Association Between Bagrada hilaris Density and Feeding Damage in Broccoli: Implications for Pest Management

Abstract

Bagrada hilaris (Burmeister) (Hemiptera:Pentatomidae) has become a serious economic pest of brassica crops in Arizona and southern California. Feeding damage on broccoli can result in excessive seedling mortality and, on established plants, in malformed plants which are not commercially marketable. Although management tactics have been developed for this new pest, a reliable sampling technique for estimating adult density is lacking. Here, we analyzed data from 18 insecticide trials conducted from 2011 to 2014 in plots planted to broccoli to determine if estimates of fresh feeding damage on broccoli plants can be used to forecast B. hilaris densities. The proportion of plants with fresh feeding damage in a plot was significantly affected by year, trial nested within year, number of insecticides applied, and time after insecticide application. Average density of B. hilaris adults per plant in a plot was significantly affected by year, trial nested within year, and number of insecticides applied, while time after insecticide application had a marginal effect on population density. Across plots and years, the proportion of plants with fresh feeding damage was strongly and positively associated with the average number of B. hilaris adults per plant. Our results suggest that sampling young plants for signs of fresh feeding damage will provide a reliable and accurate sampling technique for monitoring B. hilaris in broccoli fields. We recommend that growers and pest control advisers focus their monitoring efforts on sampling broccoli plants for the presence of fresh feeding damage, rather than adults alone, when making pest management decisions. Accepted for publication 10 November 2015. Published 12 November 2015.

Density threshold‐based acaricide application for the two‐spotted spider mite Tetranychus urticae on cassava: from laboratory to the field

“…leaf appearance, photosynthetic pigment contents and protective enzyme activities) basically coincided with the threshold that resulted in significant yield loss in the field. Several studies have indicated that plant damage caused by different pest densities could be an early warning signal for pest management intervention . However, without validation by yield loss measurements or before those conventional ‘thresholds’ (i.e.…”

“…Several studies have indicated that plant damage caused by different pest densities could be an early warning signal for pest management intervention. 19,[21][22][23][24][25] However, without validation by yield loss measurements or before those conventional 'thresholds' (i.e. economic injury level, economic threshold and action threshold) were actually confirmed, the threshold determined in the laboratory could only be an early warning rather than a reliable prediction.…”

“…The relationship between plant damage and pest density could be an early warning signal for pest management. Relevant studies could be seen in the interactions between bagrada bug‐brassicaceous plants, coccid‐lemon and fern, pine moth‐pine and cassava green mite‐cassava . In those studies, the quantifications of plant leaf damage were defined as scale, class or index presenting the damage degree of whole leaf.…”

Spatial global assessment of the pest Bagrada hilaris (Burmeister) (Heteroptera: Pentatomidae): current and future scenarios

“…This invasive species has colonized numerous regions of the world, with serious effects on brassica crops . The main negative effect of this insect is the damage it causes to plant leaves, reducing chlorophyll generation and leaf area mainly on newer leaf tissues of cotyledons and two‐leaf plants . The species is an important pest in the Old World, mainly India, Africa, Southern Europe, Middle East and Southeast Asia .…”

In-season leaf damage by a biocontrol agent explains reproductive output of an invasive plant species

“…Our results suggest that for the leaf beetle O. communa, and probably other mobile insect herbivores, in-season damage levels may provide a more robust and easier-to-quantify variable for projecting potential impact on reproductive output of A. artemisiifolia at the end of the season. Similarly, early season feeding damage of the bug Bagrada hilaris on broccoli was also found to be a reliable and accurate variable for monitoring this pest in broccoli fields (Palumbo and Carrière 2015). All but one model in which O. communa abundance explained the probability of reproductive organ formation contained an interaction with plant volume.…”