Mentha spp. essential oils: toxicity to Alphitobius diaperinus, activity against poultry pathogenic bacteria, and Beauveria bassiana compatibility.

The botanical insecticide market is growing because of limitations placed on the use of certain synthetic chemical insecticides. In this sense, the lesser mealworm Alphitobius diaperius (Coleoptera: Tenebrionidae) is the main poultry pest. The insect causes weight loss and damage to the digestive system of poultry, and it is a vector and reservoir of pathogens. Consequently, this study explored the following hypotheses: (i) essential oils (EOs) derived from Mentha spp. are toxic to A. diaperius; (ii) these EOs are compatible with Beauveria bassiana, the natural enemy of the poultry pest, that parasite A. diaperinus; (iii) these EOs also exhibit activity against bacteria that are pathogenic to poultry. In topical applications and ingestion tests, EOs from Mentha arvensis, Mentha spicata, and Mentha piperita were toxic to A. diaperinus. Chromatographic analyses revealed that menthol is the predominant compound in M. arvensis and M. piperita, whereas carvone is the major compound in M. spicata. Both (-)- and (+)-menthol, along with (-)- and (+)-carvone, underwent testing with A. diaperinus. Nevertheless, their activity was not as potent as those of the EOs, suggesting a possible synergistic and/or additive effect. The EOs did not have any adverse effects on the conidial germination, vegetative growth, or conidia production per colony of the entomopathogenic fungus B. bassiana. Consequently, these EOs are compatible with this natural enemy. The EO extracted from M. spicata exhibited significant toxicity against Staphylococcus aureus (ATCC 25923), whereas the remaining EOs displayed moderate toxicity against this bacterium. The EOs derived from Mentha spp., as assessed in this study, hold promise for the development of botanical insecticides tailored for the control of A. diaperinus. These insecticides are selective in favor of the natural enemy B. bassiana and can also serve as effective sanitizers, thanks to their antibacterial properties.

Challenges in the Biological Control of Pests in Poultry Production: a Critical Review of Advances in Brazil.

Poultry farming is an important activity in animal protein production worldwide, either by laying hen farming or broilers. Over the last decades, the change in production systems with confinement of large numbers of hens has increased productivity and reduced costs; however, it has also increased sanitary issues. In this setting, arthropods that are adapted to poultry houses have gained great importance. They cause direct damage to hens, either by blood spoliation caused by ectoparasites or lesions in the digestive tract (e.g., lesser mealworm) or by indirect damages, by transmitting pathogens or by affecting egg quality, when they attain pest status. Synthetic chemical products comprise the most frequently used control strategy against these pests, with relative efficacy and many side effects. In Europe, some countries also adopt alternative prevention or control measures. In Brazil, however, although there are some groups of researchers that work on developing alternative control, its use is virtually zero. The present review shows a critical overview of this context in Brazil, based on the alternatives that have already been studied and made available, but have not been implemented, yet, and the potential stumbling blocks created by the very poultry market against these advances.

Liquid preparation of diatomaceous earth against the lesser mealworm, Alphitobius diaperinus (Panzer, 1797) (Coleoptera: Tenebrionidae)

The lesser mealworm (LMW) is the most important pest in poultry production. Insects are associated to avian pathogens, mainly Salmonella. Its control is based on chemical insecticide, with limited efficacy in population reduction. Also, insect populations are resistant to the main active ingredients used. Diatomaceous earth (DE) is a mineral dust that has activity against the LMW when used in dust application. No information is available about DE liquid preparation against this insect. Thus, bioassays were conducted aiming to develop a strategy for DE liquid preparation to this insect control. In laboratory the ideal concentration for poultry house experiment was estimated and the effect of insect contact with poultry litter or chicken feed after application was checked. In the poultry house, DE liquid preparation (10% in water, 1 L·m­2) was applied on the dirt soil of a cleaned and empty poultry house. In the control poultry house, a chemical insecticide was used (cypermethrin 15 g + chlorpyriphos 25 g + piperonyl butoxide 15 g) (1 L·m­2). DE at all concentrations was efficient mainly when insects were dried for 24 h before contact with a substrate. In poultry house, both treatments obtained similar results at 15 days after treatment (94% of reduction of insect population). At 45 days after treatment, the insect population with DE treatment increased 39% while the insect population remained 17% smaller than the initial population with a chemical insecticide. DE liquid preparation has potential to be used as a safe treatment in LMW population management, as a shock treatment.

Association of mechanical cleaning and a liquid preparation of diatomaceous earth in the management of poultry red mite, Dermanyssus gallinae (Mesostigmata: Dermanyssidae).

The poultry red mite (PRM), Dermanyssus gallinae, is an ectoparasite of great importance related to poultry farms worldwide. Problems associated with its control have led to the search for alternative treatments, especially using inert dust, which has recently been introduced into liquid formulations. Therefore, the objective of this work was to evaluate the acaricidal activity of a liquid diatomaceous earth (DE) preparation in the laboratory and its association with mechanical cleaning (brushing) in the field. In the laboratory it was first determined that a concentration of 10% DE would be necessary for field applications. The field experiment was conducted in a commercial poultry house. The 10% DE liquid preparation was administered in three applications and associated to mechanical cleaning. Then, 42 days after the first DE application, a population reduction of 94.7% was observed in relation to the initial population of mites. These results confirm the efficiency of DE applications in association with mechanical cleaning already adopted in poultry houses as an alternative for the control of D. gallinae, which can also contribute to avoiding mite resistance to chemical acaricides.

Laboratory and field evaluation of an autoinoculation device as a tool to manage poultry red mite, Dermanyssus gallinae, infestations with Beauveria bassiana.

The poultry red mite, Dermanyssus gallinae, is a cosmopolitan ectoparasite in hens and has been considered an important threat to the egg production industry. This study evaluated an alternative to manage poultry red mite populations as a complement to conventional chemical treatments and other control strategies in poultry houses. A simple autoinoculation device prepared with corrugated cardboard (CB) or loofah sponge (LS) as inert supports to anchor Beauveria bassiana conidia was used to aggregate and infect mites from infested poultry houses. In the laboratory, mites gathered inside the traps and the average mortalities by the fungus were higher than 70% in CB and LS traps after 5 and 4 days of exposure, respectively. Conidial viability was around 80% in CB and LS traps after 14 and 60 days under unrefrigerated conditions (26 °C), respectively. Both trap types tied to hen cages efficiently captured fed mites after blood meal, and fungal infection was observed in 65-90% of the mites in field tests. Between 5 and 25% of the mites recaptured in monitoring cardboard traps installed immediately after CB and LS removal were infected by B. bassiana. According to our results, the use of B. bassiana in an autoinoculation strategy is a potential alternative method for D. gallinae control.

Sampling Methodology of Alphitobius diaperinus (Coleptera: Tenebrionidae) Population in Poultry Houses

Abstract This paper describes a methodology to evaluate Alphitobius diaperinus (Darkling beetle) population in order to estimate the effectiveness of control methods, consisting of direct sample collections from the poultry litter in 18 points, counting of adults and larvae, and subsequent comparison of the values obtained before and after of control strategies. It allows estimating the total population, population in a known area, as well to analyze the variations in different points all over the aviary. The method has shown to be very versatile, being indicated for population studies and efficacy evaluations, once it has already been validated in different experimental conditions.

Increased tolerance of Beauveria bassiana and Metarhizium anisopliae conidia to high temperature provided by oil-based formulations.

The influence of the temperature of aqueous conidial sprays on conidial viability and virulence against Diatraea saccharalis was evaluated for pure conidia, rice + fungus (technical concentrates) and oil-based formulations of Beauveria bassiana s.s. and Metarhizium anisopliae s.s. under laboratory conditions. The fungal preparations were suspended in water and maintained at 26 °C, 36 °C and 46 °C for one, four and six hours. Conidial viability was determined by plating aliquots of each suspension onto PDA medium followed by incubation for 20-22 h and observing for viable conidia (germ tubes longer than diameter of conidia). Fungal virulence was determined by spraying suspensions onto third-instar larvae of D. saccharalis. In general, germination and virulence, particularly for unformulated conidia, were negatively affected by increases in water temperature and exposure time in suspension. However, the decrease in conidial viability in the oil-in-water emulsion was less than 7% for both species after 6 h of exposure at 36 °C, in contrast to reductions of 7-21% and 28-60% for the oil-free suspensions of B. bassiana and M. anisopliae, respectively. For the sprays of conidia in an oil-in-water emulsion previously exposed to elevated water temperatures for longer periods, the levels of insect mortality were higher than those of pure conidia or technical concentrates under identical conditions. Our results indicate that emulsifiable oil-based formulations can protect the conidia of both species of fungi from the adverse effects of high water temperatures before spraying in the field.

Biological Parameters of Euschistus heros (F.) (Heteroptera: Pentatomidae) and its Susceptibility to Entomopathogenic Fungi When Fed on Different Diets

ABSTRACT: The effects of six diets on biological parameters of Euschistus heros (F.) (Heteroptera: Pentatomidae) and its susceptibility to entomopathogenic fungi Beauveria bassiana (Bb) and Metarhizium anisopliae (Ma) were studied. The diets included a standard diet (bean pods+soybeans, peanuts and sunflower) and diets in which the bean pods were combined with only one type of grain, either soybean, peanut, sunflower, pea or sesame seeds. The best performance was that of insects fed on standard diet, which had the shortest development period and 49.5% of egg-to-adult viability. The insects fed the pea diet exhibited less than 30% viability and 11% of adults had wing deformations. The finite rate of increase values for the treatment groups were: standard: 1.091; soybean: 1.077; peanut: 1.071; sunflower: 1.076; pea: 1.058; and sesame: 1.065. The susceptibility to Ma (55%) was greater than Bb (40%) only for insects fed on the sesame diet. Considering the effects of diet on susceptibility to both fungal species comparatively among the diet-treatment groups, the stink bugs fed the restrictive diets were more susceptible compared with those fed the standard diet. We concluded that diet composition affects the biological parameters of E. heros and differentially affects their susceptibility to Bb and Ma fungi.

A protocol for determination of conidial viability of the fungal entomopathogens Beauveria bassiana and Metarhizium anisopliae from commercial products.

Techniques for directly determining conidial viability have widespread use but also have limitations for quality control assessments of formulated mycoinsecticides, especially in emulsifiable oil. This study proposes a new method based on adaptations of already established protocols that use the direct viability method to make it more economical and accurate, thus enabling its use in the evaluation of formulated products. Appropriate parameters and conditions were defined using products based on Beauveria bassiana and Metarhizium anisopliae in the forms of pure conidia, fungus-colonized rice, ground fungus-colonized rice and oil dispersion. The established protocol, named ESALQ, consists of the transfer of 150 µL of a suspension containing about 0.7 and 1 × 10(6) conidia/mL onto Rodac® plates with 5 mL of potato dextrose agar culture medium + 5 mg/L of Pentabiotic® and 10 µL/L of Derosal® (Carbendazim) and subsequent counting of germinated and non-germinated conidia. For the ground fungus-colonized rice and oil dispersion formulations, prior to transferring the fungal suspension to the medium, rice should be decanted and the oil removed, respectively. This method was compared with another direct viability method and with the Colony-forming unit (CFU) and Fluorescence viability methods, comparing the accuracy obtained using the coefficient of variation (CV) of the analysis of each method. The results showed that in addition to the ease of application, the developed method has higher accuracy than the other methods (with a CV up to seven times lower than in the Standard method and up to 32 times lower than CFU). The CFU method underestimated the concentration of viable conidia in most of the tested fungal forms, and in the emulsifiable oil products, these values were 54% lower for B. bassiana and 84% lower for M. anisopliae. The adaptations and standardizations proposed in the ESALQ method showed effective improvements for routine quality assessment of mycoinsecticides.