Flea Beetle Research Articles

Evaluation of Spring-type and Winter-type Brassica napus Germplasm for Genetic Diversity in Response to Flea Beetle Herbivory in Typical and Atypical Planting Windows

Current practices of flea beetle [Phyllotreta spp.] control in Brassica napus L. rely heavily on seed treatments and due to growing concerns regarding the safety of such treatments on non-target and beneficial insect populations, genetic resistance would be beneficial for a more balanced integrated pest management strategy. However, none of the registered B. napus. canola varieties exhibit measurable resistance to flea beetle injury. To this end, an evaluation of 14 winter-type B. napus breeding lines and 15 spring-type B. napus breeding lines for resistance to flea beetle feedings was conducted, as it was found that at least one line in each family exhibited noticeably reduced flea beetle damage compared to sister lines in a breeding nursery. The study revealed natural genetic variation within B. napus for flea beetle antixenosis which could be used by dedicated breeders to develop canola varieties with higher levels of flea beetle resistance. Data indicated that host plant resistance did not vary between feeding by newly emerged adult flea beetles in the fall and the overwintered adults in the spring in either winter-type or spring-type canola, as well as for adult feeding preferences. This indicates that favourable genes identified in in either habitat-type could be used interchangeably to confer resistance even though the flea beetle life cycle is different for each planting period, while either overwintered adults or newly emerged adults can be used to evaluate feeding damage.

Antenna-Biased Odorant Receptor PstrOR17 Mediates Attraction of Phyllotreta striolata to (S)-Cis-Verbenol and (−)-Verbenone

Phyllotreta striolata, the striped flea beetle, is one of the most destructive pests in Brassicaceae plants worldwide. Given the drawbacks associated with long-term use of chemical insecticides, green strategies based on chemical ecology are an effective alternative for beetle control. However, the lack of information on beetle ecology has hindered the development of effective biocontrol strategies. In this report, we identified two odorants, (S)-cis-verbenol and (−)-verbenone, which displayed significant attraction for P. striolata (p < 0.05), indicating their great potential for P. striolata management. Using the Drosophila “empty neuron” system, an antenna-biased odorant receptor, PstrOR17, was identified as responsible for the detection of (−)-verbenone and (S)-cis-verbenol. Furthermore, the interactions between PstrOR17 and (−)-verbenone or (S)-cis-verbenol were predicted via modeling and molecular docking. Finally, we used RNAi to confirm that PstrOR17 is essential for the detection of (−)-verbenone and (S)-cis-verbenol to elicit an attraction effect. Our results not only lay a foundation for the development of new and effective nonchemical insecticide strategies based on (S)-cis-verbenol and (−)-verbenone, but also provide new insight into the molecular basis of odorant recognition in P. striolata.

Predicted impact, establishment and distribution of Heikertingerella sp. (Coleoptera, Chrysomelidae), recently released for the biological control of Tecoma stans in South Africa

Abstract Biological control practitioners are required to demonstrate that candidate agents are not only safe for release, but will establish widely in their new range with a significant impact on the target weed. We conducted this study in quarantine to provide insight into the impact and distribution of the root‐feeding flea beetle Heikertingerella sp. (Chrysomelidae), released in early 2023 against the invasive tree Tecoma stans (L.) (Bignoniaceae) in South Africa. We studied the effects of low and high beetle densities on plant growth and biomass, and F1 progeny production by the beetle. There were significant reductions in plant growth and biomass accumulation in the beetle‐exposed plants, relative to the controls. P1 adults damaged significantly more leaflets, with significantly higher F1 progeny production, at high beetle densities. The MaxEnt model predictions suggested that most of South Africa is climatically highly suitable for Heikertingerella sp., particularly along the southern and eastern coasts where the weed is most prevalent. Only the inland regions of the Northern Cape Province, depicting the driest and hottest part of the country where the weed does not occur, were predicted to be unsuitable for Heikertingerella sp. The beetle's thermal physiology, as determined by its critical thermal minimum and maximum temperatures and lower and upper lethal temperatures (LT50), suggests tolerance to temperature extremes in at least four of the eight provinces that fall within the range of T. stans in South Africa. Our results further justify the release of Heikertingerella sp. in areas predicted as suitable in South Africa.

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.

Residual Activity of Systemic Insecticides against Field-Collected Populations of Redheaded Flea Beetle (Coleoptera: Chrysomelidae), Systena frontalis, Adults under Laboratory and Greenhouse Conditions1

Abstract Systena frontalis (F.) is an insect pest of nursery production systems in the Midwest, Southeast, and Northeast regions of the United States. Adults feed on plant leaves and can reduce salability of container-grown nursery plants. Limited management options are available to protect plants from S. frontalis adult feeding damage. Insecticide spray applications to plant leaves are labor-intensive and not cost-efficient. Systemic insecticide applications to the growing medium may protect plants from S. frontalis adult feeding. In 2023, we conducted two laboratory and two greenhouse experiments to assess the residual activity of the systemic insecticides dinotefuran, thiamethoxam, and acephate against field-collected populations of S. frontalis adults. In the laboratory experiments, growing medium containing Itea virginica L. ‘Little Henry’ plants were treated with these three systemic insecticides. Twenty-five and 45 d after treatments were applied, leaves were collected and placed into petri dishes with a single S. frontalis adult. In the greenhouse experiments, Itea plants were placed into plastic observation cages. Eight S. frontalis adults were released into each cage with a single Itea plant. In the laboratory experiments 25 and 45 d after application of dinotefuran and thiamethoxam, the S. frontalis adults in the dishes with treated leaves had 66–90% mortality after 72 h. In the greenhouse experiments, dinotefuran and thiamethoxam protected Itea plants from S. frontalis adult feeding 45 d after application; 2.4 and 2.8 mm2 of leaf area were fed upon by S. frontalis adults. These results indicate that systemic insecticides can reduce feeding damage by S. frontalis adults on container-grown nursery plants.

Bio-efficacy, persistence and residual toxicity of greener insecticides against predominant flea beetles on cabbage crop in Kashmir

The flea beetles, Phyllotreta striolata (Fabricius, 1803) and Altica himensis (Shukla, 1960) (Coleoptera: Chrysomelidae: Alticinae) are one of the most serious pests of Brassica oleracea L. in Kashmir. In order to find eco-friendly control against these pests, bio-efficacy, persistence and residual toxicity of some newer insecticides viz., Emamectin benzoate 5SG @ 0.002 and 0.004 per cent, Spinosad 45SC @ 0.0035 and 0.007 per cent was evaluated against P. striolata and A. himensis infesting cabbage crop. Mortality caused by these insecticides was recorded in all the treatments. The result revealed that spinosad 45SC @ 0.007 per cent exhibited significantly lowest pest population and the highest efficacy against cabbage flea beetles. The persistence and residual toxicity of these insecticides was worked and it was found that spinosad 45SC @ at 0.007 per cent revealed the highest PT value of (346.11 & 321.43) for P. striolata and (299.57 & 322.38) for A. himensis compared to other insecticides. LT50 values of (4.13 & 3.38) for P. striolata and (3.08 & 3.84) for A. himensis were the highest for Spinosad 45SC @ 0.007 per cent. It was concluded that spinosad 45SC @ 0.007 per cent offers a feasible choice for the management of P. striolata and A. himensis.  

A new, unusually large, Clavicornaltica Scherer, 1974 flea beetle from Borneo, described and sequenced in the field by citizen scientists (Coleoptera, Chrysomelidae, Galerucinae).

The genus Clavicornaltica Scherer 1974 consists of very small, soil-dwelling flea beetles in South, Southeast and East Asia. Due to their diminutive size and morphological similarities, very little is known about their ecology and taxonomical diversity. It is likely that further studies will reveal this genus to be much more speciose than the 30 species currently recognised. A new species of Clavicornaltica from Brunei Darussalam is described, C.mataikanensis Otani et al., sp. nov. This is the second species of this genus recorded from Ulu Temburong National Park.

Modelling the impact of cabbage stem flea beetle larval feeding on oilseed rape lodging risk.

Cabbage stem flea beetle (CSFB, Psylliodes chrysocephala L.) is a major pest of oilseed rape (OSR, Brassica napus L.) in the UK and low availability of effective chemical control has increased the need for integrated pest management approaches. The risk of OSR to lodging is strongly related to stem strength, however, the impact of CSFB larval tunnelling on stem strength and subsequent risk to stem lodging is unknown. The study investigated this by applying the Generalised Crop Lodging Model to conventionally grown OSR crops scored for varying levels of CSFB larval tunnelling. Lodging risk mitigation strategies including Plant Growth Regulators (PGR) and varying nitrogen regimes were tested under high CSFB larval pressure. Stems of OSR plants were categorised by the proportion of visual damage (<5%; 5-25%; 26-50%; 51-75%; 75-100%). Stems of 26-50% damage had significantly lower breaking strengths and diameters compared to plants that scored <5%, with the associated reduction in stem failure windspeed equivalent to an order of magnitude increase in the risk of a lodging event occurring in the UK. PGR use reduced plant height and subsequently lodging risk variably across the sites. Estimating the proportion of stem tunnelling alongside larval pressure may be a useful tool in considering the contribution of CSFB pressure to lodging risk. The research demonstrates that the use of canopy management principles to optimise canopy size through nitrogen management and PGR use may help offset increased lodging risk caused by CSFB tunnelling. This article is protected by copyright. All rights reserved.

Ligand binding properties of three odorant-binding proteins in striped flea beetle Phyllotreta striolata towards two phthalate esters.

Odorant-binding proteins (OBPs) initiate insect olfactory perception and mediate specific binding and selection of odorants via uncertain binding mechanisms. We characterized the binding characteristics of four OBPs from the striped flea beetle Phyllotreta striolata (SFB), a major cruciferous crop pest. Tissue expression analysis revealed that the two ABPII OBPs (PstrOBP12 and PstrOBP19) were highly expressed mainly in the antenna, whereas the two minus-C OBPs (PstrOBP13 and PstrOBP16) showed a broad expression pattern. Competitive binding assays of cruciferous plant volatiles showed that PstrOBP12, PstrOBP16 and PstrOBP19 had very strong binding capacities for only two phthalate esters (Ki  < 20 μM), and PstrOBP13 specifically bound to four aromatic volatiles (Ki  < 11 μM). Fluorescence quenching assays displayed that two phthalate esters bound to three PstrOBPs via different quenching mechanisms. PstrOBP12/PstrOBP16-diisobutyl phthalate and PstrOBP19-bis(6-methylheptyl) phthalate followed static quenching, while PstrOBP12/PstrOBP16-bis(6-methylheptyl) phthalate and PstrOBP19-diisobutyl phthalate followed dynamic quenching. Homology modelling and molecular docking displayed that PstrOBP12-diisobutyl phthalate was driven by H-bonding and van der Waals interactions, while PstrOBP16-diisobutyl phthalate and PstrOBP19-bis(6-methylheptyl) phthalate followed hydrophobic interactions. Finally, behavioural activity analysis demonstrated that phthalate esters exhibited different behavioural activities of SFB at different doses, with low doses attracting and high doses repelling. Overall, we thus revealed the different binding properties of the three PstrOBPs to two phthalate esters, which was beneficial in shedding light on the ligand-binding mechanisms of OBPs.

Soil fertility as a mediator of interactions between an introduced specialist beetle and a native generalist nematode on an exotic invasive plant and its native congener

Abstract Invasive plants are often attacked by both introduced specialist and native generalist natural enemies in new ranges. Soil fertility can potentially alter the interactions of these natural enemies with native versus invasive plants in ways that have largely unexplored implications for biological invasions and biological control. A common garden experiment was conducted to compare the performance of an introduced specialist flea beetle, Agasicles hygrophila, and/or a native generalist nematode, Meloidogyne incognita, on invasive alligator weed, Alternanthera philoxeroides, and its native congener sessile joyweed, Alternanthera sessilis, under different levels of soil nitrogen (N) and phosphorus (P). At a relatively low or moderate N and P levels, the flea beetle and the nematodes were not significantly affected by each other. Under these conditions, alligator weed responded plastically by producing more branches and biomass, as well as longer stolons, in response to attack by the flea beetle and/or the nematode, compared to sessile joyweed responses to similar levels of damage. However, under a relatively high N and P levels, nematode infestations significantly reduced flea beetle damage on alligator weed, resulting in significantly greater above‐ and below‐ground biomass and longer stolons than plants without herbivory. In contrast, beetle herbivory significantly increased the level of nematode infestations on sessile joyweed, resulting in significantly fewer fine and coarse roots, and lower above‐ and below‐ground biomass compared to plants without herbivory. Synthesis and applications. Our findings illustrate the importance of soil fertility in mediating interactions between specialist biocontrol agents and native generalists on native versus invasive plants. High phenotypic plasticity seems to be an important attribute that contributes to the success of invasive plants like alligator weed in relatively nutrient‐poor environments. However, nutrient‐rich environments could potentially confer greater growth benefits on invasive plants than on native ones by changing herbivore–herbivore interactions on plants differently. There is a great need to fully investigate the direct and indirect interactions between biocontrol agents and generalists across food webs following classical biocontrol releases. Nutrient measurements of both soil and water bodies should also be incorporated into all stages of biocontrol programmes.

Biology, Ecology, and Management of Flea Beetles in Brassica Crops.

Brassica vegetable and oilseed crops are attacked by several different flea beetle species (Chrysomelidae: Alticini). Over the past decades, most research has focused on two Phyllotreta species, Phyllotreta striolata and Phyllotreta cruciferae, which are major pests of oilseed rape in North America. More recently, and especially after the ban of neonicotinoids in the European Union, the cabbage stem flea beetle, Psylliodes chrysocephala, has become greatly important and is now considered to be the major pest of winter oilseed rape in Europe. The major challenges to flea beetle control are the prediction of population dynamics in the field, differential susceptibility to insecticides, and the lack of resistant plant cultivars and other economically viable alternative management strategies. At the same time, many fundamental aspects of flea beetle biology and ecology, which may be relevant for the development of sustainable control strategies, are not well understood. This review focuses on the interactions between flea beetles and plants and summarizes the literature on current management strategies with an emphasis on the potential for biological control in flea beetle management.

Bioecology of &lt;i&gt;Reduviid Rhynocoris&lt;/i&gt; Rapax- Predator of &lt;i&gt;Podagrica decolorata&lt;/i&gt;

Flea beetle Podagrica decolorata (Duvivier) is a defoliator of okra. The study of some biological parameters of bedbug, Rhynocoris rapax (Stal) was carried out in locality of Man, The study is part of the control of this crop pest. Boxes were used to rear the insects. A thermohygrometer was used to determine the regular temperature and humidity. Larval monitoring revealed five larval stages, with the longest development time of 16.28±2.41 days for stage 5. The highest survival rate was observed for fifth-stage larvae (96.09± 03.14%). Female biological cycle was an mean 82.10± 09.41 days, and male biological cycle was an mean 68.67± 08.44 days. The sex ratio was 0.58. This study revealed positive correlations between humidity and the larval cycle, followed by negative correlations between temperature and the larval cycle.

Efficacy of commercially available entomopathogenic nematodes against insect pests of canola in Alberta, Canada.

Certain entomopathogenic nematodes (EPNs) in the families Steinernematidae and Heterorhabditidae are among the most studied biocontrol tools, some of which are commercially available against pest insects. Their use against foliar and subterranean insect pests is largely unexplored in the Canadian Prairies. We conducted a laboratory-based study to produce baseline information on the biocontrol potential of a few commercial EPN species. Percent mortality of flea beetles, diamondback moths (DBMs), lygus, cabbage root maggots, and black cutworms (BCWs) was assessed after 72 hours exposure to Steinernema carpocapsae, S. kraussei, S. feltiae, and Heterorhabditis bacteriophora at varying concentrations (25, 50, 100, and 200 infective juveniles (IJs) per larvae, pupae, or cm2 of soil surface). Irrespective of concentration level, S. carpocapsae and S. kraussei caused significant mortality in DBM and BCW larvae compared with H. bacteriophora.S. kraussei, and S. feltiae were more efficient than S. carpocapsae in controlling root maggot larvae. H. bacteriophora caused zero mortality to root maggots at any concentration. Root maggot pupae were resistant to entry to EPN species tested, likely due to hard outer covering. Compared with root maggot pupae, a moderate level of mortality was observed in DBM pupae, suggesting differential ability of the tested EPNs in killing different life stages of certain pests. All nematode species tested caused low mortality (≤10%) in flea beetle adults. The findings of this investigation form fundamental data essential for carrying out field-based studies on canola and other related crops aimed at control and management of these pest species.

Battling beetle pests: A comprehensive guide for effective management of okra flea beetle using chemicals

Battling beetle pests: A comprehensive guide for effective management of okra flea beetle using chemicals

Prevalence of insect pests on maize crop in District Mansehra, Khyber Pakhtunkhwa, Pakistan.

The maize crop is used as food for humans, livestock and poultries forms, it is also used in bread making, corn flakes, corn syrup, corn starch and corn oils. The field study consisted of one experimental trial, about the incidence of that insect pest complex on maize cultivar Azam during the Kharif season 2020 at the Agricultural, Research Station, Baffa, Mansehra. The trial was laid out in the Randomized Complete Block Design (RCBD), and then it was divided into three replications. The result obtained from the trial showed that a number of the pest species were recorded during the experimental period; however, the population was noticed at a low level. The obtained insect species were corn leaf aphid (6.90 ± 5.5) per square inch, corn leafhopper (1.32 ± 0.63), maize stem borer (0.63 ± 0.29), corn flea beetle (0.43 ± 0.28), Thrips (0.38 ± 0.22), Hairy caterpillar (0.21 ± 0.22), Grasshopper (0.17 ± 0.11) and shoot fly (0.11 ± 0.08) throughout the season.

Nts on the Incidence and Damage of Flea Beetle (Phyllotreta Nigripes) and Thrips (Megalurothrips Usitatus) on Mungbean

An experiment was conducted to evaluate the effectiveness of different treatments for the management of flea beetles and thrips of mungbean using BARI Mung-6 as experimental material. Nine treatments, viz., T1 = Use of White sticky trap, T2= Bioneem plus (Azadirachtin) 1%EC @ 1 ml/L of water at 40 DAS, T3 = Virtako (Chlorantraniliprole + Thiamethoxam) 40 WG @ 0.15g/L of water at 40 DAS, T4 = Amithrin plus 3% WDG @ 1 ml/L of water at 40 DAS, T5 = Ecomec (Abamectin) 1.8 EC @ 1 ml/L of water at 40 DAS, T6 = Nitro (Chlorpyriphos + Cypermethrin) 505 EC @ 1 ml/l of water at 40 DAS, T7 = Raise (Chlorantraniliprole) 20 SL @ 3 ml/L of water at 40 DAS and T8 = control were applied. Data were recorded on the number of flea beetles per plant, leaf area damaged by flea beetles, number of thrips-infested flowers per plant, and number of thrips per 20 opened flowers. Results revealed that the lowest number of flea beetles (3.00/m2 plants) and the highest percent reduction (64.71%) of flea beetle population over control were recorded in Virtako 80 WG at 0.15 g/L of water-treated plots. The lowest percent damage (3.75%) of leaf area and the highest percent reduction (79.73%) of leaf area damage over control were observed in Virtako-treated plots. The lowest number of thrips population (1.50/20 flowers), the highest percent of thrips population reduction (85.37%) over control, the lowest number of infested flowers (0.88/20 flowers) by thrips, and the highest percent reduction (88.65%) of flower infestation over control were found in mungbean plants treated with Raise 20 SL @ 3 ml/L of water. A strong negative correlation between the number of flea beetles and total yield was observed. There were negative relationships between the number of thrips, percent flower infestation, and total yield. Therefore, the application of Virtako 80 WG at 0.15 g/L and Raise (Chlorantraniliprole) 20 SL at 3 ml/L were found to be the best treatments for controlling flea beetles and thrips on mungbean. J. Asiat. Soc. Bangladesh, Sci. 49(2): 225-235, December 2023

Study on the Insect Pest-complex and Its Correlations with Environmental Factors on Fenugreek (Trigonella Foenum Graecum L.)

The present investigation was carried out during November 2022 to February 2023. The field experiment was conducted in Randomized block design with eight treatments and three replications at Experimental farm, Department of Entomology, SAS, Medziphema. The outcomes of the experiments revealed that, during period of investigation, ten insect pests and two natural enemies were observed. The activity of aphid (Aphis craccivora) infestation on fenugreek started in the 45th SMW (1.5 aphids/ three leaves) and reached its peak during 52nd SMW (23.36 aphids/ three leaves). The thrips (Scirtothrips dorsalis) was observed from 46th SMW (0.8 thrips/ three leaves) and reached its peak during 2nd SMW (9.32 thrips/ three leaves). The population of Spodoptera litura on fenugreek started appearing from 47th SMW (0.1caterpilar/ plant) and the highest incidence was recorded during 1st SMW (2 caterpillar/ plant). The serpentine leaf miner was observed from 49th SMW (0.56 maggot/ plant) and reached its peak during 2nd SMW (2.3 maggot/ plant). The population of flea beetle on fenugreek started appearing from 48th SMW (0.8 adult/ plant) and the highest incidence was recorded during 1st SMW (2.03 adult/ plant). The correlation studies with weather parameters revealed that aphid, thrips, Spodoptera litura, serpentine leaf miner and flea beetle population had significant negative correlation with maximum temperature, minimum temperature but non-significant with other remaining weather parameters.

Apennine–Pyrenees disjunct distribution: an unusual biogeographic pattern revealed in flea beetles of the Longitarsus candidulus species-group (Coleoptera, Chrysomelidae)

Abstract European mountain systems have played a crucial role in shaping the distribution of species and of their genetic diversity during the Quaternary climatic changes, with the establishment of allopatric patterns across main mountain ranges. Here we investigated the evolutionary history of flea beetles of the Longitarsus candidulus species-group showing an uncommon disjunct biogeographic pattern across the Apennine and the Pyrenees. We applied a multilocus molecular approach and multispecies coalescent models to establish a phylogenetic and systematic framework for this morphologically homogeneous species-group and to estimate the time of main cladogenetic events underlying the origin of the Apennine-Pyrenees pattern. We found strong support for the monophyly of the candidulus group with a sister relationship between Longitarsus laureolae and L. leonardii endemic to the Apennine and the Pyrenees mountains respectively. The timing of speciation events in the candidulus species-group coincides with 2 major climatic transitions during the Early and Middle Pleistocene which resulted in significant environmental changes in Europe and suggest a scenario of allopatric isolation and divergence on distinct mountain ranges. The split between the thermophilic species L. candidulus and the ancestor of the temperate species L. laureolae and L. leonardii is estimated at ~3 Ma during the transition from Pliocene to Pleistocene and was probably triggered by their segregation in xerophilous and temperate habitats. The speciation between L. laureolae and L. leonardii, estimated at ~1 Ma during the Mid-Pleistocene Transition, can be explained by the establishment of unfavorable conditions in West Alps and Central Massif underlying the onset of the Apennine-Pyrenees disjunct pattern. Finally, the strict association between members of the candidulus group and distinct Thymelaeaceae plants suggests further studies to address the hypothesis that speciation in these flea beetles might have been also associated with Pleistocene range changes of their host plants.

Integrated pest management strategy for striped flea beetle, &lt;i&gt;Phyllotreta striolata&lt;/i&gt; infesting radish (&lt;i&gt;Raphanus sativus&lt;/i&gt;)

In recent past, striped flea beetle, Phyllotreta striolata (Fabricius) was found to be very serious on radish (Raphanus sativus L.) across Haryana state and Delhi NCR in India and farmers suffered a huge economic loss. In the present study, an experiment was conducted during winter (rabi) seasons of 2020 and 2021 in predominant radish producing village of Haryana to investigate the influence of weather parameters on pest damage and validation of IPM strategy against P. striolata in radish. Results revealed that, among the different weather parameters, both maximum and minimum temperature had a significant negative relationship with leaf damage by adults (r = −0.35*; P = 0.02 and r = −0.62**; P = 0.00, respectively) and root damage by grubs of P. striolata (r = −0.91**; P = 0.00 and r = −0.86**, P = 0.00, respectively) in radish. The IPM strategy evaluated against P. striolata was effective with less leaf (10.99%) and root (12.93%) damage due to P. striolata compared to Farmers practice with 20.47% leaf and 39.43% root damage and also recorded 5.98 t/acre yield with cost: benefit ratio of 1:3.83 compared to Farmers practice (4.00 t/ acre yield and 1:1.60 C: B ratio). IPM strategy also reduced average number of insecticide sprays from 6.11 to 3.57 sprays (41.51% reduction), which clearly evince that the IPM strategy so validated can be adopted by the farmers as an economically viable option for management of P. striolata in radish.

Artificial intelligence analysis of contributive factors in determining blackleg disease severity in canola farmlands

Canola (Brassica napus L.) production is threatened by blackleg disease caused by Leptosphaeria maculans. Disease outcome is determined by interactions among pathogens, plants, farming practices, and environmental factors. Although the gene-for-gene interactions between the pathogen and its plant host are relatively clear, how precisely the pathogen interacts with the environment and farming practices is still poorly understood, making disease forecasting challenging for commercial farmlands. In recent years, artificial intelligence (AI) has been successful in forecasting disease risks based on environmental factors. In this study, we evaluated two AI methods and a data augmentation method to forecast disease risk using a dataset collected from 116 farmlands in Alberta in 2021 and 2022. We first assessed a machine learning model (support vector machine or SVM) and a deep-learning model (convolutional neural network or CNN) to predict blackleg severity based on five weather variables, flea beetle damage, root maggot damage, and crop-rotation variables. Both SVM and CNN predicted the disease risk with an accuracy of over 66%. The data augmentation method did not improve model performance. Flea beetle feeding and maggot damage contribute little to the model’s performance, and omitting these data did not appear to affect the results. In contrast, crop rotation contributes substantially to model performance. The five weather variables contribute roughly equally to the model’s performance, and removing any of the individual weather variables did not impact prediction ability for both models.