Delia Platura Research Articles

Validation of degree day threshold for Delia platura first emergence in New York State

Seedcorn maggot (Delia platura) is a globally distributed agricultural pest that feeds on the germinating seeds of economically important crops, including corn and beans. The larvae cause underground damage, which can lead to stand loss. For decades, D. platura has been managed using insecticide-coated seeds, but following the ban on neonicotinoid-coated corn, soy, and wheat seeds in New York State, this practice will no longer be available. Degree day models have been used to predict the emergence of the overwintering generation of agricultural pests since the late 1900s. However, the terminology used in the literature to distinguish degree day thresholds for first emergence and peak emergence is unclear, and previous reports of a 360 degree day emergence threshold did not align with field observations. In 2023, we captured the first emergence at four sites, and in 2024, we monitored adult D. platura at 25 sites in New York State. We observed the first adult emergence between 52 and 197 accumulated degree days (98 ± 7 degree days, mean ± 1 SE) using a biofix of January 1st, confirming that in New York State, D. platura emergence is earlier than previously reported values. Additionally, we note adult activity during December 2023 and January 2024, suggesting that warming winters may impact our ability to predict pest emergence. We propose future models should incorporate both degree day information and other regionally specific factors known to impact pests, including farm management, soil conditions, and landscape composition, for more accurate predictions.

A Nematode Isolate, Oscheius Tipulae, Exhibiting a Wide Entomopathogenic Spectrum and its Application to Control Dipteran Insect Pests.

An entomopathogenic nematode, Oscheius tipulae, was isolated from a soil sample. The identification of this species was supported by morphological and molecular markers. The nematode isolate exhibited pathogenicity against different target insects including lepidopteran, coleopteran, and dipteran insects. The virulence of this nematode was similar to that of a well-known entomopathogenic nematode, Steinernema carpocapsae, against the same insect targets. A comparative metagenomics analysis of these two nematode species predicted the existence of a combined total of 272 bacterial species in their intestines, of which 51 bacterial species were shared between the two nematode species. In particular, the common gut bacteria included several entomopathogenic bacteria including Xenorhabdus nematophila, which is known as a symbiotic bacterium to S. carpocapsae. The nematode virulence of O. tipulae to insects was enhanced by an addition of dexamethasone but suppressed by an addition of arachidonic acid, suggesting that the immune defenses of the target insects against the nematode infection is mediated by eicosanoids, which would be manipulated by the symbiotic bacteria of the nematode. Unlike S. carpocapsae, O. tipulae showed high virulence against dipteran insects including fruit flies, onion flies, and mosquitoes. O. tipulae showed particularly high control efficacies against the onion maggot, Delia platura, infesting the Welsh onion in the rhizosphere in both pot and field assays.

Effects of methyl jasmonate seed treatments on adult oviposition preference and larval performance of seed corn maggot (Delia platura) in corn (Zea mays).

Eliciting host plant resistance using plant hormones such as jasmonates has the potential to protect seeds and seedlings against insect pests; however, several hurdles exist for adapting it for pest management. This includes determining a dose that promotes resistance without limiting plant growth, an application method that growers could use, and ensuring the plants are responsive in the abiotic conditions when the pest occurs. In laboratory and field assays, we tested if treating corn seeds with multiple concentrations of methyl jasmonate would reduce the preference of ovipositing seed corn maggot adults and the performance of larvae feeding on seeds. We found that corn seeds soaked in aqueous 0.2 mM methyl jasmonate solution showed marginally lower seedling growth, but the adult oviposition preference was ~60% lower on these seeds compared to control water-soaked seeds. Seeds that were treated with methyl jasmonate using a conventional polymer-based seed coating showed no effect on seedling growth but reduced adult oviposition preference. In no-choice bioassays with adult flies, we found reduced oviposition on seeds soaked with aqueous methyl jasmonate compared to controls. Larval survival to pupation was also lower in methyl jasmonate-treated seeds. Lastly, the methyl jasmonate-induced resistance also occurred at the lower temperatures typical of the spring soil conditions when this fly is most damaging. Methyl jasmonate seed treatment in aqueous solution or using conventional polymer-based technology, has the potential to deter adult oviposition and reduce maggot performance in spring temperature conditions with minor effects on seed germination and growth. © 2024 Society of Chemical Industry.

Degree-day models for predicting adult Delia platura (Diptera: Anthomyiidae) spring flight and first emergence in New York State.

The seedcorn maggot, Delia platura (Meigen), is a pest affecting many crops, including corn. The early spring emergence of adults and belowground seed damage by maggots leave no room for rescue treatments during the short growing season in New York State. Degree-day (DD) models play a crucial role in predicting insect emergence and adult peak activity and are essential for effective pest management. The current D. platura DD model was launched on the Network for Environment and Weather Applications (NEWA) in 2022, using existing scientific literature from other North American regions. The NEWA model predicted adult D. platura first emergence at an average of 471 (39°F) DD in 2022. To gain an accurate and precise understanding of D. platura adult spring emergence and activity, we used interpolated temperature data to calculate the DD for each specific location where adults were captured in the field. DD calculations were performed using the average method, setting a biofix on January 1st and a base temperature of 39°F. In 2023, overwintering adults emerged at an average of 68 DD, and in 2022, adult activity was registered at an average of 282 DD. Accurately predicting the emergence of D. platura could contribute to informing integrated pest management strategies that incorporate timing and cultural practices over chemical solutions to protect crops and the environment.

Reproductive compatibility of two lines of Delia platura

AbstractAccurate identification of agricultural pests is a major component of integrated pest management. The seedcorn maggot, Delia platura (Meigen) (Diptera: Anthomyiidae), is a cosmopolitan polyphagous pest species that may be found in high numbers in numerous crops. Two morphologically identical genetic lines of D. platura (H and N) with distinct distributions were recently identified. To date, no study has investigated the reproductive compatibility of the two lines and thus the possibility that they may actually be two unique biological entities. A previous study described the reproductive traits of the two lines and suggested that H‐line females are highly selective toward the male with which they mate, pointing to a possible pre‐mating isolation mechanism between the lines. Using laboratory‐reared colonies originating from the Montérégie region in Québec, Canada, this study investigates the reproductive compatibility of the two D. platura lines. We found that only one of 30 H‐line females was inseminated by an N‐line male, further suggesting mate choice as a pre‐mating isolation mechanism between the lines. However, N‐line females were readily inseminated by H‐line males, suggesting a lack of pre‐mating isolation in this type of cross. The eggs laid by N‐line females mated with H‐line males had a lower hatching rate than the ones laid by females of intraline crosses, suggesting either post‐mating pre‐zygotic or post‐zygotic partial isolation. However, the larvae that did hatch had a comparable developmental success to those from intraline crosses in terms of survival and developmental time from larval hatching to adult emergence, pupal mass, and adult sex ratio, suggesting a lack of post‐zygotic isolation for these life stages. Considering the different biological traits of the two lines, we suggest the use of the ‘biotype’ terminology to designate the two biological entities and discuss their implications for integrated pest management.

Entomocomplex of Radish in Open-field Cultivation in the Central Part of the Right-Bank Forest-Steppe of Ukraine

Goal. To specify the species composition of insect pests affecting radish (Raphanus sativus (L.) convar. radicula (Pers) Sazon.) in open-field cultivation conditions in the central part of the Right-Bank Forest-Steppe of Ukraine.
 Methods. The study was conducted following commonly accepted methods in entomology and vegetable growing. From 2008 to 2022, we investigated the species diversity of insects, dominant species, their abundance, and the structure of the harmful entomocomplex in radish crops grown in open-field conditions on household plots and farms in the Cherkasy region.
 Results. In the entomological complex of radish, 59 species of phytophagous insects from 20 families and 8 orders were identified: Coleoptera — 29%, Lepidoptera — 27%, Homoptera — 15%, Diptera — 10%, Orthoptera — 9%, Thysanoptera — 5%, Hemiptera — 3%, Hymenoptera — 2%. Sixteen dominant species of phytophagous insects were found in radish crops, including diamondback moth (Plutella maculipennis Curt.), crucifer flea beetles (Phyllotreta cruciferae Goeze), striped flea beetle (Phyllotreta undulata Kutsch.), cabbage white butterfly (Pieris brassicae L.), turnip moth (Agrotis segetum Denis&Schiff.) and owlet moth (Lacanobia oleracea L.), crucifer shield bug (Eurydema ventralis Kol.), cabbage aphid (Brevicoryne brassicae L.), spring root maggot (Delia brassicae Bouche) and summer root maggot (Delia floralis Fallen), seedcorn maggot (Delia platura Mg.), sawfly (Athalia rosae L.), stem weevil (Ceutorrhynchus quadridens Panz.), tobacco thrips (Thrips tabaci Lindeman), turnip sawfly (Entomoscelis adonidis Pallas), and crucifer webworm (Evergestis extimalis Scop.). Through multi-year studies, the periods of insect damage corresponding to radish developmental stages were determined. The most critical damage to radish plants by harmful insects occurred during the initial stages of development (ВВСН 0—9) and from emergence to the growth and formation of the root crop (BBCH 42—48).
 Conclusions. It was found that among the identified phytophagous insects in radish crops, the most economically significant damage was caused by the cabbage aphid, crucifer flea beetles, striped flea beetle, spring cabbage fly, and seedcorn maggot. On average over the research period (2008—2022), the largest areas of radish crops were infested by the diamondback moth, crucifer flea beetles, and striped flea beetle, cabbage white butterfly, winter and owlet moths, cabbage shield bug, and cabbage aphid, ranging from 5% to 80%, reaching a maximum in some years up to 60—100% of the area.

Enhancement of an entomopathogenic fungal virulence against the seedcorn maggot, Delia platura, by suppressing immune responses with a bacterial culture broth of Photorhabdus temperata subsp. temperata.

In Korea, there are two maggot species in the Delia genus that commonly infest the roots and stems of the Welsh onion, thus causing serious economic damage on the crop at the seedling stage. In this study, the seedcorn maggot (Delia platura) was detected in onion fields in two different localities in Korea. After overwintering, maggot infestations occurred throughout the entire growing seasons from transplantation to harvest, but their specific patterns of occurrence varied in the two localities examined. Entomopathogenic fungi induced significant virulence against the maggot larvae, in which a strain of Beauveria bassiana was effective, though it exhibited limited mortality in its insecticidal activity. To enhance this insecticidal activity, a culture broth from an entomopathogenic bacterium, Photorhabdus temperata temperata (Ptt), was added to B. bassiana treatment. The addition of Ptt broth significantly increased the insecticidal activity of B. bassiana in a dose-dependent manner. To elucidate this enhancement in insecticidal activity, the immunosuppressive activity of Ptt broth was assessed by identifying the immune responses of the seedcorn maggots. The seedcorn maggots possessed at least three different hemocytes with plasmatocytes, crystal cells, and lamellocytes. These hemocytes exhibited nodule formation in response to the fungal infection. In addition to the cellular immunity, the maggots exhibited inducible expressions of antimicrobial peptide (AMP) genes such as cecropin and defensin. The addition of Ptt broth suppressed the nodule formation and the AMP expressions in response to the fungal infection. Altogether, this study demonstrated the innate immune responses in a non-model insect, D. platura, along with the application of immunosuppression to develop a highly efficient biological control by enhancing the virulence of B. bassiana.

Seedcorn maggot response to planting date, cover crops, and tillage in organic cropping systems.

Seedcorn maggot, Delia platura (Meigen) (Diptera: Anthomyiidae), is an economically important early-season pest of corn and soybean in the United States. Adult seedcorn maggot is attracted to decomposing plant residues for oviposition, creating potential management issues where growers typically use tillage to incorporate fertility amendments and to create a seedbed. The use of growing degree-day models to time planting dates is an important tool for effectively managing this pest, but their use has not been examined in organic crop production. Here, we report the results of experiments to determine the effects of cover crops, tillage, and relative planting date on seedcorn maggot in corn and soybean in 2 experiments: The first during the transition to organic from conventional management and the second during the 3 yr following organic certification in central Pennsylvania, United States. Overall, delaying the planting date by 1-2 wk reduced fly emergence in corn, but not in soybean in both experiments. Seedcorn maggot emergence was also consistently greater in corn than in soybean, with 6 times more flies in corn than in soy. About 15 times more seedcorn maggot flies emerged from corn in treatments in which cover crops were managed with tillage compared to treatments in which cover crops were terminated with a roller-crimper followed by no-till planting of corn. Fly emergence was negatively related to the proportion of legumes in the cover crop mixture preceding corn. These results can help inform soil, cover crop, and crop decisions for organic growers in the Mid-Atlantic United States.

Monitoring adult Delia platura (Diptera: Anthomyiidae) in New York State corn fields using blue and yellow sticky cards

Abstract The seedcorn maggot, Delia platura (Meigen; Diptera: Anthomyiidae), is a polyphagous pest that feeds on decaying organic matter, seeds, and seedlings of several crops, including corn (Zea mays L.; Poaceae). In corn and soybeans, D. platura is a sporadic pest. To make recommendations as to which sticky trap color is more effective at trapping D. platura, we sampled 52 corn fields in four regions across New York State with blue and yellow sticky cards. More adults were caught with blue (77.6 %) than yellow cards (22.4 %). The same pattern was observed when all individuals were combined and separated by females and males. The higher captures with blue sticky cards were consistent across space and time, indicating the effectiveness of trapping adults and monitoring them at a regional scale.

Evaluation of several common seed treatments for efficacy against seedcorn maggot in sweet corn, 2023

Evaluation of several common seed treatments for efficacy against seedcorn maggot in sweet corn, 2023

Diptera Pests Occurring on Vegetable Crops in Poland

Abstract In Poland, the share of Diptera in the species composition of the harmful entomofauna occurring on vegetable crops ranges from 20 to 25%. They occur on all vegetables grown in Poland (over 80 species and botanical varieties). Since the systematic registration of pests inhabiting crops in Poland in 1919, over 70 species of flies have been listed as pests of vegetable plants. Species from three families dominate in terms of population and numbers: Anthomyiidae with 12 species (Delia radicum, on early and late cultivars of cruciferous vegetables, mainly broccoli, cauliflower, white cabbage, kohlrabi, and radishes; Delia platura occurs annually on bean and cucumber; Delia antiqua on onion and garlic; and Pegomya hyoscyami on beetroot), Cecidomyiidae with 10 species (two species dominate, Contarinia nasturtii and Dasineura napi, on cruciferous vegetables), and Agromyzidae with 23 species (Liriomyza bryoniae on cucumbers, tomatoes, and peppers, and Phytomyza gymnostoma on leeks). Short-term, gradational occurrence of some dominant species was found, including Botanophila gnava (lettuce), Chamaepsila rosae (carrot, parsley), Delia platura (asparagus, bean), Delia radicum (broccoli, cauliflower, kohlrabi, radishes, white cabbage), Phytomyza gymnostoma (leek), Oscinella frit (corn), and Suillia lurida (garlic). However, they did not affect the level of plant production in the following years of cultivation. Apart from phytophagous species, taxa with a different trophic structure are common. These are copro-, necro-, sapro-, and zoophagous species. The most numerous were flies from the Drosophilidae family (Drosophila busckii, Drosophila limbata, Scaptomyza pallida, Fanniidae (Fannia canicularis, Fannia scalaris), Heleomyzidae (Tephrochlamys tarsalis), and Muscidae (Muscina levida, Muscina stabulans, Phaonia trimaculata). Natural enemies of insects play an important role in vegetable agrocenoses. Species belonging to the order of Coleoptera beetles (Carabidae and Staphylinidae), Syrphidae, Tachinidae, and Muscidae, mainly Phaonia trimaculata larvae, play the most important role in reducing the number of Diptera. In addition, the number of phytophages is limited by other organisms, e.g., Diplopoda, Nematoda, Arachnida, and pathogens of viral, bacterial, and fungal origin.

Sticky traps and water pan traps to monitor Delia planipalpis (Diptera: Anthomyiidae), an emerging pest of broccoli in Mexico

The radish fly, Delia planipalpis (Meigen), is an emerging pest that infests broccoli in Mexico. Females oviposit near the stem of broccoli plants or in the inflorescence. Effective monitoring systems are necessary for the development of integrated pest management programs against this insect. Laboratory and field experiments were performed to determine the fly's responses to stick traps and water pan traps. Both yellow and blue sticky traps captured significantly more males than females. Yellow traps captured higher numbers of D. planipalpis than blue traps, but with a lower capture of Delia platura (Stein) and other non-target insects. Sticky traps or yellow water pan traps captured similar numbers of D. planipalpis in broccoli crops, but water pan traps captured significantly more females than sticky traps. The addition of the host attractant allyl isothiocyanate significantly increased the capture of flies when used in sticky traps but not in water pan traps. Sticky traps or water pan traps could be used for surveillance of D. planipalpis. Water pan traps require more servicing time as specimens need to be dried before identification. In contrast, sticky traps allow rapid identification of insects, but some insects become damaged on the sticky surface.

New records, host, and plant symptoms description of the recently reported Delia sanctijacobi (Bigot) (Diptera: Anthomyiidae) in Brazil

Delia Robineau-Desvoidy, composed of flies popularly known as root maggot flies, is a diverse genus with unclear delimitation. It comprises polyphagous species and some important agricultural pests. Delia sanctijacobi (Bigot) is native to South America, occurring in Argentina, Brazil, Chile, Peru, and Uruguay; the larvae are commonly known as “potato worms” and have been misidentified as Delia platura (Meigen) in Brazil. Delia sanctijacobi attacks the seeds and seedlings of several plants of commercial importance. We present new geographic records of D. sanctijacobi in Brazil and describe the damage caused by their larvae on commercial bean and onion in Paraná and Santa Catarina between 2019-2022. Delia Robineau-Desvoidy, composed of flies popularly known as root maggot flies, is a diverse genus with unclear delimitation. It comprises polyphagous species and some important agricultural pests. Delia sanctijacobi (Bigot) is native to South America, occurring in Argentina, Brazil, Chile, Peru, and Uruguay; the larvae are commonly known as “potato worms” and have been misidentified as Delia platura (Meigen) in Brazil. Delia sanctijacobi attacks the seeds and seedlings of several plants of commercial importance. We present new geographic records of D. sanctijacobi in Brazil and describe the damage caused by their larvae on commercial bean and onion in Paraná and Santa Catarina between 2019-2022.

Occurrence and management of two emerging soil-dwelling pests ravaging cabbage and onions in Kenya

Cabbage and Onion production in sub-Saharan Africa face numerous pest constraints that needs to be overcome to feed the rapidly growing population. This study aimed to establish the occurrence, incidence, and severity of soil-dwelling pests of cabbage and onions, and current management practices in five Counties of Kenya. Our findings revealed that most farmers grew hybrid vegetables on a small scale, which were highly dominated by various pest species (Delia platura, Maladera sp., and Agriotes sp. for cabbage and Atherigona orientalis and Urophorus humeralis for onion. The occurrence, incidence and severity of the various pest species on both crops varied considerably. Over 95% of the farmers relied on synthetic insecticides, which were applied weekly or bimonthly with limited success. Our findings demonstrate that invasive and polyphagous A. orientalis and D. platura were the most devastating pests of onion and cabbage without effective control options. Therefore, effective, sustainable, and affordable management strategies are required to control the spread of these pests to other crops in the region.

Dominant species of radish (Raphanus sativus (L.) convar. radicula (Pers) Sazon.) pests in the Right Bank Forest Steppe of Ukraine

Based on the results of phytosanitary monitoring (2008–2022), the species composition of pests in agroecosystems of radish (Raphanus sativus (L.) convar. radicula (Pers) Sazon.) in the central part of the Right-Bank Forest-Steppe of Ukraine has been specified. In radish crops, 59 species of phytophagous insects, two species of nematodes, and one species of slugs were identified. The harmful entomocomplex structure includes insects from 20 families of 8 orders. Representatives of the orders Coleoptera (17 species), Lepidoptera (16 species), and Homoptera (9 species) dominate the taxonomic structure, collectively occupying 71% in the structure of the harmful entomocomplex. Representatives of the orders Diptera and Orthoptera were presented by species from 6 and 5 families, respectively, and in the entomocomplex structure, they occupied 10% and 8%, respectively. The least species diversity was found for the order Thysanoptera, Hemiptera, and Hymenoptera, which collectively occupied 10% in the structure of the harmful entomocomplex. Sixteen constant species were identified (Plutella maculipennis Curt., Phyllotreta cruciferae Goeze, Phyllotreta undulata Kutsch., Pieris brassicae L., Agrotis segetum Denis&Schiff., Lacanobia oleracea L., Eurydema ventralis Kol., Brevicoryne brassicae L., Delia brassicae Bouche, Athalia rosae L., Delia platura Mg., Ceutorrhynchus quadridens Panz., Delia floralis Fallen, Thrips tabaci Lindeman, Entomoscelis adonidis Pallas, Evergestis extimalis Scop.), which caused significant damage to radish plants throughout the vegetation period. These species were trophically specialized, with 75% being oligophagous and 81% being phytophagous. Flea beetles such as Phyllotreta cruciferae Goeze, Phyllotreta undulata Kutsch., diamondback moth (Plutella maculipennis Curt.), cabbage aphid (Brevicoryne brassicae L.), turnip moth (Agrotis segetum Denis&Schiff.), and armyworm (Lacanobia oleracea L.) were found with high and medium frequencies in the studied agroecosystems, with population densities reaching maximum levels of 60–100% in some years.

The effect of sex ratio and group density on the mating success of two lines of Delia platura (Diptera: Anthomyiidae)

Abstract The seedcorn maggot, Delia platura (Meigen) (Diptera: Anthomyiidae), is reported as a polyphagous pest species found in numerous crops, including onion, corn, crucifers, and soy. Two morphologically identical genetic lines of D. platura (H- and N-lines) with distinct distribution ranges were recently discovered. Although many biological traits have been described for D. platura, no study to date has been conducted on the life history strategies and reproductive behaviours of its two lines. Using laboratory-reared colonies, this project investigates the effect of group composition (sex ratio and density) on the mating success and preoviposition period of the two D. platura lines. We found a substantial increase in mating success with increasing proportion of males within mating groups for both lines, whereas we found group density had negligible effects. However, the H-line had a lower average mating probability across treatments compared to the N-line. The preoviposition period decreased as the ratio of males to female increased at low density only for the N-line, and the opposite trend was observed at high density for both lines. These results suggest differences between the mating systems of these two lines, thereby highlighting the need for further research into the factors that influence their respective mating systems.

Effects of pesticides on seedcorn maggots in sweetcorn

Effects of pesticides on seedcorn maggots in sweetcorn

Effects of seed treatments on seedcorn maggots in direct-seeded onions

Effects of seed treatments on seedcorn maggots in direct-seeded onions

Evaluation of seed treatments for seedcorn maggot control in sweet corn in Wisconsin, 2022

Evaluation of seed treatments for seedcorn maggot control in sweet corn in Wisconsin, 2022

The seedcorn maggot Delia platura (Diptera: Anthomyiidae): An emerging pest of garlic crops in Tunisia

AbstractDuring routine phytosanitary inspections performed in February 2021 on vegetable crops in the region of Sidi Bouzid, Central Tunisia, unusual severe and generalized damage on young garlic, Allium sativum L., crops were observed. The causal agent was later identified as the seedcorn maggot Delia platura Meigen (1826) (Diptera: Anthomyiidae) using morphological and DNA‐based approaches. Symptoms on garlic are described and brief notes on diagnostic features of both adult and juvenile instars are presented. Possible phytosanitary risks and control measures are discussed.