Field Trial with the Entomopathogenic Fungus Metarhizium anisopliae var. acridum against Bands of the Grasshopper Rhammatocerus schistocercoides in Brazil

The efficacy of a mycoinsecticide formulated in vegetable oil was tested in Brazil against the grasshopper Rhammatocerus schistocercoides . A set of experiments was conducted in the Chapada dos Parecis region (Mato Grosso state), a permanent zone of outbreaks for this pest. Experiments were performed in zones of natural vegetation, against grasshopper bands in the third nymphal instar. Three nymphal bands were treated with a mycoinsecticide formulation based on conidia of the entomopathogenic fungus Metarhizium anisopliae var. acridum ( =M. flavoviride ), strain CG 423. Three non-treated bands were used as control. The application was made with the aid of a hand-held ULV sprayer adjusted to deliver 2 l of the formulation ha -1 , each containing 1 ×10 13 conidia. Treatments were limited to the surface of the grasshopper bands and their immediate borders (5-10 m). The efficacy of the mycoinsecticide was evaluated through band survival after treatment (grasshopper numbers, surface, density, behaviour and daily movement of the band), allowing the insects to move freely in their natural environment. Insects were regularly surveyed and maintained in the laboratory, allowing estimates of the infection rate. Field and laboratory studies showed a clear effect of the product 10 days after treatment. At 14 days post-spraying, mortality caused by the mycoinsecticide in the field was approximately 88%.     

Infection of the Coffee Berry Borer Hypothenemus hampei (Coleoptera: Scolytidae) by Brazilian Isolates of the Entomopathogenic Fungi Beauveria bassiana and Metarhizium anisopliae (Deuteromycotina: Hyphomycetes)

The virulence of four fungal isolates (three Beauveria bassiana and one Metarhizium anisopliae ) against adult female coffee berry borers (CBB) was investigated. The most virulent isolate from initial bioassays, B. bassiana LPP1, with a LT 50 of 3.4 days, was further investigated by application to berries prior to infestation and to berries already infested with CBB. At the highest concentration applied to berries (1 ×10 7 conidia mL -1 ), CBB mortality was 83% (berries inoculated prior to infestation) and 62% (berries inoculated after infestation).     

Field Treatment of Desert Locust ( Schistocerca gregaria Forskal) Hoppers in Mauritania Using an Oil Formulation of the Entomopathogenic Fungus Metarhizium flavoviride

A field trial was conducted to test the efficacy of an oil formulation of the entomopathogenic fungus , Metarhizium flavoviride Gams & Rozsypal (Deuteromycotina: Hyphomycetes) , as a control agent for the desert locust , Schistocerca gregaria Forskal (Orthoptera: Acrididae) , in Mauritania . The treatment was applied to hopper bands in the field . In caged samples of the treated insects , 99% mortality was observed in 15 days . On average during application only 51% of the hoppers received spray droplets directly , the additional mortality being due to pick - up of spores from the spray residue . This mortality was assessed by exposing insects to a treated plot at intervals , and monitoring disease levels during subsequent incubation in cages . The spray residue remained highly infective for a period of 6 days after application . The number of nymphs in the hopper bands was estimated using a computer - based photographic image - processing technique . Unfortunately , most of the hopper bands dispersed into small groups , but a population reduction could be demonstrated for one hopper band . Maximal daily mortality in the field was observed 10 - 11 days after application , compared with 6 - 10 days in cages .     

First Record of the Entomopathogenic Fungus Sorosporella sp. (Deuteromycotina: Hyphomycetes) in Locusta migratoria (Orthoptera: Acrididae) from Madagascar: Symptoms of Infection, Morphology and Infectivity

In Madagascar, a fungal disease was observed in the migratory locust, Locusta migratoria capito, which was caused by the deuteromycete Sorosporella sp. Multiplication of the fungus in locusts results in the formation of brick-red resting spores filling the body of the insect, and in a pale and fragile cuticle which breaks easily, releasing these spores. The conidia of the fungus (only observed in artificial cultures) are cylindrical in shape, measuring 11.0 2.8 mu m. The growth of the fungus was compared on several solid and liquid media, but was invariably slow. The best growth was obtained on a medium containing 3% ground rice, 3% malt extract, 0.3% peptone and 1.5% agar. Attempts were made to initiate artificial infections in L. migratoria migratorioides and Schistocerca gregaria from a laboratory stock. This was carried out by feeding resting spores or through contact with Sorosporella material from agar cultures. However, it rarely resulted in mortalities with typical symptoms. Inoculations by injection were more successful, and resulted in the formation of resting spores in the cadavers 12 to 21 days after inoculation. In Madagascar, Sorosporella sp. seems to be an important, and frequently occurring, locust pathogen. However, the natural mode of infection and the ecology of the fungus are still unclear. Une mycose causee par le champignon deuteromycete Sorosporella sp. a ete observee a Madagascar chez le criquet migrateur Locusta migratoria capito. La multiplication du champignon dans le corps des criquets entraine la formation de spores rouge-briques, qui emplissent celui-ci. Les individus infestes developpent en outre une cuticule pale et fragile, qui se brise facilement, laissant ainsi les spores se disseminer. Les conidies (observees uniquement en cultures artificielles) mesurent 11.0 2.8 mum. La croissance du champignon reste lente sur tous les milieux solides et liquides compares. La meilleure croissance a ete obtenue sur un milieu contenant 3% de riz, 3% d'extrait de malt, 0.3% de peptone et 1.5% d'agar. Des essais d'infection par ingestion de spores d'une part, par contact avec du materiel de culture sur agar d'autre part, ont etes effectues avec L. migratoria migratorioides et Schistocerca gregaria (mate riel d'elevage). Ces essais n'ont abouti que rarement a une mortalite avec des symptomes typiques. Des resultats plus positifs ont ete obtenus au moyen d'inoculations par injection. Ils se forment dans ce cas des spores dans les cadavres des criquets 12 a 21 jours apres l'inoculation. Sorosporella sp. semble etre un agent pathogene des criquets important et frequent a Madagascar. Le mode d'infection naturel, ainsi que l'ecologie de ce champignon restent cependant peu connus.     

Susceptibility of Sitophilus zeamais (Motsch.) (Coleoptera: Curculionidae) and Prostephanus truncatus (Horn) (Coleoptera: Bostrichidae) to Entomopathogenic Fungi from Ethiopia

The efficacy of 13 isolates of entomopathogenic fungi belonging to Beauveria , Metarhizium or Paecilomyces spp. was assessed against Sitophilus zeamais (Coleoptera: Curculionidae) and Prostephanus truncatus (Coleoptera: Bostrichidae) using a total immersion bioassay technique in the laboratory. Fungi were applied at concentrations of 1 ×10 7 and 1 ×10 8 conidia mL -1 for P. truncatus and S. zeamais , respectively. All isolates tested were virulent to P. truncatus (98-100% mortality, and median survival time (MST) ranged from 2.85-4.05 days). Metarhizium anisopliae and B. bassiana were also virulent to S. zeamais (92-100% mortality, MST ranged from 3.58-6.28 days). The isolate of Paecilomyces sp. was found to be the least virulent against S. zeamais , causing only 26.32 ±4.29% mortality with MST of 10.38 ±0.29 days. P. truncatus proved more susceptible to the entomopathogenic fungi tested than S. zeamais . One M. anisopliae (PPRC-EE) and three B. bassiana isolates (PPRC-HH, PPRC-9609 and PPRC-9614) were selected for further study and dose-mortality relationships were assessed on S. zeamais . The tested concentrations ranged from 1 ×10 4 -1 ×10 7 conidia mL -1 . M. anisopliae (PPRC-EE) showed the lowest LC 50 (3.39 ×10 5 conidia mL -1 ) followed by B. bassiana PPRC-HH (2.04 ×10 6 conidia mL -1 ). PPRC-9609 and PPRC-9614 showed slight differences in LC 50 but not at LC 90 . The results revealed the higher potency of M. anisopliae as compared with the B. bassiana isolates tested. The study suggests that the use of entomopathogenic fungi may hold promise as an alternative method to control pests of stored-products in Ethiopia.     

New bioassay method to assess the pathogenicity of Colombian strains of Metarhizium anisopliae (Metsch.) Sorokin and Paecilomyces sp. (Deuteromycotina: Hyphomycetes) against the subterranean burrower bug Cyrtomenus bergi Froeschner (Hemiptera: Cydnidae)

Using a new sand bioassay method, the pathogenicity of three Colombian strains of Metarhizium anisopliae (i.e., CIAT 224, 245, and 230) and one strain of Paecilomyces sp. (CIAT 308) were tested against fourth instars of the subterranean burrower bug Cyrtomenus bergi Froeschner (Hem.: Cydnidae) in the laboratory. The proposed bioassay simulates the habitat of C. bergi and at the same time enables the evaluation of a large number of insects in a short period of time and under controlled conditions. All tested fungal species/strains were pathogenic against C. bergi. However, only low levels of mortality were obtained, and never exceeded 55%. In the screening experiment, M. anisopliae strains CIAT 224 and CIAT 245 caused the highest levels of mortality. The use of the bioassay procedure described herein is discussed.