The effect of the combination of diatomaceous earths and Phytoseiulus persimilis on the biological control of Tetranychus urticae under laboratory conditions

Coffee is one of the leading commodities in tropical America. Although plantations are usually established under a canopy of trees in most producing countries in the region, Brazilian coffee is mostly produced under full sun conditions. Such simple, single-crop agroecosystems with intensive agrochemical inputs often suffer with pests like mites. Predatory mites of the family Phytoseiidae are the main natural enemies associated with pest mites in the field. However, these beneficial arthropods struggle to survive in intensive agroecosystems such as coffee monocultures due to unfavorable microclimatic conditions, widespread pesticide use, and lack of alternative food (pollen, nectar). Conservation biological control uses a range of management strategies to sustain and enhance populations of indigenous natural enemies such as predatory mites. We discuss here conservation biological control as a strategy to improve biological control of pest mites by native predatory mites in Brazilian coffee monocultures as well as some related patents. Keywords: Broad mite, coffee red spider mite, coffee ringspot mite, pesticide selectivity, predatory mites

Coffee is one of the leading commodities in tropical America. Although plantations are usually established under a canopy of trees in most producing countries in the region, Brazilian coffee is mostly produced under full sun conditions. Such simple, single-crop agroecosystems with intensive agrochemical inputs often suffer with pests like mites. Predatory mites of the family Phytoseiidae are the main natural enemies associated with pest mites in the field. However, these beneficial arthropods struggle to survive in intensive agroecosystems such as coffee monocultures due to unfavorable microclimatic conditions, widespread pesticide use, and lack of alternative food (pollen, nectar). Conservation biological control uses a range of management strategies to sustain and enhance populations of indigenous natural enemies such as predatory mites. We discuss here conservation biological control as a strategy to improve biological control of pest mites by native predatory mites in Brazilian coffee monocultures as well as some related patents.

Soft soap at three dosages (3 ml/L, 5 ml/L and 7 ml/L) and abamectin (12.5 mg/100L) were applied to bean plants determine their residual effects on the predatory mite, Phytoseiulus persimilis A-H (Acari: Phytoseiidae) later released for the control of the two-spotted spider mite (TSSM), Tetranychus urticae Koch (Acari: Tetranychidae) under laboratory conditions. The contact toxicity of soft soap and abamectin were evaluated and classified according to IOBC(International Organization for Biological Control) standards. The soap at 3 ml/L and 5 ml/L did not supress TSSM populations and could not provide satisfactory control when compared with soap at 7ml/L and abamectin. The efficacy of soap at 5 ml/L with P. persimilis gave sufficient control of TSSM when compared with soap at 3 ml/L with P. persimilis, and the predator alone. Both the soap at 7 ml/L and abamectin in combination with the predatory mite gave satisfactory control of TSSM ,but in the abamectin treatment, the predatory mite population was not observed due to harmful effects of abamectin. However, use of soft soap at suitable dosage, with or without predatory mite, gave encouraging results for controlling TSSM but was moderately toxic at 5 ml/L and 7 ml/L P. persimilis in contact toxicity testing by causing 50.0 % and 42.3 % mortality, respectively, to adulst of P. persimilis. In addition, abamectin at 12.5 and 25 mg/L (ppm) dosages was evaluated as harmful (T) to adults of P. persimilis. Separately, soft soap caused no phytotoxicity to host plants. However, its phytotoxicity needs to be further investigated under greenhouse and field conditions.

Influence of leaf trichomes on predatory mite density and distribution in plant assemblages and implications for biological control

Predatory mites belonging to the family Phytoseiidae are the main agents used globally for the biological control of pest mites, especially predators of the genus Neoseiulus, particularly Neoseiulus californicus (McGregor) and Neoseiulus idaeus (Denmark & Muma). A major target is the ubiquitous mite Tetranychus urticae (Koch). A major factor limiting the effectiveness of natural enemies in biological control programmes is unfavourable climatic conditions at the release site. This study aimed to determine the climatic envelopes of N. californicus and N. idaeus to predict the geographical areas with the highest climatic suitability of each species where its efficacy as a biological control agent would be maximized. Site occurrence data and the associated environmental variables were obtained from pre-existing spatial information found in online databases. These data were analysed using the MaxEnt software to map the geographic areas worldwide most suitable for each species. The climate suitability for N. californicus was especially limited by conditions of high temperature, while limiting factors for N. idaeus were annual variation in temperatures and low annual precipitation. Suitable areas for N. californicus were observed in all five continents, concentrated in latitudes close to the tropics of Cancer and Capricorn. In relation to N. idaeus, suitable areas were observed on four continents and are concentrated in countries close to the Equator, particularly those in the southern hemisphere. N. californicus and N. idaeus have distinct climate suitability areas. The results may be helpful for selecting the predator species for introduction.

In this investigation, the impact of the predatory mite, Phytoseiulus persimilis (PM) and entomopathogenic fungus, Isaria fumosorosea (F) at three levels (F1=104, F2=106 and F3=108 conidia/ml) alone or in grouping state as compared with Ortus (acaricide) was evaluated on eggs and motile stages of two-spotted spider mites (TSSM). Nine treatments (CK=control, F1, F2, F3, PM, F1+PM, F2+PM, F3+PM and Ortus) were performed. On the other hand, the effect of the used entomopathogenic fungus on numbers of eggs and motile stages of the predatory mite was detected only at four treatments (PM, PM+F1, PM+F2, and PM+F3). Applications of I. fumosorosea at all chosen doses caused significant decreases in the mean population density of TSSM eggs (50.15-58.81% in 2016 and 59.63-68.37% in 2017) and motile stages (62.61-74-66% in 2016 and 68.47-75.32%) in comparison to the control. The effect of PM addition on TSSM eggs was higher than that of I. fumosorosea using but on TSSM motile stages, the pattern differed. The combination of both I. fumosorosea and P. persimilis showed greater influence on TSSM eggs and motile stages than the use of I. fumosorosea or P. persimilis individually. Spraying I. fumosorosea with releasing P. persimilis led to small reductions in eggs (11.88-22.42% in 2016 and 7.86-21.73% in 2017), and motile stages (9.84-21.33% in 2016 and 6.75-17%) of P. persimilis. Results of this study concluded that the combination of entomopathogenic fungus, I. fumosorosea and predatory mite, P. persimilis was strongly succeeded in the biological control process of TSSM on soybean plants under field conditions.

Abstract: Populations of predatory and phytophagous mites were sampled weekly throughout the growing season in first‐ and second‐level integrated pest management (IPM) blocks in 12 commercial apple orchards in Massachusetts in 1993. In first‐level blocks, insecticides were used throughout the growing season. In second‐level blocks, no insecticides were sprayed after early June. Among the 12 orchards, 92% contained Amblyseius fallacis, 8% contained Typhlodromus pyri and 50% contained Zetzellia mali as predaceous species, while 100% contained Panonychus ulmi and 58% contained Tetranychus urticae as pest species. When averaged over the entire season, populations of predaceous A. fallacis and Z. mali and populations of pest P. ulmi were numerically, but not statistically, greater in second‐level blocks than in first‐level blocks. The opposite was true for T. urticae. Initial time of appearance of each species was about the same in both types of blocks. Panonychus ulmi peaked in mid‐July, much earlier than A. fallacis, the most frequently observed predaceous mite. Populations of the latter peaked in September at relatively low densities, too late in the growing season for this species to provide, by itself, timely biological control of pest mites. Winter mortality from cold temperatures and spring/summer mortality from the use of fungicides are suspected to be the principal agents responsible for the slow build‐up of A. fallacis. Zetzellia mali was present in early spring and increased slowly until reaching peak levels in autumn. Absence of pre‐bloom oil and other acaricide sprays in a small portion of each second‐level block did not facilitate build‐up of predaceous mites, but did result in rapid build‐up of P. ulmi.

The effects of overhead and drip tube irrigation on twospotted spider mite (TSMs) (Tetranychus urticae Koch) and predatory mite (PMs) (Phytoseiulus persimilis Athias-Henriot) populations, as well as the biological control of TSMs by PMs, were investigated on Impatiens wallerana Hook. f. `Impulse Orange'. To determine the effects of the two irrigation methods on TSM populations, plants were inoculated with female TSMs 6 weeks after seeding. Plants were then irrigated twice every three days, and TSM counts were taken 3 weeks later. To assess the effects of irrigation method on PMs, plants were inoculated with TSMs 6 weeks after seeding, PMs were released 10 days later, plants were irrigated about once per day, and the number of predatory mites on plants was counted 3 weeks after release. To assess the effects of irrigation method on the biological control of TSMs by PMs, plants were inoculated with TSMs and PMs were released as before, but then plants were irrigated either three times every 2 days or three times every 4 days using either drip or overhead irrigation. The number of TSMs on plants and the number of leaves showing TSM feeding injury were measured 3 weeks after predator release. Overhead watering significantly reduced TSM and PM populations as much as 68- and 1538-fold, respectively, compared to drip irrigation with microtubes. Perhaps more important, overhead watering with or without predators significantly reduced the number of leaves sustaining TSM feeding injury as much as 4-fold compared to drip irrigation. These results confirm the common observation that TSM infestations and injury may be reduced by irrigation systems that wet plant foliage. However, predators still reduced TSMs even though overhead irrigation had a suppressive effect on predatory mites. Predators are particularly useful for reducing TSM injury when plants are watered infrequently. Overhead watering could be used in tandem with biological control as a component of an integrated crop management program for TSMs in ornamental greenhouses by rapidly lowering TSM population levels in hot spots before PMs are released.

Simple SummaryConserving predators of orchard pests is a critical part of pest management. To achieve this, growers can choose pesticides that are minimally harmful to these predators. While this information is commonly available for insecticides, there is little information about how herbicides affect pest predators. Knowing which herbicides are harmful to predators is particularly important as growers move away from using glyphosate due to consumer safety concerns. Adjuvants are chemicals that are sometimes added to pesticides to increase their efficacy, and their effects on predators are also poorly described. In apple orchards in Washington State, U.S.A., two species of predatory mites are known to be critical for maintaining pest mite populations below damaging levels. We tested seven pesticides and five adjuvants for effects on these important mite predators in laboratory assays. We found that three herbicides (glufosinate, paraquat, and oxyfluorfen) either killed the adult predators or reduced their reproduction. The adjuvants were minimally harmful to the predator mites. Because glufosinate and paraquat are likely replacements for glyphosate, pest mite outbreaks in orchards could result from their increased use.The phytoseiid mites Galendromus occidentalis and Amblydromella caudiglans are critical for conservation biological control of pest mites in Washington State, U.S.A. apples. While the non-target effects of insecticides on phytoseiids are well described, research on herbicide effects is limited. Using laboratory bioassays, we examined lethal (female mortality) and sublethal (fecundity, egg hatch, larval survival) effects of seven herbicides and five adjuvants on A. caudiglans and G. occidentalis. The effects of mixing herbicides with recommended adjuvants were also tested to determine if the addition of an adjuvant increased herbicide toxicity. Glufosinate was the least selective herbicide tested, causing 100% mortality in both species. Paraquat caused 100% mortality in A. caudiglans and 56% mortality in G. occidentalis. Sublethal effects were significant for both species when exposed to oxyfluorfen. Adjuvants did not cause non-target effects in A. caudiglans. The non-ionic surfactant and methylated seed oil increased mortality and decreased reproduction in G. occidentalis. The high toxicity of glufosinate and paraquat for both predators is concerning; these are the primary “burn down” herbicide alternatives to glyphosate, which is decreasing in use due to consumer toxicity concerns. Field studies are needed to determine the extent to which herbicides disrupt orchard biological control, focusing on glufosinate, paraquat, and oxyfluorfen. Consumer preferences will need to be balanced with natural enemy conservation.

Evaluation of selected crops for rearing predatory mite (Phytoseiulus persimilis), a predator of two-spotted red spider mites

Detecting two-spotted spider mites and predatory mites in strawberry using deep learning

The two-spotted spider mite (TSSM, Tetranychus urticae Koch) is a significant agricultural pest, particularly in strawberries. Management of TSSM has traditionally relied on synthetic acaricides, but to mitigate dependency on these chemicals, the control of TSSM on strawberry is often combined with biological control measures and chemical control strategies. The predatory mite, Phytoseiulus persimilis, is a promising biological control agent, preying on all TSSM developmental stages. In this study, we examined the toxicity of six common acaricides on TSSM and P. persimilis, and cyetpyrafen was selected due to its highest relative toxicity value. Then, we examined the compatibility of cyetpyrafen with P. persimilis for TSSM management on strawberries. The results suggested that cyetpyrafen revealed no substantial differences in prey consumption or longevity when compared to the control, though minor effects on the development durations of protonymphs and deutonymphs were noted in the subsequent generation. Additionally, cyetpyrafen's toxicity on key pollinators, such as Apis mellifera and Bombus terrestris, was found to be low. Thus, an integrated strategy combining cyetpyrafen (0.83 mg/L) with P. persimilis (predator–prey ratio of 1:30) was examined under laboratory and field conditions. Laboratory trials demonstrated a reduction in mites per leaf from 32.72 to 14.50 within 3 days, correlating to a 70.23% control efficiency. This efficacy increased to 96.04% by day 9 and was sustained until the experiment concluded on day 27. Field trials similarly showed a reduction in TSSM from 53.93 to 9.63 mites/leaf by day 6, achieving an 83.64% control efficiency, and culminated in a 98.46% reduction by day 10. These findings suggested that an integrated approach utilizing cyetpyrafen in conjunction with P. persimilis can be an effective alternative for TSSM management on strawberry plants.

The Two-Spotted Spider Mite (TSSM) is a prevalent mite pest found worldwide and is extensively distributed in Mongolian greenhouses. In this study, we conducted a field experiment using predatory mites and botanical pesticides on eggplants infested by TSSM. We observed promising results in terms of reducing pest populations and achieving overall improved outcomes. The experiment took place in a 120 sq.m. greenhouse located at the "Agropark" training-research center of the Mongolian University of Life Sciences. The aim of this experiment was to test the effectiveness of the following treatments in controlling Two-Spotted Spider Mite (TSSM): Treatment A (predatory phytoseiid mites at a ratio of 1:5), Treatment B (predatory phytoseiid mites + Neem), Treatment C (Neem alone), Treatment D (Neem + BEB), and Treatment E (untreated control). The experiment utilized a total of 20 plots, each with a size of 6 square meters, and 24 plants were grown in each plot, resulting in a total of 480 plants. Each plot was replicated four times. To assess TSSM control, mortality rates of TSSM were calculated for each treatment as follows: - Treatment A (Predatory phytoseiid mites): 44.4% to 94.7% - Treatment B (Predatory phytoseiid mites - 1:5 + Neem - 30ml/4.5L of water): 76.3% to 96.3% - Treatment C (Neem - 30ml/4.5L of water): 61.8% to 90.8% - Treatment D (Neem - 30ml/4.5L of water + BEB - 20ml/10L of water): 68.6% to 88.2%. The combination of all these treatments have shown apromising results in controlling TSSM in the greenhouse, significantly reducing the TSSM population, according to our research findings. However, it is important to release the predatory mites after a 5-day interval following the application of botanicals (Neem). We recommend a release of predatory mites (Phytoseiilus persimilis and Amblyseius swirskii) either alone or in combination with botanicals for controlling TSSM in the greenhouse, because it is effective and a safe plant protection measurement to use in the greenhouse.

Studying the nutritional ecology of Neoseiulus cucumeris (Oudemans) at different temperatures is a fundamental tool for improving mass production for use in biological control of pest mites. The current research studied the impact of both food types and temperatures on the life history and demographic parameters of the predator mite N. cucumeris. Mite cultures in the laboratory were developed using Tetranychus urticae Koch, and N. cucumeris was collected from field plants. The developmental stages of N. cucumeris fed on date palm pollen and the immature stages of T. urticae were investigated in a laboratory setting at different temperatures. Our research revealed that N. cucumeris readily accepted both food types at all the tested temperatures. The developmental stages and adult longevity of N. cucumeris, both female and male, decreased dramatically when the temperature increased from 18 °C to 34 °C. The net reproductive rate (R0) reached its greatest values of 22.52 and 9.72 offspring/individual at 26 °C, and the intrinsic rate of increase (rm) reached its maximum values of 0.17 and 0.13 day-1 at 34 °C and minimum of 0.12 and 0.10 day-1 at 18 °C, when fed on date palm pollen and immature stages of T. urticae, respectively. Conversely, the average generation time (T) showed a notable reduction from 22.48 to 16.48 and 20.88 to 16.76 days, accompanied by an upsurge in temperature from 18 °C to 34 °C, when fed on date palm pollen and immature stages of T. urticae, respectively. The finite rate of growth (λ) exhibited distinct variations, reaching its highest value at 34 °C, 26 °C, and 18 °C when fed on date palm pollen and immature stages of T. urticae, respectively. From these results, we can conclude that N. cucumeris was successfully fed date palm pollen as an alternate source of nourishment. In addition, the immature stages of T. urticae are suitable as food sources for N. cucumeris because they shorten the mean generation time. Therefore, the success of mass-rearing the predator mite N. cucumeris on a different, less expensive diet, such as date palm pollen, and determining the most suitable temperature for it has increased its spread as a biocontrol agent.

PCR-based identification of the pathogenic bacterium, Acaricomes phytoseiuli, in the biological control agent Phytoseiulus persimilis (Acari: Phytoseiidae)