Performance of Three Isolates of Metarhizium anisopliae and Their Virulence against Zeugodacus cucurbitae under Different Temperature Regimes, with Global Extrapolation of Their Efficiency

Abstract

The performance of entomopathogenic fungi in pest control is usually affected by both biotic and abiotic factors. This study aimed to determine the effects of various temperatures (15, 20, 25 and 30 °C) on conidial germination, mycelial growth and conidial density and virulence to the melon fly Zeugodacus cucurbitae of three selected isolates of Metarhizium anisopliae. The three isolates, ICIPE 18, ICIPE 30 and ICIPE 69, had previously been selected in laboratory bioassays. Percentage mortality by the three isolates ranged between 16.25% and 100.0% across the different temperatures. The isolates ICIPE 69 and ICIPE 18 recorded the highest percentage mortality of 96.25% and 100% and the shortest LT50 values of 2.61 and 2.63 days, respectively, at 30 °C. However, at 30 °C, ICIPE 69 produced the highest number of conidia of 90.5 × 107 /mL and was therefore selected for global mapping to predict its efficacy against Z. cucurbitae using the geospatial temperature data layer and the best fitted quadratic model. The map showed that the isolate would be more effective in the tropics than in temperate climates.

Susceptibility of Myzus persicae, Brevicoryne brassicae and Nasonovia ribisnigri to Fungal Biopesticides in Laboratory and Field Experiments

“…Good control in the field is reliant on the ability to deliver a lethal dose of spores to the target and requires favourable environmental conditions including suitable temperatures [39]. Many strains of hypocrealean EPF investigated as biopesticides have an optimum temperature of 25 • C or more [40][41][42][43] and in countries such as the UK, where mean summer (day/night) temperatures are consistently lower than this [44], there is a question of whether EPF biopesticide products are able to perform adequately under field temperature conditions. Finally, moulting of nymphs every few days during development may allow aphids to 'escape' infection from fungal spores that have adhered to the outer cuticle but have not yet grown and penetrated through to the haemocoel [45].…”

Transcriptomic Analysis of the Brown Planthopper, Nilaparvata lugens, at Different Stages after Metarhizium anisopliae Challenge

“…The resistance of N. lugens to many chemical insecticides has received much attention and increased the interest in reducing insecticide use [46][47][48]. Microbial control shows effective potential for replacing/reducing the use of chemical insecticides for the control of insect pests, such as Z. cucurbitae [22], L. migratoria [49], and H. armigera [50]. The entomopathogenic fungus M. anisopliae, as an important biological control agent, can be used to control many insect pests, including the rice pest N. lugens, and suppress populations of this pest in field conditions [30].…”

“…The entomopathogenic fungi Beauveria bassiana and M. anisopliae are the two most commonly used biological control agents against insect pests and have achieved good results [15,16]. For instance, B. bassiana can be used to control insect pests, such as Helicoverpa armigera [17], Atta cephalotes [18], and Alphitobius diaperinus [19], and M. anisopliae can be used to control insect pests such as Locusta migratoria [20], Chironomus riparius [21], Zeugodacus cucurbitae [22], and Meccus pallidipennis [23]. Moreover, these entomopathogenic fungi also show good potential for the control of insecticide-resistant pests, which may be due to their specific infection mechanisms [24][25][26].…”

The African citrus triozid Trioza erytreae Del Guercio (Hemiptera: Triozidae): temporal dynamics and susceptibility to entomopathogenic fungi in East Africa

“…Among the tested isolates, M. anisopliae ICIPE 18 and 69 caused the highest mortalities of more than 80% to T. erytreae adults. Both isolates induced high mortalities in the Tephritid fruit flies, Zeugodacus cucurbitae (Onsongo et al 2019) and the legume pod borer, Maruca vitrata (Tumuhaise 2015) whereas ICIPE 69 has been effective against the false codling moth, Thaumatotibia leucotreta (Mkiga et al 2020), the western flower thrips Frankliniella occidentalis (Niassy et al 2012) and three species of African Tephritid fruit flies (Dimbi et al 2003;Ekesi et al 2002). Given that ICIPE 69 has already been commercialized, extension of labels to T. erytreae upon validation of its efficacy under field conditions would be useful for citrus farmers, especially the small scale farmers.…”

“…It is important to develop and implement safe and sustainable management strategies to control T. erytreae. Biological control using entomopathogenic fungus has been currently identified as a sound alternative management strategy against many insect pests, not only as stand-alone control agents, but also as a component of IPM approaches (Chandler et al 2011;Inglis et al 2001;Mkiga et al 2020;Onsongo et al 2019;Opisa et al 2018;Prince and Chandler 2020).…”