Arthropod predator community associated with soybean gall midge, Resseliella maxima (Diptera: Cecidomyiidae), in Minnesotan soybean fields.

The soybean gall midge, Resseliella maxima Gagné (Diptera: Cecidomyiidae), is a pest that injures soybeans in the Midwest United States. Little is known about the natural enemies of R. maxima or the potential for biological control. Therefore, we performed a 2-yr survey in Minnesota to examine the predator community associated with R. maxima infestations. We found that Orius insidiosus (Say) (Heteroptera: Anthocoridae) and Pterostichus melanarius (Illiger) (Coleoptera: Carabidae) were the most common foliar- and ground-foraging predators, respectively. Some of the commonly encountered predator species were tested in laboratory predation experiments. Harmonia axyridis (Pallas) (Coleoptera: Coccinellidae) and O. insidiosus represented the foliar-foraging predators tested, and H. axyridis consumed significantly more R. maxima larvae than O. insidiosus. Among the ground-foraging predators, 4 carabids were tested. Poecilus lucublandus (Say) (Coleoptera: Carabidae) and Pt. melanarius consumed significantly more R. maxima larvae than Poecilus chalcites (Say) (Coleoptera: Carabidae) and Bembidion quadrimaculatum oppositum (Say) (Coleoptera: Carabidae). We conclude that Pt. melanarius should receive further attention as a potential biological control agent of R. maxima, due to its high abundance in the soybean fields in this study, temporal overlap with the pest, and high propensity to feed on the pest.

Spatial and temporal dynamics of soybean gall midge (Resseliella maxima) parasitism by Synopeas maximum.

BACKGROUND: Soybean gall midge, Resseliella maxima Gagné (Diptera: Cecidomyiidae), is a pest that impacts soybean yield in the Midwest United States. While biological control using parasitoids may be a promising approach for managing this pest, it is crucial to have a deep understanding of parasitism dynamics to ensure effective implementation. We investigated R. maxima parasitism using a combination of three methods: rearing of field-collected hosts, dissection, and molecular assays. RESULTS: We confirmed parasitism of R. maxima by the recently described wasp Synopeas maximum Awad & Talamas (Hymenoptera: Platygastridae) and used our combinatorial approach to observe the spatial and temporal relationships between R. maxima and its parasitoid in the field. The number of R. maxima adults was greater in symptomatic plants on field edges than the field interior, but such a pattern was inconsistent for parasitism rates. Parasitism rates were generally highest early and late in the season, and lower in the middle of the season when the number of R. maxima was highest. CONCLUSION: In Minnesota, overall season-long parasitism rates of R. maxima were low (< 2%). To facilitate a wider investigation of the biological control of R. maxima, we designed a protocol for high throughput DNA extraction and quantitative polymerase chain reaction (qPCR) that can be used across a broader geography. Further research should evaluate how parasitism rates by Synopeas maximum could be promoted in production fields. © 2023 Society of Chemical Industry.

The genome of the soybean gall midge (Resseliella maxima).

The cecidomyiid fly, soybean gall midge, Resseliella maxima Gagné, is a recently discovered insect that feeds on soybean plants in the Midwestern United States. R. maxima larvae feed on soybean stems that may induce plant death and can cause considerable yield losses, making it an important agricultural pest. From three pools of 50 adults each, we used long-read nanopore sequencing to assemble a R. maxima reference genome. The final genome assembly is 206 Mb with 64.88× coverage, consisting of 1,009 contigs with an N50 size of 714 kb. The assembly is high quality with a Benchmarking Universal Single-Copy Ortholog (BUSCO) score of 87.8%. Genome-wide GC level is 31.60%, and DNA methylation was measured at 1.07%. The R. maxima genome is comprised of 21.73% repetitive DNA, which is in line with other cecidomyiids. Protein prediction annotated 14,798 coding genes with 89.9% protein BUSCO score. Mitogenome analysis indicated that R. maxima assembly is a single circular contig of 15,301 bp and shares highest identity to the mitogenome of the Asian rice gall midge, Orseolia oryzae Wood-Mason. The R. maxima genome has one of the highest completeness levels for a cecidomyiid and will provide a resource for research focused on the biology, genetics, and evolution of cecidomyiids, as well as plant-insect interactions in this important agricultural pest.

The Genome of the Soybean Gall Midge ( Resseliella maxima ).

The cecidomyiid fly, soybean gall midge, Resseliella maxima Gagné, is a recently discovered insect that feeds on soybean plants in the Midwest US. Resseliella maxima larvae feed on soybean stems which may induce plant death and can cause considerable yield losses, making it an important agricultural pest. From three pools of 50 adults each, we used long-read nanopore sequencing to assemble a R. maxima reference genome. The final genome assembly is 206 Mb with 64.88X coverage, consisting of 1009 contigs with an N50 size of 714 kb. The assembly is high quality with a BUSCO score of 87.8%. Genome-wide GC level is 31.60% and DNA methylation was measured at 1.07%. The R. maxima genome is comprised of 21.73% repetitive DNA, which is in line with other cecidomyiids. Protein prediction annotated 14,798 coding genes with 89.9% protein BUSCO score. Mitogenome analysis indicated that R. maxima assembly is a single circular contig of 15,301 bp and shares highest identity to the mitogenome of the Asian rice gall midge, Orseolia oryzae (Wood-Mason). The R. maxima genome has one of the highest completeness levels for a cecidomyiid and will provide a resource for research focused on the biology, genetics, and evolution of cecidomyiids, as well as plant-insect interactions in this important agricultural pest.