Evaluation of Locally Isolated Entomopathogenic Fungi against Multiple Life Stages of Bactrocera zonata and Bactrocera dorsalis (Diptera: Tephritidae): Laboratory and Field Study

Abstract

Fruit flies including Bactrocera zonata and B. dorsalis (Diptera: Tephritidae) are considered major pests of orchard systems in Pakistan. This study evaluated the laboratory virulence, sub-lethal effects, horizontal transmission, greenhouse, and field-cage efficacy of locally isolated entomopathogenic fungi (EPF) against B. zonata and B. dorsalis. In virulence assays against third instars and adults, all 21 EPF isolates (Beauveria bassiana and Metarhizium anisopliae) tested were pathogenic and caused varying levels of mortality to the fruit flies. Based on the initial screening, four isolates (B. bassiana WG-21 and WG-18 and M. anisopliae WG-07 and WG-02) were selected for further study. The isolate WG-18 was the most virulent against larvae and adults of B. zonata and B. dorsalis followed by WG-21, WG-02, and WG-07. In both species, adults were more susceptible than larvae to all isolates, and pupae were the least susceptible. Isolates WG-18 and WG-21 strongly decreased female fecundity and fertility, the highest adult and larval mortality, and longest developmental time of larvae and pupae. Fungal conidia were disseminated passively from infected to healthy adults and induced significant mortality, particularly from infected males to non-infected females. In greenhouse and field-cage experiments, WG-18 and WG-21 were the most effective isolates in reducing adult emergence when applied to larvae and pupae of both fruit fly species. Our results indicate that B. bassiana isolates WG-18 and WG-21 were the most virulent against multiple life stages of B. zonata and B. dorsalis, and also exerted the strongest sub-lethal effects.

Combined application of entomopathogenic nematodes and fungi against fruit flies, Bactrocera zonata and B. dorsalis (Diptera: Tephritidae): laboratory cups to field study

“…Two fungal isolates ( Beauveria bassiana WG‐18 and Metarhizium anisopliae WG‐02) were selected based on previous virulence evaluations 54 . To culture conidia, EPF were inoculated on potato dextrose agar (PDA) (BD‐Difco) in Petri plates (100 mm) (Thermo Fisher Scientific, Waltham, MA, USA), wrapped with parafilm and incubated at 25 °C with 14 h:10 h, light:dark photoperiod for 7–10 days.…”

“…Two fungal isolates (Beauveria bassiana WG-18 and Metarhizium anisopliae WG-02) were selected based on previous virulence evaluations. 54 To culture conidia, EPF were inoculated on potato dextrose agar (PDA) (BD-Difco) in Petri plates (100 mm) (Thermo Fisher Scientific, Waltham, MA, USA), wrapped with parafilm and incubated at 25 °C with 14 h:10 h, light:dark photoperiod for 7-10 days. After incubation, the dry conidia were harvested with a sterile scalpel and placed inside 50-mL sterile falcon tubes that contained 30 mL of 0.05% Silwet L-77 solution with the addition of eight glass beads to facilitate agitation.…”

Efficacy of Entomopathogenic Trichoderma Isolates against Sugarcane Woolly Aphid, Ceratovacuna lanigera Zehntner (Hemiptera: Aphididae)

“…Insect fungal diseases are common and widespread. More than 700 fungal species of 90 genera have the ability to cause diseases [6,7] at all the development phases of a wide range of insect pests in nursery, storage, greenhouses, and field conditions [8][9][10][11]. The pathogenicity of entomopathogenic fungi depends on the fungal species and the virulence of the strain [12].…”

Sublethal Effects of Beauveria bassiana Strain BEdy1 on the Development and Reproduction of the White-Backed Planthopper, Sogatella furcifera (Horváth) (Hemiptera: Delphacidae)

“…According to our results, when WBPH nymphs were treated with a sublethal dose of B. bassiana , which had adverse effects on the growth, development and reproduction of the parent and offspring, consistent with previous research results [ 38 ], the longevity of Nilaparvata lugens (Stål) (Homoptera: Delphacidae) parental females sublethal treated with B. bassiana NJBb2101 did not change the longevity significantly compared with the control, but the fecundity of F 0 females decreased. The development duration of the offspring nymphs of WBPH treated with B. bassiana BEdy1 LC 25 was significantly prolonged, and the average fecundity of F 1 females was significantly lower than that of the control; similarly, the effect of entomopathogenic fungus on N. lugens , Aedes albopictus (Skuse) (Diptera: Culicidae), Brevicoryne brassicae (L.) (Hemiptera: Aphididae), Bactrocera zonata (Saunders) (Diptera: Tephritidae) and Bactrocera dorsalisi (Hendel) (Diptera: Tephritidae) was found to be that the nymphal stage was prolonged and fecundity was reduced compared with those of the control [ 38 , 39 , 40 , 41 ]. However, the difference is that neither Metarhizium anisopliae (Metschn.)…”