Yellowmargined Leaf Beetle Research Articles

Host preferences of an invasive specialist herbivore and native predators on chemically defended plants

Abstract Herbivorous insects generally choose host plants that optimize their growth. However, many specialists choose chemically defended host plants that slow their growth, prioritizing protection from natural enemies. Invasive specialist herbivores may have an added advantage in their non‐native range where they lack co‐evolved specialist natural enemies, in addition to being unpalatable to generalist predators. Here, we explore the diet preferences of the invasive yellowmargined leaf beetle, Microtheca ochroloma and those of native natural enemies. We measured M. ochroloma preferences among six Brassica cultivars varying in glucosinolate concentrations. In both field and laboratory experiments, M. ochroloma preferred the relatively less defended host plants, mizuna and Chinese cabbage. M. ochroloma grew quickest on mizuna. Generalist predators also preferred to eat M. ochroloma larvae that had been fed mizuna in choice trials, yet in the field, predatory insects were least commonly found on mizuna, and most commonly found on plants dominated by native herbivores. M. ochroloma consumes plants that increase their susceptibility to predators, but predation pressure in the field appears to be generally low. Our results suggest that invasive specialist herbivores may prioritize growth over protection against natural enemies. Weak top‐down regulation of specialist herbivore invaders might enable them to exploit less‐defended host plants in their novel range that facilitate faster growth and exacerbate crop damage. Invasive pests may be more effectively managed by leveraging plant preferences in the novel host range in trap crop systems.

Who eats the yellowmargined leaf beetle? Field observations and genetic surveillance to identify local predators of a novel invasive pest

The yellowmargined leaf beetle, Microtheca ochroloma Stahl (Coleoptera: Chrysomelidae), invaded the Southeastern United States and rapidly emerged as a leading pest of crucifer crops, yet little is known about which native predators might effectively provide biological control. The objective of this research is to identify potential predators of this understudied invader through field observation and genetic surveillance. Over two years, arthropods were surveyed on a variety of susceptible Brassica cultivars and a shortlist of commonly associated predators was developed. In a survey of turnip plants in year 1, lady beetles were positively predicted by densities of M. ochroloma, suggesting a numerical response to densities of the invasive pest. Surveys at a different site in year 2 revealed that big-eyed bugs were also positively predicted by M. ochroloma, while pink-spotted lady beetles negatively associated, suggesting a pattern of suppression. Ants (primarily the red imported fire ant) and spiders were commonly observed predators on plants in both years, but neither associated with densities of M. ochroloma. No predators were observed consuming M. ochroloma eggs. Molecular gut-content analysis using specially generated M. ochroloma primers confirmed the observed predatory links and suggested a density-dependent tracking response from pink-spotted lady beetles and ground beetles also have density-dependent tracking re Table 3. Our results may enable farmers to bolster these predator populations with fine-tuned habitat management tools and better suppress the spreading pest.

THE COLEOPTERISTS SOCIETY YOUTH INCENTIVE AWARDS

CONGRATULATIONS to YIA Senior winner Isabella Daza (above) from Port St. Lucie, Florida. Her project examines the use of the entomopathogenic fungus Isaria fumosorosea Wize as a method for biological control of the invasive yellowmargined leaf beetle, Microtheca ochroloma Stal. The project’s main objective is to evaluate in the laboratory the repellency of the fungus to reduce feeding by the beetle on crucifer crops. Her results were presented at the Treasure Coast Science and Engineering Fair in February 2014.

The Coleopterists Society Youth Incentive Awards

CONGRATULATIONS to YIA Senior winner Isabella Daza (above) from Port St. Lucie, Florida. Her project examines the use of the entomopathogenic fungus Isaria fumosorosea Wize as a method for biological control of the invasive yellowmargined leaf beetle, Microtheca ochroloma Stal. The project’s main objective is to evaluate in the laboratory the repellency of the fungus to reduce feeding by the beetle on crucifer crops. Her results were presented at the Treasure Coast Science and Engineering Fair in February 2014.

Yellowmargined Leaf Beetle, Microtheca ochroloma Stål (Insecta: Coleoptera: Chrysomelidae)

The yellowmargined leaf beetle, Microtheca ochroloma Stål, is a pest of cruciferous crops and was first recorded in the United States from Mobile, Alabama, in March 1947, where it was found feeding on turnip, cabbage, collard, mustard, and radish (Chamberlin and Tippin 1949). It can devastate high value crops such as mizuna and mibuna (Japanese leafy vegetables), napa cabbage, turnip and watercress (Bowers 2003). This document is EENY-348, one of a series of Featured Creatures from the Entomology and Nematology Department, Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida. Published: May 2005.
 EENY348/IN625: Yellowmargined Leaf Beetle, Microtheca ochroloma Stål (Insecta: Coleoptera: Chrysomelidae) (ufl.edu)

First Report of the Yellowmargined Leaf Beetle, Microtheca ochroloma Stål, 1860 (Coleoptera: Chrysomelidae), in Pennsylvania

First Report of the Yellowmargined Leaf Beetle, Microtheca ochroloma Stål, 1860 (Coleoptera: Chrysomelidae), in Pennsylvania

Efecto del Hongo Isaria fumosorosea Wize Sobre la Herbivoría por los Adultos del Escarabajo de Margen Amarillo, Microtheca ochroloma Stal (Coleoptera: Chrysomelidae)

El escarabajo de margen amarillo, Microtheca ochroloma Stål (Coleoptera: Chrysomelidae) es una plaga que causa pérdidas económicas en la producción de crucíferas (Brassicaceae) en Argentina y el sureste de los Estados Unidos. El control biológico utilizando el hongo entomopatógeno Isaria fumosorosea Wize (Hypocreales: Cordycipitaceae) es una alternativa para reducir las poblaciones de esta plaga. Este estudio evaluó el efecto que tiene este hongo en la cantidad de herbivoría por los adultos del escarabajo al ser alimentados con hojas aplicadas con I. fumosorosea. Se evaluaron cuatro concentraciones (0.1, 0.5, 1.0 y 2.0 g) de la formulación PFR-97 20% WDG cepa Apopka 97 por 100 ml de agua destilada y se usó como tratamiento control únicamente agua destilada. Se realizaron dos ensayos, cada ensayo con 10 plantas de bok choy por tratamiento, cada planta con seis escarabajos. A los 7 días se midió el área foliar consumida por los escarabajos. En el primer ensayo, las plantas aplicadas con 1.0 y 2.0 g/100 ml sufrieron significativamente menos daño que el control. Para el segundo ensayo hubo diferencia significativa entre el control y la concentración 2.0 g/100 ml. El control tuvo 3.7 y 2.0% más daño comparado con los demás tratamientos en el primer y segundo ensayo, respectivamente.Ceiba, 2016. Volumen 54(2):118-126

Yellowmargined Leaf Beetle Control With Organic Insecticides in Turnip

Yellowmargined Leaf Beetle Control With Organic Insecticides in Turnip

Infection and mortality of Microtheca ochroloma (Coleoptera: Chrysomelidae) by Isaria fumosorosea (Hypocreales: Cordycipitaceae) under laboratory conditions

ABSTRACTMicrotheca ochroloma Stål, the yellowmargined leaf beetle, is a pest in crucifer crops during the late fall and winter months in Florida. On organic farms, it is difficult to control due to the restricted use of insecticides, in addition to the lack of specific natural enemies. The objective of this study was to evaluate a blastospore-formulated product of Isaria fumosorosea (PFR-97TM 20% WDG) against this beetle. In the first experiment, four of the beetle's life stages were treated with a suspension of 3 × 107 blastospores/ml. Mean corrected mortality of treated insects was significantly higher in 1st and 3rd instars than in the egg, pupal, and adult stages. Larvae infected by I. fumosorosea exhibited reduced growth and unsuccessful molting. The second experiment quantified mortality of first instars of M. ochroloma by four concentrations of PFR-97TM. Mean corrected larval infection/treatment was significantly (2.6 times) higher with a concentration of 4 g of product per 100 ml of water compared to concentrations of 1–3 g per 100 ml of water. Different factors that might have affected the pathogenicity of I. fumosorosea against M. ochroloma are discussed.

Management of Yellowmargined Leaf Beetle Microtheca ochroloma (Coleoptera: Chrysomelidae) Using Turnip as a Trap Crop.

The yellowmargined leaf beetle, Microtheca ochroloma Stål, is a major pest of cruciferous vegetable crops in organic production systems. Very few organically acceptable management options are currently available for this pest. Field studies were conducted at a research station in Alabama and at a commercial organic vegetable farm in Florida to investigate the effectiveness of turnip, Brassica rapa rapa, as a trap crop for M. ochroloma. In the research station trial with cabbage planted as the cash crop, perimeter planting of turnip as a trap crop effectively reduced beetle numbers and crop damage below levels recorded in the control. During the first season of our on-farm trial, with napa cabbage and mustard as the cash crops, using turnip as a trap crop effectively reduced both beetle numbers and cash crop damage below levels found in the control plots, but economic damage was still high. In the second season, beetle populations were too low for significant differences in damage levels to occur between the trap crop and control plots. Together, these results suggest that turnip planted as a trap crop can be an effective control tactic for cruciferous crops, like cabbage, that are much less attractive to M. ochroloma than turnip. In crops, like mustard and napa cabbage, that are equally or only slightly less attractive than turnip, planting turnip as a trap crop would have to be used in combination with other tactics to manage M. ochroloma.

Suitability of Microtheca ochroloma (Coleoptera: Chrysomelidae) for the Development of the Predator Chrysoperla rufilabris (Neuroptera: Chrysopidae).

Microtheca ochroloma Stål, the yellowmargined leaf beetle, is one of the most destructive pests of crucifer vegetables on organic farms. Larvae of the green lacewing Chrysoperla rufilabris Burmeister have been observed preying on M. ochroloma, but no studies have evaluated the suitability of M. ochroloma as prey for C. rufilabris or the efficacy of this predator as a biological control agent of the pest. This study quantified the killing rate, developmental time, and survivorship of C. rufilabris when offered eggs and larvae of M. ochroloma at 10, 15, 20, or 25°C. Mean number of prey killed daily increased from 8.4 eggs and 4.0 larvae at 15°C to 18.6 eggs and 10.2 larvae at 25°C. However, predator larvae killed 78% fewer total eggs at 25°C than at 15°C; total number of first-instar prey killed did not vary significantly with temperature. Mean developmental time of predator larvae decreased from 75.5 d at 15°C to 26.6 d at 25°C when they were fed eggs, whereas it decreased from 54.0 d at 15°C to 21.4 d at 25°C when they were fed larvae. Predator survivorship was reduced by 80% at 15°C and no larvae survived at 10°C. We conclude that C. rufilabris can complete development on a diet of eggs of M. ochroloma, but its effectiveness to control M. ochroloma populations will be lessened during cool months, from November to April, when crucifers are produced in Florida and the beetle is actively developing, reproducing, and causing crop damage.

Yellowmargined Leaf Beetle: A Pest of Cole Crops

The yellowmargined leaf beetle is a pest of cole or cruciferous crops that is native to South America. Since first reported in Mobile, Alabama, in 1947, the beetle has spread throughout the Gulf Coast from Texas to Florida and up into Georgia and North Carolina. It has also been reported from Illinois and California. Not considered a major pest in conventionally grown cruciferous crops because it is susceptible to a wide range of insecticides, it poses a significant threat to the growing organic industry in the southeastern United States. It is a particular problem on Asian greens such as mizuna, mibuna, and napa cabbage, as well as on other high-value cruciferous crops like turnip, mustard, and watercress. This 4-page fact sheet was written by Elena M. Rhodes and Oscar E. Liburd, and published by the UF Department of Entomology and Nematology, September 2014. ENY-872/IN1049: Yellowmargined Leaf Beetle: A Pest of Cole Crops (ufl.edu)

Susceptibility ofMicrotheca ochroloma(Coleoptera: Chrysomelidae) to Botanical and Microbial Insecticide Formulations

ABSTRACT The yellowmargined leaf beetle, Microtheca ochroloma Stal (Coleoptera: Chrysomelidae), is a key pest of organic crucifer production in the southern United States. The susceptibility of larvae and adults of M. ochroloma to some botanical and microbial insecticide formulations was evaluated using laboratory leaf-dip bioassays. Insecticides evaluated included OMRI (Organic Material Review Institute) approved formulations of PyGanic® (pyrethrum), Entrust® (spinosad), Mycotrol O® (Beauveria bassiana strain GHA), and NOFLY® (Isaria fumosoroseus strain FE 9901). Others were MBI-203 (experimental organic formulation of Chromobacterium subtsugae) and BotaniGard® 22WP (conventional formulation of Beauveria bassiana strain GHA). The insecticides were first evaluated at the field recommended rate against M. ochroloma larvae and adults, followed by multiple-concentration assays to determine the LC50 and LT50 for promising formulations. At the field recommended rates, all tested formulations were toxic to the ...

Temperature-Dependent Development and Cold Tolerance of Microtheca ochroloma (Coleoptera: Chrysomelidae), a Pest of Cruciferous Crops in the Southeastern United States

Abstract The yellowmargined leaf beetle, Microthecaochroloma (Stål) (Coleoptera: Chrysomelidae ), is an adventive pest of cruciferous crops in the southeastern United States. Despite its pest status, there is limited information about the infiuence of temperature on development and survival of M. ochroloma. The objectives of this study were to assess the effect of temperature on the development and survival of immature stages, and determine the cold tolerance of immature and adult stages. Development was evaluated at 15,20, 25, and 30°C, and cold tolerance was measured at 5,0, and -5°C inside environmentally controlled chambers. Survival of M. ochroloma from egg to adult was ≈80% at 15,20, and 25°C, but only 24% at 30°C. Mean developmental time was longest at 15°C (57 d) and shortest at 30°C (17 d). Leaf area consumed by the fourth instar was 7.4-fold lower at 30°C compared with consumption at 15, 20, or 25°C. The lower developmental threshold varied from 7.3 to 9.8°C and the total degree-days required to complete development from egg to adult was 333. At 5,0, and -5°C, the LT90 values for the first instar were shorter compared with all other stadia, suggesting that the first instar is the most susceptible to cold temperatures. Eggs were most cold tolerant, followed by pupae and adults. Based on the LT50 (13d) andLT90 (38d) of eggs at 0°C, the predicted northern distribution of M. ochroloma extends to Kansas, Illinois, Kentucky, and Virginia.

Evaluation of the Predation Capacity of <I>Podisus maculiventris</I> (Hemiptera: Pentatomidae) on <I>Microtheca ochroloma</I> (Coleoptera: Chrysomelidae) in Field Cages

The predation capacity of the spined soldier bug, Podisus maculiventris (Say) (Hemiptera: Pentatomidae), was evaluated at three release rates in field cages containing larvae of the yellowmargined leaf beetle, Microtheca ochroloma Stål (Coleoptera Chrysomelidae), a pest of organic crucifer (Brassicaceae) crops in the United States. The experiment was conducted twice, in February-March 2009 and in February-March 2010. On the same day as the introduction of 132 first instars of M. ochroloma into the cages, four (= low), 10 (= medium), or 16 (= high) first instars of P. maculiventris were released evenly among six turnip (Brassica rapa L.) plants in cages. Control treatment cages received no predators. In 2009, the mean number of M. ochroloma larvae declined progressively during the first four sampling dates. On the final (seventh) sampling date, the mean numbers of total M. ochroloma in the two higher release-rate treatments were significantly lower than in the low release-rate and control treatments. Overall survivorship of P. maculiventris was 39.1% in the high release-rate treatment. In 2010, the mean number of M ochroloma larvae declined progressively during the first four sampling dates. On the fourth sampling date and the final (ninth) sampling date, there were no significant differences among treatments involving predator releases. The lowest overall survivorship of P. maculiventris (3.1%) was in the high release-rate treatment. Two tentative recommendations for growers emerged from this study: 1) release 10 first instars of P. maculiventris per six plants if the plants are expected to have > or = 7 leaves per plant; or 2) release four first instars of P. maculiventris per six plants if the plants are expected to have < or = 6 leaves per plant.

Evaluation of organically acceptable insecticides as stand‐alone treatments and in rotation for managing yellowmargined leaf beetle, Microtheca ochroloma (Coleoptera: Chrysomelidae), in organic crucifer production

Yellowmargined leaf beetle, Microtheca ochroloma, is the most damaging pest of organic crucifer crops in the southern United States. Experiments were conducted over four growing seasons (2007-2010) in Alabama to evaluate some botanical and microbial insecticides approved by the Organic Materials Review Institute (OMRI) against M. ochroloma in organically grown crucifer crops. Insecticides evaluated included PyGanic(®) (pyrethrum), Aza-Direct(®) (azadiractin), Entrust(®) (spinosad), Mycotrol O(®) (Beauveria bassiana strain GHA) and NOFLY(®) [Isaria ( = Paecilomyces) fumosoroseus strain FE 9901]. Two experimental organic formulations, Tick-Ex (Metarhizium anisopliae strain F52) and MBI-203 (Chromobacterium subtsugae), and one non-OMRI-listed formulation, Novodor(®) (Bacillus thuringiensis subspecies tenebrionis), were also evaluated. The insecticides were applied as stand-alone treatments at recommended field rates on a weekly schedule. In 2010, some of the treatments were also evaluated in rotation/alternation with Entrust(®) . Insecticide efficacy was determined by comparing densities of M. ochroloma larvae and adults and crop damage ratings in treated versus untreated turnip plots. Entrust(®) consistently performed well in suppressing M. ochroloma adults, larvae and crop damage. PyGanic(®) was the second best treatment. PyGanic(®) or NOFLY(™) can be applied in rotation with Entrust(®) for effective management of M. ochroloma. Entrust(®) applied weekly or in alternation with PyGanic(®) or NOFLY(™) provided acceptable control of M. ochroloma in organic crucifer production.

Host Finding and Acceptance Preference of the Yellowmargined Leaf Beetle, Microtheca ochroloma (Coleoptera: Chrysomelidae), on Cruciferous Crops

The yellowmargined leaf beetle, Microtheca ochroloma Stål (Coleoptera: Chrysomelidae), is an introduced pest of cruciferous crops in the southern United States, and arguably the most damaging pest of organic crucifer vegetable production in the region. Studies were conducted in the greenhouse and laboratory to investigate host finding and acceptance preference of M. ochroloma on four commonly grown cruciferous crops: cabbage (Brassica oleracea L. variety capitata), collards (B. oleracea L. variety acephala), napa cabbage [B. pekinensis (Lour.)], and turnip (B. rapa L.) First, adult beetles were allowed to choose among the four plants in a multiple-choice greenhouse cage experiment and host preference was evaluated by using three parameters: number of beetles on each plant, number of larvae on each plant, and plant damage ratings. The results showed that M. ochroloma adults actively discriminated among the four host plants, with significantly higher numbers recorded on turnip and napa cabbage than on cabbage or collards. Significantly higher numbers of larvae also were recorded on turnip and napa cabbage starting on day 10. Similarly, higher damage ratings were recorded on turnip and napa cabbage than on the remaining two hosts. Results of four-choice olfactometer experiments, which compared attraction of M. ochroloma to headspace volatiles of the four host plants, demonstrated that host preference is mediated primarily by plant volatiles. Both sexes were significantly more attracted to napa cabbage than to the remaining treatments, with turnip being the second most attractive plant. These results confirm that turnip and napa cabbage are two preferred host plants of M. ochroloma, and may support the development of a trap crop system and attractant-based strategies for managing M. ochroloma in crucifer production.

Effect of Straw Mulch on Populations ofMicrotheca ochroloma(Coleoptera: Chrysomelidae) and Ground Predators in TurnipBrassica rapain Florida

ABSTRACT Microtheca ochroloma Stal (Coleoptera: Chrysomelidae), the yellow-margined leaf beetle, is a serious pest of crucifer crops in the southeastern USA. The objective of this study was to investigate the effect of straw mulch on the abundance of M. ochroloma and ground predators in turnips in Florida, and subsequent influence on crop damage and yield. Eight plots (5 m long × 9 m wide) were established, and each plot consisted of 5 beds with 10 turnip plants each (50 turnips per plot). An 8–10-cm layer of straw mulch was applied by hand 2 d after planting to half of the plots in a complete randomized block design. The abundance of M. ochroloma and other insect herbivores were recorded twice weekly from Mar 13 to Apr 24, 2009. In addition, 3 pitfall traps per plot were used for sampling predatory arthropods during each sampling period. Higher numbers of M. ochroloma were found in plots with mulch compared to plots with no mulch, whereas greater numbers of ground predators were obtained in the no mulch ...

Biology of the Yellowmargined Leaf Beetle (Coleoptera: Chrysomelidae) on Crucifers

Multi-generation survivorship, developmental biology, fecundity, and adult longevity of the yellowmargined leaf beetle, Microtheca ochroloma Stål, were studied in the laboratory on cabbage, Brassica oleracea var. capitata L., collard, B. oleracea var. acephala L., mustard, B. juncea Cosson, turnip, B. rapa L., and radish, Raphanus sativus L. Host plant significantly affected multi-generation survivorship; survivorship was 0% on cabbage but &amp;gt;70% on the other hosts when tests were terminated in the fourth generation. Duration of development of life stages and total duration of development from oviposition to adult emergence did not vary significantly with host at 20°C. The latter averaged 27 d among hosts. Development averaged 7.8 d for eggs, 10 d for the four larval instars, 3 d for prepupae, and 5.6 d for pupae. Fecundity and adult longevity were significantly affected by host plant. Egg numbers per female were significantly higher on turnip than on collard but did not differ significantly among cabbage, mustard and radish. Sex did not affect longevity, but beetles lived significantly longer on radish than cabbage, collard, mustard, or turnip.

Control of Yellowmargined Leaf Beetle on Turnip, 1995

Abstract Insecticide treatments were applied at labeled rates on 11 May and 18 May at the Burden Research Plantation, Baton Rouge, LA, 1995 on turnip. A CO2 powered backpack sprayer calibrated to deliver 40 gallons per acre at 30 psi through a spray boom with three nozzles was used. Experimental plots consisted of single rows (30 ft long, 4 ft wide) arranged in a RCB design with 4 replications. Insect counts were made with beat sheets (3 X 2) on 10 and 17 May (pre-treatment counts) and 12 and 19 May (post-treatment counts). Three samples were taken from each plot and the number of insects present of each species was recorded.