Aphid Species Research Articles

Monitoring of the flight of aphids on potato plantations in the Arkhangelsk region

The results of the catch of aphids in vegetative plantings of potatoes in 2018–2021 are presented. The studies were carried out in the southern part of the Arkhangelsk region (Kotlas region). Yellow water traps were used to catch winged aphids. It was revealed that 25 species of winged aphids migrate to potato plantations with an average annual number of 162 individuals during the growing season. Of the total number, 7 species of aphids carrying potato viruses were identified. These included Acyrthosiphon pisum Harr., Aphis fabae Scop., Aphis nasturtii Kalt., Aulocarthum solani Kalt., Hyperomyzus lactucae L., Macrosiphum euphorbiae Thomas, and Rhopalosiphum padi L. These species account for 70 to 82% of the abundance structure. Not a single individual of the most harmful species Myzus persicae Sulz was caught. In the group of virus-carrying aphids, the most numerous species are R. padi L. (an average of 48 individuals per season) and A. fabae Scop. (an average of 35 individuals per season). It has been established that the flight of aphids is largely influenced by average daily air temperatures. In the conditions of the hottest year (2021) at an average daily air temperature of 19 °C, the largest annual number of aphids was identified - 181 individuals. Winged aphids are present in potato agrocenoses throughout the entire growing season, which indicates the need for annual monitoring of their numbers and the use of protective measures.

Studies to identify an alternative aphid host for culturing the predatory syrphid, Ischiodon scutellaris (Fabricius) (Diptera: Syrphidae)

BackgroundAphidophagous syrphid, Ischiodon scutellaris (Fabricius) (Diptera: Syrphidae) is an effective predator of aphids that infest many agricultural and horticultural crops. Cowpea aphid, Aphis craccivora Koch (Hemiptera: Aphididae), is the natural host for culturing syrphid predator, I. scutellaris. The present study was conducted to evaluate the feeding and development of I. scutellaris on seven species of aphid hosts viz., A. craccivora, Aphis fabae Scopoli, Aphis gossypii Glover (from cotton), Schoutedenia emblica (Patel & Kulkarni), Brevicoryne brassicae (L.), Aphis gossypii (from okra) and Hyperomyzus carduellinus (Theobald) and to identify an alternative aphid host to maintain the culture of I. scutellaris during the situation of non-availability/loss of the culture of A. craccivora.ResultsAphis fabae was not accepted for feeding by the larvae of I. scutellaris. The larvae of I. scutellaris did not survive on S. emblica. The descending order of feeding potential of aphids by I. scutellaris was A. craccivora > H. carduellinus > B.brassicae > A. gossypii (from cotton) > A. gossypii (from okra) > S. emblica. The larva of I. suctellaris completed its development in combination of the aphid prey (A. craccivora + H. carduellinus). The net reproductive rates (R0) of I. scutellaris when fed on A. craccivora and H. carduellinus were 308.28 and 302.33, respectively. The intrinsic rate of increase (r) of I. scutellaris was significantly higher when reared on H. carduellinus (0.155 ± 0.003) than on A. craccivora (0.143 ± 0.004).ConclusionThe results confirmed that H. carduellinus reared on Lactuca virosa could serve as an alternate host for the mass production of I. scutellaris.

Weeds as Reservoirs of Beneficial Insects to Control Pests in Crops

Although aphids are pests and can cause 100% crop loss, they also are food for natural enemies and birds. The objective of this work was to determine predators and parasitoids of aphids and agroecological characteristics of weeds. The study was done in monocultures of intensive agriculture at El Copal Irapuato. Twenty-two plant species were collected, predominantly Asteraceae with eight species; nine species of aphids were collected. Aphis craccivora Koch was on four plant species. Aphidius colemani Viereck parasitized as many as 84% of Uroleucon ambrosiae (Thomas). Allograpta oblicua (Say), Pseudodorus clavatus (F.), and Paragus tibialis (Fallén) hoverflies were found in larvae preying on aphids. The larva of Micromus posticus (Walker) fed on aphids, the first record of immatures of the species of Hemerobiidae in the State of Guanajuato. Other species of predators were reported.

Citrus tristeza virus Promotes the Acquisition and Transmission of 'Candidatus Liberibacter Asiaticus' by Diaphorina citri.

Diaphorina citri Kuwayama (D. citri) is an insect vector of phloem-limited 'Candidatus Liberibacter asiatus' (CLas), the presumed pathogen of citrus Huanglongbing (HLB). Recently, our lab has preliminarily found it acquired and transmitted Citrus tristeza virus (CTV), which was previously suggested to be vectored by species of aphids. However, the influences of one of the pathogens on the acquisition and transmission efficiency of the other pathogen remain unknown. In this study, CLas and CTV acquisition and transmission by D. citri at different development stages under field and laboratory conditions were determined. CTV could be detected from the nymphs, adults, and honeydew of D. citri but not from the eggs and exuviates of them. CLas in plants might inhibit CTV acquisition by D. citri as lower CTV-positive rates and CTV titers were detected in D. citri collected from HLB-affected trees compared to those from CLas-free trees. D. citri were more likely to obtain CTV than CLas from host plants co-infected with the two pathogens. Intriguingly, CTV in D. citri facilitated the acquisition and transmission of CLas, but CLas carried by D. citri had no significant effect on the transmission of CTV by the same vector. Molecular detection and microscopy methods confirmed the enrichment of CTV in the midgut after a 72-h acquisition access period. Collectively, these results raise essential scientific questions for further research on the molecular mechanism of pathogen transmission by D. citri and provide new ideas for the comprehensive prevention and control of HLB and CTV.

Intraspecific chemodiversity provides plant individual- and neighbourhood-mediated associational resistance towards aphids.

Some plant species express an extraordinarily high intraspecific diversity in phytochemicals (= chemodiversity). As discussed for biodiversity, higher chemodiversity may provide better protection against environmental stress, including herbivory. However, little is known about whether the resistance of a plant individual towards herbivores is mostly governed by its own chemodiversity or by associational resistance provided by conspecific neighbours. To investigate the role of chemodiversity in plant-aphid interactions, we used the Asteraceae Tanacetum vulgare, whose individuals differ pronouncedly in the composition of leaf terpenoids, forming distinct chemotypes. Plants were set up in a field consisting of plots containing five individuals of either the same or different chemotypes. Presence of winged aphids, indicating attraction, and abundance of winged and unwinged aphids, indicating fitness, were counted weekly on each plant. During the peak abundance of aphids, leaf samples were taken from all plants for re-analyses of the terpenoid composition and quantification of terpenoid chemodiversity, calculated on an individual plant (Shannon index, Hsind, also considered as α-chemodiversity) and plot level (Hsplot, = β-chemodiversity). Aphid attraction was neither influenced by chemotype nor plot-type. The real-time odour environment may be very complex in this setting, impeding clear preferences. In contrast, the abundance was affected by both chemotype and plot-type. On average, more Uroleucon tanaceti aphids were found on plants of two of the chemotypes growing in homogenous compared to heterogenous plots, supporting the associational resistance hypothesis. For Macrosiphoniella tanacetaria aphids, the probability of presence differed between plot-types on one chemotype. Terpenoid chemodiversity expressed as a gradient revealed negative Hsplot effects on U. tanaceti, but a positive correlation of Hsind with M. tanacetaria abundance. Aphids of M. fuscoviride were not affected by any level of chemodiversity. In conclusion, this study shows that not only the chemotype and chemodiversity of individual plants but also that of conspecific neighbours can influence certain plant-herbivore interactions. These effects are highly specific with regard to the plant chemotype and differ between aphid species and their morphs (winged vs. unwinged). Furthermore, our results highlight the importance of analysing chemodiversity at different levels.

Insights into the Effects of Insecticides on Aphids (Hemiptera: Aphididae): Resistance Mechanisms and Molecular Basis

With the passage of time and indiscreet usage of insecticides on crops, aphids are becoming resistant to their effect. The different classes of insecticides, including organophosphates, carbamates, pyrethroids and neonicotinoids, have varied effects on insects. Furthermore, the molecular effects of these insecticides in aphids, including effects on the enzymatic machinery and gene mutation, are resulting in aphid resistance to the insecticides. In this review, we will discuss how aphids are affected by the overuse of pesticides, how resistance appears, and which mechanisms participate in the resistance mechanisms in various aphid species as significant crop pests. Gene expression studies were analyzed using the RNA-Seq technique. The stress-responsive genes were analyzed, and their expression in response to insecticide administration was determined. Putative insecticide resistance-related genes, cytochrome P450, glutathione S-transferase, carboxylesterase CarEs, ABC transporters, cuticle protein genes, and trypsin-related genes were studied. The review concluded that if insecticide-susceptible aphids interact with ample dosages of insecticides with sublethal effects, this will result in the upregulation of genes whose primary role is to detoxify insecticides. In the past decade, certain advancements have been observed regarding insecticide resistance on a molecular basis. Even so, not much is known about how aphids detoxify the insecticides at molecular level. Thus, to attain equilibrium, it is important to observe the manipulation of pest and insect species with the aim of restoring susceptibility to insecticides. For this purpose, this review has included critical insights into insecticide resistance in aphids.

Chemical composition and aphidicidal properties of castor-bean leaves against Rhopalosiphum maidis and Sipha flava (Hemiptera: Aphididae)

Plant extracts are a great source of molecules with insecticidal activity and are used to control pests in various crop production systems. In this study, we evaluated the aphidicidal properties in vitro of the n-hexane extract of leaves of castor-bean (Ricinus communis L.; Euphorbiaceae) at different concentrations (0.5, 1.0, 2.5, 5.0 and 10 kg m-3) against apterous adults of corn leaf aphid (Rhopalosiphum maidis Fitch) and the yellow sugarcane aphid (Sipha flava Forbes). The observed effects were dose-dependent, and the highest concentration evaluated (10 kg m-3) caused 82% mortality in R. maidis and 79% in S. flava. To identify chemical compounds, present in the extract we used mass gas chromatography, identifying 16 compounds. Palmitic acid was the major compound, with 45.34% abundance. The data obtained indicate the existence of insecticidal compounds in the castor-bean n-hexane extract, which could be used as an alternative bioinsecticide in the integrated management of these two aphid species.

Comparative transcriptomics of aphid species that diverged > 22 MYA reveals genes that are important for the maintenance of their symbiosis

Most plant-sap feeding insects have obligate relationships with maternally transmitted bacteria. Aphids require their nutritional endosymbiont, Buchnera aphidicola, for the production of essential amino acids. Such endosymbionts are harbored inside of specialized insect cells called bacteriocytes. Here, we use comparative transcriptomics of bacteriocytes between two recently diverged aphid species, Myzus persicae and Acyrthosiphon pisum, to identify key genes that are important for the maintenance of their nutritional mutualism. The majority of genes with conserved expression profiles in M. persicae and A. pisum are for orthologs previously identified in A. pisum to be important for the symbiosis. However, asparaginase which produces aspartate from asparagine was significantly up-regulated only in A. pisum bacteriocytes, potentially because Buchnera of M. persicae encodes its own asparaginase enzyme unlike Buchnera of A. pisum resulting in Buchnera of A. pisum to be dependent on its aphid host for aspartate. One-to-one orthologs that explained the most amount of variation for bacteriocyte specific mRNA expression for both species includes a collaborative gene for methionine biosynthesis, multiple transporters, a horizontally transmitted gene, and secreted proteins. Finally, we highlight species-specific gene clusters which may contribute to host adaptations and/or accommodations in gene regulation to changes in the symbiont or the symbiosis.

Wheat as a new host for potato aphid Macrosiphum euphorbiae Thomas (Hemiptera: Aphididae) and construction of its age-stage two-sex life tables.

Wheat (Triticum aestivum L.) is the major global staple food crop that meets the food security demands of various nations across the continents. The recent reduction in wheat production is attributed to several biotic and abiotic factors especially, temperature and rainfall patterns, and pest occurrence. Among insect pests, aphid species are emerging as new pests of economic importance in India and elsewhere. The present investigation identified a new association of Macrosiphum euphorbiae Thomas with the wheat crop. Life table parameters were studied for M. euphorbiae and Rhopalosiphum padi fed on wheat foliage. The total nymphal duration and life cycle duration, respectively, of R. padi (4.76 ± 0.54 and 9.71 ± 1.38days) and M. euphorbiae (5.84 ± 0.69 and 9.96 ± 1.31days) were significantly different for these species. The fecundity of the two aphid species was 23.95 ± 8.67 and 11.6 ± 4.10 progeny/female, respectively. Age-specific survival rate (lx), age-specific fecundity (fx), and population age-specific fecundity (mx) were higher in R. Padi compared to M. euphorbiae. Reproductive value (Vxj) was high in R. padi and the duration of reproduction was less, while these parameters showed an opposite trend in M. euphorbiae. The gross reproduction rate (GRR) was found higher in R. Padi (29.17 offspring/adult lifetime) compared to M. euphorbiae (19.58 offspring/adult lifetime). The M. euphorbiae being a pest of solanaceous crops seems to have shifted to a new host, i.e., wheat. This new adaptation strategy to survive for long periods on a wheat crop might pose a serious threat to wheat crop cultivation in near future.

A Further Contribution to the Aphid (Hemiptera:Aphidoidea) Fauna of Turkey Including a Description of a New Host Plant Associations and Colony Appearances

Aphids fascinated scientists due to their unique life cycles, being a one of the important agricultural pest worldwide, overcoming various applied control strategies and also relatively benefited from global climate change. The importance of aphid studies in developing countries like a Turkey requires additional attention because the effects of aphids on agricultural production. In this aspect, 3 genera, Anthemidaphis Tashev, 1967, Olegia Shaposhnikov, 1979; Pentalonia Coquerel, 1859 and 15 aphid species added to Turkey aphid fauna which are; Anthemidaphis oligommata Tashev 1967, Aphis (Aphis) coreopsidis (Thomas, 1878), Aphis (Aphis) narzikulovi Szelegiewicz, 1963, Aphis (Aphis) pseudeuphorbiae Hille Ris Lambers, 1948, Aphis (Aphis) picridis (Börner, 1950), Chaitophorus clarus Tseng & Tao 1936, Chaitophorus parvus Hille Ris Lambers, 1935, Dysaphis (Pomaphis) gallica (Hille Ris Lambers, 1955), Melanaphis sorghi Theobald, 1904, Metopolophium (Metopolophium) festucae Theobald, 1917, Olegia ulmifoliae (Aoki, 1973), Schizaphis (Schizaphis) nigerrima (Hille Ris Lambers, 1931), Semiaphis heraclei (Takahashi, 1921), Semiaphis pastinacae Börner, 1950, Pentalonia nigronervosa Coquerel, 1859. Recorded species were evaluated for host plant relations, colony appearances, also ant attendance and new interactions observed. Number of the listed aphid species for Turkey aphid fauna increased to 631 with these new records.

Factors affecting host plant selection in alfalfa aphids.

Alfalfa (Medicago sativa L.) hosts several species of aphid, Acyrthosiphon pisum (Harris), Aphis craccivora Koch and Therioaphis trifolii (Monell). The preference of the aphids of alfalfa plants for dense assemblies or individual plants, as well as for healthy or infested plants, was investigated in the field as in the laboratory. Years of field research have revealed the specific preferences of all three species of aphid. A. pisum and T. trifolii are most commonly found in alfalfa crops, while A. craccivora is mostly found on alfalfa weeds. Also, a single species of aphid alone is usually present on a plant. In order to determine the reason for this clear preference and to establish whether at the very beginning, i.e. at the stage of choosing a host, aphid species distance themselves from each other, we tested the effect of the volatiles of healthy and infested plants on their attractiveness to aphids. A. craccivora is repelled by the volatiles of dense crops and plants previously infested with one of the other two species. A. pisum and T. trifolii choose a dense assembly of plants, repelled by the volatiles of plants previously infested with A. craccivora. A. pisum displays the weakest competitive traits, and A. craccivora the strongest. This research showed that competition between aphid species does not occur only when they find themselves on the same plant at the same time, fighting for resources, but also in the choice of plant, in order to avoid later competition.

Buchnera breaks the specialization of the cotton-specialized aphid (Aphis gossypii) by providing nutrition through zucchini.

The cotton aphid, Aphis gossypii Glover, is a species of polyphagous aphid with many biotypes, and its host transfer has always been the focus of research on the control of cotton aphid. An important factor affecting aphid specialization is the nutritional association with microbial symbionts that provide the host with nutrients lacking in the diet. We analyzed the microbial composition and biodiversity of reared on zucchini for 10 generations (T1-T10) and cotton as a control (CK), by high-throughput Illumina sequencing of 16S ribosomal RNA genes. The findings showed that the change in plant hosts decreased the richness and variety of microbial species. Regardless of whether the plant host is altered or not, Proteobacteria and Firmicutes are the predominate phyla in cotton-specialized aphid. Additionally, cotton-specialized aphids that live in zucchini had considerably lower relative abundances of non-dominant phyla (Bacteroidetes) than cotton hosts. At the genus level the dominant communities were Buchnera, Acinetobacter, and Arsenophonus. The relative abundance of Buchnera was significantly higher in aphids reared on zucchini than those on cotton, whereas the opposite was observed for Acinetobacter, as well as for some non-dominant communities (Stenotrophomonas, Pseudomons, Flavobacterium, Novosphingobium). Collectively, this study clarifies the dynamic changes of symbiotic bacteria in cotton-specialized aphids reared on zucchini for multiple generations. Among them, Buchnera is crucial for the cotton-specialized aphid to get nutrients during the transfer of the host and has a favorable impact on the colonization of cotton-specialized aphid populations on zucchini hosts. It not only enriches our understanding of the relationship between the bacterial microbiota of aphids and their adaptability to new hosts, zucchini, but also expands the current body of research on the mechanisms underlying the host shifting ability of cotton-specialized aphids.

Effects of wheat undersowing and sweet alyssum intercropping on aphid and flea beetle infestation in white cabbage in Germany and Japan

An undersowing system with additional intercropping of flowering plants was assessed in field trials in Germany and Japan to estimate regulating effects on pests and possible negative effects on white cabbage (Brassica oleracea var. capitata). In particular, we tested cabbage undersown with wheat (Triticum aestivum L.) and cabbage undersown with wheat plus additional sweet alyssum (Lobularia maritima L. Desv.) intercropping. Counts of the aphid species Brevicoryne brassicae (L.) and Myzus persicae (Sulzer), as well as related predators on cabbage plants, were determined. Abundance of Phyllotreta spp. flea beetles and their feeding damage on cabbage plants were recorded and cabbage yield was compared. In both countries, trials showed that wheat undersowing reduced the abundance of M. persicae but not B. brassicae. The occurrence of natural enemies on cabbage plants was not significantly affected by any of the companion plants. Additional sweet alyssum intercropping increased the abundance of adult hoverflies at the German but not at the Japanese location. However, it also significantly increased flea beetle infestation on cabbage plants at both locations. Neither wheat undersowing nor additional sweet alyssum intercropping significantly reduced cabbage harvest weight.In conclusion, adding companion plants can be a promising method to improve pest control in vegetable crops. However, intercropping crucifer crops with sweet alyssum may not be recommended in regions where flea beetles are a relevant pest because of the observed enhancing effect on them. In contrast, to prove the positive effect of wheat undersowing on white cabbage, results from further years of investigation are needed.

Sıcaklık Değişkenliğinin Afitlerin Yaşam Döngüsüne Etkileri: Dört Örnek Tür

Global warming has great potential to influence all organisms including many animal species, in particular aphids. It has been shown that four aphid species, Cinara cedri, Cinara tujafilina, Metopolophium dirhodum, Pterochloroides persicae, maintained their parthenogenetic generations in Niğde and Artvin Provinces during the winter season in contrast to common life cycles related with cooler and dry conditions. It has been considered that determined aphid species should spend winter season as an overwintering egg as these species mainly show holocyclic life cycles in Niğde and Artvin. Fluctuations in winter average temperature in Niğde and Artvin during last two years enable them to produce more parthenogenetic generations as an indicator of the influences of the temperature fluctuations. These findings are in coincidence with the general approaches that increase in temperature most probably result in more generations in aphid species and in turn let these species to become a severe pest.

Comparative bionomics and life table studies ofLipaphis erysimi pseudobrassicae(Davis) andMyzus persicae(Sulzer) (Hemiptera: Aphididae) on three cabbage varieties

Lipaphis erysimi pseudobrassicae (Davis) and Myzus persicae (Sulzer) are important pests of brassica crops, causing significant yield losses on cabbage in Ghana. To inform the development of ecologically sound and sustainable pest management strategies for these pests, their biological and population growth parameters were studied on three cabbage varieties (Oxylus, Fortune, and Leadercross). The study was conducted in a screen house under ambient conditions at 30 ± 1°C and 75 ± 5% RH and 12:12 h photoperiod from September to November 2020. The parameters of the preadult developmental period, survival rates, longevity, reproduction, and life table were evaluated following the female age-specific life table. There were significant differences in the nymphal developmental time, longevity, and fecundity on the cabbage varieties for both aphid species. The highest population growth parameters, net reproductive rate (R0), intrinsic rate of increase r, and finite rate of increase (λ) were recorded on Oxylus variety for both L. e. pseudobrassicae and M. persicae. The lowest was recorded on Leadercross variety for L.e pseudobrassicae and Fortune for M. persicae. The results from this study suggest that Leadercross is a less suitable host for L. e. pseudobrassicae and Fortune for M. persicae, thus, should be considered as less susceptible varieties for use in primary pest management by small-scale farmers or as a component of an integrated pest management strategy for these pests on cabbage.

Biology and Feeding Potential of the Predator, Hippodamia convergens Guér., on Four Aphid Species Under Laboratory Conditions

Saleh, A.A.A., H.S. El-Tahawe, H. El-Nagar and A.S. Jabbar. 2023. Biology and Feeding Potential of the Predator, Hippodamia convergens Guér., on Four Aphid Species Under Laboratory Conditions. Arab Journal of Plant Protection, 41(1): 48-53. https://doi.org/10.22268/AJPP-41.1.048053 Suitability of the aphid species Brevicoryne brassicae L., Aphis craccivora Koch, Hyalopterus pruni Geoffroy and Aphis illinoisensis Shimer as preys for the predator Hippodamia convergens Guérin-Méneville (Coleoptera: Coccinellidae) development and reproduction was evaluated under laboratory conditions of 20±2ºC temperature and 70±5% relative humidity. Results obtained revealed that the prey species had significant effect on the development and predation rate of H. convergens immatures. The shortest total larval developmental period (12.82 days) was observed for the beetle fed on A. craccivora, whereas the longest (16.32 days) was recorded for the beetle fed on H. pruni. H. convergens consumed significantly more individuals of H. pruni (278.34) during its larval period than A. craccivora (186.76), B. brassicae (227.87) and A. illinoisensis. (211.94). The lowest immature stages mortality rate was recorded when they were fed on A. craccivora (6.47%), followed by those fed on A. illinoisensis (8.05%), B. brassicae (9.65%) and H. pruni (13.6%). Meanwhile, adult females consumed significantly more individuals of H. pruni (4937.40) than B. brassicae, A. illinoisensis (3693.92, 3432.15) and A. craccivora (2953.5). Highest fecundity (564.00 eggs) was recorded when females of H. convergens were fed on A. craccivora. In addition, beetle adult females and males that fed on H. pruni had significantly longer life span than those fed on the other three aphid species. The investigation provides useful information for the utilization of the H. convergens predator in IPM programs to protect faba bean, cabbage, grapevine and stone fruit trees from aphids as well as other sap sucking pests. Keywords: Hippodamia convergens, Brevicoryne brassicae, Aphis craccivora, Hyalopterus pruni, Aphis illinoisensis, biology, reproduction, feeding capacity.

The novel pyridazine pyrazolecarboxamide insecticide dimpropyridaz inhibits chordotonal organ function upstream of TRPV channels.

Pyridazine pyrazolecarboxamides (PPCs) are a novel insecticide class discovered and optimized at BASF. Dimpropyridaz is the first PPC to be submitted for registration and controls many aphid species as well as whiteflies and other piercing-sucking insects. Dimpropyridaz and other tertiary amide PPCs are proinsecticides that are converted in vivo into secondary amide active forms by N-dealkylation. Active secondary amide metabolites of PPCs potently inhibit the function of insect chordotonal neurons. Unlike Group 9 and 29 insecticides, which hyperactivate chordotonal neurons and increase Ca2+ levels, active metabolites of PPCs silence chordotonal neurons and decrease intracellular Ca2+ levels. Whereas the effects of Group 9 and 29 insecticides require TRPV (Transient Receptor Potential Vanilloid) channels, PPCs act in a TRPV-independent fashion, without compromising cellular responses to Group 9 and 29 insecticides, placing the molecular PPC target upstream of TRPVs. PPCs are a new class of chordotonal organ modulator insecticide for control of piercing-sucking pests. Dimpropyridaz is a PPC proinsecticide that is activated in target insects to secondary amide forms that inhibit the firing of chordotonal organs. The inhibition occurs at a site upstream of TRPVs and is TRPV-independent, providing a novel mode of action for resistance management. © 2023 BASF Corporation. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Essential Oil Composition of Seven Bulgarian Hypericum Species and Its Potential as a Biopesticide.

Hypericum species and especially H. perforatum L. are well known for their therapeutic applications. The present study assessed the essential oil (EO) composition, and antifungal and aphid suppression activity of seven Bulgarian Hypericum species. The EOs were analyzed by GC-MS-FID. Two experiments were conducted. In the first experiment, H. perforatum, H. maculatum, and H. hirsutum were used. Additionally, the EO composition of H. perforatum extracted via hydrodistillation (ClevA) and via commercial steam distillation (Com) were compared. The second experiment compared the EOs of H. perforatum, H. cerastoides, H. rumeliacum, H. montbretii, and H. calycinum (flowers and leaves) extracted via hydrodistillation and collected with n-hexane. Overall, the EO constituents belonged to four classes, namely alkanes, monoterpenes, sesquiterpenes, and fatty acids. The main class for compounds in H. maculatum and H. perforatum (section Hypericum) were sesquiterpenes for both experiments except for H. perforatum (Com). Hypericum montbretii (section Drosocarpium) EO had monoterpenes (38.09%) and sesquiterpenes (37.09%) as major groups, while H. hirsutum EO (section Taeniocarpium) contained predominately alkanes (67.19%). Hypericum hirsutum EO contained cedrol (5.04%), found for the first time in Hypericum species. Fatty acids were the main compounds in H. cerastoides (section Campylopus), while monoterpenes were the most abundant class in H. rumeliacum and H. calycinum EOs. α-Pinene and germacrene D were the major EO constituents of all analyzed Hypericum species except for H. hirsutum and H. cerastoides. Hypericum perforatum EO (Com) had significant repellent and insecticidal activity against two aphid species, Rhopalosiphum padi (Bird Cherry-oat aphid) and Sitobion avenae (English grain aphid) at concentrations of 0%, 1%, 2.5%, 3.5%, 4.5%, and 5%. The tested EOs did not show significant activity against selected economically important agricultural fungal pathogens Fusarium spp., Botrytis cinerea, Colletotrichum spp., Rhizoctonia solani, and Aspergillus sp. The EO of the Hypericum species found in the Bulgarian flora could be utilized for the development of new biopesticides for aphid control.

Quantitative Study of Aphid Natural Enemies in Central Oklahoma Canola Fields

Winter canola (Brassica napus L.) is planted in late September through October in central Oklahoma and harvested in June. Three aphid species typically infest canola fields in central Oklahoma: cabbage aphid, Brevicoryne brassicae L.; green peach aphid, Myzus persicae (Sulzer); and turnip aphid, Lipaphis pseudobrassicae (Davis). Predatory insects and spiders and hymenopteran parasitoids that prey on aphids are present in canola fields in central Oklahoma. We used a D-vac suction device to sample aphids and natural enemies in a total of 23 canola fields in central Oklahoma in early November and mid-March of three growing seasons. During the three growing seasons, 2.4 to 50.9 aphids were collected per 120 placements of the D-vac sampler per canola field. Diaeretiella rapae (McIntosh) was the most abundant parasitoid, with 0.04 to 5.1 individuals per 120 placements, while Araneae (spiders) were the most abundant predators ranging from 0.35 to 4.9 per 120 placements. Other predators were Chrysopidae, Hemerobiidae, Nabidae, and Syrphidae, with relative density of most taxa increasing from November to March. Correlations of relative density of D. rapae and larval Coccinellidae to aphid relative density were positive and significant suggesting the taxa had a reproductive and/or aggregative numerical response to aphids in canola. D. rapae, Coccinellidae, and perhaps spiders killed the most aphids in central Oklahoma canola fields.

Newly recorded plant-aphid associations: Implications for PLRV and PVY control in potato crops

The most important viral diseases in potato crops are PVY and PLRV, and they are efficiently transmitted by numerous aphids being Myzus persicae and Macrosiphum euphorbiae, the most important. These vector aphids are highly polyphagous and are widely distributed; and since PVY and PLRV have a broad host range there can be a wide diversity of plants hosting vector aphids, and/or being reservoirs of the viruses, in the community of plants associated with potato crops. Here, we searched for plants growing in the areas adjacent to potato crops in Salta, Argentina, to find plants that represent a risk for potato crops for being hosts of aphid vectors and/or reservoirs of PLRV and PVY. We found 34 plant species belonging to 16 families hosting aphids, from these 11 plant species were reported as hosts for PVY and/or PLRV. Also, we found 27 aphid species and 18 of them have been reported as vectors for PLRV and/or PVY. Three aphid species were found on most plants; M. persicae, M. euphorbiae and Aphis gossypii. Altogether, we found 95 plant-aphid associations in potato fields, of which 16 are newly recorded plant-aphid associations. These new associations likely arose from the great diversity of plants hosting a great diversity of aphids reported as vectors of PLRV and PVY, in a changing and dynamic agricultural ecosystem. The results that we present have implications for PLRV and PVY control in potato and other related crops.