Comparison of an Organophosphate Insecticide with a Mycoinsecticide for the Control of Oedaleus senegalensis (Orthoptera: Acrididae) and Other Sahelian Grasshoppers at an Operational Scale

Operational scale field trials were conducted in 1996 and 1997, in the east of the Niger Republic, on 50 and 800 hectare plots, to compare the efficacy of an oil based formulation of the entomopathogenic fungus, Metarhizium anisopliae (flavoviride) var. acridum (Deuteromycotina: Hyphomycetes) with fenitrothion for the control of Sahelian grasshoppers. The Senegalese Grasshopper Oedaleus senegalensis Krauss was the most abundant species in the trials. M. anisopliae was applied at 5 x 1012 spores ha-1 at volume application rates of 2 and 0.5 l ha-1 in successive years. Fenitrothion was applied at 220 g/ha-1 at 1.25 and 0.22 l ha-1 volume application rates. Ultra low volume equipment mounted on a vehicle (1996) or a fixed wing aircraft (1997) was used for application. The M. anisopliae treatment reduced the grasshopper population significantly after 7 days and by 93% within 16 days. Fenitrothion caused a population reduction of more than 90% shortly after application, but due to immigration, the grasshopper population recovered to the initial level within 16 days. Grasshoppers treated with the fungus and given the opportunity to thermoregulate in the sun died more slowly than grasshoppers incubated in the shade. The survival of spores in the spray residue of the M. anisopliae plots assessed by exposing grasshoppers to the sprayed vegetation at intervals and monitoring disease levels during subsequent laboratory incubation, showed the spray residue to remain highly infective, for three weeks after spraying. At the end of the 1997 season, egg pod density and viability in the plot treated with the fungus was reduced compared with both untreated and the fenitrothion plots. Compared with the existing practice of large-scale treatment of grasshopper infestations with fenitrothion, use of M. anisopliae would not only be safer to mammals and less damaging to non-target organisms, but also be more effective in the long-term control of grasshoppers.     

Reduction of Feeding by the Variegated Grasshopper, Zonocerus variegatus , Following Infection by the Fungal Pathogen, Metarhizium flavoviride

The effect of infection by the fungal entomopathogen , Metarhizium flavoviride, on feeding by the tropical grasshopper pest , Zonocerus variegatus, was investigated in field - cage studies . A significant reduction in feeding , as indicated by faecal production , was recorded 2 - 3 days after inoculation for a range of spore doses (104 , 105 and 5 105 spores per insect) . This was before any mortality was recorded due to infection . All infected individuals died by day 7 . At this time , faecal production of the treated grasshoppers was equivalent to less than 2 days faecal production by grasshoppers untreated with spores . This reduction in feeding (69 , 71 and 74% total reduction by day 7 in the 104 , 105 and 5 105 doses respectively in comparison to controls) is a substantial contribution to the overall effects of the slow acting pathogen . Furthermore , the rapid reduction in feeding indicated that this effect was not simply due to invasion of the host tissues by the pathogen or production of secondary metabolites . The possibility that reduction in feeding is associated with a behavioural response in which there is a trade - off between host defence and feeding during early stages of infection is discussed     

Entomopathogenic Fungi Associated with Natural Populations of the Moroccan Locust Dociostaurus maroccanus (Thunberg) (Orthoptera: Gomphocerinae) and Other Acridoidea in Spain

The entomopathogenic fungi Beauveria bassiana Vuill . and Metarhizium anisopliae (Metschnikoff) have been found in natural populations of the Moroccan locust Dociostaurus maroccanus (Thunberg) and other species of acridoids that cohabit the same locust breeding areas in southern Spain . Infection levels of B. bassiana on insects collected in the field and maintained under laboratory conditions were relatively high (1 . 6 - 20 . 5%) . The prevalence of the disease extended from spring to summer in the three consecutive years monitored . A local isolate of this fungus demonstrated high virulence (LD = 440 conidia / insect) against the 50 locust D. maroccanus in the laboratory bioassay . The relatively wide host range of B. bassiana and its adaptation to the dry and hot conditions dominating the locust breeding area suggest that this isolate could be considered in the development of a biological control programme against D. maroccanus.     

Effects of Moisture Content and Temperature on Storage of Metarhizium flavoviride Conidia

The effects of moisture content and temperature on the medium-term (3-4 months) storage of conidia of Metarhizium flavoviride were investigated. Conidia harvested after 24 days of culturing on rice showed greater tolerance to long storage than conidia from 12-day cultures. The moisture content of the conidia was of greatest importance; at harvest from the culture, conidial moisture contents could be 40%, while the optimal moisture content for storage was found to be 4-5%. Dried conidia stored in oil benefited from the addition of dried silica gel, as did conidia stored as powder. A range of mineral oils proved satisfactory for storage, and when dried silica gel was added to suspensions, germination levels were 79.8% after 105 days at 28-32 C. Dried conidia stored in oil maintained germination levels of up to 96 and 85% after 80 days at 10-14 C and 28-32 C respectively. Dried conidia stored as powder retained germination levels of 95% at 10-14 C, but only up to 27% at 28-32 C. In another experiment, dried conidia maintained greater than 90% germination over 128 days, with or without silica gel at 10 - 14 C or -15 - -18 C.     

Effects of a Mycoinsecticide on Feeding and Fecundity of the Brown Locust Locustana pardalina

The entomopathogenic fungus Metarhizium anisopliae var. acridum is being developed for use as a mycoinsecticide against locusts and grasshoppers in Africa. In addition to causing significant mortality, studies have shown the pathogen to cause reductions in feeding of a number of target species during the disease incubation period. The present study extends this work by demonstrating significant reductions in feeding following infection in another important pest species, the brown locust Locustana pardalina (Walker). Insects collected from the field following a spray application and subsequently maintained in a field laboratory showed a significant reduction in per capita feeding, as indicated by faecal production, as early as 2 days after treatment; this was before any pathogen-induced mortality. This per capita reduction in feeding by infected individuals contributed to a total reduction in feeding of 65% relative to controls. In addition to this laboratory based assessment, experiments were conducted to examine the effects of infection on mortality, feeding and fecundity in the field. Mortality rates of infected individuals in the field were significantly slower than those in the laboratory (average survival time of approximately 39 days compared with 6 days), although total mortality and percentage mycosis were equivalent. Treated individuals showed a significant reduction in body fat accumulation at sexual maturity compared with controls. This may reduce dispersal ability and total reproductive fitness. However, treated individuals exhibited a reduced pre-oviposition period resulting in them laying more eggs than untreated individuals within the first weeks following fledging. Thus, no significant reductions in fecundity were recorded by the end of the assessment period when mortality of treated individuals exceeded 90%. Given that many untreated locusts were still alive and had the potential to continue oviposition for several more weeks, however, it is likely that differences in fecundity would have become apparent if the assessment had continued. These results provide important insights for evaluating overall impacts of spray applications of the mycoinsecticide.     

Evaluating the importance of residual effects from previous years' treatment on the efficiency of different strategies for control of Sahelian grasshoppers with Metarhizium anisopliae var. acridum

A model for the residual effect of previous years' treatment with the mycoinsecticide Metarhizium anisopliae var. acridum has been constructed based on field data from treatment of two different grasshopper species in east Niger. This model was incorporated in an earlier developed simulation model to evaluate control strategies for the grasshopper Oedaleus senegalensis in West Africa and the model system was used to assess the potential importance of second year's residual effects for the efficiency of different treatment strategies. It has earlier been hypothesized that the persistence of M. anisopliae and the ability of this agent to impose long-term control on grasshopper populations through secondary cycling in some cases might render the use of M. anisopliae more efficient than the use of chemical insecticides like fenitrothion. Results show that this effect is possible if M. anisopliae is used in a repetitive treatment strategy where control operations are concentrated in the main millet production areas.     

The extracellular constitutive production of chitin deacetylase in Metarhizium anisopliae: possible edge to entomopathogenic fungi in the biological control of insect pests

The possible contribution of extracellular constitutively produced chitin deacetylase by Metarhizium anisopliae in the process of insect pathogenesis has been evaluated. Chitin deacetylase converts chitin, a beta-1,4-linked N-acetylglucosamine polymer, into its deacetylated form chitosan, a glucosamine polymer. When grown in a yeast extract-peptone medium, M. anisopliae constitutively produced the enzymes protease, lipase, and two chitin-metabolizing enzymes, viz. chitin deacetylase (CDA) and chitosanase. Chitinase activity was induced in chitin-containing medium. Staining of 7.5% native polyacrylamide gels at pH 8.9 revealed CDA activity in three bands. SDS-PAGE showed that the apparent molecular masses of the three isoforms were 70, 37, and 26 kDa, respectively. Solubilized melanin (10microg) inhibited chitinase activity, whereas CDA was unaffected. Following germination of M. anisopliae conidia on isolated Helicoverpa armigera, cuticle revealed the presence of chitosan by staining with 3-methyl-2-benzothiazoline hydrazone. Blue patches of chitosan were observed on cuticle, indicating conversion of chitin to chitosan. Hydrolysis of chitin with constitutively produced enzymes of M. anisopliae suggested that CDA along with chitosanase contributed significantly to chitin hydrolysis. Thus, chitin deacetylase was important in initiating pathogenesis of M. anisopliae softening the insect cuticle to aid mycelial penetration. Evaluation of CDA and chitinase activities in other isolates of Metarhizium showed that those strains had low chitinase activity but high CDA activity. Chemical assays of M. anisopliae cell wall composition revealed the presence of chitosan. CDA may have a dual role in modifying the insect cuticular chitin for easy penetration as well as for altering its own cell walls for defense from insect chitinase.     

Investigation of native isolates of entomopathogenic fungi for the biological control of three citrus pests

The pathogenicity of 15 isolates of Beauveria bassiana (Balsamo) Vuillemin, five isolates of Metarhizium anisopliae (Metschnikoff) Sorokin and one isolate of M. flavoviride (Gams and Rozsypal) were tested under laboratory conditions against the subterranean life stages of the citrus pests, Ceratitis rosa Karsch, C. capitata Wiedemann (Diptera: Tephritidae) and Thaumatotibia leucotreta Meyrick. (Lepidoptera: Tortricidae). When these citrus pests were treated with a concentration of 1×10⁷ conidia mL^?1, fungal isolates had a significantly greater effect on the adults of C. rosa and C. capitata than they did on the puparia of these two fruit fly species. Further, C. rosa and C. capitata did not differ significantly in their response to entomopathogenic fungi when adult and pupal mycosis were considered. Depending on fungal isolate, the percentage of T. leucotreta adults which emerged from fungal treated sand ranged from 5 to 60% and the percentage of pupae with visible signs of mycosis ranged from 21 to 93%. The relative virulence of the four most promising fungal isolates, as well as the commercially available B. bassiana product, BroadBand® (Biological Control Products, South Africa), were compared against one another as log-probit regressions of mortality against T. leucotreta which exhibited a dose-dependent response. The estimated LC₅₀ values of the three most virulent B. bassiana isolates ranged from 6.8×10⁵ to 2.1×10⁶ conidia mL^?1, while those of the least pathogenic ranged from 1.6×10⁷ to 3.7×10⁷ conidia mL^?1.     

Control of Zonocerus variegatus by Ultra-low Volume Application of an Oil Formulation of Metarhizium flavoviride Conidia

An oil-based formulation of Metarhizium flavoviride conidia, applied at 2 1012 spores ha-1 in 1 l ha-1 gave good control of Zonocerus variegatus in 1-ha plots in southern Benin. In a three-replicate, randomized, complete block (RCB) trial in Mono province, a significant reduction in insect counts between treated and control plots was observed 10-15 days after application; treatment reduced the population by about 90%. A four-replicate RCB trial in Oue me province also gave high mortality. Although a significant difference between treated and untreated plots was observed 10-18 days after application, insect dispersal out of cassava fields towards oviposition sites interfered with a clear demonstration of control. Significantly more Z. variegatus cadavers with M. flavoviride infection were found in treated plots than control plots.     

Importance of timing of application of the entomopathogenic fungus,metarhizium anisopliae for the control of legume flower thrips,megalurothrips sjostedti and its persistence on cowpea

Field experiments were conducted for two seasons to evaluate the timing of application of the entomopathogenic fungus, Metarhizium anisopliae for the control of legume flower thrips, Megalurothrips sjostedti on cowpea. One application of M. unisopliae timed at flower bud stage and another at flowering stage did not protect cowpea yield against M. sjostedti as does chemical insecticide, Karate (Lambda‐cyhalothrin). Instead, one application of the fungus given at flower bud stage and two applications given at flowering were required to keep M. sjostedti population in check through these stages, which are very sensitive to thrips damage with a concomitant increase in cowpea yield which was significantly higher than the Karate treatment. Studies of persistence showed that M. anisopliae remained active in the field for 3–4 days.     

Selection of entomopathogenic fungi for the control of the western corn rootworm Diabrotica virgifera virgifera

Abstract:  The western corn rootworm Diabrotica virgifera virgifera Le Conte (Col., Chrysomelidae), a serious pest of maize, has been recently introduced into Europe. Several approaches for its control are presently under investigation including microbial agents. During a field survey in Hungary in 2005, naturally occurring entomopathogenic fungi were found to attack this pest. These novel isolates together with standard isolates were tested for virulence against D. v. virgifera larvae and adults. Twenty strains of Metarhizium anisopliae , Beauveria bassiana and Beauveria brongniartii were used in bioassays in the laboratory. Larvae and adults were dipped into a spore suspension with a concentration of 1 × 10⁷ conidia (con.)/ml. They were kept for 14 days at 22°C (±2°C) and 70% relative humidity. The number of infected larvae and adults were counted and infection rates were calculated. Adults were significantly more susceptible to entomopathogenic fungi than larvae. The most virulent isolate infected about 47% of larvae ( M. anisopliae Ma2277), whereas the infection rate in adults was up to 97% ( M. anisopliae Ma2275). Isolates of M. anisopliae caused significantly higher mortalities than isolates of B. brongniartii and B. bassiana . Most of the adult beetles were killed within 12 days. Isolates from D. v. virgifera were more virulent than those from other hosts.     

Debilitation in conidia of the entomopathogenic fungi Beauveria bassiana and Metarhizium anisopliae and implication with respect to viability determinations and mycopesticide quality assessments

Germination of Beauveria bassiana (Bb) and Metarhizium anisopliae (Ma) conidia determined from a fast-rehydration (FR) protocol were compared to those obtained when dry conidia were subjected to slow rehydration (SR) by holding under high humidity conditions prior to aqueous suspension. Differences in viability estimates obtained using the FR vs. SR protocols increased markedly after conidia were exposed to various stress factors in storage (high a_w, temperature, and O₂ concentrations), with the SR protocol producing higher estimates of viability in all cases. After Bb conidia were stored under moist conditions for 21 days at 25 °C, the SR estimate of viability was >21% greater than the FR estimate. In jars flushed with different O₂ concentrations and stored at 50 °C for 34 days, proportional differences between protocols varied, depending on water activity, from 18-44% in jars flushed with 0% O₂ (100% N₂) to as high as 63-93% when treated with 21-22% O₂. For conidia stored over a broad range of moderate to high temperatures in the absence of O₂, SR-FR differences were ?9% at 25-40 °C but 30% at 50 °C. Germination of stressed Bb and Ma conidia increased substantially when incubation time on the germination substrate was increased from 24 to 72 h, whereas germination of non-stressed conidia showed little change. Conidia debilitated by stress were characterized by hypersensitivity to lethal imbibitional damage (damage that is mitigated by slow rehydration) and slow germination. Viability protocols that may provide more reliable assessments of overall mycopesticide quality are discussed.     

Susceptibility of different life stages of the European cherry fruit fly,Rhagoletis cerasi,to entomopathogenic fungi

The effects of six fungus isolates on the mortality of different life stages of the European cherry fruit fly, Rhagoletis cerasi (Diptera: Tephritidae), were assessed in a series of laboratory experiments to find an isolate suitable for biological control. In a first step, the effects of fungus treatments on mortality, mycosis and fecundity of adult flies at a concentration of 10⁷ conidia/ml were evaluated. All fungus isolates caused mycosis but virulence varied considerably among the isolates. Beauveria bassiana and Isaria fumosorosea caused 90–100% mortality and had the strongest influence on fecundity. Metarhizium anisopliae also induced high rates of mortality, while the pathogenicity of Isaria farinosa was low. The effects of lower conidia concentrations and the influence of the age of flies were assessed in a second step. Higher conidia concentrations generally resulted in a higher mortality. B. bassiana was most efficient at low concentrations. Young flies showed lower mortality rates than older flies but, sub‐lethal effects on eclosion rate of eggs were greater in younger flies. Finally, the effects on L₃ larvae were tested: none of the fungus isolates induced mortality in more than 25% of larvae. As L₃ larvae and pupae are not susceptible to fungus infection, field control of R. cerasi should be focused on adult flies.     

Characterisation of entomopathogenic fungi used in the biological control programme of Diaphorina citri in Mexico

The production of biological insecticides requires the identification and selection of candidate isolates of entomopathogenic fungi (EPF). The objective of this study was to characterise by virulence factors, single-spore strains of the CHE-CNRCB 303, 305, 307 strains initially identified as Isaria fumosorosea and the 224 strain of Metarhizium anisopliae to identify those with outstanding quality parameters that can serve to improve the control programme for Diaphorina citri (Hemiptera: Liviidae) in Mexico. The size of conidia and phialides was evaluated. The internal transcribed spacers established molecular identity. The selection of single-spore strains was done using radial growth (RG), the production of conidia (PC) and germination (G) rates. Principal component analysis (PCA) was used to determine the correlation between the variables and as screening criterion. Molecular and morphometric analysis confirmed that isolates 303, 305 and 307, and their single-spore strains correspond to the Isaria javanica species. The 224 strain and its single-spore strain were identified as M. anisopliae sensu lato. The statistical analysis of the RG, PC and G variables showed significant differences (P ≤ 0.05) between single-spore strains and their multi-spore strains. PCA showed a correlation between the RG and PC. The assay with Pr1 proteases associated with the surface of the conidia showed significant differences (P ≤ 0.05) for single-spore strains of I. javanica 303/2, 305/1 and 305/5 compared to the original strains. The characterisation of genetically homogeneous populations of EPF will allow us to obtain improved isolates, which are needed for the mass production of mycoinsecticides.     

Laboratory bioassays of entomopathogenic fungi for control of Delia radicum (L.) larvae

Laboratory soil bioassays were performed at economic field rates for in-furrow (3.85 x 10(6)spores/g dry soil) and broadcast (3.85 x 10(5)spores/g dry soil) applications with three isolates of Metarhizium anisopliae (F52, ATCC62176, and ARSEF5520) and one isolate of Beauveria bassiana (GHA). All isolates tested were infective to second instar Delia radicum (L.). The conditionally registered M. anisopliae isolate (F52) performed best killing an average of 85 and 72% of D. radicum larvae at the high and low concentration, respectively. The mean LC50 and LC95 of F52 against second instar D. radicum was 2.7 x 10(6) and 1.8 x 10(8)spores/g dry soil, respectively. The use of F52 in an integrated management program is discussed.     

Biological control of insects in Brazil and China: history,current programs and reasons for their successes using entomopathogenic fungi

Brazil and China have been successful in the use of microbial control methods to manage several agricultural and forest insects. In both countries, entomopathogenic fungi (EF) have been used for pest management since the 1970s. However, EF production and commercialization have not been constant in either country. Several companies and cooperatives suspended their activities or shut down from the 1970s to the 1990s. This was due to loss of confidence in available mycoinsecticides by Brazilian farmers or due to reduced involvement and government subsidies for biological control in China; and, consequently, mycoinsecticides were largely replaced by inexpensive chemical insecticides. Starting in the 1990s and continuing until today, however, new Brazilian and Chinese private companies have arisen. In Brazil, the area treated with M. anisopliae for spittlebug control alone is estimated to be approximately one million hectares in 2008, 75% of which was for control of spittlebugs in sugarcane plantations and the remainder for spittlebugs in pasture grass (primarily Brachiaria spp.) and other smaller programs. In China, the fungus Beauveria bassiana was used annually in 0.8–1.3 million ha until the 1980s. Several factors were important for the success of these programs, such as: governmental support (at least during the initial steps of biocontrol programs); availability of indigenous virulent fungal isolates; low-cost substrates for mass production; retail prices of mycoinsecticides lower than their chemical counterparts; and sale by contract which allows the products to be immediately available for use, rather than stored. In this report, we discuss the current biocontrol programs using insect fungi in these two developing countries, as well as the future and main challenges they must face to further encourage the adoption of mycoinsecticides.     

Efficacy of entomopathogenic bacteria for control of Musca domestica

The aim of this study was to evaluate the larvicidal activity, and sub lethal effects of entomopathogenic bacteria Brevibacillus laterosporus, Bacillus thuringiensis var. israelensis, B. thuringiensis var. kurstaki, and a commercial formulation of Bacillus sphaericus on Musca domestica. Bacterial suspensions were prepared in different concentrations and added to the diet of newly-hatched larvae which were monitored until the adult stage. The larvae were susceptible to the B. laterosporus, B. thuringiensis var. israelensis, and B. thuringiensis var. kurstaki bacteria in varied concentration levels. These bacteria have larvicidal and sub lethal effects on the development of flies, reducing both adult size, and impairing the reproductive performance of the species.     

Evaluation of entomopathogenic fungi as potential biological control agents of the dengue mosquito,Aedes aegypti (Diptera: Culicidae)

Dengue is a global health concern. Growing insecticide resistance in the primary mosquito vector, Aedes aegypti, limits the effectiveness of vector control, so alternative tools are urgently needed. One approach is the use of biopesticides comprising entomopathogenic fungi, e.g., Beauveria bassiana and Metarhizium anisopliae. These fungi may decrease disease transmission by reducing mosquito vector longevity and also occur worldwide, although many isolates have not been tested for virulence against mosquitoes. Ninety-three isolates of entomopathogenic fungi representing six species (B. bassiana, M. anisopliae, Isaria fumosorosea, I. farinosa, I. flavovirescens, and Lecanicillium spp.) were screened as potential biological control agents of Aedes aegypti. A hierarchical, multi-criteria experimental design was undertaken to find suitable isolates. Initial screening was performed via in vitro assays measuring radial growth and spore persistence, eliminating isolates with poor growth or viability on nutrient-rich substrate. Subsequent measurements of spore persistence revealed that only nine of 30 strains tested had half-lives exceeding 3 weeks. Ten isolates were chosen for in vivo bioassays against adult Ae. aegypti. From these assays, two Australian isolates of B. bassiana, FI-277 and FI-278, appeared to be most promising. Both isolates were shown to be virulent against Ae. aegypti at 20, 26, and 32°C. Spreading spores manually onto substrate was found to be more efficacious than spraying. Ae. aegypti infected by manually-spread spores on cotton substrate were found to have an LT₅₀ of 3.7±0.3 days. These characteristics suggest that FI-277 has promise as a dengue mosquito biocontrol agent, either alone or combined with conventional chemical insecticides.     

Use of entomopathogenic fungi combined with biorational insecticides to control Dichroplus maculipennis (Orthoptera: Acrididae: Melanoplinae) under semi-field conditions

Grasshoppers are among the invertebrate herbivores that cause most economic losses in grasslands throughout Argentina’s Pampas and parts of Patagonia. Chemical insecticides remain the sole option for grasshopper control in this area, despite being of significant environmental concern. Our aim was to evaluate the efficacy of combinations between three entomopathogenic fungi strains (Beauveria bassiana LPSc 1067 and LPSc1082), and Metarhizium anisopliae (LPSc 907), two biorational insecticides (luphenuron and methoxyfenozide), and a new synthetic chemical pesticide (rynaxypyr) in the control of the pest grasshopper Dichroplus maculipennis under field cage conditions. Fungal strains used were adjusted to 1 × 10⁸, 1 × 10⁶ and 1 × 10⁴ conidia/ml. Insecticides were tested at three concentrations: the average concentration recommended for application in the field (100%), 50% of that level and finally 25%. Combinations of the insecticides with B. bassiana (LPSc 1067, LPSc 1082) and M. anisopliae (LPSc 907) caused higher mortality to D. maculipennis nymphs than any of the individual agents used alone. The three insecticides tested did not negatively affect the isolates of the two species of entomopathogenic fungi employed.     

Development of a model for evaluating the effects of environmental temperature and thermal behaviour on biological control of locusts and grasshoppers using pathogens

1 Recent years have seen an upsurge in locust and grasshopper populations in many parts of the world. Environmentally sustainable approaches to locust and grasshopper control may be possible through the use of biopesticides based on entomopathogenic fungi. Unfortunately, the performance of these biopesticides is highly variable with environmental temperature and host thermoregulatory behaviour critically determining the pattern and extent of mortality after applications. Here, we present a temperature‐dependent model that enables us to predict the field performance of Metarhizium anisopliae var. acridum, the key fungal pathogen used in locust biopesticides. 2 The model was constructed using mortality rate data generated across a range of temperatures in the laboratory and is driven by environmental temperature data linked through host body temperature models. 3 Model predictions were validated against empirical field data obtained for five species, Locustana pardalina, Oedaleus senegalensis, Zonocerus variegatus, Nomadacris septemfasciata and Chortoicetes terminifera. Mortality predictions were accurate to a 2‐day error in every 10 days. This level of resolution is satisfactory to guide operational use of the biopesticide. 4 The model was subsequently used for a prospective evaluation of the performance of M. anisopliae var. acridum against two additional pest species, Dociostaurus maroccanus and Calliptamus italicus in Spain. Results suggest that this pathogen would work reasonably well against these species as long as early instars are targeted. 5 The model could provide a useful tool to assist in interpreting effectiveness of control operations, develop improved application strategies to optimize the performance of the biopesticide and identify appropriate target species and environments.