Control of plant sap-sucking insects using entomopathogenic fungi Isaria fumosorosea strain (Ifu13a)

Abstract

Poslušná J. Plachká E., Mazáková J. (2018): Influence of selected fungicides registered in the Czech Republic for winter oilseed rape on in vitro Sclerotinia sclerotiorum mycelial growth. Plant Protect. Sci., 54: 101-110.The baseline sensitivity of 55 isolates of Sclerotinia sclerotiorum, collected from oilseed rape in 6 regions of the Czech Republic, to selected fungicides was determined during the period 2013-2015. One single-component fungicide -Horizon (tebuconazole), and four multicomponent fungicides -Pictor (boscalid, dimoxystrobin), Efilor (boscalid, metconazole), Prosaro 250 EC (prothioconazole, tebuconazole), and Propulse (fluopyram, prothioconazole), were chosen as these are commonly used locally. The effect of each fungicide on the in vitro pathogen radial mycelial growth and EC 50 values for the respective fungicides were determined. The following MIC values were estimated; for the fungicides Horizon 250 EW, Efilor, and Propulse the mean MIC values ranged between 0.125 and 0.250 µl/ml, for Prosaro 250 EC ranged between 0.0625 and 0.125 µl/ml, and for Pictor ranged from 0.00781 to 0.01562 µl/ml. No strains of S. sclerotiorum resistant to the tested fungicides were detected and the growth of all isolates was fully inhibited at concentrations corresponding to their registered dose rates. The highest fungicidal efficacy on the collected S. sclerotiorum isolates was recorded for Pictor, followed by Prosaro 250 with an EC 50 value 0.05856 µl/ml and then the remaining fungicides Propulse, Efilor, and Horizon 250 EW (EC 50 values 0.07277, 0.07221, and 0.08519 µl/ml, respectively).

The Efficacy of Entomopathogenic Fungi for Antestia Bugs (<i>Antetiopsis intircata</i>: Pentatomidea, Hemimptera) Control

“…This is in-line with Tamiru et al who reported PPRC-56 and PPRC-2 recorded higher mortality of antestia bug at higher concentration [44]. The study agreed with Sanjaya et al who found the maximum mortality of the tested insect species at higher concentration (1×10 8 conidia/ml) [40,47,56]. Muller documented the infection and killing speed of Locuslana pardalina (Walker) observed the highest mortality at highest concentration while mortality decreased as concentrations decrease [57].…”

“…Similarly, Bugti et al reported that dose dependency in fungal disease normally indicates a higher density of conidia and often results in a faster control of targeted insects [56]. This study is also in-line with Younas et al, who showed Beauveria spp.…”

“…All the fungal products varied in ability to infect June beetle larvae, and their impact on mortality largely depended on the conidial concentrations applied and the elapsed time after application [45]. On other hand, Bugti et al reported that to control large insect pest populations higher conidial concentrations are more effective than lower concentrations to avoid pest populations reaching economic injury levels [56]. Mouatcho also indicated that mortality rates are associated with length of exposure to conidia because increasing length of exposure increases the potential for acquiring a lethal fungal infection [42].…”

Control of sweet potato whitefly (Bemisia tabaci) using entomopathogenic fungi under optimal and suboptimal relative humidity conditions

“…14,15 Several studies have investigated the use of EPFs against Bemisia tabaci in both glasshouse and field settings, but their optimum efficacy against the pest has been reported to be inconsistent. 3,16 For instance, Aschersonia aleyrodis, a highly specific EPF, was found to alter the survival of first, second, and third nymphal instar of Bemisia tabaci at 1 × 10 7 conidial/mL in laboratory bioassay but showed weak sublethal effects on the nymphal instars in the open environment. 11 In addition, Bemisia tabaci populations, reared on cucumber and eggplants, were reported to be less susceptible to I. fumosorosea treatments at ≤ 5 × 10 6 conidial/mL.…”

“…Several studies have investigated the use of EPFs against Bemisia tabaci in both glasshouse and field settings, but their optimum efficacy against the pest has been reported to be inconsistent 3 , 16 11 .…”