Coccinellidae Research Articles

Predation dynamics and mutual interference among ladybird beetles in managing Diaspis echinocacti (Bouché) infestation on Opuntia spp

Predation dynamics and mutual interference among ladybird beetles in managing Diaspis echinocacti (Bouché) infestation on Opuntia spp

Behavioral responses of the lady beetles Cryptolaemus montrouzieri and Tenuisvalvae notata to specific mealybug prey

AbstractLady beetles (Coleoptera: Coccinellidae) are important biocontrol agents that are considered generalist predators, although some tribes, such as Scymnini, are specialized in predation of sucking pests, such as mealybugs, aphids, and whiteflies. However, prey preference or pre‐imaginal conditioning may occur as coccinellids are subjected to large‐scale rearing. Thus, predator–prey interaction may be an outcome of conditioning to prey stimuli. To evaluate possible pre‐imaginal conditioning, population lines were created for the lady beetles Cryptolaemus montrouzieri Mulsant and Tenuisvalvae notata (Mulsant), each fed for at least eight generations the mealybugs Ferrisia dasylirii (Cockrell) or Planococcus citri Risso (Hemiptera: Pseudococcidae). Next, the behavioral response of these coccinellids was measured in arenas treated with prey volatiles or footprints, regarding walking time, walking speed, walking distance, and residence time. Finally, food preference between prey species was measured in laboratory and semi‐field conditions on infested cotton plants. Conditioned coccinellids responded similarly to volatiles released by either prey species offered. Furthermore, there were no changes in predator behavior towards footprints of either prey species. Both predator species consumed more P. citri in all tests, regardless of rearing prey indicating no pre‐imaginal conditioning. These results suggest that rearing prey may not affect the predator behavior, and both coccinellid species are effective in the biological control of mealybugs.

Coccinellid predation efficiency on Aphis gossypii (Hemiptera: Aphididae) under laboratory conditions.

In this study, we investigated the biological aspects and predation efficiency of 3 aphidophagous ladybird beetles, Coccinella novemnotata, Hippodamia variegata, and Coccinella septempunctata, on the cotton aphid, Aphis gossypii, reared on cucumber plants (Cucumis sativus L. cultivar barracuda) under laboratory conditions. The developmental periods of C. novemnotata, H. variegata, and C. septempunctata were observed to be 16.00 ± 0.25, 16.00 ± 0.25, and 20.58 ± 0.40 days, respectively. The larvae of these ladybird beetles consumed an average of 218.93 ± 8.86, 254.77 ± 8.86, and 537.36 ± 10.49 aphids, respectively. Fourth-instar larvae were particularly efficient, consuming 53.68%, 52.68%, and 52.64% of total aphids for C. novemnotata, H. variegata, and C. septempunctata, respectively. Adult emergence rates were promising, with 91.67%, 100.00%, and 92.86%, accompanied by sex ratios of 63.64%, 53.84%, and 61.54%, respectively. Notably, a single female of C. novemnotata, H. variegata, and C. septempunctata consumed an average of 2,215.30, 2,232.00, and 3,364.50 aphids, respectively, over its lifespan. Coccinella septempunctata demonstrated the highest predation efficiency among the 3 species, suggesting its potential for biological control of A. gossypii in both open fields and greenhouses, promoting sustainable agricultural practices.

Impact of Aphis pomi-tending Formica rufa (Hymenoptera: Formicidae) on biological parameters of Hippodamia variegata (Coleoptera: Coccinellidae).

One of the key reasons for the poor performance of natural enemies of honeydew-producing insect pests is mutualism between ants and some aphid species. The findings demonstrated that red wood ant, Formica rufa Linnaeus (Hymenoptera: Formicidae) had a deleterious impact on different biological parameters of the lady beetle, Hippodamia variegata Goeze (Coleoptera: Coccinellidae). H. variegata laid far fewer eggs in ant-tended aphid colonies, laying nearly 2.5 times more eggs in ant absence. Ants antennated and bit the lady beetle eggs, resulting in significantly low egg hatching of 66 per cent over 85 per cent in ant absent treatments. The presence of ants significantly reduced the development of all larval instars. The highest reduction was found in the fourth larval instar (31.33% reduction), and the lowest in the first larval instar (20% reduction). Later larval instars were more aggressively attacked by ants than earlier instars. The first and second larval instars stopped their feeding and movement in response to ant aggression. The third and fourth larval instars modified their mobility, resulting in increased ant aggression towards them. Adult lady beetles were shown to be more vulnerable to ant attacks than larvae. However, H. variegata adults demonstrated counterattacks in the form of diverse defensive reaction behaviours in response to F. rufa aggression.

Molecular mechanisms for selective action of afidopyropen to Myzus persicae and Coccinella septempunctata.

Afidopyropen is a novel insecticide with high selectivity between sucking insects such as the peach aphids Myzus persicae and natural enemies like the seven-spotted lady beetle Coccinella septempunctata. However, the mechanisms of selective action for afidopyropen remain unknown. The LC50 values of afidopyropen to the 1st-4th instar larvae and adult C. septempunctata were 372- to more than 7267-fold higher than that to adult M. persicae. Though the activity of cytochrome P450s in M. persicae was 6.1- to 7.5-fold higher than that in C. septempunctata, the latter has much higher activities of carboxylesterase (CarEs) and glutathione S-transferases (GSTs), and the crude enzyme of C. septempunctata and M. persicae showed similar metabolism efficiency to afidopyropen. Molecular docking results demonstrated that afdopyropen showed higher binding affinity to the vanilloid-type transient receptor potential (TRPV) channel of M. persicae (-9.1 kcal/mol) than to that of C. septempunctata (-8.2 kcal/mol). And the EC50 value of afdopyropen to the TRPV channel of C. septempunctata (41 360 nM) was 19 885-fold higher than that in M. persicae (2.08 nM). Our results demonstrated that the significantly different sensitivity of M. persicae and C. septempunctata TRPV channel to afidopyropen play a key role in the high selectivity of afidopyropen. These findings provide new insights into the selective mechanisms of afidopyropen against insect pests and natural enemies as well as the theory support for coordinated application of chemical control and biological control. © 2024 Society of Chemical Industry.

First Confirmed Locality Record of Ladybird Beetle Synona melanopepla (Mulsant, 1850) (Coleoptera: Coccinellidae) from Nepal

Synona melanopepla (Mulsant, 1850) is a ladybird beetle belonging to the subfamily Coccinellinae of the family Coccinellidae. This species has been confirmed for the first time from Nepal through this study. A single specimen of this species was collected from Ranibari Community Forest, Kathmandu, Nepal.

A study on the aerodynamic behaviors learned from microscopy imaging of beetle corrugated hindwing.

Beetle hindwings have the unique advantages of lightweight and high strength, which play a key role in flight. In this study, the beetle hindwings were cut along the chordal direction, then the first groove microstructure of different vein cross sections was investigated using the 3D microscope system and the laser scanning confocal microscope. It was found that the position of the first groove relative to the entire chordal cross section of the wing gradually moves backward, which has an effect on the flying aerodynamic behaviors of the beetle. Next, three corrugated airfoils learned from the microscopy imaging of the ladybird beetle hindwing were designed. Then, aerodynamic behaviors were calculated by the ANSYS Fluent software, and it was confirmed that the position of the first groove microstructure affects the aerodynamic performance of the airfoil. For further study, the influence of corrugated structural and motion parameters on the aerodynamic, 2D 'simplified' airfoil models with triangular wave airfoil models (TWA models) was developed and studied. RESEARCH HIGHLIGHTS: The position of the first groove microstructure affects the aerodynamic performance of the airfoil. The pressure difference of different corrugation patterns shows significantly asymmetric during the upstroke and downstroke. The aerodynamic is optimal of 2D-TWA models, when the number of corrugations is five, the corrugation is right angle, and the flapping frequency is 75 Hz.

Potential of Thuja occidentalis L. Essential Oil and Water Extracts against Field Crop Pests.

Thuja occidentalis L. essential oil (EOTO) and its compounds, such as terpinyl acetate, bornyl acetate, and β-thujone, are claimed to be highly effective against some storage pests, sanitary insects, or pests of fruit trees, while data about its use in protecting field crops are very scarce. There is also a lack of information in the literature about the insecticidal value of water extracts from T. occidentalis (WETOs). Both essential oils (EOs) and water extracts (WEs) from various plants have advantages and disadvantages in terms of their use as insecticides. EOs are generally more effective, but their preparation is more complicated and quite expensive. In turn, WEs are simple to prepare and cheap, but they often have limited effectiveness. Moreover, significant differences in responses exist depending on the species of the donor plant, the method of preparing the extract, its concentration, the species of the pest being controlled, the developmental stage, and even the gender of the pest. The goals of the research were to assess the effect of EOTO and WETOs prepared from dry and fresh matter on the mortality, feeding, and body mass changes of important crop pests, i.e., the black bean aphid, pea leaf weevil, and Colorado potato beetle (CPB), respectively, as well as on the mortality and voracity of non-target organism Asian lady beetle young larvae. EOTO showed significant aphicidal activity with LC50 = 0.8267% and 0.2453% after 42 h of the experiment for nymphs and wingless females of black bean aphid, respectively. Adults of CPB were more resistant to EOTO than aphids, with LC50 values for females equal to 1.5327% and 1.3113% after 48 h and after 72 h of the experiment. There was no significant effect of EOTO on CPB foraging. Calculated LC50 values for pea leaf weevil adults were lower than those for CPB (0.9638% and 0.8573% for males after 12 h and 24 h, respectively). In the case of this pest, a clear reduction in foraging was obtained, with higher concentrations of EOTO resulting in more pronounced reductions in foraging behavior. Concentrations of EOTO above 0.5%, which showed efficacy against the aphid, were lethal to 3-day-old larvae of the Asian lady beetle. WETOs, in turn, showed significant potential in inhibiting adult pea leaf weevil feeding, with very low or no effectiveness in reducing A. fabae and CPB, respectively.

Metabolism, digestion, and horizontal transfer: potential roles and interaction of symbiotic bacteria in the ladybird beetle Novius pumilus and their prey Icerya aegyptiaca.

In this study, we first time sequenced and analyzed the 16S rRNA gene data of predator ladybird beetles Novius pumilus and globally distributed invasive pest Icerya aegyptiaca at different stages, and combined data with bacterial genome sequences in N. pumilus to explored the taxonomic distribution, alpha and beta diversity, differentially abundant bacteria, co-occurrence network, and putative functions of their microbial community. Our finding revealed that Candidatus Walczuchella, which exhibited a higher abundance in I. aegyptiaca, possessed several genes in essential amino acid biosynthesis and seemed to perform roles in providing nutrients to the host, similar to other obligate symbionts in scale insects. Lactococcus, Serratia, and Pseudomonas, more abundant in N. pumilus, were predicted to have genes related to hydrocarbon, fatty acids, and chitin degradation, which may assist their hosts in digesting the wax shell covering the scale insects. Notably, our result showed that Lactococcus had relatively higher abundances in adults and eggs compared to other stages in N. pumilus, indicating potential vertical transmission. Additionally, we found that Arsenophonus, known to influence sex ratios in whitefly and wasp, may also function in I. aegyptiaca, probably by influencing nutrient metabolism as it similarly had many genes corresponding to vitamin B and essential amino acid biosynthesis. Also, we observed a potential horizontal transfer of Arsenophonus between the scale insect and its predator, with a relatively high abundance in the ladybirds compared to other bacteria from the scale insects.IMPORTANCEThe composition and dynamic changes of microbiome in different developmental stages of ladybird beetles Novius pumilus with its prey Icerya aegyptiaca were detected. We found that Candidatus Walczuchella, abundant in I. aegyptiaca, probably provide nutrients to their host based on their amino acid biosynthesis-related genes. Abundant symbionts in N. pumilus, including Lactococcus, Serratia, and Pseudophonus, may help the host digest the scale insects with their hydrocarbon, fatty acid, and chitin degrading-related genes. A key endosymbiont Arsenophonus may play potential roles in the nutrient metabolisms and sex determination in I. aegyptiaca, and is possibly transferred from the scale insect to the predator.

The extent of regeneration is impacted by the stage of amputation in ladybird beetles: A case study in Cheilomenes sexmaculata

AbstractRegeneration has been a topic of interest across a range of taxa for centuries, and arthropods are no exception. Trade‐offs associated with regeneration are likely to involve the reallocation of resources away from other metabolic activities such as growth, development or reproduction. This might be reflected in costs to some developmental traits of the organism, despite regeneration being advantageous. These associated costs might also differ with the stage of injury or amputation. Here, we hypothesise that the extent of regeneration and trade‐offs associated with it may be stage‐specific. To test this hypothesis, the right forelimb of four larval stages of the ladybird beetle Cheilomenes sexmaculata (Fabricius) (Coleoptera: Coccinellidae) was amputated. Amputated individuals were reared until adulthood, and all developmental transitions were recorded. Regenerated legs in all the treatments were smaller than the controls, which did not experience the amputation, and the regenerative potency of early larval stages was higher than that of late larval stages. Limb regeneration caused delays in post‐amputation developmental duration in all the treatments, increasing their total developmental period. The length of the unamputated left foreleg as well as the wing and antenna size were also reduced in regenerated beetles, showing some internal trade‐off. However, there were no significant differences observed between regenerated and control adults in their fresh body weight and body size. Thus, limb regeneration depends upon the stage of larval development at which the amputation was performed. Amputation also affects the development of other appendages. The delay in normal beetle development might have been observed because of extra resource requirement, their allocation as well as reprogramming of the expression of some genes during regeneration.

Niche overlap with an exotic competitor mediates the abundant niche‐centre relationship for a native lady beetle

AbstractAimThe abundant niche‐centre hypothesis has been used to describe patterns of species abundance relative to position in ecological niche space. Such relationships, however, are inconsistently recovered and may be obscured due to non‐equilibrium distributions, such as those caused novel interactions with exotic species. Here, we explore patterns of fitness for the nine‐spotted lady (Coccinella novemnotata) following the introduction of an exotic competitor, the seven‐spotted lady beetle (C. septempunctata). We examine how niche overlap between species may be causing a range reduction for C. novemnotata through a modified abundant niche‐centre relationship.LocationNorth America.MethodsWe applied a time‐oriented view of the abundant niche‐centre relationship for C. novemnotata, both before and after the introduction of C. septempunctata. We tested for both niche overlap and correlation between C. novemnotata body size (i.e. fitness) and the distance from its niche centroid relative to the invasion status of C. septempunctata.ResultsThe current niche space currently occupied by C. novemnotata is equivalent to its historic niche but has shifted to avoid overlap with C. septempunctata. A historic abundant niche‐centre relationship with larger individuals closer to the niche centroid was observed for C. novemnotata. However, this pattern changed to have smaller beetles near the niche centroid when the current distribution was considered.Main ConclusionsFitness patterns displayed by C. novemnotata are effectively described by the abundant niche‐centre hypothesis. However, this relationship was modified with the introduction of C. septempunctata. Coccinella novemnotata is not excluded from previously suitable areas that correspond to niche space nearest to its niche centroid. Abundant niche‐centre relationships may provide strong predictions of species' fitness across a species geographic range; however, these relationships may be obscured by novel pressures resulting in non‐equilibrium states.

Morphological and structural characteristics of the elytra reduce impact damage to ladybird beetles

Beetle elytra act as natural protective covers and effectively shield their flexible abdomens and fragile hindwings from damage. The existing studies have attributed this contribution of the elytra to its honeycomb structures. In this combined experimental and theoretical study, we used the seven-spotted ladybird beetle to demonstrate that both biological morphology and the hollow structure of the dome-like elytra combined to reduce damage during falling. The falling ladybird beetles had a high probability (59.52%) of hitting the ground with the costal edge of the elytra. This strategy could assist with converting the translational energy into rotational kinetic energy, resulting in the reduction of the impulse during falling. In addition, the hollow structures on the elytra could further absorb the residual impact energy. In the future, this biological paradigm could be used as a basis for the development of falling/landing techniques for advanced robots.

Local and landscape factors differentially influence predatory arthropods in urban agroecosystems

AbstractLike other urban green spaces, urban community gardens can act as biodiversity refugees, especially for small organisms like arthropods. In turn, arthropods can provide important ecosystem pest control services to these agroecosystems. Thus, an often‐asked question among urban gardeners is how to improve gardens and surrounding areas for natural enemies and associated pest control services. We examine how local vegetation and garden characteristics, as well as the surrounding landscape composition, affect ground‐dwelling beetles (Coleoptera: Carabidae and Staphylinidae), spiders (Araneae), opilionids (Opiliones), and ladybird beetles (Coleoptera: Coccinellidae), all of which are important predators. In the summer of 2019, we collected predators, vegetation, ground cover, and garden and landscape characteristic data from 10 community gardens in the city of Seattle, Washington. We found that different groups of natural enemies are associated with different environmental variables and at different scales; probably related to differences in their dispersal capabilities, habits, and diets. Floral variables (number of flowers and number of species in flower) had a negative effect on nonflying natural enemies (spiders, opilionids, and ground‐dwelling beetles), but not on flying ones (ladybird beetles). The only taxon that was significantly affected by a landscape‐scale variable was Opiliones, the only group examined that exclusively disperses by ground. Our results show contrasting results to similar studies in different regions and highlight the need to expand the taxa and regions of study.

Compatibility of Entomopathogenic Nematode (Steinernema sp.) and Coccinelid (Cheilomenes sexmaculata) with Insecticides registered against Fall Army Worm (Spodoptera frugiperda) in Corn

Cyantraniliprole, Chlorantraniliprole, Emamectin benzoate, Spinosad, Flubendiamide, Teflubenzuron, Novaluron+Indoxacarb, Broflanilide, Chlorafenapyr and Azadirachtin are some important registered insecticides against S. frugiperda in corn. Bioagents such as entomopathogenic nematodes (EPNs) and lady beetles have also role to reduce its population. Integration of bioagents with chemical insecticides is current need for sustaianable pest management. So, the present evaluation was conducted at laboratory condition to knowhow the fate of EPNs, Steinernema sp. and coccinelid (Cheilomenes sexmaculata) after their exposure with above mentioned insecticides used for S. frugiperda. Lab research was conducted during spring (2021) at BCKV, Burdwan campus (West Bengal). EPNs was multiplied on larva of Corcyra cephalonica. Cheilonemes sexmaculata (grubs and pupa) was collected from field. Ten novel insecticides recommended for S. frugiperda were evaluated against the mentioned bioagents. Corected mortality data of EPNs and coccinelid was analyzed statistically and accordingly insecticides were grouped into different toxicity class. Except Emamectin benzoate, all the chemicals were proved to be safe to Steinernema sp. E. benzoate caused 100 % reduction to insect infectivity by EPN, followed by Chlorafenapyr (80 %). Slightly harmful effect for grubs (C. sexmaculata) was noted in Cyantraniliprole and Emamectin benzoate and for pupa in emamectin benzoate and Novaluron + Indoxacarb. Otherwise all others were harmless both for grubs and pupal stage of C. sexmaculata. These pieces of information might be practical in decision making for IPM of S. frugiperda.

Inventory of insect pests of rice in agro-ecosystems of far north region of Cameroon

The entomofauna vector of rice yellow mottle virus was studied from June to September 2023 in the rainfed rice ecosystem of Maroua and in the main irrigated rice ecosystems of Yagoua and Maga in the Far North Region, Cameroon . Insect vector sampling was conducted in rainfed and irrigated rice fields every two weeks using a sweep net and a D-Vac (vacuum trap). From the samples obtained in the different rice-growing sites, the dominant structure of insect vectors of rice yellow mottle as well as their natural enemies was analyzed according to the phenology of rice. It appears from the inventory of insects in irrigated rice (Maga, Yagoua) and rainfed rice (Maroua) that this crop harbors many vectors of the rice yellow mottle virus. In the different rice-growing sites, we have numbers of vector insect individuals captured of 267, 286 and 385 respectively in Maroua (rainfed rice), Maga and Yagoua (irrigated rice). The vector insects captured are distributed as follows, eight species of vector insects in irrigated rice in Maga belonging to five families divided into three orders: Chnootriba similis (Coleoptera: Coccinellidae), Chaetocnema pulla (Coleoptera: Chrysomelidae), Locris rubra ( Hemiptera: Cicadellidae), Nephotettix nigropictus (Hemiptera: Cicadellidae), Sogatella furcifera (Hemiptera: Delphacidae), Cofana spectra (Hemiptera: Cicadellidae), Niparvata lugens (Hemiptera: Delphacidae) and Diopsis thoracica (Diptera: Diopsidae). In irrigated rice in Yagoua, eleven species of vector insects belonging to seven families divided into three orders were collected: Chnootriba similis (Coleoptera: Coccinellidae), Chaetocnema pulla (Coleoptera: Chrysomelidae), Locris rubra (Hemiptera: Cicadellidae), Nephotettix nigropictus (Hemiptera: Cicadellidae), Sogatella furcifera (Hemiptera: Delphacidae), Cofana spectra (Hemiptera: Cicadellidae), Recilia dorsalis (Hemiptera: Cicadellidae), Niparvata lugens (Hemiptera: Delphacidae), Leptocorisa oratorius (Hemiptera: Alydidae), Diploxys spp. (Hemiptera: Pentatomidae) and Diopsis thoracica (Diptera: Diopsidae). As for rainfed rice in Maroua, thirteen vector insect species belonging to seven families and three orders were collected: Chnootriba similis (Coleoptera: Coccinellidae), Chaetocnema pulla (Coleoptera: Chrysomelidae), Trichispa sericea (Coleoptera: Chrysomelidae), Locris rubra (Hemiptera: Cicadellidae), Nephotettix nigropictus (Hemiptera: Cicadellidae), Sogatella furcifera (Hemiptera: Delphacidae), Cofana spectra (Hemiptera: Cicadellidae), Recilia dorsalis (Hemiptera: Cicadellidae), Niparvata lugens (Hemiptera: Delphacidae) and Diopsis thoracica (Diptera: Diopsidae). These species proved to be particularly important by the size of their populations at the tillering stage of rice. The irrigated rice ecosystems of Yagoua and Maga are the most infested by insect vectors of rice yellow mottle virus and among these insect vectors Nephotettix nigropictus (Hemiptera: Cicadellidae) is the abundant species with 87 and 90 individuals collected respectively from Maga and Yagoua. Nephotettix nigropictus (Hemiptera: Cicadellidae) was collected in abundance at the tillering stage of rice. As for the predators and parasitoids present in the rice fields, there were spiders Araneus sp. (Araneae: Araneidae), Tetragnatha sp. (Araneae: Tetragnatidae), Pardosa injucunda (Araneae: Lyconidae) and lady beetles Xanthadalia effusa (Coleoptera: Coccinellidae) as predators and Hydrellia griseola (Diptera: Ephydridae), Bracon sp. (Hymenoptera: Braconidae), Xiphosomella sp. (Hymenoptera: Braconidae), Platygaster sp. (Hymenoptera: Platygasteridae) as parasitoids. The parasitoid species Hydrellia griseola (Diptera: Ephydridae) and the predatory species Araneus sp. (Araneae: Araneidae) are the most abundant natural enemies in the rice ecosystems of the Far North.

GREGARINA LUTESCENS N. SP. INFECTING THE HARLEQUIN LADYBIRD HARMONIA AXYRIDIS (COLEOPTERA: COCCINELLIDAE).

Gregarina lutescens n. sp. is described from the alimentary canal of the harlequin ladybird or multicolored Asian lady beetle, Harmonia axyridis (Coleoptera: Coccinellidae) collected from prairie fleabane, Erigeron strigosus, at Peru State College, Peru, Nemaha Co., Nebraska. Our specimens differ from all 11 known species of Gregarina infecting coccinellid beetles worldwide by differences in size and relative shape, color, and association structure. Gregarina lutescens n. sp. is smaller than 7 known species infecting coccinellid beetles but larger than the other 4 known species based on confidence interval exclusion of means. Our specimens are unique among known species of interest in their quince-yellow cytoplasm and precocious but ephemeral serial associations of up to 5 satellites. Nucleotide sequence (18S) phylogenetic analyses place the new species basal to a member of an internal clade of Gregarina that comprises gregarines parasitizing chrysomelid beetles. Phylogenetically, the analysis recovered 3 major lineages within the gregarines, representing the superfamilies Gregarinoidea, Stenophoroidea, and Stylocephaloidea and indicating the propensity of gregarines to track host lineages and environments through evolutionary time. These findings confirm the polyphyletic nature of Gregarina, which currently comprises over 300 described species, only a handful of which have documented genetic sequences suitable for phylogenetic analysis. Recollection, redescription, and molecular clarification of gregarine species infecting coccinellids would likely result in identification of a unique clade that would be an excellent system for studying the effect of intraguild host competition on parasite diversification and community structure. Ecologically, patterns of prevalence in this study indicate that G. lutescens reproduces primarily in larval hosts but depends on infections in adult beetles to overwinter, reflecting the differential vagility and frost tolerance of larval and adult host life cycle stages.

Direct Effect of Cannibalism and Intraguild Predation in Menochilus sexmaculatus (Coleoptera: Coccinellidae)

Abstract Menochilus sexmaculatus F. (Coleoptera: Coccinellidae) is a generalist predator with potential as a biological control candidate for suppressing many insect pests, including the cotton mealybug, Phenacoccus solenopsis Tinsley (Hemiptera: Pseudococcidae). However, the potential control capacity of M. sexmaculatus on P. solenopsis may depend not only on its fitness and predatory efficacy, but also on the consequences of both conspecific and heterospecific interactions with other individuals that share the same resource. This study investigated the aggressiveness and vulnerability of different life stages of M. sexmaculatus when encountering various stages of M. sexmaculatus or Harmonia axyridis (Pallas). The results showed that M. sexmaculatus could act as predator and/or prey with the presence of conspecific and heterospecific ladybird beetles. The success of predation is affected by the ladybird beetle life stage and, in most cases, young stages of the ladybird beetles were most susceptible to relatively older life stages of ladybird beetles. Predation between M. sexmaculatus/H. axyridis larvae of the same developmental stage was always asymmetric, favoring H. axyridis. Moreover, M. sexmaculatus exhibited intensive aggressiveness toward their own species over heterospecific individuals, but was more vulnerable to H. axyridis than to M. sexmaculatus individuals. Overall, H. axyridis could negatively affect the population densities of M. sexmaculatus by its high aggressiveness and low vulnerability. However, because our study was conducted in an oversimplified and confined area, more research should be conducted under more realistic conditions to explore the impacts of H. axyridis on the population dynamics of M. sexmaculatus.

Niche Study of Major Pests and Natural Enemies in Peach Orchards with Different Vegetative Ground Covers

Abstract As a modern orchard management tool, vegetative ground cover can increase biodiversity, enhance the effect of natural enemies, and reduce the amounts of chemical agents used to control pests. This study aimed to investigate the temporal niche relationship between pests and natural enemies in peach orchards (1) planted with flowering plants as a ground cover or (2) with naturally occurring vegetative ground cover or (3) plowed, with the objective of clarifying the conservation effect of peach orchard ground cover on different natural enemies. The results showed that the niche width value of natural enemies in peach orchards planted with the flowering plants was the highest, followed by natural vegetation peach orchards. The ladybird beetle (Coccinellidae) ecological niche width values were the highest in the natural enemy communities of the two types of peach orchards. These results demonstrate that vegetative ground cover in peach orchards can effectively harbor natural enemies and that coccinellids are highly adapted for the ecological environment of the peach orchard.

Canola bee pollen is an effective artificial diet additive for improving larval development of predatory coccinellids: a lesson from Harmonia axyridis.

Pollen is a common plant-derived food source for predatory ladybird beetles under field conditions, yet the potential for pollen to improve the quality of artificial diets remains largely unexplored. In this study, we developed three pollen diets by incorporating varying proportions of canola bee pollen (7.5%, 15.0% and 22.5% with 2.5%, 5.0%, and 7.5% of water, respectively) into a conventional diet. The feeding efficiency of Harmonia axyridis, an omnivorous predator, was evaluated and compared on three pollen diets, a conventional nonpollen diet and pea aphids. The larvae fed a medium or high pollen diet exhibited significantly higher survival in the 4th instar, pupa and adult stages than those fed a nonpollen diet. These larvae also developed into significantly heavier adults, and their survival rates in adulthood were comparable to those fed pea aphids. Specifically, we revealed the underlying mechanisms through which a high pollen diet enhances pupal development. Consumption of high pollen diet versus nonpollen diet resulted not only in a significant decrease in pupal glycogen content, but also an increase in adult lipid content. Both diet treatments induced similar changes in carbohydrate and glycogen content compared to the aphid diet while exhibiting different alterations in pupal protein content and adult lipid content. Furthermore, the transcriptome analysis revealed that the nutrient metabolism, immune response, and cuticle development pathways were predominantly enriched among the differentially expressed genes (DEGs). Canola bee pollen offers diverse advantages in terms of rearing H. axyridis larvae with an artificial diet, which will advance the development of effective diets for predaceous coccinellids. © 2024 Society of Chemical Industry.

Environmental Factors Impacting the Development of Toxic Cyanobacterial Proliferations in a Central Texas Reservoir.

Cyanobacterial harmful algal proliferations (cyanoHAPs) are increasingly associated with dog and livestock deaths when benthic mats break free of their substrate and float to the surface. Fatalities have been linked to neurotoxicosis from anatoxins, potent alkaloids produced by certain genera of filamentous cyanobacteria. After numerous reports of dog illnesses and deaths at a popular recreation site on Lady Bird Lake, Austin, Texas in late summer 2019, water and floating mat samples were collected from several sites along the reservoir. Water quality parameters were measured and mat samples were maintained for algal isolation and DNA identification. Samples were also analyzed for cyanobacterial toxins using LC-MS. Dihydroanatoxin-a was detected in mat materials from two of the four sites (0.6-133 ng/g wet weight) while water samples remained toxin-free over the course of the sampling period; no other cyanobacterial toxins were detected. DNA sequencing analysis of cyanobacterial isolates yielded a total of 11 genera, including Geitlerinema, Tyconema, Pseudanabaena, and Phormidium/Microcoleus, taxa known to produce anatoxins, including dihydroanatoxin, among other cyanotoxins. Analyses indicate that low daily upriver dam discharge, higher TP and NO3 concentrations, and day of the year were the main parameters associated with the presence of toxic floating cyanobacterial mats.