Field Efficacy of Entomopathogenic Fungi and Nematodes Targeting Caged Last-Instar Plum Curculio (Coleoptera: Curculionidae) in Michigan Cherry and Apple Orchards

Abstract

The plum curculio (Conotrachelus nenuphar Herbst) is a key pest of pome and stone fruit in eastern North America. We tested the efficacy of five pathogens over the course of three seasons in 10 Michigan apple and cherry orchards, with introductions of larvae to caged pots containing pathogen-treated soil. The nematode Steinernema riobrave was the most effective pathogen in the 2 yr it was tested, but only in soils with the highest sand content (81-88%) and when it was applied 1 h or 5 d after last instars of plum curculio. S. carpocapsae in an organic formulation was less effective, but significantly reduced plum curculio emergence in 1 yr of the study when applied 3 d before C. nenuphar larvae were introduced. Beauveria bassiana was effective in only 1 of the 3 yr it was tested, only in soils with lower sand content, and only when it was introduced within 1 h of plum curculio larvae. Metarhizium anisopliae and Heterorhabditis bacteriophora were ineffective. Michigan orchards may require sprinkler irrigation coupled with precise timing recommendations and oviposition monitoring to enhance entomopathogen application efficacy against soil-dwelling last instars.

Elucidating the Common Generalist Predators of Conotrachelus nenuphar (Herbst) (Coleoptera: Curculionidae) in an Organic Apple Orchard Using Molecular Gut-Content Analysis

“…Predation studies in the field and the laboratory provide evidence that biocontrol is an important component of pest management for orchard systems [ 16 ]. In addition, entomopathogenic fungi and nematodes show efficacy for biocontrol of apple pests [ 31 , 32 ]. However, little is known about the food webs in these systems and our data provide much needed information on elucidating this important aspect.…”

Integration of Entomopathogenic Fungi into IPM Programs: Studies Involving Weevils (Coleoptera: Curculionoidea) Affecting Horticultural Crops

“…Moderate (60–80%) to high (>80%) mortality of weevils such as C. nenuphar , C. caryae , C. elephas and C. nucum was obtained after treatment with virulent isolates [ 209 , 210 , 211 , 212 ], Mycotrol ® and Naturalis ® [ 213 , 214 , 215 ] but only low (<60%) to moderate (60–80%) levels of control were achieved when adult weevils or larvae (e.g., C. caryae ) were introduced four days after EPF application [ 208 , 216 ]. Low to moderate mortality of C. caryae [ 204 , 217 , 218 ], C. sikkimensis [ 206 , 207 ], C. nucum [ 219 ] and C. nenuphar [ 220 ] was also achieved in the field after the application of virulent EPF isolates or commercial products (Beaupro ® , Metapro ® and Botanigard ® ), suggesting that the weevils moved onto the ground several days after fungal application [ 208 , 216 ]. To mitigate poor infectivity of EPF in the field, Shapiro-Ilan and Brown [ 215 ] suggested that using earthworms ( Lumbricus terrestris ) as phoretic hosts for B. bassiana in the soil could improve fungal infectivity in comparison to the more traditional applications of EPF directly to the topsoil.…”

“…It is difficult to draw direct comparisons between EPF and EPNs because their mode of action and their effective concentrations are different. Studies show that when EPF or EPNs are applied on the topsoil before introducing weevil larvae, the EPNs provide better control of both C. caryae [ 226 ] and C. nenuphar [ 220 ] compared to EPF. However, when larvae are immersed in the fungal suspension and compared with EPNs (applied on the topsoil), the mortality of both C. elephas [ 227 ] and C. nenuphar [ 203 ] caused by EPF was always higher than that caused by EPNs.…”

Agroecological management of a soil‐dwelling orthopteran pest in vineyards

“…Cohn, 1872, Serratia sp. Bizio, 1823) (Shah & Pell, ; Ansari et al ., ; Lacey & Shapiro‐Ilan, ; Jackson & Jaronski, ; Pereault et al ., ). However, this strategy has some limitations, such as entomopathogenic and microbial products being unable to reach the target pest in the soil, as well as the failure of most applied microbes to survive in the soil environment (Jackson, ).…”