A simple computerized Arduino-based control system for insect rotary flight mills.

Flight mills are widely used to investigate insect flight behavior. As technology advances, the means to build a computerized control system for a flight mill has become more accessible in terms of both price and availability of components. However, the specialized electronics and programming knowledge required to build such a system can still present an obstacle to interested parties. Here, we describe a simple and inexpensive flight mill control system that can be easily assembled and operated without specialized experience. The hardware and software components are built around an Arduino single-board microcontroller, which outputs raw data in the form of timestamped detections of rotations of the flight mill arm. This control system is suitable both as the basis for new flight mills and for replacing outdated computer controls on existing flight mills. Additionally, it can be used with any rotary flight mill design that uses an electronic sensor to count rotations.

Correlation-Based Network Analysis of the Influence of Bemisia tabaci Feeding on Photosynthesis and Foliar Sugar and Starch Composition in Soybean.

Bemisia tabaci (MEAM1) represents a species of economic importance in soybean. One of the obstacles to the management of B. tabaci is the quantification of damage by the pest because damage is indirectly inferred through losses in productivity. The objective of this study was to characterize the influence of B. tabaci feeding on soybean by assessing effects on photosynthetic parameters and the sugar and starch content of soybean leaves. The goal was to identify the optimal parameter to directly quantify pest damage on crop yield. Correlation networks were created among data on sugar content (fructose, glucose, and sucrose), starch and photosynthetic parameters (initial fluorescence, performance index on absorption basis, and turn-over number), and the number of nymphs at each of three infestations level (low, medium, and high) during both the vegetative and reproductive stage of the crop. In general, nymphs were more abundant during the vegetative stage. Starch content was strongly correlated with nymph density. A strong positive correlation was observed between fructose and nymph density during the vegetative stage. Among the photosynthetic parameters, the turn-over number N was positively correlated with nymph density at a low-infestation level and negatively correlated with nymphs when they occurred at a high-infestation level. B. tabaci feeding affected the plant's physiology and its interaction is reflected in part by the relationships among photosynthetic parameters as well as the levels of sugars and starch. This understanding might be useful in developing better monitoring tools for pest management.

Alternative Formulations of Trap Lures for Operational Detection, Population Monitoring, and Outbreak Forecasting of Southern Pine Beetle in the United States.

The southern pine beetle, Dendroctonus frontalis Zimmermann (Coleoptera: Curculionidae: Scolytinae) is a major destructive pest of Pinus L. In the southeastern United States, numbers of this species and a major predator, Thanasimus dubius (Fabricius) (Coleoptera: Cleridae), captured during an annual springtime trapping survey are used to make forecasts of the likelihood and severity of an outbreak during the following summer. We investigated responses by both species to six lure formulations to evaluate their suitability for the survey and allow integration of historical data sets produced with differing lure compositions. Trapping trials were performed at four locations across three states (Louisiana, Mississippi, and Alabama) during spring, and at these and one additional location (North Carolina) in fall 2016. All lures included the pheromone component frontalin. Southern pine beetle preferred lures that additionally included the pheromone component endo-brevicomin and turpentine as a source of host odors (rather than a 7:3 mixture of monoterpenes alpha- and beta-pinene). Thanasimus dubius displayed little discrimination among lure compositions. Lure preferences by southern pine beetle did not differ significantly among locations in spring but were influenced by season. Gas chromatography (GC)-electroantennographic detection analyses with southern pine beetle and GC-mass spectrometry identified numerous known and potential semiochemicals that distinguished volatiles released by the tested host odor devices. The lure combination that included endo-brevicomin and alpha/beta-pinene is recommended for the trapping survey because of its high sensitivity for southern pine beetle and potential for greater data integrity resulting from its reproducible composition.

Sublethal Effects of Diamide Insecticides on Development and Flight Performance of Chloridea virescens (Lepidoptera: Noctuidae): Implications for Bt Soybean Refuge Area Management.

High-dose and refuge are the most important strategies for delaying resistance evolution in Bt crops. Insecticide sprays in refuge areas could be necessary and may limit refuge effectiveness. Here, we evaluated the sublethal effects of two diamide insecticides (chlorantraniliprole and flubendiamide) on Chloridea virescens life history traits and flight performance. Sublethal concentrations of chlorantraniliprole and flubendiamide increased larval and pre-pupal development times and decreased larval weight; flubendiamide increased pupal development times. Chlorantraniliprole increased adult male longevity and reduced female fertility, while flubendiamide reduced fecundity. Overall life table parameters were negatively impacted by both treatments. Males exposed to either insecticide showed significant reductions in flight duration and distance for unsustained flights (<30 min). The duration and distance of the first flights were reduced when exposed to chlorantraniliprole. Sustained flights (>30 min) were generally unaffected by insecticide exposure and both sexes flew >6400 m in a single flight. The sublethal effects of flubendiamide and chlorantraniliprole on C. virescens' population dynamics could lead to generation asynchrony and provide insufficient susceptible moths when sprayed on refuge crops. However, the distance and duration of flight may still be sufficient to ensure mixing of potentially resistant and susceptible populations from refuge plots.

Effects of foliar and systemic insecticides on whitefly transmission and incidence of Cucurbit yellow stunting disorder virus.

BACKGROUND: Cucurbit yellow stunting disorder virus (CYSDV) is a cosmopolitan viral disease transmitted by Bemisia tabaci that infects cucurbit crops. Cantaloupe production in the southwestern USA has been confronted by epidemics of CYSDV since 2006 when it was first identified in Arizona and California. As a phloem-limited virus that is vectored in a semi-persistent manner by B. tabaci, CYSDV has transmission characteristics that may be suppressed by select insecticide applications. RESULTS: Eight active ingredients formulated as foliar and/or soil-applied insecticides were tested to determine the suppressive effect on transmission and incidence of CYSDV in greenhouse and field studies. Many compounds limited virus transmission to <10% infected plants even when challenged by 30 viruliferous whiteflies. Foliar formulations had greater knockdown activity than their soil-applied analogs and resulted in lower virus transmission. Insecticides that had the greatest effect on reducing virus transmission in the greenhouse also showed the lowest incidence of CYSDV in field trials. CONCLUSIONS: Select insecticides can significantly reduce transmission of CYSDV. However, insecticide management of CYSDV incidence in cantaloupes has limitations in chronically high infestation areas such as the southwestern USA, and is often only able to delay disease onset rather than prevent its occurrence. © 2016 Society of Chemical Industry.

Comparative susceptibility of Bemisia tabaci to imidacloprid in field- and laboratory-based bioassays.

BACKGROUND: Bemisia tabaci biotype B is a resistance-prone pest of protected and open agriculture. Systemic uptake bioassays used in resistance monitoring programs have provided important information on susceptibility to neonicotinoid insecticides, but have remained decoupled from field performance. Simultaneous bioassays conducted in field and laboratory settings were compared and related to concentrations of imidacloprid in plant tissue for clearer interpretation of resistance monitoring data. RESULTS: Mean mortalities of adult whiteflies confined on cantaloupe leaves field-treated with three rates of imidacloprid did not exceed 40% in two trials. In contrast, laboratory bioassays conducted on different subsets of the same whitefly populations yielded concentration-response curves suggestive of susceptibility to imidacloprid in five populations (LC50 values from 1.02 to 6.4) relative to a sixth population (LC50 = 13.8). In the field, densities of eggs and nymphs were significantly lower on the imidacloprid-treated cantaloupes compared with the untreated control, but the margin of control was greater in 2006 than in 2007. The potential impact of imidacloprid on whitefly eggs was explored in a greenhouse test that showed egg mortality occurring in both early (one-day-old) and late (three-day-old) eggs on cotton leaves systemically treated with imidacloprid. Quantification of imidacloprid residues in cotton leaves used routinely in systemic uptake bioassays revealed concentrations that greatly exceeded concentrations found in the field-treated cantaloupe leaves, at least at the three highest solution concentrations used for uptake. CONCLUSION: Systemic uptake bioassays have been widely used for monitoring B. tabaci resistance to imidacloprid, but without knowledge of imidacloprid concentrations that occur in test leaves relative to field concentrations. Higher mortality observed in systemic uptake bioassays relative to field-treated cantaloupes in this study suggests that field rates of imidacloprid are only partially effective against B. tabaci adults, in contrast to systemic uptake bioassays that showed susceptibility to imidacloprid. The discrepancy between field- and laboratory-based mortalities is probably due to extraordinarily high concentrations of imidacloprid that can occur in leaves of systemic uptake bioassays, potentially skewing perception of susceptibility to imidacloprid. Published 2013. This article is a U.S. Government work and is in the public domain in the USA.