Triatomine bugs carry the parasitic protozoa Trypanosoma cruzi, the causal agent of Chagas disease. It is known that both the parasite and entomopathogenic fungi can decrease bug survival, but the combined effect of both pathogens is not known, which is relevant for biological control purposes. Herein, the survival of the triatomine Meccus pallidipennis (Stal, 1872) was compared when it was coinfected with the fungus Metarhizium anisopliae (Metschnikoff) and T. cruzi, and when both pathogens acted separately. The immune response of the insect was also studied, using phenoloxidase activity in the bug gut and hemolymph, to understand our survival results. Contrary to expectations, triatomine survival was higher in multiple than in single challenges, even though the immune response was lower in cases of multiple infection. We postulate that T. cruzi exerts a protective effect and/or that the insect reduced the resources allocated to defend itself against both pathogens. Based on the present results, the use of M. anisopliae as a control agent should be re-considered.

The sweet potato weevil (SPW), Cylas formicarius, is a serious pest of sweet potato in Australia and Papua New Guinea. Ten strains of Metarhizium sp. isolated from Australian soil samples were evaluated for their growth characteristics and screened for virulence to adult SPW under laboratory conditions. All isolates except QD62 (48.6%) had moderate to high germination (66–97%), and all took 2 to 4 days to sporulate at 25 °C. The optimal temperature for radial growth for the majority of isolates was 30 °C, and there was a significant interaction between isolate and temperature (P< 0.05). Isolate QS155 showed the fastest radial growth at 30 °C. The internal transcribed spacer sequences showed slight variations among the isolates; however, all isolates were shown to be Metarhizium anisopliae. Isolates varied greatly in their virulence. At 10 days after inoculation (DAI) by immersion in a suspension of 1 × 107conidia/ml, 9 of the 10 isolates were virulent, causing 80–100% mortality of adult SPW. Only two isolates (QS001-6 and QS155) caused more than 50% mortality at 5 DAI. In dose-mortality bioassays, isolate QS155 had the lowest 20-day LC50 and LC90 values; however, there were no statistically significant differences in mortality among the three most promising isolates tested (QD66, QS001-6 and QS155). These results show that M. anisopliae isolate QS155 has potential as a microbial control agent for SPW, and that further evaluation under glasshouse and field conditions is warranted.

In the present study, the susceptibility of different developmental stages (eggs, larvae, protonymphs, deutonymphs and adults) of Tetranychus urticae Koch to the entomopathogenic fungi Beauveria bassiana (Balsamo-Crivelli) Vuillemin and Metarhizium anisopliae (Metchnikoff) Sorokin was evaluated in the laboratory. At each developmental stage, four concentrations (3 × 105, 1 × 106, 3 × 106 and 1 × 107 conidia/ml) of both fungi were sprayed. Egg viability and motile-stage mortality varied among the fungal isolates and conidial concentrations. The highest conidial concentration (1 × 107 conidia/ml) significantly reduced the viability of eggs and increased the mortality of motile stages. However, deutonymphs and adults were more susceptible to fungal infection than larvae and protonymphs. The lethal concentration values to 50% (LC50) and 90% mortality (LC90) varied with the fungal isolates and developmental stages. The results show the prospects of B. bassiana and M. anisopliae for the control of T. urticae.

A cotton field was used to set up an arena trial for investigating the dose transfer of oil-based ultra-low-volume sprays of Metarhizium anisopliae (Metchnikoff) Sorokin to the cotton bollworm Helicoverpa armigera (Hübner). Two doses of conidia (75 and 50 g/ha, being 3.75 × 1012 and 2.5 × 1012 conidia/ha, respectively) formulated in 2 litres (70:30, kerosene–peanut oil) were applied using a Berthoud ‘Micro Ulva’ to three groups of larvae of cotton bollworms positioned in three rows downwind of a single spray line. Both the distribution of the droplets and the effect of direct contact with spray droplets were quantified. The mean number of droplets decreased from 416 ( ± 60) droplets per cm2 (line 1; 0.4 m) to 45 ( ± 36) droplets per cm2 (line 3; 5 m). To achieve 50% mortality, >10 and >13 days were necessary for 75 and 50 g/ha, respectively. From day 15, the difference in mortality rates was significant between the two treatments. At line 3 (5 m), at 12 days after application, the mortality rate reached 52% for 75 g/ha and 47% for 50 g/ha. The results are discussed in view of optimizing the application of the biopesticides.

This study evaluated the potential use of commercial mycoinsecticide formulations against red-gum lerp psyllid Glycaspis brimblecombei Moore in semi-field conditions. Eucalypt seedlings infested with psyllid nymphs were sprayed with different formulations and two concentrations of each product. Conidial deposits were evaluated after spraying for control efficiency. The conidial deposit was affected by the pathogen species and by formulation types. Higher conidial deposits were associated with mycoinsecticide formulation concentrates of lower granulometry and oil dispersion. However, some products with low deposits of conidia were highly efficient against psyllid nymphs. The results showed that the use of entomopathogenic fungi is a promising alternative method for controlling the red-gum lerp psyllid.

The role of pathogens in insect ecology is widely appreciated but remains insufficiently explored. Specifically, there is little understanding about the sources of the variation in the outcome of insect-pathogen interactions. This study addresses the extent to which immune traits of larvae and pupae of the moth Orgyia antiqua L. (Lepidoptera: Lymantriidae) depend on the host plant species and individual condition of the insects. The two host plants, Salix myrsinifolia Salisb. and S. viminalis L., were chosen because they differ in the concentration of phenolic glycosides, harmful to most polyphagous insects. Individual condition was assumed to be reflected in body weight and development time, and was manipulated by rearing larvae either singly or in groups of four. The resistance traits recorded were survival and time to death after fungal infection in the larval stage and the efficiency of encapsulating a nylon implant by the pupae. The survival of the infected larvae was mainly determined by the species of the host plant. Encapsulation response was not associated with the resistance to the pathogen, suggesting that the host plant affected the pathogen rather than the immune system of the insect. Interestingly, the host plant supporting better larval growth led to inferior resistance to the pathogen, indicating a trade-off between different aspects of host plant quality.

Infectivity of the entomopathogenic fungus Metarhizium anisopliae against workers of the arboreal termite Odontotermes sp. was assayed under laboratory conditions. Test isolates were collected from different sources, including soil from varied locations and insect hosts from the orders Lepidoptera, Coleoptera, Hemiptera and Orthoptera. All the 23 isolates tested and the standard (ARSEF 7413) were pathogenic to the workers of Odontotermes sp. at a concentration of 107 conidia/ml, with mean mortality ranging from 57.5 to 100%. Two of the isolates (Ma2, Ma13) and the standard caused 100% mortality in the termite species. A detailed bioassay was subsequently conducted with the five most promising isolates, namely Ma1, Ma2, Ma13, Ma16 and Ma17, at concentrations ranging from 104 to 107 conidia/ml. The lethal concentrations (LC50) of these isolates ranged from 0.01 to 0.46 × 105 conidia/ml. The average survival time (AST) for the termites treated with the most virulent isolate (Ma2) varied from 4.2 to 5.7 days across the four spore loads, while AST with the standard isolate ranged from 5.3 to 6.3 days. Two of the isolates, Ma2 and Ma13, were found to be significantly more pathogenic to Odontotermes sp. workers than all the others, including the standard.

Field experiments were conducted for two seasons to assess the efficacy of the entomopathogenic fungus Metarhizium anisopliae in the control of termites in maize. Application of the fungus at planting was found to significantly reduce maize lodging and increase grain yield in both seasons. However, data from treatment application at tasselling were not consistent. Our results suggest that a granular formulation of M. anisopliae might be a useful option for the management of termites in the maize agroecosystem.

Conidial suspensions of four isolates each of Beauveria bassiana and Metarhizium anisopliae were evaluated in the laboratory for their virulence to adult Ootheca mutabilis. All the isolates tested were pathogenic to the beetle, but to varying degrees. Three of them, B. bassiana CPD 3 and CPD 10 and M. anisopliae CPD 6 were superior to all other isolates in terms of mortality induced on adult beetle, LT50 and LC50, with B. bassiana CPD 3 having the lowest LC50 value. In feeding assays; consumption by beetles treated with B. bassiana CPD 3 was significantly reduced within 2 days treatment (DAT) and the trend continued until 7 DAT, when all the beetles died. The antifeedant effects of the pathogen on O. mutabilis could partly offset its slow speed of kill, and might play an important role in field control.

The influence of three cultivars of Sorghum bicolor (L.) on the activity of the fungus Metarhizium anisopliae on the stemborer Chilo partellus was investigated in the field and laboratory. Fungal activity in the field varied with the plant cultivar and the inoculum concentration. Larvae fed on different cultivars and inoculated with the fungus in the laboratory did not vary in their susceptibility to the pathogen. However, time to 50% mortality (LT50) of the larvae was shorter in cultivar IS 1044 than in cultivars ICS 3 and ICS 4. Compatibility of the fungus with cultivars is therefore an important consideration when using fungi for the biological control of stemborers.

A technique for infecting adult tsetse with an entomopathogenic fungus was developed and tested in the laboratory. A nitrocellulose filter membrane (Millipore) was used as substrate for retaining conidia after fitration, and a cylindrical plastic tube served as a chamber for the flies. The technique was designed to allow accurate estimation of inoculum on the substrate, thereby permitting comparison of virulence during the screening of fungal pathogens against tsetse flies. Glossina morsitans centralis adults were susceptible to Metarhizium anisopliae at all doses tested, and mortalities were dose dependent. No significant differences in mortalities were observed when flies were exposed for different durations to the pathogen. The number of conidia picked up by flies varied considerably with exposure time and concentration.

Time-specific life tables were constructed for the Mexican beetle, Zygogramma bicolorata Pallister (Coleoptera: Chrysomelidae), which is a promising biological control agent of the Neotropical weed, Parthenium hysterophorus L. (Asteraceae) in and around Bangalore, India. Infertility of eggs (46.00–71.10%) was found to be the key mortality factor, followed by death during the pupal stage (15.76–21.38%), as confirmed by key mortality factor analysis and construction of survivorship curves. No parasitoids or predators were recorded on this insect, while some of the dead pupae/pre-pupae (2.27–17.24%) were found to be infected by Metarhizium anisopliae (Metchnikoff) Sorokin. The high generation trend values (305.88–557.14), give an indication of the biotic potential of this insect, which was found to cause rapid defoliation of the weed under field conditions.