Attenuative Effect of Diallyl Trisulfide on Caspase Activity in TNF-α-induced Triple Negative Breast Cancer Cells.

BACKGROUND/AIM: Diallyl trisulfide (DATS) has been shown to prevent and inhibit carcinogenesis in cancer cells. We have previously shown DATS's ability to decrease the percentage of viable cells, inhibit cell migration and modulate genes involved in the nuclear factor kappa-light-chain-enhancer of activated B cells (NF-B) and mitogen-activated protein kinase (MAPK) signaling. MATERIALS AND METHODS: This study aimed to compare the efficacy of DATS in tumor necrosis factor alpha (TNF-α) induced MDA-MB-231 and MDA-MB-468 cells and investigate its role in cell-death signaling via cell cycle, flow cytometry, and caspase assay. RESULTS: DATS exhibit a time-dependent accumulation of G2/M phase cells in both cell lines, with higher effects in the MDA-MB-468 for all time points. DATS's ability to decrease the percentage of viable cells in both MDA-MB-231 and MDA-MB-468 cells was shown by a significant but slight increase of early and late apoptosis in the presence of DATS compared to control. Moreover, MDA-MB-468 cells showed more sensitivity to the DATS effect, evidenced by the higher percentage of apoptosis than MDA-MB-231 cells. The caspase studies showed a significant increase in caspase 3 and 8 activity in the presence of DATS, compared to control, in both cell lines. DATS showed no significant increase in caspase 9 activity in both cell lines compared to the control. CONCLUSION: DATS-induced apoptosis in human breast cancer cells is mediated, at least in part, by cell cycle arrest and caspase activity. These findings provide information for future studies into the role of DATS in TNBC therapy and prevention.

Estimating the Cost of Production of Two Pentatomids and One Braconid for the Biocontrol of Spodoptera frugiperda (Lepidoptera: Noctuidae) in Maize Fields in Florida.

The fall armyworm is a polyphagous lepidopteran pest that primarily feeds on valuable global crops like maize. Insecticides and transgenic crops have long been a primary option for fall armyworm control, despite growing concerns about transgenic crop resistance inheritance and the rate of insecticide resistance development. Global dissemination of the pest species has highlighted the need for more sustainable approaches to managing overwhelming populations both in their native range and newly introduced regions. As such, integrated pest management programs require more information on natural enemies of the species to make informed planning choices. In this study, we present a cost analysis of the production of three biocontrol agents of the fall armyworm over a year. This model is malleable and aimed towards small-scale growers who might benefit more from an augmentative release of natural enemies than a repetitive use of insecticides, especially since, though the benefits of using either are similar, the biological control option has a lower development cost and is more environmentally sustainable.

Effects of Three Cultural Practices on Drosophila suzukii (Diptera: Drosophilidae) in Open Blueberry Fields in Florida.

The spotted-wing Drosophila (SWD), Drosophila suzukii, is native species in Southeast Asia. For over a decade, this invasive pest has been globally expanding. The economic losses to soft fruits and stoned fruits in the United States are increasing every year. Presently, the only viable tool to reduce the SWD population is the continued use of broad-spectrum insecticides. Pesticide resistance is appearing in the populations for the SWD. Organic farmers have limited options to control this pest in open fields. The major goal of this study was to develop cost-effective pest management strategies to manage the SWD using three types of mulches (two plant-based and one fabric-based) to reduce fly population and damage in open blueberry fields in north Florida. The study was conducted in two fruiting seasons (2017 and 2018). The study results demonstrated that the fly trap catches in 2017 shortleaf pine needle mulch had much higher populations (about 2.5-fold) of the SWD than all other treatments. In 2018, the numbers were about 1.7-fold more on shortleaf pine needle mulch than on other treatments. The fine texture of the mulch (pine needles) can easily facilitate the emergence of the SWD if the mulch is not thick enough. Although the pine needles covered the soil surface, it may have been too thin and thus allowed the SWD adults to emerge from the soil without much hindrance. In 2018, a higher population of the SWD was recorded from all the mulching practices. However, there were no significant differences in trap catches between all treatments. In general, the fly population is reduced with the use of pine bark and black weed fabric mulches. This is the first study that reports the effects of three mulches in controlling the SWD populations, which could benefit conventional and organic blueberry growers.

Intraguild Interactions of Three Biological Control Agents of the Fall Armyworm Spodoptera frugiperda (JE Smith) in Florida.

The fall armyworm, Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae), is a maize pest worldwide. Its host range comprises more than 350 reported plant species, and it is the primary insect pest attacking maize in Florida. Global trade has not only assisted but accelerated its invasion into the Eastern Hemisphere. Regular pesticide use promotes resistance in the species; therefore, there is an urgent need for alternative pest management strategies. This study evaluated the interactions of biological control agents within a similar guild. Some of the reported interactions could potentially lead to the integration of these agents within the same niche to increase biological control efficiency against the fall armyworm. We evaluated three biocontrol agents that are natural enemies of Lepidopteran pests, the true bugs Podisus maculiventris and Euthyrhynchus floridanus (Hemiptera: Pentatomidae) and a parasitoid, Cotesia marginiventris (Hymenoptera: Braconidae). Depending on their intraguild interactions, these agents could potentially be useful for biological control of the fall armyworm. The study investigated these three biocontrol agents and concluded that integrating these agents to control the fall armyworm is a possibility; however, only under certain conditions. Investigations were focused on evaluating the predator-parasitoid and devised pairing interactions. Predator response to prey in a choice or no-choice scenario and choices based on olfaction or other bodily cues were studied under experimental laboratory conditions.

First Report of Insecticide Resistance to Organophosphates and Pyrethroids in the Small Hive Beetle (Coleoptera: Nitidulidae) and Development of a Resistance Monitoring Technique.

The small hive beetle, Aethina tumida Murray (Coleoptera: Nitidulidae), is a serious threat to the honey bee industry, which relies on chemicals for the control of major honey bee pests. We developed a glass vial bioassay for resistance monitoring of adult A. tumida populations in honey bee colonies. We also determined concentrations that could be used to discriminate between susceptible and resistant strains. These include the pyrethroids cypermethrin (25.0 µg per vial) and fluvalinate (25.0 µg per vial) and the organophosphates malathion (10.0 µg per vial), chlorpyrifos (2.5 µg per vial), and coumaphos (25.0 µg per vial). Here, we report that resistance to fluvalinate and coumaphos was widespread in A. tumida populations in Florida in 2019. Aethina tumida populations were still susceptible to cypermethrin, malathion, and chlorpyrifos. The levels of resistance differed between pyrethroid and organophosphate insecticides. Over the last 10 yr, A. tumida populations have developed 43.7-fold resistance to coumaphos and 5.4-fold to fluvalinate. The levels of insecticide resistance were not similar within insecticides in the same class, which suggest that this type of resistance is manageable. Our results demonstrate the usefulness of glass vial bioassays to detect resistance in adult A. tumida and provide the foundation for a resistance management strategy. To the best of our knowledge, this is the first report of insecticide resistance in small hive beetle populations and suggests an urgent need for alternative control strategies for these serious pests of honey bee colonies.

Molecular Assessment of Genes Linked to Immune Response Traits of Honey Bees in Conventional and Organically Managed Apiaries.

Honey bees are of great economic importance, not only for honey production but also for crop pollination. However, honey bee populations continue to decline mainly due to exposure to pesticides, pathogens and beekeeping practices. In this study, total soluble protein was measured, total RNA was extracted and first-strand cDNAs were generated. Quantitative PCR was used to assess the relative expression (transcript abundances) of immune function-related genes in honey bees collected from organically and conventionally managed hives. Honey bees collected from conventionally managed hives with 0% Varroa mite infestation levels displayed an upregulated expression of the prophenoloxidase gene (cellular defense). Similarly, honey bees collected from organically managed hives had increased levels of the vitellogenin gene (immune function and longevity). The gene expression for malvolio (sucrose responsiveness) was highest in organically managed hives with 0% Varroa mite infestations. Young adult bees collected from organically managed hives with 5% Varroa mite infestation levels had upregulated expressions of the gene spaetzle, whereas bees from similarly infested, conventionally managed hives did not, suggesting that honey bees from organically managed hives could mount an immune response. In young adult bees collected from organically managed hives only, the expression of the immune deficiency gene (antimicrobial defense) was upregulated. The relative gene expression for superoxide dismutase 1 increased in young adult bees collected from hives with 5% Varroa mite infestation levels as expected. However, for superoxide dismutase 2, there was a high level of gene expression in adult bees from both conventionally managed hives with 0% Varroa mite infestation levels and organically managed hives with 5% Varroa mite infestations. The gene CYP9Q3 (pesticide detoxification) that metabolizes coumaphos and fluvalinate was upregulated in adult bees collected from organically managed bees. Overall, these findings provide useful insights into the genetic response of honey bees to some environmental stressors and could be an important component of best beekeeping practices that intend to enhance honey bee health.

Evaluation of Monitoring Traps and Lures for Drosophila suzukii (Diptera: Drosophilidae) in Berry Plantings in Florida.

Drosophila suzukii (Diptera: Drosophilidae) is an invasive insect pest that was detected in Florida in August 2009 in Hillsborough County. Very limited information is available for berry growers to properly detect and monitor this serious pest in southern highbush blueberry (hybrids of Vaccinium corymbosum L. × V. darrowi Camp), rabbiteye blueberry (Vaccinium virgatum L.), and blackberry (Rubus fruticosus L.) production systems. We compared several D. suzukii traps and lures/baits at two sites in Florida. The traps evaluated included Trécé, Scentry, and a standard homemade cup trap. These traps were compared with various baits and lures, including Trécé lure, Scentry lure, yeast bait, and Suzukii trap, under Florida production systems. Early detection is important to develop an effective monitoring system so management action can be taken before economic damage occurs. Data were recorded as overall trends, as well as in 4-5 trapping periods from early to late season. Overall, the Scentry trap baited with Scentry lure, the Trécé trap baited with Trécé lure + yeast, and the Trécé trap baited with Scentry lure were the best performing traps. Yeast-based traps were also attractive to D. suzukii early in the season, but they did not provide consistent captures as the season progressed. The Scentry trap with yeast bait, the Scentry trap with Scentry lure, the Trécé trap with Trécé lure + yeast bait, and a cup trap with yeast bait caught most of the flies during the first trapping period in 2015 and 2016 in the rabbiteye blueberry. In the southern highbush blueberry, the population of D. suzukii was much lower than in the rabbiteye blueberry planting, and the Scentry trap with Scentry lure captured the highest number of flies during the first trapping period in 2016. In the blackberry, the Scentry trap with Scentry lure numerically had the highest captures during the first trapping period, but this was not significantly different from the cup trap with yeast bait, the Trécé trap baited with Suzukii trap, and the Trécé trap with Trécé lure. Overall, the Scentry trap with Scentry lure was the most consistent trap that captured D. suzukii flies throughout the season in the three production systems-rabbiteye blueberry, southern highbush blueberry, and blackberry. Growers in low pressure systems that are similar to Florida can use the Scentry trap with Scentry lure to monitor D. suzukii populations.

Brassica nigra and Curcuma longa Compounds Affecting Interactions Between Spodoptera exigua and Its Natural Enemies Cotesia flavipes and Podisus maculiventris.

The interaction Spodoptera exigua Hübner (Lepidoptera: Noctuidae) × its natural enemies Cotesia flavipes Cameron (Hymenoptera: Braconidae) and Podisus maculiventris Say (Heteroptera: Pentatomidae) × botanical compounds with and without synergist is unknown; therefore, it was studied under controlled conditions. The objective of this study was to evaluate the direct mortality of P. maculiventris nymphs and adults and indirect by this predator feeding on S. exigua larvae treated after being exposed to parasitism by C. flavipes. Brassica nigra L. (Brassicales: Brassicaceae) and Curcuma longa L. (Zingiberales: Zingiberaceae) compounds, with and without lead (II) oxide (PbO), were tested as insecticides. The mortality of first and second instars P. maculiventris was high with turmeric essential oil by topical application. The PbO increased the predator mortality in combination with turmeric powder, crude essential oil, and ar-turmerone. This last derivative caused also the highest mortality of P. maculiventris nymphs when ingested through treated S. exigua larvae that were previously subjected to parasitism. Turmeric powder and its derivatives, with and without PbO, should not be used in areas with P. maculiventris due to the high mortality caused to this predator.

Monitoring for Insecticide Resistance in Asian Citrus Psyllid (Hemiptera: Psyllidae) Populations in Florida.

The development of insecticide resistance in Asian citrus psyllid, Diaphorina citri Kuwayama, populations is a serious threat to the citrus industry. As a contribution to a resistance management strategy, we developed a glass vial technique to monitor field populations of Asian citrus psyllid for insecticide resistance. Diagnostic concentrations needed to separate susceptible genotypes from resistant individuals were determined for cypermethrin (0.5 µg per vial), malathion (1.0 µg per vial), diazinon (1.0 µg per vial), carbaryl (1.0 µg per vial), carbofuran (0.1 µg per vial), methomyl (1.0 µg per vial), propoxur (1.0 µg per vial), endosulfan (1.0 µg per vial), imidacloprid (0.5 µg per vial), acetamiprid (5.0 µg per vial), chlorfenapyr (2.5 µg per vial), and fenpyroximate (2.5 µg per vial). In 2014, resistance to two carbamate insecticides (carbaryl and carbofuran), one organophosphate (malathion), one pyrethroid (cypermethrin), and one pyrazole (fenpyroximate) was detected in field populations of Asian citrus psyllid in Immokalee, FL. There was no resistance detected to diazinon, methomyl, propoxur, endosulfan, imidacloprid, and chlorfenapyr. The levels of insecticide resistance were variable and unstable, suggesting that resistance could be successfully managed. The results validate the use of the glass vial bioassay to monitor for resistance in Asian citrus psyllid populations and provide the basis for the development of a resistance management strategy designed to extend the efficacy of all classes of insecticides used for control of the Asian citrus psyllid.

Monitoring for resistance to organophosphorus and pyrethroid insecticides in Varroa mite populations.

The occurrence of resistance in Varroa mite populations is a serious threat to the beekeeping industry and to crops that rely on the honey bee for pollination. Integrated pest management strategies for control of this pest include the judicious use of insecticides. To monitor field populations of Varroa mite for insecticide resistance, a glass vial bioassay procedure was developed to use in the development of a resistance management strategy. Diagnostic concentrations needed to separate susceptible genotypes from resistant individuals were determined for cypermethrin (0.1 microg per vial), fluvalinate (5.0 microg per vial), malathion (0.01 microg per vial), coumaphos (10.0 microg per vial), diazinon (5.0 microg per vial), methomyl (0.5 microg per vial), propoxur (0.1 microg per vial), and endosulfan (2.5 microg per vial). Resistance to organophosphorus insecticides (malathion, coumaphos) and pyrethroids (cypermetrhrin, fluvalinate) was widespread in both La Media Ranch, TX, and Wewahitchka, FL, from 2007 to 2009. There was no resistance to endosulfan, diazinon, methomyl, and propoxur in field populations of Varroa mite in the two locations where resistance was monitored. The seasonal patterns of resistance in Wewahitchka were different from those of La Media Ranch. In the former location, the frequency of resistance to all insecticides tested decreased significantly from 2007 to 2009, whereas it increased in the latter location. Resistance levels were unstable, suggesting that resistance could be successfully managed. The results validate use of the glass vial bioassay to monitor for resistance in Varroa mite and provide the basis for the development of a resistance management strategy designed to extend the efficacy of all classes of insecticides used for control of Varroa mite.

Development of a user-friendly delivery method for the fungus Metarhizium anisopliae to control the ectoparasitic mite Varroa destructor in honey bee, Apis mellifera, colonies.

A user-friendly method to deliver Metarhizium spores to honey bee colonies for control of Varroa mites was developed and tested. Patty blend formulations protected the fungal spores at brood nest temperatures and served as an improved delivery system of the fungus to bee hives. Field trials conducted in 2006 in Texas using freshly harvested spores indicated that patty blend formulations of 10 g of conidia per hive (applied twice) significantly reduced the numbers of mites per adult bee, mites in sealed brood cells, and residual mites at the end of the 47-day experimental period. Colony development in terms of adult bee populations and brood production also improved. Field trials conducted in 2007 in Florida using less virulent spores produced mixed results. Patty blends of 10 g of conidia per hive (applied twice) were less successful in significantly reducing the number of mites per adult bee. However, hive survivorship and colony strength were improved, and the numbers of residual mites were significantly reduced at the end of the 42-day experimental period. The overall results from 2003 to 2008 field trials indicated that it was critical to have fungal spores with good germination, pathogenicity and virulence. We determined that fungal spores (1 × 10(10) viable spores per gram) with 98% germination and high pathogenicity (95% mite mortality at day 7) provided successful control of mite populations in established honey bee colonies at 10 g of conidia per hive (applied twice). Overall, microbial control of Varroa mite with M. anisopliae is feasible and could be a useful component of an integrated pest management program.

Efficacy of strips coated with Metarhizium anisopliae for control of Varroa destructor (Acari: Varroidae) in honey bee colonies in Texas and Florida.

Strips coated with conidia of Metarhizium anisopliae (Metschinkoff; Deuteromycetes: Hyphomycetes) to control the parasitic mite, Varroa destructor (Anderson and Trueman) in colonies of honey bees, Apis mellifera (Hymenoptera: Apidae) were compared against the miticide, tau-fluvalinate (Apistan) in field trials in Texas and Florida (USA). Apistan and the fungal treatments resulted in successful control of mite populations in both locations. At the end of the 42-day period of the experiment in Texas, the number of mites per bee was reduced by 69-fold in bee hives treated with Apistan and 25-fold in hives treated with the fungus; however mite infestations increased by 1.3-fold in the control bee hives. Similarly, the number of mites in sealed brood was 13-fold and 3.6-fold higher in the control bee hives than in those treated with Apistan and with the fungus, respectively. Like the miticide Apistan, the fungal treatments provided a significant reduction of mite populations at the end of the experimental period. The data from the broodless colonies treated with the fungus indicated that optimum mite control could be achieved when no brood is being produced, or when brood production is low, such as in the early spring or late fall. In established colonies in Florida, honey bee colony development did not increase under either Apistan or fungal treatments at the end of the experimental period, suggesting that other factors (queen health, food source, food availability) play some major role in the growth of bee colonies. Overall, microbial control of Varroa mites with fungal pathogens could be a useful component of an integrated pest management program for the honey bee industry.

Management of insecticide resistance in Oriental fruit moth (Grapholita molesta; Lepidoptera: Tortricidae) populations from Ontario.

The development of resistance in the Oriental fruit moth, Grapholita molesta (Busck) to organophosphorus (OP) insecticides (azinphos-methyl and phosmet) is a serious threat to the tender fruit industry in Ontario (50% crop losses in 1994). Resistance to carbamate insecticides and increased survival of field-collected moths at diagnostic concentrations of pyrethroids were widespread. As a result, four different treatment regimes were tested to manage resistance in G molesta, and the changes in resistance frequencies under each treatment regime were monitored from 1996 to 1999. The data indicated that the levels of resistance were significantly influenced by the various treatment regimes. The seasonal pattern of resistance was similar for all treatment regimes, in that resistance peaked in mid-season and declined in the late season. Levels of resistance in G molesta to OPs decreased from 55% to 14% and that to pyrethroids declined from 30% to 10% from 1996 to 1999 under a treatment regime consisting of endosulfan-organophosphate-pyrethroid rotation. Similarly, under a treatment regime implemented in commercial orchards (organophosphate-pyrethroid rotation), resistance to OP insecticides declined from 50% to 12% and resistance to pyrethroids evolved to around 16%. The overall data indicated that resistance was unstable; a strategy based on rotation of insecticides by class for each generation of G molesta was successful in managing resistance to both OP and pyrethroid insecticides. The rotational strategy has been widely adopted by growers and is applied to ca 85% of the acreage.