Amblyseius Swirskii Research Articles

Genetic and morphological features of some Turkish populations of Amblyseius swirskii (Athias-Henriot) (Acari: Phytoseiidae)

Amblyseius swirskii is one of the most important phytoseiid mites commercialized worldwide for controlling pest mites and small insect pests. The study aims to investigate morphological and genetic variation among seven populations collected from different locations and plant species (cotton, orange) in Türkiye. The DNA sequences (12S rRNA and Cytb mitochondrial DNA markers) were also compared with those of commercial populations. The average genetic distance among the Turkish populations was quite low (0.7% for 12S rRNA and 0.9% for Cytb mtDNA), ranging from 0 to 2.8% and 0 to 1.5%, respectively. The phylogenetic trees show two distinct groups, separated by genetic distances of 0.9% and 1.3% for the 12S rRNA and the Cytb mtDNA fragments, respectively. The genetic differences were not explained by location or host plant. However, specimens from some populations were exclusively or predominantly included in one of the two clades, and commercialized specimens of A. swirskii only included in one clade, along with specimens collected in orange orchards. Specimens from cotton fields and Solanum nigrum, were found in both clades, but in different proportions. Results show a globally low genetic diversity within A. swirskii for the two DNA fragments. The existence of two clades raises questions about the presence of a clade derived from commercial releases. However, this result may be related to other factors. Morphological analyses demonstrated substantial variability among the populations, except for the population sampled from orange in Adana Kozan. Despite this, the morphological and molecular results are relatively consistent.

The impact of different concentrations of nano-capsulated Aleppo oak extraction on the biological performance of Amblyseius swirskii (Acari: Phytoseiidae)

Essential oils have demonstrated promising results in controlling mites. However, their impact on predatory mites, which are widely used in pest management programs, remains uncertain. In the present study, the effects of 1, 2 and 3 (g a.i. L-1) of nano-capsulated Aleppo oak extraction on the biological parameters of Amblyseius swirskii Athias-Henriot (Acari: Phytoseiidae) were investigated under laboratory condition. Based on the results, the pre-adult period of the predator was significantly longer in the 2 (g a.i. L-1) concentration (6.66 days) compared with the control and the 1 (g a.i. L-1) concentration. Additionally, the total lifespan in the control group (39.42 days) was significantly longer than the treatment with a 3 (g a.i. L-1) concentration (31.50 days). The total fecundity in the 2 (g a.i. L-1) concentration (47.60 eggs/female) was significantly higher than the other treatments, indicating a positive effect of this botanical pesticide at the concentration recommended by the manufacturer on the reproductive system of the predatory mite. No significant differences were observed among the different treatments and the control group in terms of population growth parameters (GRR, R0, r, and λ). Only the mean generation time (T) showed a significant difference, with the longest period being recorded in the 2 (g a.i. L-1) concentration (15.44 ± 0.21), which was significantly longer than the control and the 1 (g a.i. L-1) concentration. The lack of significant differences in population growth parameters between the treatments indicates that nano-capsulated Aleppo oak extraction is safe for use along with the predatory mite A. swirskii.

Functional Response of Four Phytoseiid Mites to Eggs and First-Instar Larvae of Western Flower Thrips, Frankliniella occidentalis.

The predation capacity and functional responses of adult females of the phytoseiid mites Amblyseius largoensis (Muma), Proprioseiopsis lenis (Corpuz and Rimando), Paraphytoseius cracentis (Corpuz and Rimando), and Amblyseius swirskii (Athias-Henriot) were studied on eggs and first instars of the western flower thrips, Frankliniella occidentalis (Pergande), in the laboratory at 25 °C and 30 °C. At both temperatures, the functional response of all four phytoseiid mites was type II to first instars of the thrips. In contrast, when offered thrips eggs, the functional response was type III. At both temperatures tested, A. swirskii had the highest mean daily consumption of first-instar F. occidentalis, followed by A. largoensis, P. cracentis, and P. lenis. Amblyseius largoensis had the shortest handling time and the highest maximum attack rate when first-instar thrips were the prey. When fed on thrips eggs, A. largoensis had the highest mean daily consumption, followed by A. swirskii, P. cracentis, and P. lenis. On thrips eggs, A. swirskii showed the shortest handling time and highest maximum attack rate. Our findings indicate that all four phytoseiids had a better ability to prey on first-instar larvae of F. occidentalis compared to thrips eggs. At 25 and 30 °C, A. largoensis was the better predator on thrips larvae, whereas A. swirskii was superior in consuming eggs of F. occidentalis. Proprioseiopsis lenis was the inferior predator on both thrips larvae and eggs compared to the other phytoseiids tested.

Residual effect of commonly used insecticides on key predatory mites released for biocontrol in strawberry.

Florida is the second largest producer of strawberries in the United States. However, the production system faces numerous challenges, especially Scirtothrips dorsalis Hood (Thysanoptera: Thripidae) infestations. Management of this pest involves applying insecticides and use of predatory mites, particularly Amblyseius swirskii Athias-Henriot, Neoseiulus cucumeris Oudemans, and Neoseiulus californicus McGregor (Mesostigmata: Phytoseiidae). Strawberry growers in Florida are concerned about the compatibility of the commercial formulations of insecticides used in strawberry pest management with predatory mites. This study assessed the residual effect of commercial insecticides used in strawberry production on the survival, feeding, and oviposition of the 3 predators. Using Munger cells, predators were exposed to commercial formulations of spinetoram, cyantraniliprole, azadirachtin + pyrethrin, Beauveria bassiana, Cordyceps javanica, capsicum, garlic, and canola oil extracts, and water control. There was a gradual decline in the survival and feeding of predatory mites when exposed to all insecticides. Spinetoram had the highest impact on the survival and feeding of all predators compared to other insecticides, while C. javanica had the lowest impact. Cyantraniliprole and azadirachtin + pyrethrin significantly reduced predator survival after 72h of exposure, whereas capsicum, garlic, and canola oil extracts caused a similar reduction after 96h. All predators consumed low proportions of S. dorsalis across all treatments. Oviposition was low in all treatments, with no discernable variation among treatments. These results highlight the potential of using entomopathogenic fungi in conjunction with A. swirskii, N. cucumeris, and N. californicus for the management of S. dorsalis and T. urticae in strawberries.

Spirodiclofen toxicity in Tetranychus urticae and safety to natural enemies Proprioseiopsis asetus and Amblyseius swirskii

Proprioseiopsis asetus and Amblyseius swirskii are excellent natural enemies of plant-feeding mites and small pests. In order to clarify the safety of the acaricide spirodiclofen to the predatory mites P. asetus and A. swirskii, here, we investigated the toxicity of the acaricide on the pest mite T. urticae (nymphs and adult females) and on both species of predatory mites, P. asetus and A. swiskii (eggs, nymphs, and female adults) by using the spray, slide-dip, and leaf residual toxicity methods, compared the selective toxicity and assessed the safety to these natural enemies. The results demonstrated that the corrected mortality in P. asetus and A. swirskii female adults was <5% at recommended spirodiclofen concentrations in the spray method. In the leaf residual toxicity method, P. asetus and A. swirskii egg-hatching rates did not differ significantly from the pure water control group. In the slide-dip method, spirodiclofen lethal concentration 50 (LC50) in P. asetus and A. swirskii female adults was noted to be 9,494.875 and 3,064.187 mg·L−1, respectively. In the spray method, spirodiclofen LC50 in P. asetus and A. swirskii nymphs was found to be 4,292.664 and 1,081.609 mg·L−1, respectively, and that in T. urticae female adults and nymphs was 55.189 and 40.862 mg·L−1, respectively. Spiroclofen selective toxicity ratios (STRs) in P. asetus female adults–T. urticae and P. asetus nymphs–T. urticae were 172.013 and 105.053, respectively, indicating that spiroclofen has a high positive selectivity toward the pest T. urticae and its natural enemy P. asetus. In contrast, spiroclofen STRs in A. swirskiis female adults–T. urticae and A. swirskiis nymphs–T. urticae were 55.522 and 26.470, respectively, indicating spiroclofen has a moderate positive selectivity toward the pest T. urticae and its natural enemy A. swirskii. In the safety evaluation, the spirodiclofen safety factor for P. asetus female adults and nymphs was 158.248–237.37 and 71.544–107.317, respectively, whereas that for A. swirskii female adults and nymphs was 50.070–76.605 and 18.027–27.040 respectively. All spirodiclofen safety factor values were much higher than 5, indicating that spirodiclofen is highly safe for P. asetus and A. swirskii; in particular, spirodiclofen is safer for P. asetus than for A. swirskii.

Role of eggplant trichome in whitefly oviposition and its relevance to biological control under greenhouse conditions.

The combined release of the predatory mite Amblyseius swirskii (Athias-Henriot) and the mirid Nesidiocoris tenuis (Reuter) provides effective biological control of the tobacco whitefly (Bemisia tabaci (Gennadius)) in greenhouse eggplant. However, knowing how plants' trichomes affect pest-predator interactions could improve whitefly management. Here, the effect of two varieties with either the presence or absence of trichomes was assessed on naturally occurring whitefly populations and predator abundance in a first experiment under field conditions. Predator-prey models were developed to assess the effect of trichomes on pest and predator population dynamics under field conditions. In a second semi-field experiment, the occurrence and oviposition preferences of B. tabaci and A. swirskii in the same eggplant varieties were compared. Significantly higher numbers of whitefly and mite, adults and eggs, were found on the hairy variety in both experiments. However, no differences were found in N. tenuis abundance between varieties under field conditions. Predator-prey models showed that whitefly growth rate increased in the hairy variety. N. tenuis and A. swirskii showed different fitness parameters according to the variety, with the former displaying better performance in the hairless variety and the latter in the hairy variety. Both predators effectively controlled the increase in whitefly populations in both varieties. Overall, the findings suggest that the hairless variety is more effective in deterring whiteflies. Additionally, the higher population of A. swirskii on the hairy variety indicates that this predator benefited from both the presence of trichomes and the prey.

Assessing performance of Amblyseius swirskii as a predatory mite of Tetranychus urticae and Frankliniella occidentalis: life table and foraging behaviour studies

ABSTRACT Life table parameters of Amblyseius swirskii when Frankliniella occidentalis and Tetranychus urticae were offered solely as diet were investigated. The switching behaviour of this predator was studied on F. occidentalis in the presence of spider mites. The data showed that feeding on the spider mite resulted in significantly longer developmental time compared to thrips. We found a significant effect of prey on the total life span, adult pre-oviposition period (APOP), and total pre-oviposition period (TPOP) of the predatory mite. The length of the oviposition period and the number of laid eggs per female were not affected by the kind of the offered prey. None of population growth parameters was affected by the type of diet except for mean generation time (T). Predators fed on spider mite had a longer T than those reared on thrips. Furthermore, our data illustrated a negative switching in the behaviour of A. swirskii when T. urticae and F. occidentalis were present. In other words, the predator switched from the abundant prey to the rarer prey. The results of this study are needed to understand and forecast the performance of A. swirskii in greenhouse environments where both T. urticae and F. occidentalis can be present.

The impact of different photoperiod regimes on vital life traits of Amblyseius swirskii and Neoseiulus cucumeris (Acari: Phytoseiidae).

Environmental factors, such as photoperiod can play an important role in the development and performance of predatory mites. The influence of five photoperiod regimes (0: 24, 8: 16, 12: 12, 16: 8, and 24: 0h; Light: Dark) on the population parameters of the predatory mites, Amblyseius swirskii Athias-Henriot and Neoseiulus cucumeris (Oudemans) was studied under the laboratory conditions at 25°C and 25 ± 1°C, 65 ± 5% RH. Regarding A. swirskii, the longest and shortest total pre-adult and total preoviposition periods (TPOP) were in the photoperiod of 12L:12D and 16L:8D, respectively. The oviposition days, adult longevity, total life span, fecundity, gross reproductive rate (GRR), and net reproductive rate (R0) of the predator had no significant difference in all photoperiods tested. The intrinsic rate of increase (r) and the finite rate of increase (λ) in 16L:8D photoperiod had no significant difference with the other photoperiods tested except 12L:12D. Regarding N. cucumeris, the shortest total pre-adult and TPOP were in full darkness. The oviposition days and fecundity were significantly higher in 16L:8D than the others. The value of R0 in 16L:8D was significantly higher than 8L:16D. The highest values of the parameters r and λ were observed in full darkness, which had no significant difference with 16L:8D and 24L:0D. According to the results, the photoperiod regime had a more significant influence in terms of development and reproduction on N. cucumeris than A. swirskii, and 16:8 (L: D) h photoperiod was recognized as the proper regime for their rearing.

The potential application of Czenspinskia transversostriata in biological control.

Phytoseiid predatory mites are one of the most important groups of biocontrol agents, commonly used in biological control. The ability to produce these predatory mites economically, at high density on cheap factitious food sources, is a major contributor to their success. Astigmatid mites are the most widely used factitious food for this purpose. In this study, we investigated the potential application of the leaf-dwelling astigmatid mite Czenspinskia transversostriata (Oudemans) (Acari: Winterschmidtiidae) as a prey mite in biological control. We tested whether C. transversostriata is a suitable food source for the predatory mite Amblyseius swirskii Athias-Henriot (Acari: Phytoseiidae), both in the laboratory and on cucumber plants. Based on a reproduction trial, C. transversostriata proved to be an equally good food source compared to both pollen of Typha angustifolia L. (Poales: Typhaceae) and a frequently used prey mite Carpoglyphus lactis L. (Acari: Carpoglyphidae). In a pre-establishment trial on cucumber plants, populations of A. swirskii reached equally high densities when supplemented with C. transversostriata, compared to C. lactis. Lastly, we show that C. transversostriata is capable of feeding and reproducing on powdery mildew growing on cucumber plants, thereby slowing down the development of the pathogenic fungus. Results derived from this study show that C. transversostriata may have multiple potential applications in biological control programs.

Field efficacy of a biopesticide and a predatory mite for suppression of Scirtothrips dorsalis (Thysanoptera: Thripidae) in strawberry.

Chilli thrips, Scirtothrips dorsalis Hood (Thysanoptera: Thripidae) has emerged as a severe invasive pest of strawberry Fragaria × ananassa Duchesne in the United States. The objective of this study was to assess the field efficacy of a biopesticide and thrips predator, Amblyseius swirskii Athias-Henriot for S. dorsalis management in field grown strawberry compared to synthetic insecticide applications that are current industry standard (spinetoram) conducted at UF/IFAS GCREC, FL during 2021-2022 and 2022-2023 in a 2-year field study. The following treatments were applied in the field: (1) biopesticide, capsicum oleoresin extract + garlic oil + canola oil application at maximum label rate; (2) predatory mite of thrips, A. swirskii released at 30 predators per plot; (3) spinetoram applied at maximum label rate; and (4) biopesticide applied 24 h before release of A. swirskii. A control plot with no insecticide or predatory mite releases was maintained. Results show that the capsicum extract can be used for management of S. dorsalis, especially during the latter stages of strawberry field season when resistance to spinetoram is high. The field performance of A. swirskii was variable and extensive research is needed to highlight factors affecting field performance of predatory mites for thrips management.

Sublethal effects of a spiromesifen and abamectin combination on Tetranychus urticae (Acari: Tetranychidae) and its predators Phytoseiulus persimilis and Amblyseius swirskii (Acari: Phytoseiiidae).

The two-spotted spider mite, Tetranychus urticae Koch (TSSM), is an important cosmopolitan pest of agricultural crops that is often managed in greenhouses by augmentation of predatory mites in combination with acaricides. Here we examined the transgenerational effects of low lethal concentrations of a widely-used acaricide, Oberon Speed® (a combination of spiromesifen and abamectin), on the life history traits and population growth of T. urticae and two of its predators, Phytoseiulus persimilis Athias-Henriot and Amblyseius swirskii Athias-Henriot (Acari: Phytoseiidae). The concentrations employed corresponded to the LC10, LC20 and LC30 values estimated for TSSM protonymphs 48h post-exposure in a topical bioassay, which yielded an LC50 value of 207.2ppm. Parental exposure of TSSM to all three low concentrations increased the total developmental time of progeny; both the LC20 and LC30 treatments reduced adult longevity and number of oviposition days, but only the LC30 treatment increased the preoviposition period. Similarly, both the LC20 and LC30 treatments significantly reduced life table parameters (r, R0, λ, and GRR), and increased generation time (T) and population doubling time (DT). Although maternal exposure to the acaricide had various impacts on progeny life history, A. swirskii was less affected than P. persimilis, suggesting the former species would be more compatible for integration with Oberon Speed® for control of T. urticae in greenhouse vegetable production.

Complex Habitats Boost Predator Co-Occurrence, Enhancing Pest Control in Sweet Pepper Greenhouses

Sweet pepper is a crop that benefits from phytosanitary treatments with low environmental impact, especially the successful control of pests through the introduction of biological control agents in greenhouses. However, predators that naturally occur in these surroundings often enter greenhouses. The precise roles of these natural predators and their interactions with the introduced predatory insects and mites are often unknown. This study investigated the relationships between Nesidiocoris tenuis, which is naturally present, and Amblyseius swirskii and Orius laevigatus, which are two species of generalist predators released for the control of multiple pests. This study was conducted for two years on 13 commercial sweet pepper crops in various types of greenhouses (tunnels and traditional greenhouses) in Sicily. The environmental complexity value (ECV) for each site was estimated based on 18 points detected around the site according to the different habitats that occurred at each coordinate. The results showed that the occurrence of N. tenuis in greenhouses, independently of their typology (tunnel or traditional greenhouse), was mainly promoted by the greater diversification of habitats immediately surrounding the pepper crops (in a circular area with a diameter of 500 mt), with an increase in its density during the crop season. Moreover, N. tenuis–O. laevigatus’s co-occurrence in flowers suggested that they were not impacted by each other’s presence and that their co-occurrence had a significant effect on pest reduction, although their co-occurrence was density-dependent. As an intraguild predator, N. tenuis competed with O. laevigatus for Frankliniella occidentalis when many predators were present. In addition, N. tenuis also competed with A. swirskii when they both occurred in flowers at a higher density. This study highlights the importance of pepper plant flowers in promoting a higher occurrence of juvenile forms of N. tenuis within flowers. Amblyseius swirskii colonized the plants in 3 weeks, distributing itself almost uniformly over the leaves with a clear control action against not only Bemisia tabaci but also F. occidentalis when present on the flowers. Thus, this concurrent analysis of several commercial pepper sites within the same production area suggests that, even with similar pest control plans, the diverse variability in the presence of natural enemies must be considered when selecting control strategies for pepper crop pests and that N. tenuis, favored by complex surrounding habitats, contributes actively to pest reduction.

Laboratory Investigations on the Potential Efficacy of Biological Control Agents on Two Thrips Species, Onion Thrips (Thrips tabaci Lindeman) and Western Flower Thrips (Frankliniella occidentalis (Pergande)).

Thrips biocontrol research in greenhouse crops has focused primarily on western flower thrips (WFT; Frankliniella occidentalis). However, recent outbreaks of onion thrips (OT; Thrips tabaci) in Ontario, Canada, demonstrate that biocontrol-based IPM programs for WFT do not control OT sufficiently to prevent crop losses. A lack of comparative studies makes it difficult to determine which program components for WFT are failing for OT. We conducted several laboratory trials examining the extent to which commercial biocontrol products kill OT compared to WFT. These included phytoseiid mites (Amblyseius swirskii, Neoseiulus cucumeris, Amblydromalus limonicus, Iphiseius degenerans), a large generalist predator (Orius insidiosus), an entomopathogenic fungus (Beauveria bassiana strain GHA), and entomopathogenic nematodes (Steinernema feltiae, S. carpocapsae, Heterorhabditis bacteriophora). In no-choice trials, A. swirskii and O. insidiosus consumed more OT than WFT (first instars and adults, respectively). In choice trials, A. swirskii, N. cucumeris, and O. insidiosus consumed more OT than WFT. Steinernema feltiae caused higher mortality in OT than WFT. There was no difference in mortality between thrips species exposed to other biocontrol agents. This suggests available tools have the potential to manage OT as well as WFT. Possible explanations why this potential is not realized in commercial settings are explored.

Life table parameters of Amblyseius largoensis, Amblyseius swirskii and Proprioseiopsis lenis (Acari: Phytoseiidae) fed on eggs and larvae of Frankliniella occidentalis.

The immature development and reproduction of the predatory mites Amblyseius largoensis (Muma), Proprioseiopsis lenis (Corpuz and Rimando), and Amblyseius swirskii Athias-Henriot (Acari: Phytoseiidae) were investigated using both thrips eggs and first instars of the western flower thrips, Frankliniella occidentalis Pergande, as prey in a controlled laboratory environment at 25°C and 60% relative humidity. When provided with thrips eggs as food, A. largoensis exhibited a notably shorter immature development period for both males (7.05 days) and females (6.51 days) as compared with A. swirskii (8.05 and 7.19 days, respectively) and P. lenis (8.10 days and 7.05 days, respectively). Amblyseius largoensis also displayed a higher oviposition rate (2.19 eggs/female/day) than A. swirskii and P. lenis (1.79 and 1.78 eggs/female/day, respectively). Moreover, it exhibited the highest fecundity (25.34 eggs/female), followed by P. lenis (24.23 eggs/female) and A. swirskii (22.86 eggs/female). These variations led to A. largoensis having the highest intrinsic rate of increase (rm) at 0.209, followed by A. swirskii at 0.188, and P. lenis at 0.165. However, when the predatory mites were provided with first instars of F. occidentalis, A. swirskii demonstrated a faster immature development period for both males (7.67 days) and females (7.59 days) as compared with P. lenis (9.00 days and 7.86 days, respectively) and A. largoensis (8.47 days and 8.61 days, respectively). While the oviposition rates of P. lenis (1.92 eggs/female/day) and A. swirskii (1.90 eggs/female/day) were similar when feeding on this prey, A. largoensis produced fewer eggs (1.83 eggs/female/day). Further, A. swirskii exhibited the highest fecundity (31.93 eggs/female), followed by A. largoensis (25.71 eggs/female) and P. lenis (23 eggs/female). Consequently, the intrinsic rate of increase (rm) on thrips first instars was highest in A. swirskii (0.190), followed by A. largoensis (0.186), and P. lenis (0.176). In summary, our findings indicate that in terms of life history parameters A. largoensis performs optimally when feeding on thrips eggs, whereas A. swirskii performs best when preying on the mobile first instars of the thrips. These insights into the dietary preferences and reproductive capabilities of the studied predatory mite species have important implications for their potential use as biological control agents against F. occidentalis in agricultural settings.

Side Effects of Some Insecticides and Acaricides on Different Beneficial Insects in Laboratory Conditions

Side effects studies are important for the development of Integrated Pest Management (IPM) strategies, especially due to the adverse impacts of broad-spectrum pesticides on natural enemies. This study was conducted to evaluate the side effects of commonly used pesticides on Chilocorus bipustulatus L. (Coleoptera: Coccinellidae), Anagyrus pseudococci (Girault) (Hymenoptera: Encyrtidae), and Amblyseius swirskii Athias-Henriot (Acari: Phytoseiidae) under laboratory conditions. The results revealed varying mortality rates among the natural enemies, with Abamectin exhibiting the highest mortality rates of 65.00%, 71.50%, and 78.75% respectively. Spirodiclofen (S1) showed the lowest mortality rate of 17.50% for C. bipustulatus, while Buprofezin (B) and Spirodiclofen (S2) showed rates of 18.78% and 18.93%, respectively for A. pseudococci. For A. swirskii, Spirodiclofen (S1 and S2) recorded the lowest mortality rates of 21.25% and 23.75% respectively. According to the IOBC classification, Spirodiclofen (S1 and S2) was classified as harmless (N,) against all three natural enemies. Abamectin (A) was classified as slightly harmful (M) for all three species, while Buprofezin was rated as slightly harmful (M) for C. bipustulatus but harmless (N,) for A. pseudococci and A. swirskii. This research highlights the differential effects of pesticides on different natural enemies and underlines the importance of considering such impacts in pest management strategies.

Are predatory mites effective as biological control agents to suppress Oligonychus ilicis (Acari: Tetranychidae) in blueberry plantings?

Southern red mite, Oligonychus ilicis McGregor (Acari: Tetranychidae), is an important polyphagous spider mite pest that causes economic damage to many ornamentals, coffee, and fruit crops. Blueberry growers in the Southeastern United States, including Florida and Georgia, have experienced severe losses due to outbreaks of O. ilicis. Predatory mites are an important management tool used for controlling spider mites; however, predators have not been studied and successfully evaluated in blueberry systems. Amblyseius swirskii Athias-Henriot, Phytoseiulus persimilis Athias-Henriot, and Neoseiulus californicus (McGregor) (Acari: Phytoseiidae) are among the most economically important arthropod agents used in augmentative biological control worldwide. To evaluate the potential of these 3 commercially available predatory mites for use in blueberry plantings, we conducted experiments under controlled laboratory conditions and in the greenhouse. In preliminary laboratory experiments, P. persimilis and N. californicus significantly reduced the number of O. ilicis motile stages below those found in the untreated control, indicating the potential for these 2 predatory mite species to suppress O. ilicis populations. Amblyseius swirskii did not perform well controlling O. ilicis motiles in the laboratory. Under greenhouse conditions, N. californicus and P. persimilis significantly reduced the number of eggs after 7 days of release and the number of motile stages after 14 days of release. This is the first report of using phytoseiid mites to suppress O. ilicis in blueberry systems in the United States. Further studies on predator behavior, feeding preferences, and acaricide compatibility with predators are required to investigate the possibility of using P. persimilis, and N. californicus as biological control agents of O. ilicis in blueberry systems.

Insecticidal effects of the fast pyrolysis bio-oil against Spodoptera littoralis and Aphis gossypii insect pests

The detrimental effects of agricultural pesticides on human and environmental health necessitate the development of alternatives to conventional pesticides. In the laboratory, the cotton leafworm (Spodoptera littoralis) and aphid (Aphis gossypii) insects were used to evaluate the insecticidal activity of bio-oil derived from olive cake. The application of bio-oil by leaf dipping against S. littoralis demonstrated no mortality at a concentration of 1 % bio-oil. In contrast, the bio-oil showed better results against A. gossypii by slide dip method with LC50 = 1310.40 mg/l and LC90 = 3117.40 mg/l. The combined activity of bio-oil and the biopesticide Beauveria bassiana (bio-oil/B.b) was comparable, with LC50 = 1386.94 mg/L and LC90 = 3142.05 mg/L. The field application (two sprays) of bio-oil, bio-oil/B.b, and a commercial insecticide (alpha super) on aphids revealed a reduction of 52 %, 74.33 %, and 74.67 % in the first spray and 59.67 %, 63.33 %, and73.67 % in the second spray for, bio-oil, bio-oil/B.b, and super alpha respectively. The bio-oil and bio-oil/B.b had significantly less effect on the population densities of two predators (predator mite Amblyseius swirskii and aphid lion Chrysoperla carnea) than the insecticide used. Analyses of bio-oil by gaschromatography–mass spectrometry (GC–MS) identified 30 compounds possibly have pesticidal activity. The most abundant compounds are 9 octadecenoicacid methyl ester, hexadecanoic acid, methyl ester, 6 octadecenoic acid, methyl ester and Phenol, 2methoxy. The pyrolysis byproduct (bio-oil) of olive cake biomass contains bioactive compounds that can be used as biopesticide.

Biological Control and Habitat Management for the Control of Onion Thrips, Thrips tabaci Lindeman (Thysanoptera: Thripidae), in Onion Production in Quebec, Canada.

Onion thrips (Thrips tabaci) can pose a significant threat to onion crops, causing leaf damage, reduced bulb size and quality, and yield loss during severe infestations. Conventional insecticide use has been the primary method for managing this pest species, but the efficacy of this approach is inconsistent. Furthermore, emerging pest resistance is a growing concern in some regions. This two-year field study aimed to assess the effectiveness of several pest management strategies in controlling onion thrips populations and limiting their impact on onion yields. The strategies tested consisted of habitat manipulations (including flower strips and straw mulch), biological control agents (Stratiolaelaps scimitus, Neoseiulus cucumeris, Amblyseius swirskii, and Beauveria bassiana), as well as physical barrier control methods (exclusion nets, kaolin, and mineral oil). Habitat manipulation techniques, particularly the use of flower strips, reduced thrips populations by up to 50% and increased onion yields by 25%. In contrast, exclusion nets had a detrimental effect on onion yields, and the other alternative control methods produced results comparable to those obtained for untreated controls. When used alone, biological control agents were not effective at maintaining thrips populations below economically damaging levels. This study offers valuable insights into effective and sustainable pest management practices for the onion industry.

Biological Control of Three Major Cucumber and Pepper Pests: Whiteflies, Thrips, and Spider Mites, in High Plastic Tunnels Using Two Local Phytoseiid Mites.

To enhance food security, food safety, and environmental health, a bio-based integrated pest management (BIPM) strategy was evaluated at two coastal locations in Lebanon as an alternative to toxic pesticide sprays in commercial high-arched plastic tunnels common in many countries. The evaluation occurred during two cucumber and pepper cropping seasons: spring and fall. At each site, two commercial tunnels were used; farmers' conventional practices were applied in one tunnel, while the BIPM approach was followed in the second tunnel. In the farmers' practices, a total of 14 sprays of insecticide/acaricide mixtures were applied during the spring growing season, and 6 sprays were applied during the fall. In the BIPM tunnels, hotspot releases of local strains of Amblyseius swirskii and Phytoseiulus persimilis were applied. By the end of the spring season, the number of whitefly nymphs (WFNs)/leaf and thrips/leaf in the pesticide treatment were 4.8 and 0.06, respectively, compared to 0.1 and 0.33, respectively, in the BIPM treatment. Similarly, at the end of the fall season, the WFNs reached 19.7/leaf in the pesticide control as compared to 1.2/leaf in the BIPM treatment, proving the efficacy of A. swirskii. Farmers using conventional acaricides during both cropping seasons failed to control Tetranychus urticae, the two-spotted spider mite (TSSM). However, hotspot releases of P. persimilis were successful in controlling TSSM. By the end of June, the number of TSSMs reached 7.8/leaf in the BIPM treatment compared to 53/leaf in the pesticide treatment. Likewise, in December, TSSM numbers reached 9/leaf in the BIPM treatment compared to 40/leaf in the pesticide treatment. Preliminary observations of pepper showed that both predatory mites (A. swirskii and P. persimilis) gave similar or better efficacy against the three pests. The two local predatory phytoseiid mites seem to be effective in controlling these three major pests and to be adapted to local environmental conditions. A rate of increase of 0.86 was observed for P. persimilis and 0.22 for A. swirskii, in June, when maximum temperatures were close to 40 °C. This also shows a compatibility between the two predators. In conclusion, our BIPM approach was efficient under a Mediterranean climate in arched plastic tunnels with relatively poor aeration.

Relevance of diet diversification in the coexistence between Orius laevigatus and Amblyseius swirskii: prey switching and intraguild predation

AbstractOmnivores obtain resources from more than one trophic level, choosing food based on quantity and quality. They usually engage in intraguild predation (IGP) when prey is scarce. Orius laevigatus is an example of omnivore that becomes superior predator of the predatory mite Amblyseius swirskii when released in a combined system under low levels of the preferred prey, the thrips Frankliniella occidentalis. Here, we test two genetically enhanced O. laevigatus strains for bigger size and better fitness feeding on pollen (BIG30 and 2POL-11, respectively), hence with a wider dietary diversification, to elucidate the potential effects on prey preference and IGP on the predatory mite, in comparison with a commercial population of O. laevigatus. To do that, predation rates were registered on adult phytoseiids solely or in a choice situation at different availability ratios of adult thrips under laboratory conditions. The effect of pollen as supplemental food on IGP and prey preference was examined, too. We found that our two enhanced lines killed up to 9% less predatory mites and fed preferably on adult thrips, compared to the commercial population. While BIG30 showed a significantly higher total predation rate, killing up to 150% more adult thrips, 2POL-11 is defined as an efficient user of resources, switching between different prey and pollen showing low IGP. Pollen supplementation had a significant effect on reducing IGP, but only for 2POL-11 the influence on prey preference was significant. The theory of intraguild predation and the impact of prey switching on food webs and biological control strategies are also discussed.