An Inexpensive and Comprehensive Method to Examine and Quantify Field Insect Community Influenced by Host Plant Olfactory Cues

Brown midrib (BMR) and plant age impact fall armyworm (Spodoptera frugiperda) growth and development in sorghum-sudangrass (Sorghum x drummondii)

Economic losses from insect herbivory in agroecosystems has driven the development of integrated pest management strategies that reduce pest incidence and damage; however, traditional chemicals-based control is either being complemented or substituted with sustainable and integrated methods. Major sustainable pest management strategies revolve around improving host plant resistance, and one of these traits of interest is Brown midrib (BMR). Originally developed to increase nutritional value and ease of digestion for animal agriculture, BMR is a recessive plant gene usually found in annual grasses, including sorghum and sorghum-sudangrass hybrids. In sorghum-sudangrass, BMR expressed plants have lower amounts of lignin, which produces a less fibrous, more digestible crop, with possible implications for plant defense against herbivores- an area currently unexplored. Fall Armyworm (FAW; Spodoptera frugiperda) is a ruinous pest posing immense threat for sorghum producers by severely defoliating crops and being present in every plant stage. Using FAW, we tested the effect of seed treatment, BMR, and plant age on FAW growth, development, and plant defense responses in sorghum-sudangrass. Our results show that seed treatment did not affect growth or development, or herbivory. However, presence of BMR significantly reduced pupal mass relative to its non-BMR counterpart, alongside a significant reduction in adult mass. We also found that plant age was a major factor as FAW gained significantly less mass, had longer pupation times, and had lower pupal mass on the oldest plant stage explored, 60-days, compared to younger plants. These findings collectively show that pest management strategies should consider plant age, and that the effects of BMR on plant defenses should also be studied.

Can trap color affect arthropod community attraction in agroecosystems? A test using yellow vane and colorless traps

Vane trapping is one of the most effective methods for sampling flower-visiting arthropods. Despite its importance in pollinator studies, the effects of trap color on the abundance and richness of pollinators are less understood. To test this, we conducted a 3-season field experiment over 2 years with two types of vane traps: yellow and colorless. We set up twelve traps each in three field sites within the Lower Rio Grande Valley in south Texas, planted with Vigna unguiculata, Crotalaria juncea, Raphanus raphanistrum, and Sorghum drummondii. At each site, six colorless vane and six yellow vane traps were placed equidistant from each other. The experiment was replicated three times across three seasons, first during the pre-flowering season, when the crops were in full bloom, and when there was no crop on the field. In total, we collected 1912 insects, out of which 76.7% were pollinators. Generalized Linear Regression analyses showed that yellow traps consistently attracted significantly more arthropods and pollinators, but these differences were also season dependent. Furthermore, we noticed that Hymenoptera, followed by Coleoptera, were the most prevalent orders in both the yellow vane and colorless vane traps. Interestingly, although there was no significant difference in species richness of the arthropods in the yellow and colorless vane traps, our results suggest that trap color plays a significant role in capturing pollinators, including non-target arthropods. Our data add another line of evidence suggesting that trap color should be accounted for designing experiments that estimate pollinator and arthropod community diversity.