emerge under superparasitism with a short interval (<24 h) between the first and second ovipositions. We determined the female parasitoid's behavioral responses under self- and conspecific superparasitism bouts with first-to-second oviposition intervals of ≤2 h. The self- and conspecific superparasitizing frequencies increased up to an oviposition interval of 0.75 h, with the former remaining lower than the latter, particularly for oviposition intervals of ≤0.25 h, suggesting the existence of self-/conspecific discrimination. The superparasitizing frequency plateaued for oviposition intervals of ≥0.75 h, with no difference between self- and conspecific superparasitism. The ovicidal-probing frequency did not differ under self- and conspecific superparasitism, and was usually <20%. The females exhibited no preference for the oviposition side (i.e., ovipositing on the side with or without the first progeny) and almost always laid female eggs for any oviposition interval under self- and conspecific superparasitism. The sex ratio was not affected by the type of superparasitism, oviposition sides, or the occurrence of ovicidal probing. These observed results about the oviposition side, ovicidal probing, and sex ratios differed from the predictions obtained assuming that the females behave optimally. Possible reasons for the discrepancies are discussed: likely candidates include the high cost of selecting oviposition sides and ovicidal probing, and, for the sex ratio, the low frequency of encountering suitable hosts before superparasitism bouts.

Pathogenicity of Aspergillus westerdijkiae to females and oothecae of Periplaneta Americana / Patogenicidade de isolado de Aspergillus westerdijkiae a fêmeas e ootecas de Periplaneta americana

ABSTRACT: Cockroach control is performed by the application of chemical insecticides which exert high selective pressure on populations and introduces synthetic substances in the environment, motivating the search for other methods of control such as entomopathogenic fungi. The objectives of this study were to investigate the pathogenicity of the JAB 42 Aspergillus westerdijkiae to females and oothecae of Periplaneta americana and to demonstrate its mechanism of action on oothecae. Suspensions containing 106 to 108 conidia/ml were used to infect females and oothecae. Mortality and other variables such as scanning electron microscopy were used to demonstrate the mechanism of action of the fungus. The isolated JAB 42 A. westerdijkiae is pathogenic to oothecae of P. americana, with low capacity to kill females. Adhesion, germination, penetration and extrusion of the fungus on the cockroach oothecae were observed.

RESUMO: O controle de baratas realizado através da aplicação de inseticidas químicos exerce alta pressão seletiva sobre as populações e introduz substâncias sintéticas no ambiente, motivando a procura por outros métodos de controle, como os fungos entomopatogênicos. Os objetivos deste trabalho foram investigar a patogenicidade do isolado JAB 42 de Aspergillus westerdijkiae a fêmeas e ootecas de Periplaneta americana e demonstrar o mecanismo de ação sobre ootecas. Suspensões contendo 106 a 108 conídios/mL do isolado foram usadas para infectar fêmeas e ootecas. A ação do fungo foi analisada pela mortalidade e outras variáveis, e por microscopia eletrônica de varredura. O isolado JAB 42 de A. westerdijkiae é patogênico a ootecas de P. americana, tendo baixa capacidade de matar fêmeas. Foi observada a adesão, germinação, penetração e extrusão do fungo sobre ootecas da barata.

Ação de inseticidas sobre os ovos e lagartas da broca-pequena-dofruto do tomate, em bioensaio de laboratório / Action of insecticides on the eggs and larvae of the borer small-fruit tomato in laboratory bioassay

A broca-pequena-do-fruto é praga-chave na cultura do tomate por causar danos significativos às partes reprodutivas. Devido a isto, foi objetivo deste trabalho avaliar a eficiência de inseticidas sobre ovos e lagartas recém-emergidas, com e sem a adição de óleo vegetal (0,25%), em bioensaios de laboratório. Frutos com ovos foram coletados em cultivo de tomate estaqueado na quinzena posterior à última aplicação de agrotóxicos, sendo selecionados os frutos com ovos de coloração variável de branco a marrom claro, com 1 e 4 dias de incubação, e imersos em 1 L da calda inseticida por 5 segundos. O delineamento estatístico utilizado foi o inteiramente casualizado, com média de 18 frutos nos tratamentos e de, aproximadamente, 4 ovos/fruto. A avaliação da ação inseticida de 24 produtos foi realizada após a imersão na calda inseticida, observando-se, sob microscópio estereoscópico, os ovos quanto à integridade do córion, textura e coloração, lagartas emergidas, bem como os orifícios de entrada e de saída das larvas (aos 7 e 21 dias). Os produtos testados diferiram da testemunha quanto à densidade de lagartas eclodidas, bem como quanto à redução populacional de lagartas, podendo-se destacar Trebon 100 SC (etofenprox; 200 mL do produto comercial/100 L), Lannate BR (methomil; 100 mL), Thiobel 500 (cartap; 250 g) e Vertimec 18 CE (abamectin; 100 mL). A adição de óleo vegetal resultou em incremento na eficiência dos produtos.

Action of insecticides on tomato fruit borer eggs and larvae using laboratory bioassay. The tomato fruit borer is a key tomato pest in light of its damages to the plants’ reproductive parts. Therefore, the present study was aimed to evaluate the effectiveness of insecticides on the eggs and newly hatched larvae, when applied alone or associated with vegetable oil (0.25%), in laboratory bioassays. Fruits with eggs were collected in staked tomato crops fifteen days after the last application of agro-chemicals, selecting the fruits with eggs colored from white to light brown, which had between 1 and 4 days of incubation, followed by immersion of the fruit for 5 seconds in 1 L of the insecticide solutions. The experimental design was completely randomized, with an average of 18 fruits per treatment (24 insecticides and a control) and about 4 eggs per fruit. The evaluations were performed 7 and 21 days after immersion, using a stereomicroscope to observe the corion integrity, egg color, number of larvae emerged, and larvae fruit holes (entry and exit). The insecticides differed significantly from the control, most notably Trebon SC 100 (etofenprox; 200 mL of the commercial product/100 L), Lannate BR (methomil; 100 mL), Thiobel 500 (cartap; 250 g) and Vertimec 18 CE (abamectin; 100 mL). The addition of vegetable oil increased the insecticides’ effectiveness.

Avaliação in vitro do extrato hidroalcoólico (EHA) de alecrim pimenta (Lippia sidoides Cham. ) sobre o desenvolvimento de ovos de nematódeos gastrointestinais (Trichostrongylidae) / In vitro evaluation of alecrim pimenta (Lippia sidoides Cham. ) hydroalcoholic extract (HAE) on the development of gastrointestinal nematode (Trichostrongylidae) eggs

Atualmente a fito medicina vem sendo usada no controle de diversas doenças parasitárias particularmente as parasitoses gastrointestinais. Objetivou-se com este estudo avaliar a eficácia do extrato hidroalcoólico (EHA) de Lippia sidoides Cham sobre o desenvolvimento de ovos de nematódeos gastrointestinais. O efeito ovicida foi determinado através de análise probabilística, modelo logístico, utilizados os softwares R versão 2.2.1 e EPI6. Foram obtidos ovos embrionados em fezes de cabras naturalmente infectadas com nematóides Trichostrongylidae e o número de ovos fecais foi determinado usando-se a técnica modificada de McMaster. Cinquenta μL da suspensão contendo 40 ovos foram transferidas a placas de poliestireno e incubadas com 12 concentrações diferentes do EHA sendo avaliada durante 72 horas a temperatura ambiente. Os resultados demonstraram diferentes eficácias para o fito medicamento com menor taxa de desenvolvimento de ovos na concentração de 500 mg mL-1 . Conclui-se que o EHA pode ter papel importante sobre o desenvolvimento in vitro de ovos de nematóides gastrintestinais, revelando atividade ovicida.

Phytomedicine has been currently used in the control of several parasitic diseases, particularly gastrointestinal ones. The aim of this study was to evaluate the efficacy of the hydroalcoholic extract (HAE) from Lippia sidoides Cham. on the development of gastrointestinal nematode eggs. The ovicidal effect was determined through probabilistic analysis, logistic model, by using the programs R version 2.2.1 and Epi InfoTM 6. Embryonated eggs were obtained from feces of goats naturally infected with Trichostrongylidae nematodes and the fecal egg count was determined by using the modified McMaster technique. Fifty microliters of the suspension containing 40 eggs were transferred to polystyrene plates and incubated with 12 different HAE concentrations, and evaluations were performed during 72h at room temperature. The results demonstrated different efficacy of extracts, with lower egg development rate at 500 mg mL-1. In conclusion, HAE may play an important role on the in vitro development of gastrointestinal nematode eggs, indicating ovicidal activity.

In vitro study on thiabendazole action on viability of Ascaris lumbricoides (Lineu, 1758) eggs

The in vitro activity of thiabendazole on Ascaris lumbricoides eggs, which were recovered from uteri of worm excreted after chemotherapeutic treatment, was studied. Four concentrations of the drug were used: 1 - 2.5 - 5 - and 10 ppm during 24, 48 and 72 hours of exposure. Subsequently, the eggs were centrifuged, washed three times and H(2)SO(4)0.1N was added. The eggs were maintained in an incubator for 20 days at 28 degrees C. Finally, the percentage of embryonated eggs was determined under a lightmicroscope at a 100X magnification. After 48 and 72 hours of thiabendazole exposure, at a concentration of 10ppm, the drug showed complete inhibition of egg embryonation.

Foi estudada, in vitro, a ação do tiabendazol, contra ovos de Ascaris lumbricoides , retirados de úteros de vermes eliminados após tratamento. Foram utilizadas quatro concentrações da droga: 1 ¾ 2,5 - 5 e 10 ppm em três diferentes períodos de tempo: 24, 48 e 72 horas. Decorridos estes tempos a suspensão com os ovos foi centrifugada, lavada por três vezes com água destilada, adicionada de solução de H2SO4, 0,1N e mantida em estufa a 28°C por 20 dias. Em seguida, os ovos foram levados ao microscópio óptico, no aumento de 100X, para observação do percentual de embrionamento. Na concentração de 10ppm, nos tempos de 48 e 72 horas de exposição à droga, verificou-se completa inibição do embrionamento dos ovos.