Flea Beetle (Coleoptera: Chrysomelidae) Populations, Effects of Feeding Injury, and Efficacy of Insecticide Treatments on Eggplant and Cabbage in Southwest Virginia

Flea beetles, are common pests of cabbage Brassica oleracea L. (Brassicales: Brassicaceae) and eggplant Solanum melongena L. (Solanales: Solanaceae), but little is known about the flea beetle populations in Virginia, their impact on yield, or the most effective control methods. This research investigates flea beetle populations and the impact of their feeding injury on cabbage and eggplant in Southwest Virginia and determines the most efficacious control methods. In Whitethorne, VA, cabbage and eggplant crops were vacuum sampled weekly throughout two summers (2015, 2016). Crucifer flea beetle, Phyllotreta cruciferae (Goeze) (Coleoptera: Chrysomelidae), and striped flea beetle, Phyllotreta striolata Fabr. (Coleoptera: Chrysomelidae) were found on cabbage; whereas, eggplant flea beetle, Epitrix fucula (Crotch) (Coleoptera: Chrysomelidae), and the tobacco flea beetle, Epitrix hirtipennis (Melsheimer) (Coleoptera: Chrysomelidae) were found on eggplant. To evaluate the impact of flea beetle feeding on these plants flea beetle densities and defoliation were assessed weekly and individual plant, as well as whole plot yields, assessed at harvest. For cabbage, significant yield reductions were observed between 1 and 20% and >60% defoliation. Similarly, significant yield reductions were observed between 41 and 60% and >60% defoliation for eggplant. The efficacy of various insecticides was also evaluated. Soil application of the systemic neonicotinoid dinotefuran, imidacloprid, and the foliar-applied bifenthrin resulted in the fewest beetles, the least amount of leaf defoliation, and the highest yield in cabbage and eggplant. This research helps vegetable growers to better understand the severity of these pests and how to effectively combat them.

Flea beetle (Coleoptera: Chrysomelidae) species in canola (Brassicaceae) on the northern Great Plains of North America

Flea beetle (Coleoptera: Chrysomelidae) species and numbers were determined from yellow sticky traps (n=11 180) set out in canola (Brassica Linnaeus, Brassicaceae) fields at 300 site years and 15 ecoregions across the Canadian Prairie provinces in each spring of 2007–2011 and in North Dakota, United States of America in 2010–2011. Peak numbers and relative species abundance varied with year, site, and ecoregion. Phyllotreta striolata (Fabricius) was most common in northern ecoregions, whereas Phyllotreta cruciferae (Goeze) dominated nearer the 49th parallel. The proportion of P. striolata in northern areas increased dramatically compared with surveys in the 1970s. Phyllotreta striolata displaced Psylliodes punctulata Melsheimer as the most common flea beetle in the Peace River Lowlands, displaced P. cruciferae as the most common flea beetle in the Aspen Parkland of central Alberta, Canada, and increased in proportion in central Saskatchewan and much of Manitoba, Canada. Once rare in southern ecoregions, P. striolata was found there in increasing numbers. Temperature was the most consistent weather parameter to predict occurrence of both P. cruciferae and P. striolata. Although P. striolata became more numerous over years in four of seven principal ecoregions, P. cruciferae remained the predominant species on traps with the highest numbers of flea beetles.

Field growth traits and insect-host plant interactions of two transgenic canola (Brassicaceae) lines with elevated trichome numbers

Plant growth and insect resistance characteristics were determined for two Brassica napus Linnaeus (Brassicaceae) lines, AtGL3+ and K-5-8, developed for enhanced trichome densities relative to their parental cultivar Westar. In the field, both transgenic lines had glabrous cotyledons that curled upwards at emergence but flattened with time, and young leaves with elevated trichome density. Flea beetle (Phyllotreta cruciferae (Goeze) and Phyllotreta striolata (Fabricius); Coleoptera: Chrysomelidae) feeding was reduced on true leaves of both lines by 30–50% compared with insecticide-free Westar. Flea beetle feeding levels on cotyledons of the two hairy-leaved lines were lower than on unprotected Westar and similar to those seen on insecticide-treated Westar. Antixenosis and antibiosis resistance was observed when diamondback moths (Plutella xylostella (Linnaeus); Lepidoptera: Plutellidae) interacted with the hairy AtGL3+ and K-5-8 lines in the laboratory. Although the numbers of eggs laid by female diamondback moths on the transformed lines were similar to or higher than on Westar, in feeding bioassays larvae moved off AtGL3+ plants and larval feeding injury decreased on the transformed lines compared with Westar leaves. No agronomic or seed yield penalties were found for plants of K-5-8. These data highlight the utility of manipulating trichome regulatory genes to increase plant resistance against brassicaceous insect pests.

Comparative Efficacy of Tephrosia vogelii and Moringa oleifera against Insect Pests of Watermelon (Citrullus lanatus Thumb)

Despite the fact that synthetic insecticides are fast acting, they constitute environmental hazard thereby necessitating the use of ecologically based alternative such as plant based insecticide. This experiment was conducted during the late and early planting seasons of 2011 to determine the insecticidal efficacy of Tephrosia vogelii and Moringa oleifera extracts at three tested concentrations (5, 10 and 20% v/v) against insect pests of watermelon. The experiment was set up in a randomized complete block design with three replicates. The results showed that M. oleifera extracts had 62% reduction of Phyllotreta cruciferae compared with T. vogelii which had 45% control. However, T. vogelii extracts had 64% control of Diabrotica undecimpunctata and Bactrocera curcubitea but M. olefera extracts had 50% control. The plant extracts proved effective against studied insects when compared with untreated plots. However, the effectiveness of the two plants extracts were concentration dependent. Therefore, the two plant extracts can be used in the control of insect pests of the watermelon

Comparative Efficacy of Tephrosia vogelii and Moringa oleifera against Insect Pests of Watermelon (Citrullus lanatus Thumb)

Despite the fact that synthetic insecticides are fast acting, they constitute environmental hazard thereby necessitating the use of ecologically based alternative such as plant based insecticide. This experiment was conducted during the late and early planting seasons of 2011 to determine the insecticidal efficacy of Tephrosia vogelii and Moringa oleifera extracts at three tested concentrations (5, 10 and 20% v/v) against insect pests of watermelon. The experiment was set up in a randomized complete block design with three replicates. The results showed that M. oleifera extracts had 62% reduction of Phyllotreta cruciferae compared with T. vogelii which had 45% control. However, T. vogelii extracts had 64% control of Diabrotica undecimpunctata and Bactrocera curcubitea but M. olefera extracts had 50% control. The plant extracts proved effective against studied insects when compared with untreated plots. However, the effectiveness of the two plants extracts were concentration dependent. Therefore, the two plant extracts can be used in the control of insect pests of the watermelon