Pedro M. O. J. Neves

Compatibility of entomopathogenic fungi with neonicotinoid insecticides

The in vitro fungitoxic effect of the neonicotinoid insecticides acetamiprid (Saurus 200 SP), imidacloprid (Confidor 700 WDGr) and thiamethoxam (Actara 250 WG) in three concentrations (AR= average field recommendation; 0.7 AR and 1.3 AR) to the entomopathogenic fungi Beauveria bassiana, Metarhizium anisopliae and Paecilomyces sp. was studied. The effect of the insecticides on conidia germination, vegetative growth and conidiogenesis was compared. The insecticides had no effect on conidia germination, except under the highest concentration (1.3 AR) of acetamiprid, in which significant inhibition of M. anisopliae occurred. Vegetative growth of B. bassiana and M. anisopliae was significantly inhibited only by the three concentrations of acetamiprid treatment. Thiamethoxam treatment, in the AR and 1.3 AR concentrations, was significantly lower for B. bassiana vegetative growth. Paecilomyces sp. vegetative growth was higher than the control in the following treatments: 0.7 AR and AR of acetamiprid; all concentrations of imidacloprid; and in the two smallest concentrations, 0.7 AR and AR, of thiamethoxam. Conidia production was significantly smaller for Paecilomyces sp. and M. anisopliae, in the highest concentration (1.3 AR) of acetamiprid treatment and, for Paecilomyces sp., in the highest concentration (1.3 AR) of imidacloprid. Thiamethoxam significantly inhibited M. anisopliae conidia production, only in the smallest concentration (0.7 AR).Significant increase in the conidia production of Paecilomyces sp. fungus was observed in the following treatments: two concentrations, 0.7 AR and AR of acetamiprid; and in the two highest concentrations, AR and 1.3 AR, of thiamethoxam treatments. The use of insecticides, in the recommended formulations and other concentrations tested, in most cases, had no negative effect on conidia germination, conidia production and vegetative growth of B. bassiana, M. anisopliae and Paecilomyces sp. Consequently, these products, in the formulations and concentrations tested, may be used in IPM programs in which the entomopathogens are important pest regulators.

Biologia de Spodoptera eridania (Cramer) (Lepidoptera: Noctuidae) em diferentes hospedeiros

Spodoptera eridania (Cramer) is a pest under expansion in cotton and soybean fields in the cerrado, and biology studies are needed on different hosts. In order to gain knowledge about the biology and leaf intake of S. eridania on cotton, soybean and morning glory (Ipomoea grandifolia), newly-hatched caterpillars were individualized and reared in the laboratory (27 ± 2oC, R.H. 60 ± 10%, photophase of 14h). Parameters related to biology, leaf intake and reproduction were observed. The larval development period of caterpillars was shorter when fed on cotton and morning glory leaves than on soybean leaves, even though, the survival on soybean had been satisfactory (80%). Caterpillars fed on cotton and morning glory leaves had similar mean pupal weights, however 1.3 and 1.4 times higher than those obtained for male and female pupae, respectively, on soybean leaves. The soybean also influenced prepupal (37.5%) and pupal survival (68.3%) negatively, in contrast with the values obtained on the two other hosts, which were above 91.8%. In general, the soybean leaves were the least suitable for the development of S. eridania, causing 6.3% of pupal deformities. Variables like the pre-oviposition and oviposition periods, number of egg clutches/female and total number of eggs/female were not affected by the diets. Even though cotton leaves were less consumed, they provided good development to the insect. The morning glory weed was shown a suitable alternate host for the species, allowing its development and reproduction in the absence of cultivated hosts.

Effect of Biofertilizers and Neem Oil on the Entomopathogenic Fungi Beauveria bassiana (Bals.) Vuill. and Metarhizium anisopliae (Metsch.) Sorok

The in vitro fungitoxic effect of three biofertilizers, E.M.-4, Multibion O and Supermagro used in organic agriculture and the neem oil (Azadirachta indica A. Juss) on the entomopathogenic fungi Metarhizium anisopliae and Beauveria bassiana was studied. These products were mixed in a medium where the two fungi were inoculated, and germination, vegetative growth and conidiogenesis were assessed. The biofertilizers Supermagro and E.M.- 4 showed to be less toxic for the two fungi whereas MultibionO caused major inhibition on M. anisopliae, with reductions in germination (-37.74%), colony diameter (-30.26%) and conidiogenesis (-42.62%). Neem oil promoted a larger negative effect on B. bassiana, inhibiting germination (-45.27%), colony diameter (-36.62%) and conidiogenesis (-84.93%).

Compatibility of Beauveria bassiana with acaricides

The in vitro compatibility of the entomopathogenic fungus Beauveria bassiana (Bals.) Vuil. with 12 acaricide formulations was evaluated. The active ingredients Clorfenapyr, Fenpyroximate, Amitraz, Acrinathrin, Hexythiazox, Abamectin, Pyridine, Dimethoate, Pyridaphethion, Fenbutatin Oxide, Azocyclotin and Cyhexatin were tested in three different concentrations (mean concentration - MC, half MC and twice the MC). The formulations tested affected conidial germination, vegetative growth and sporulation of the fungus in different levels. The formulations more compatible with B. bassiana were Avermectin and the pyrethroids. The acaricides belonging to the organophosphate and organostanic chemical groups, however, drastically affected conidial germination as well as vegetative growth and sporulation.

External events related to the infection process of Cornitermes cumulans (Kollar) (Isoptera: Termitidae) by the entomopathogenic fungi Beauveria bassiana and Metarhizium anisopliae

The objectives of this study were to observe the external development of Metarhizium anisopliae and Beauveria bassiana on workers and soldiers of Cornitermes cumulans (Kollar) and to establish comparisons between the insect fixation techniques known as critical point and desiccator. Termite workers and soldiers inoculated with B. bassiana (447) and M. anisopliae (1037) were utilized. After inoculation, the insects were left at 25±0.5°C. In order to make observations, samples from both castes were removed at 0, 6, 12, 24, 48, 72, 96, 120, 144, and 168h after inoculation. The external development of M. anisopliae and B. bassiana conidia on the termite C. cumulans showed that M. anisopliae and B. bassiana conidial germination occurred on several regions of the termites body mainly between 6h and 12h and penetration mainly between 12h and 24h after fungal application. Several penetration points were observed originating from the same germ tube. Colonization of the host by M. anisopliae occurred between 24h and 72h, and most insects died between 72h and 96h. Conidiogenesis began between 96h and 120h with the peak between 144h and 166h for M. anisopliae and between 120h and 144h for B. bassiana. Thus, only conidiogenesis for B. bassiana started earlier, probably because this fungus/isolate shows a higher insect colonization speed. This factor, in addition to multiple penetration points for the same germination tube, could explain the higher virulence of the isolates. The critical point fixation technique provided the best preservation of structures in both the pathogen and the insect.

Ocorrência natural de Beauveria bassiana (Bals.) Vuilleman (Moniliales: Moniliaceae) sobre o cascudinho, Alphitobius diaperinus (Panzer) (Coleoptera: Tenebrionidae), em aviário comercial de Cascavel, PR

One of the main problems in poultry houses in Brazil is the lesser mealworm, Alphitobius diaperinus Panzer. This insect inhabits the litter, manure and soil of poultry houses, feeding on bird manure, cadavers and spilt feed. The lesser mealworm serves as a reservoir of many animal pathogens. Chickens also feed readily on the beetles in infested litter and this sometimes causes nutritional problems and affects weight gain. Current control measures are generally unsatisfactory and microbial control may be a promising strategy to control A. diaperinus. Natural occurrence of entomopathogens is very important for the natural control of insect pests and this paper records the occurrence of Beauveria bassiana (Bals.) Vuill. on the lesser mealworm in commercial poultry houses, in Brazil. The evaluation was carried out weekly for six months (September/2002 to February/2003). The soil around the poultry house was collected and transferred to Zoology Laboratory from Unioeste, at Cascavel, PR. Infected larvae and adults were always present, but infected pupae were registered twice. Larvae were more susceptible than pupae and adults (incidence ranging from 49% to 100%, mean 74%, 33% to 50%, mean 6.9%; 0.9% to 100%, mean 40.7%, respectively). The pathogenicity of the fungus was confirmed under laboratory conditions following procedures outlined in Kochs postulates.

[Characterization of the damage of Spodoptera eridania (Cramer) and Spodoptera cosmioides (Walker) (Lepidoptera: Noctuidae) to structures of cotton plants].

The cotton plant, Gossypium hirsutum, hosts various pests that damage different structures. Among these pests, Spodoptera cosmioides (Walker) and Spodoptera eridania (Cramer) (Lepidoptera: Noctuidae) are considered important. The objectives of this study were to characterize and to quantify the potential damage of S. eridania and S. cosmioides feeding on different structures of cotton plants. For this purpose, newly-hatched larvae were reared on the following plant parts: leaf and flower bud; leaf and boll; flower bud or boll; and leaf, flower bud and boll. The survival of S. cosmioides and S. eridania was greater than 80% and 70% for larvae fed on cotton plant parts offered separately or together, respectively. One larva of S. eridania damaged 1.7 flower buds, but did not damage bolls, while one larva of S. cosmioides damaged 5.2 flower buds and 3.0 cotton bolls. Spodoptera eridania and S. cosmioides can be considered species with potential to cause economic damage to cotton plants because they can occur throughout cotton developmental stages causing defoliation and losses of reproductive structures. Therefore, the results validate field observations that these two species of Spodoptera are potential pests for cotton.

Seleção de isolados de Beauveria bassiana para o controle biológico da broca-do-café, Hypothenemus hampei (Ferrari) (Coleoptera: Scolytidae)

Hypothenemus hampei (Ferrari) (Coffee Berry Borer) is one of the most important coffee pests. Its control is carried out mainly using synthetic chemical products, which contaminate the environment, food and farmers. The entomopathogenic fungus Beauveria bassiana is a natural enemy of coffee berry borer and presents potential for biological control. With the objective to select strains of B. bassiana for the management of H. hampei, the virulence of 61 strains, from diverse hosts and geographic regions, were tested. The selection was carried out in two phases: in the first phase 11 strains, with confirmed mortality above 60%, were selected. In the second phase, for the 11 preselected strains, we determined: LC50, sporulation rate (confirmed mortality/total mortality) and conidia production on H. hampei cadavers. The CG425 strain presented the greater total and confirmed mortality, highest sporulation rate and CL50 = 2.5 x 106 conidia/ml and CB102 strain, presented highest conidia production on insects, 11.6 x 106 conidia/insect. These isolates present height potential to be used in biological control programs of coffee berry borer with B. bassiana.

Ocorrência de Metarhizium anisopliae (Metsch.) Sorok. em adultos de cascudinho (Alphitobius diaperinus) (Panzer) (Coleoptera: Tenebrionidae) em aviários comerciais em Cascavel, PR

Alphitobius diaperinus (Panzer), the lesser mealworm, is the most important pest in large-scale poultry production and is capable of harboring several types of poultry pathogens. Chickens feed readily on the beetles in infested litter and this sometimes causes nutritional problems and the weight gain may be affected. Chemical insecticides are usually applied, however beetle infestation are very difficult to control using these products. Besides, this control method can also offer risks to chicken and man. Microbial control may be a promising strategy to control A. diaperinus in poultry houses and natural occurrence of entomopathogenic fungi is very important to control the lesser mealworm in poultry houses. The objective of this work was to register the occurrence of Metarhizium anisopliae on adults of the lesser mealworm in commercial poultry houses in Brazil.

Selection of Beauveria bassiana (Bals.) Vuill. and Metarhizium anisopliae (Metsch.) Sorok. strains for control of Cornitermes cumulans (Kollar)

Fifty strains of the entomopathogenic fungi Beauveria bassiana (Bals.) Vuill. and Metarhizium anisopliae (Metsch.) Sorok. were tested against the termite Cornitermes cumulans. In the first phase of the experiments, several bioassays were conducted and the five best strains were selected. The criterion for strain selection during this phase was the confirmed mortality above 50% five days after application of the fungus. Three M. anisopliae and two B. bassiana strains were the most virulent. The second phase of the experiments consisted of a bioassay and a conidial production test using a rice medium. The best M. anisopliae and B. bassiana strains were selected using both the confirmed insect mortality nine days after application of the fungus and the yield of conidia. Considering results from the bioassay, M. anisopliae 1037 showed the highest confirmed (57.8%) and total (89.2%) mortalities after nine days. Among the B. bassiana strains, 447 was the most virulent with confirmed and total mortalities of 45.9% and 89.8%, respectively. M. anisopliae 1037 had the highest conidial yield with mean of 3.37 x 1012 conidia/kg of rice, followed by B. bassiana strain 447 with 2.66 x 1012 conidia/kg of rice. The M. anisopliae strain 1037 was the highest virulent followed by B. bassiana strain 447. This strains showed the greatest potential as agents to be used in biological control programs against C. cumulans.