Compatibility of Entomopathogenic Nematodes with Chemical Insecticides for the Control of Drosophila suzukii (Diptera: Drosophilidae)

Abstract

The spotted-wing drosophila, Drosophila suzukii (Matsumura) (Diptera: Drosophilidae), is a pest that reduces the productivity of small fruits. Entomopathogenic nematodes (EPNs) and chemical insecticides can suppress this pest, but the compatibility of the two approaches together requires further examination. This laboratory study evaluated the compatibility of Steinernema brazilense IBCBn 06, S. carpocapsae IBCBn 02, Heterorhabditis amazonensis IBCBn 24, and H. bacteriophora HB with ten chemical insecticides registered for managing D. suzukii pupae. In the first study, most insecticides at the recommended rate did not reduce the viability (% of living infective juveniles (IJs)) of S. braziliense and both Heterorhabditis species. The viability of S. carpocapsae was lowered by exposure to spinetoram, malathion, abamectin, azadirachtin, deltamethrin, lambda-cyhalothrin, malathion, and spinetoram after 48 h. During infectivity bioassays, phosmet was compatible with all the EPNs, causing minimal changes in infectivity (% pupal mortality) and efficiency relative to EPN-only controls, whereas lambda-cyhalothrin generally reduced infectivity of EPNs on D. suzukii pupae the most, with a 53, 75, 57, and 13% reduction in infectivity efficiency among H. bacteriophora, H. amazonensis, S. carpocapsae, and S. brazilense, respectively. The second study compared pupal mortality caused by the two most compatible nematode species and five insecticides in various combinations. Both Heterorhabditis species caused 78–79% mortality among D. suzukii pupae when used alone, and were tested in combination with spinetoram, malathion, azadirachtin, phosmet, or novaluron at a one-quarter rate. Notably, H. bacteriophora caused 79% mortality on D. suzukii pupae when used alone, and 89% mortality when combined with spinetoram, showing an additive effect. Novaluron drastically reduced the number of progeny IJs when combined with H. amazonensis by 270 IJs and H. bacteriophora by 218. Any adult flies that emerged from EPN–insecticide-treated pupae had a shorter lifespan than from untreated pupae. The combined use of Heterorhabditis and compatible chemical insecticides was promising, except for novaluron.

Laboratory Evaluation of Indigenous and Commercial Entomopathogenic Nematodes against Red Palm Weevil, Rhynchophorus ferrugineus (Coleoptera: Curculionidae)

“…EPN isolation from soil typically requires sampling and isolation procedures, such as baited traps containing G. mellonella [13]. Due to their reliance on insect aggregation, EPNs are more likely to be found in clusters in the soil rather than dispersed uniformly [36].…”

“…Pesticides, while ineffective against RPW infestations, negatively impact biodiversity and the ecosystem [11]. Biocontrol agents such as entomopathogenic nematodes (EPNs) can be utilized in integrated pest management because ENPs are compatible for use with chemical insecticides [12,13] to control RPW and safeguard the environment [14][15][16].…”

Impact of Abiotic and Biotic Environmental Conditions on the Development and Infectivity of Entomopathogenic Nematodes in Agricultural Soils

“…This is due to the rapid development of the nematode population in the host and the rapid destruction of its body. Of the dozens of beetle species in which the larvae are sensitive to the nematode S. carpocapsae, only a few have been successfully studied with respect to natural invasion, namely, Zabrus tenebrioides Goeze (Coleoptera: Carabidae) (the wheat ground beetle) [237], Agriotes lineatus Linnaeus (Coleoptera: Elateridae) (the lined click beetle) [238], Melolontha melolontha Linnaeus (Coleoptera: Scarabaeidae) (the cockchafer), Drosophila suzukii Matsumura (Diptera: Drosophilidae), and Melolontha hippocastani Fabricius (Coleoptera: Scarabaeidae) (the forest cockchafer) [10,239]. It has also been possible to isolate S. feltiae from flies [240] and Heterorhabditis heliothidis Khan, Brooks and Hirschmann (Rhabditida: Heterorhabditidae) from Helicoverpa zea Boddie (Lepidoptera: Noctuoidea) (the corn earworm) [241].…”

“…Tens to hundreds of thousands of new EPNs can be produced from a single infested insect host and then travel to infest new hosts, thus theoretically allowing EPNs to persist in the field throughout the growing season [ 3 , 4 ]. EPNs are compatible with most other agrochemicals, with which they can be co-applied [ 5 , 6 , 7 , 8 , 9 , 10 , 11 ], and have minimal undesirable side effects on nontarget organisms. This is the case with chemical pesticides, which lead to soil contamination and bioaccumulation [ 4 , 12 ].…”