Predatory Thrips Research Articles

Positive Correlation of the Gene Rearrangements and Evolutionary Rates in the Mitochondrial Genomes of Thrips (Insecta: Thysanoptera).

Simple SummaryAeolothrips, commonly known as banded thrips, is the largest genus of the family Aeolothripidae (predatory thrips). In the current study, we sequenced the mitochondrial genome (mitogenome) of the banded thrip species Aeolothrips xinjiangensis. We found a novel gene arrangement in this mitogenome that has not been reported in Thysanoptera. By comparing the gene order and rearrangement patterns, we found seven identical gene blocks and three identical rearrangement events in two mitogenomes of banded thrips. There was marked variation in the mitochondrial gene order across thrip species, with only two conserved gene blocks shared by all 14 thrips. In addition, we found a positive correlation between the degree of gene rearrangement and evolutionary rate. Our results suggested that the mitogenomes of thrips have tended to be stable since their massive rearrangement.Extensive gene rearrangement is characteristic in the mitogenomes of thrips (Thysanoptera), but the historical process giving rise to the contemporary gene rearrangement pattern remains unclear. To better understand the evolutionary processes of gene rearrangement in the mitogenomes of thrips, we sequenced the mitogenome of the banded thrip species Aeolothrips xinjiangensis. First, we found a novel mitochondrial gene order in this species. This mitogenome is 16,947 bp in length and encodes the typical 37 coding genes (13 protein-coding genes, 22 tRNA genes, and two rRNA genes) of insects. The gene arrangement was dramatically different from the putative ancestral mitogenome, with 26 genes being translocated, eight of which were inverted. Moreover, we found a novel, conserved gene block, trnC-trnY, which has not been previously reported in the mitogenomes of thrips. With this newly assembled mitogenome, we compared mitogenome sequences across Thysanoptera to assess the evolutionary processes giving rise to the current gene rearrangement pattern in thrips. Seven identical gene blocks were shared by two sequenced banded thrip mitogenomes, while the reversal of ND2 combined with TDRL events resulted in the different gene orders of these two species. In phylogenetic analysis, the monophyly of the suborders and families of Thysanoptera was well supported. Across the gene orders of 14 thrips, only two conserved gene blocks, ATP8-ATP6 and ND4-ND4L, could be found. Correlation analysis showed that the degree of gene rearrangement was positively correlated with the non-synonymous substitution rate in thrips. Our study suggests that the mitogenomes of thrips remain stable over long evolutionary timescales after massive rearrangement during early diversification.

Effect of cold storage on development and demographic parameters of Scolothrips longicornis fed on two-spotted spider mite.

Cold storage effects on the female predatory thrips Scolothrips longicornis Priesner (Thysanoptera: Thripidae) fed on Tetranychus urticae Koch eggs for different time periods (5, 10, 20 and, 30 days) at 5 or 25 °C (control) on development and life table parameters were examined. Female adult duration and female total longevity were not influenced by the period of cold storage. The minimum mean female total longevity (28.1 ± 0.32 day) was observed in the 30-day treatment. The oviposition period decreased with increasing cold storage duration. All life table parameters of S. longicornis demonstrated a significant difference across treatments. Our results demonstrated that the female adult of S. longicornis could be maintained at 5 °C for 5-days with minimal reduction in the life-history process. This would be beneficial in the storage and mass production of S. longicornis in biocontrol programs involving T. urticae.

A novel type of counterattack against predatory thrips in Schizotetranychus brevisetosus (Acari: Tetranychidae)

ABSTRACT Numerous predators prey on herbivorous arthropods, and some prey species have evolved counterattacks against predators (predator–prey reversal). Counterattacks often entail a lethal cost but increase the fitness of the attacking individuals and their nearby relatives. Spider mites (Acari: Tetranychidae) live on leaf surfaces, and some live in aggregations with relatives in a web nest. Counterattacks have been studied in Stigmaeopsis species, but have rarely been studied in other web-nesting species. We investigated counterattacks against predatory thrips, Scolothrips takahashii Priesner, by Schizotetranychus brevisetosus Ehara, which inhabits Quercus glauca L. (Fagaceae). Here, thrips nymphs introduced onto a mite-infested piece of leaf quickly entered the nest but were driven out by females using their stylets. However, in another experiment, we could not find a difference between treatments (10 adult females per leaf or none per leaf) in the number of eggs consumed at 48 h, probably because the thrips repeatedly re-entered the nest. Additionally, we did not detect a significant effect of web presence on predation. Although the defensive effect is undetectable, this study shows that S. brevisetosus counterattacks occur both inside and outside the nest, and the latter especially is the first report of such behaviour in Acari.

Methyl Salicylate Can Benefit Ornamental Pest Control, and Does Not Alter Per Capita Predator Consumption at Close-Range

Methyl salicylate (MeSA) is an herbivore-induced plant volatile widely tested for attracting natural enemies for pest control. MeSA is commercially sold as slow-release lures or as a spray. While MeSA application has increased the abundance of natural enemies in numerous food crops, its ability to reduce pests for crop protection is not as frequently demonstrated. Our first objective was to test MeSA lures in ornamental fields where few studies have been done, and monitor natural enemies, pests, and crop protection. A 2-year study in spruce container yards revealed more aphid parasitoids (Pseudopraon sp.), fewer aphids (Mindarus obliquus) on shoot tips, and less shoot tip damage in MeSA plots during the first year. A 2-year study in red maple fields revealed more predatory lady beetles and rove beetles, and parasitic Ceraphronidae, Diapriidae, and Chalcidoidea in one or both years with MeSA. Fewer pest thrips were also captured in MeSA plots, though it is not clear whether this was due to enhanced predation or reduced colonization. Maple growth as measured by stem diameter change did not differ with MeSA use. A 2-year study examining predation on sentinel Halyomorpha halys eggs in various mature ornamental stock blocks found no increase in predation except for 1 month, though green lacewings, lady beetles, and predatory thrips occurred more in MeSA plots in the first year. While MeSA is expected to enhance biological control by herding in natural enemies, the impacts that applied volatiles have on predator efficiency is mostly unknown. Thus, our second objective examined how volatiles would impact feeding rates at close-range. Adult carabid Pterostichus melanarius, adult coccinellids Coccinella septempunctata and Harmonia axyridis, and larval lacewing Chrysoperla rufilabris consumed their prey at similar rates in the presence/absence of MeSA when food was presented directly in a 28 cm2 or 30 ml arena, or when foraging in a 520 cm2 outdoor soil arena or 946 ml arena with aphids on leaves.

A Review of Franklinothrips vespiformis (Thysanoptera: Aeolothripidae): Life History, Distribution, and Prospects as a Biological Control Agent.

Simple SummaryPredatory species are a small but significant part of the Thysanoptera, which is often overlooked. Franklinothrips are found throughout the tropics and are regarded as major natural enemies of thrips and other small arthropod prey. In this review, we summarized the geographical background, morphology, and prey associations, with an emphasis on Franklinothrips vespiformis, the most widely distributed predatory thrips species. This literature review could serve as a foundation for future research into Franklinothrips as biocontrol agents for economically important insect and mite pests in China.Predatory species comprise a small but important and often overlooked component of the Thysanoptera. A case in point, the ant-mimicking Franklinothrips are widely distributed in the tropics and are considered important generalist natural enemies for thrips and some other small arthropod prey. Franklinothrips present an addition to biocontrol applications, i.e., greenhouse or commercial application for certain target pests and situations. Current knowledge, including distribution, biological features, life history pa rameters, prey specificity, host plant associations and lass production is yet insufficient to decide to what extent Franklinothrips could contribute for biological control programs. In this review, we summarized the geographical background, morphology, and prey associations, with a focus on F. vespiformis, the most widely distributed species of predatory thrips. This literature review serves as the basis for future research into the use of Franklinothrips as biocontrol agents for economically significant insect and mite pests in China and elsewhere.

Native natural enemies in Mediterranean melon fields can provide levels of pest control similar to conventional pest management with broad-spectrum pesticides

Pest control in Mediterranean open-field melon crops currently relies on repeated pesticide applications. A lack of IPM programs that take into account naturally occurring biological control agents in the crop could be due, in part, to a lack of knowledge of the natural enemies associated with melon and their pest control potential. We estimated the abundance of pests and natural enemies in fields managed with a conventional insecticide regime (CPR) and a ‘no insecticide’ regime (NPR), with all fields receiving fungicide applications (sulphur or triadimenol), as required. In a two-year study, six melon fields were sampled periodically during spring and early summer by visual observations of leaves and the extraction of arthropods from flowers using Berlese funnels. The most abundant phytophagous arthropods on melon leaves were thrips (38.9% of total counts), aphids (31.5%), spider mites (26.8%) and whiteflies (2.8%). Aphis gossypii was significantly more abundant in CPR than in NPR fields, whereas whiteflies and thrips had similar abundance in the two treatments. Spider mites were more abundant in NPR than in CPR fields. The main groups of natural enemies on leaves were Orius spp. (76.1% of total counts), phytoseiids (7.4%), predatory thrips (7.1%) and cecidomyiids (5.6%), and all were significantly more abundant in NPR than in CPR fields. The primary predators in flowers were Orius spp. (67.4%) and Aeolothrips spp. (32.6%), and both were significantly more abundant in NPR than in CPR fields. Orius spp. was inferred to be the primary biological control agent of aphids, as few aphids were mummified by parasitoids. The control of aphids by Orius spp. was probably mediated by apparent competition with thrips, which are a preferred prey of Orius spp. In summary, elimination of pesticides from the management regime enhanced the abundance of natural enemies in the melon crop, and natural biological control limited pest infestations in NPR fields as well as did broad-spectrum insecticides in CPR fields. Therefore, IPM strategies for melon production should consider conservation of natural biological control agents as an effective alternative to conventional regimes that rely primarily upon insecticides.

Natural enemies associated with Tuta absoluta and functional biodiversity in vegetable crops

Tuta absoluta Meyrick (Lepidoptera: Gelechiidae) is considered one of the main pests threatening tomato production worldwide. In the Mediterranean, the use of predatory mirids is widespread, and although several larval parasitoid species have been recorded in the area, their contribution to the biological control of the pest is often neglected. With the general objective of improving the biological control of T. absoluta, our field study aimed to determine the relative abundance of natural enemies associated with T. absoluta in tomato fields and to assess whether insectary plants placed in the vicinity of vegetable crops would help to improve functional biodiversity in the farms. The study was conducted during two years in six commercial tomato fields in Northeast Spain that were managed using an integrated pest management program based on predatory mirid conservation. Our results indicated that Necremnus tutae Ribes & Bernardo (Hymenoptera: Eulophidae) was by far the main natural enemy responsible for larval parasitism of T. absoluta. The flowering plants used in the present study were attractive to several natural enemies that are of interest not only for tomato but also for other vegetable crops coexisting at the farm level, including parasitoid wasps, hoverflies, and other important beneficials, such as Orius spp., ladybeetles and predatory thrips.

Temperature impact on the phenology of Nesidiocoris tenuis feeding on Tetranychus urticae: simulation through life cycle modelling

Climatic factors especially temperature has direct impact on the survival of insects. The mirid bug Nesidiocoris tenuis Reuter is an important predator of whiteflies, leafminers, thrips, mites, and various lepidopterans. The impact of temperature on population parameters of N. tenuis was studied by developing model. The rearing temperature had significant impact on the development of N. tenuis. The development time of each nymphal stage decreased with the increase in rearing temperature. The rate of development for each stage increased linearly with the increase in temperature. The optimum temperature, lower and upper developmental thresholds for immature development of the bug varied from 29.9–33.28, 10.1 to 12.25 and 38.82 to 41.1 °C, respectively. The fertility statistics generated for N. tenuis reared on Tetranychus urticae Koch at different temperatures indicate that temperature between 20 and 35 °C is suitable for population growth and multiplication of the bug, whereas, low temperature (15 °C or below) is not suitable for the same. The present study, however, provides useful information on the impact of temperature on the development, survival, reproduction and life-fertility parameters of N. tenuis which could be used for spatial mapping of the distribution and abundance of the bug, and its possible utilization as bio-control agent under expected climate change.

Inventory of Philippine Thrips (Insecta: Order Thysanoptera)

All known records of Philippines thrips published from 1905–2019 were reviewed and consolidated. Species endemism and species with biological control potential against arthropod pests of plants were noted. Two hundred and thirteen (213) species of Thysanoptera in 98 genera under two suborders – Terebrantia and Tubulifera – were recorded in the country. Terebrantians under the family Aeolothripidae are represented by two genera and two species while Thripidae is represented by 43 genera and 95 species – with three species under subfamily Dendrothripinae, 16 species under Panchaetothripinae, two species under Sericothripinae, and 74 species under Thripinae. Tubuliferans under the family Phlaeothripidae are represented by 53 genera and 116 species, with 21 species under subfamily Idolothripinae and 95 species under Phlaeothripinae. Aeolothripids are 100% endemic while thripids and phlaeothripids are 20% and 50% endemic, respectively. Altogether, there are 79 endemic species in the Philippines. Based on the literature, the following species are potential predators of mites, scale insects, plant-feeding thrips, and coffee berry borer: Franklinothrips rarosae Reyes (Aeolothripidae), Karnyothrips flavipes (Jones) (Phlaeothripidae), K. melaleucus (Bagnall) (Phlaeothripidae), and Podothrips lucasseni (Kruger) (Phlaeothripidae). Beneficial and endemic species of thrips are recommended for conservation.

On collection of predatory thrips (Insecta: Thysanoptera) in wheat fields

Some thrips species are known as predators of eggs, exist as the inactive stages of mites, and can be tiny, especially phytophagous thrips. This study aimed at evaluating the population fluctuation and species diversity of predatory thrips in wheat fields of Eyvan county (Ilam province, Iran) in the year 2016. Thrips specimens were collected and identified by weekly sampling during wheat growth stages (from early April to late June). Wheat bushes were shaken on a white dish. Finally, microscopic slides were prepared and all samples were enumerated. The population fluctuation of predatory thrips was calculated. In this study, six species of predatory thrips belonging to three genera were identified. Amongst them, Aeolothrips intermedius Bagnall (family Aeolothripidae) was the dominant species in both irrigated and rainfed wheat fields accounting for 72.43% and 50.85% of all species, respectively. Biodiversity indices were calculated using the number of species and their relative abundance. Shannon diversity, Simpson’s, Margalef’’s and species richness indices were 1.76, 0.86, 1.25 and 1, respectively. The highest biodiversity was in rainfed fields and during the wheat flowering stage, and the highest Shannon-Wiener evenness index was also in rainfed fields and at the ripening stage. The richness of thrips in rainfed wheat fields during the stem elongation stage was higher than in other wheat stages. Correlation of the density of predatory thrips with temperature and humidity showed a significantly positive correlation with temperature.

Functional response of Amblyseius herbicolus (Acari: Phytoseiidae) on Sericothrips staphylinus (Thysanoptera: Thripidae), an ineffective biocontrol agent of gorse

Sericothrips staphylinus was introduced to New Zealand as a biological control agent for gorse, Ulex europaeus (Fabales: Fabaceae), an invasive weed of European origin, but has proven to be an ineffective agent. We investigated and compared the functional responses of a predatory mite found on gorse in New Zealand, Amblyseius herbicolus, with two well-known mite predators of thrips: Amblydromalus limonicus, and Neoseiulus cucumeris when fed on varying densities (2, 4, 8, 16, and 24/491 mm2) of S. staphylinus first instar larvae. We also compared the functional response of A. herbicolus on S. staphylinus with previously published data for mite predators of thrips. Amblyseius herbicolus, A. limonicus, and N. cucumeris all exhibited a type II functional response. A. herbicolus generally exhibited higher capture rates and lower handling times than those reported for other predatory mites that are effective biocontrol agents of pest thrips on crops, except for A. limonicus. These results indicate that the presence of A. herbicolus on gorse in New Zealand is a likely explanation for the failure of S. staphylinus as a weed biocontrol agent.

Evaluation of a philic egg-consumption predatory thrips Scolothrips takahashii for control of the citrus red mite Panonychus citri

Panonychus citri is a major pest mite that is of great economic importance in most citrus orchards in China. Utilizing native predatory natural enemies is one of the useful biological control strategies to maintain pest population below the level where damage occurs for an extended period of time. Although a handful of pesticides and predatory natural enemy species have proven effective on the integrated control of the citrus red mite, they are not hard-hitting tactics for control of the P. citri eggs due to the protection of egg-shell. This study evaluated the potential of a native species of philic egg-consumption predatory thrips, Scolothrips takahashii, for control of P. citri in southwestern Chinese citrus orchards. An age-stage, two sex life table of S. takahashii was constructed, showing this predatory thrips could develop and reproduce successfully when fed on all stages of P. citri. All the functional responses of S. takahashii adult males and females on different stages of P. citri fit the Holling II disc equation, whereas this predatory thrips preferred eggs of P. citri significantly more than their larvae or nymph. Mutual interference results indicated that the searching efficiency and predation rate of S. takahashii decreased significantly with increased predator densities when supplied with sufficient P. citri eggs. Overall, this study indicated the potential of S. takahashii as a biological control agent of P. citri and helped to characterize the role of native predatory thrips in pest mite management.

THE FEATURES OF BIOLOGY OF HARMONIA AXYRIDIS PALL. AND THE MOST COMMON SPECIES OF COCCINELLIDS IN UKRAINE AGROCOENOSIS

The research was conducted in 2017–2019 years in the Institute of Plant Protection of The National Academy of Agrarian Sciences of Ukraine in the Laboratory of entomology and resistance of agricultural crops against pests (Kyiv, Ukraine). The objective of the research is investigation of particular biology features of Harmonia axyridis Pall. in comparison with the main species of coccinellids in typical agrocoenosis. The research methods are the following: laboratory method that means laboratory maintenance of coccinellids; mathematical-statistical method that means statistical processing of the obtained results. The Coccinellidae family (Latreille, 1807) has an important economic value in the human business activities. Most species are predators of aphids, scale insects, thrips, spider mites, leafhoppers, whiteflies, eggs and larvae of other small arthropods. Coccinellids are marked by their high gluttony, polyphagous, fertility. Beetles and larvae of ladybirds play a significant role in the quantity control of pests of agricultural, forest and ornamental plants. Since 2009 researchers in Ukraine have devoted great attention to identification and distribution of invasive species of Asian lady beetle, or Multicolored Asian lady beetle, Harlequin ladybird, Halloween ladybeetle (Harmonia axyridis Pallas, 1773). H. axyridis Pall. is characterized by its wide ecological plasticity, trophic specialization, greater gluttony, fertility and number of generations leading to the gradual displacement of local species of coccinellids. The comparative results of researches of some biology features of H. axyridis Pall. and the most common species of ladybirds are presented. The survival of coccinellids imago during the wintering, in the active period in the absence of feed, their gluttony for different species of aphids is examined. Features of oviposition and duration of various stages of coccinellids development are presented. In the laboratory the Asian lady beetle was marked among other species by the number of its laid eggs, oviposition period, duration of various stages of its development, survival and gluttony

Dynamics of the Composition and Density of Insects on Aboveground Organs of Alfalfa in the Forest-Steppe of Samara Province

This paper presents analysis of the effects of the alfalfa crop age, sowing method, phenological development phases, and green mass mowing on the composition and density of insects and spiders on the aboveground organs of alfalfa grown in crop rotation without irrigation, pest control measures, and fertilizers. The main inhabitants of alfalfa crops comprised over 50 species, with prevalence of the chewing herbivores: alfalfa weevil Hypera postica, alfalfa seed chalcid Bruchophagus roddi, nodule weevils Sitona lineatus and S. inops; the sucking herbivores: flower thrips Odontothrips sp., gorse shield bug Piezodorus lituratus, lucerne bug Adelphocoris lineolatus, plant bug Lygus pratensis, cowpea aphid Aphis craccivora, and pea aphid Acyrthosiphon pisum; the predators: spiders, predatory bug Orius niger, predatory thrips Aeolothrips sp., and variegated ladybug Hippodamia variegata. The seasonal dynamics of the composition and density of dominant groups was more pronounced in the first-year crops than in 2–4 year old ones. In field crop rotations without the use of insecticides, plots with periodic green mass mowing during the budding and flowering phases of alfalfa seed crops should alternate with unmown plots, so that plots with blossoming plants should be present in the field throughout the summer. This measure would promote the development and maintenance of highly diverse insect complexes, attract predators and pollinators, provide additional feeding for parasitic Hymeno­ptera, and reduce the number and harmfulness of herbivores as the result of greater trophic competition between them as well as of the impact of entomophages.

Nutritional quality of Drosophila melanogaster as factitious prey for rearing the predatory bug Orius majusculus.

The predatory bug, Orius majusculus (Reuter), is an important predator of thrips commercially produced for augmentative releases using the eggs of the Mediterranean flour moth Ephestia kuehniella (Zeller). In this study, we assessed the potential for using frozen adults of fruit flies, Drosophila melanogaster (Meigen), either as nymphal rearing diet or as diet throughout the entire life-cycle. We compared life-history traits and reproduction of predators when fed D. melanogaster with high lipid body content (lipid-rich) and with high protein body content (protein-rich), using a diet of 100% E. kuehniella eggs as control. We also analyzed the biochemical composition of both prey and predator in order to assess the nutritional quality of each diet, which partially explained the adequacy of the different diets for O. majusculus. There were significant differences between predators fed the two types of D. melanogaster, with the protein-rich flies as diet providing the best results in terms of mortality and fecundity. Furthermore, we show that while feeding O. majusculus throughout their development with D. melanogaster increases mortality and reduces reproduction, protein-rich D. melanogaster can be used as nymphal diet with minimal reduction in reproductivity and minimal increase in mortality.

Almond spider mite, Schizotetranychus smirnovi (Acari: Tetranychidae): population parameters in laboratory and field conditions

Schizotetranychus smirnovi Wainstein is a serious pest of almond in Iran and its population has extremely increased recently in Chaharmahal va Bakhtiari province. Biological parameters of this mitewere determined on almond leaves (Mamaei variety), under laboratory conditions at 27.5 ± 1 °C, 50 ± 10 % RH, and photoperiod of 14:10 (L:D). More-over, population fluctuation of S. smirnovi and its predator, Scolothrips longicornis Priesner, were studied on almond (Mamaei c.v.) under field conditions (from April to October) during two successive years 2008–2009. Laboratory results showed that egg incubation period is the longest (3.25 ± 0.25 and 3.05 ± 0.25 days for female and male, respectively) in the immature stage. In addition, the female total immature period (2.91 ± 0.43 days) is longer than the male (2.87 ± 0.64 days). Female and male longevity were calculated as 13.20 ± 1.10 and 9.25 ± 0.75 days, respectively. Mean fecundity of the mite was calculated as 58.13 ± 6.60 eggs/female. Field studies showed that the mite overwintered as eggs around the buds of almond shoots. Overwintering eggs hatched depending on the climate conditions from the third decade of March (in 2008) to the third decade of April (in 2009). In both years, mite population continuously increased and reached to a maximum density during June and July. According to total degree-days the mite could produce 12–14 generations per year under field conditions. In addition, S. longicornis showed a strong response (F1,25 = 20.58, r = 0.69, P = 0.0001) to the S. smirnovi fluctuations; population of the mite and predatory thrips fluctuated simultaneously. Our findings may provide practical information about the seasonal abundance of S. simrnovi and be useful for agricultural experts and farmers to develop a successful integrated pest management (IPM) program.

Development and Fecundity of Orius minutus (Hemiptera: Anthocoridae) and O. laevigatus Reared on Tetranychus urticae (Acari: Tetranychidae).

The polyphagous predator Orius species is a dominant predator of thrips, mites, and aphids. Orius laevigatus (Fieber) is a well-known commercialized and effective biological control agent, whereas Orius minutus (L.) distributed widely over the world has not been commercialized. To assess potentials of developing O. minutus as a commercial biological control agent, we compared the biological parameters of O. minutus with O. laevigatus when reared on mixed stages of Tetranychus urticae Koch at 27.5°C. Nymphal development of O. laevigatus was shorter (11.30 d) than that of O. minutus (12.25 d), but there was no significant difference in survivorship between the two species. Also, no significant difference was found in either the preoviposition or oviposition periods, lifetime fecundity, or longevity between the two species. However, O. minutus eggs had a higher hatch rate (0.77) than O. laevigatus (0.71). In life table analysis, no difference was found in any parameters, i.e., R0, rm, λ, T, and DT, between O. laevigatus and O. minutus in two-tailed t-tests. In a predation bioassay, O. minutus consumed 1.39 times more adult T. urticae in 24 h than did O. laevigatus, although the predation rate on T. urticae eggs was similar between the two species. These results suggest that O. minutus native to Korea could be developed as a biological control agent against T. urticae.

<p class="Body"><strong>Biological traits of acarophagous thrips, <em>Scolothrips longicornis</em> (Thysanoptera: Thripidae) on <em>Schizotetranychus smirnovi</em> (Acari: Tetranychidae): Application of female age-specific and age-stage, two-sex life tables</strong></p>

Schizotetranychus smirnovi Wainstein is an important phytophagous pest of almond trees which causes serious damage in southwestern Iran. Scolothrips longicornis Priesner has been considered as an efficient predatory thrips that feeds on this spider mite and hence its efficiency for controlling S. smirnovi should be evaluated. In the current study, all main biological parameters of S. longicornis fed on S. smirnovi were determined under laboratory conditions. Data analysis was performed using both female age-specific and age-stage, two-sex life table theories. Duration of incubation, larval, pre-pupal, pupal and pre-adult periods of male predators were 4.73, 3.18, 1.05, 1.86 and 10.82 days, respectively. These periods in female individuals lasted 4.57, 3.92, 1.04, 1.87 and 11.00 days, respectively. Our findings showed that each female laid an average of 62.74 eggs during its ovipositional period (13.61 days). Using the age-stage, two-sex life table, the values of the net reproductive rate (R0), intrinsic rate of increase (r), finite rate of increase (λ) and mean generation time (T) were estimated to be 26.236 (eggs/individual), 0.171 (day-1), 1.186 (day-1) and 19.130 (days), respectively. Using the female age-specific life table, these parameters had different values. Our findings revealed that S. longicornis has a reliable capability to increase its population by feeding on S. smirnovi. This information can expand our knowledge for assessing biological efficiency of this predatory thrips in sustainable management of the destructive mite pest.

Bioecology of the tea thrips, Scirtothrips bispinosus Bagnall (Thysanoptera: Thripidae) infesting tea in south India

Investigations were carried out on the life history and seasonal abundance of the thrips, Scirtothrips bispinosus infesting tea at Coonoor, The Nilgiris, Tamilnadu. The total developmental duration of females from egg to adult stage was 18.15±0.23, 12.55±0.15 and 10.30±0.23 days at 20, 25 and 30oC respectively. The net reproductive rate (Ro), mean generation time (Tc), intrinsic rate of natural increase (rm), finite rate of increase (ë) and weekly multiplication (Wm) rates were high at 25oC followed by 30oC and 20oC. Multiple regression analysis revealed that population density of S. bispinosus showed a negative relationship with rainfall (-0.266), maximum temperature (-38.839) and maximum relative humidity (-3.356) and positive relationship with minimum temperature (63.205), minimum relative humidity (1.686) and sunshine period (2.887). Incidence of thrips was high in the fields recovering from pruning followed by second, third and fourth year in a pruning cycle. The number of thrips per shoot was significantly higher on the plucking table when compared to the shoots present below the plucking table and side branches. In the tea plantations of South India, four species of predatory mites (Amblyseius cucumeris, A. fallacies, A. degenerans and Balaustium sp.), two species of predatory thrips (Franklinothrips vespiformis and Leptothrips mali), an anthocorid predator (Orius sp.) and one parasitoid (Trichogramma sp.) were found feeding and parasitizing on tea thrips, S. bispinosus.

Efficacy of insecticides for season-long control of thrips (Thysanoptera: Thripidae) in winter strawberries in Florida

Flower thrips (primarily Frankliniella spp.) can be significant strawberry pests, and recently in Florida, Scirtothrips dorsalis Hood has become an established, early-season, foliar pest. Insecticides that were used for flower thrips management are now also used for S. dorsalis, resulting in the need to evaluate newer insecticides in order to diversify rotations and mitigate overuse of insecticides with the same mode-of-action. We evaluated 10 and 12 season-long insecticide programs in field plots in central Florida during the 2016–2017 and 2017–2018 winter strawberry seasons, respectively. We found that most programs reduced thrips populations and strawberry injury due to thrips feeding, while having limited effects on Orius spp., a primary thrips predator. An early season application of chlorantraniliprole + thiamethoxam, commonly used for other strawberry pests, reduced S. dorsalis populations and strawberry injury, although S. dorsalis populations were relatively low in both study years. When repeat applications of the same insecticide were made throughout the growing season, cyantraniliprole was nearly as effective as spinetoram against Frankliniella spp., while tolfenpyrad and sulfoxaflor did not perform as well. Flupyradifurone was as effective as acetamiprid when used as a follow-up application to spinetoram or cyantraniliprole. Programs including or entirely composed of OMRI-listed insecticides for organic production were not as effective as conventional insecticide programs, with only spinosad providing acceptable thrips control. In conclusion, spinetoram, acetamiprid and spinosad were confirmed to be effective against thrips and can be used as the backbone of rotation programs in conventional and organic strawberry production systems. Diamide insecticides were effective when used repeatedly and in rotation, while flupyradifurone and flonicamid may be used when follow-up applications are needed. Continued research is critical for fine-tuning insecticide programs, with a focus on testing against high S. dorsalis populations in early-planted strawberries and on developing effective sampling methods to optimize timing and reduce the number of applications.