Development of a toxic bait for control of eastern lubber grasshopper (Orthoptera: Acrididae)

This study assessed baits for eastern lubber grasshopper, Romalea guttata (Houttuyn). When offered a choice among several grain-based baits (rolled oats, wheat bran, oat bran, yeast, corn meal, cornflakes) and vegetable oils (canola, corn, peanut, soybean), eastern lubber grasshopper adults preferred bait consisting of wheat bran carrier with corn oil as an added phagostimulant. Other carriers were accepted but consumed less frequently. Discrimination by eastern lubber grasshoppers among oils was poor. Similarly, addition of flavorings (peppermint, anise, lemon, banana) resulted in few significant effects. The carbaryl, wheat bran, and oil bait developed in this study was effective at causing eastern lubber grasshopper mortality in field-cage studies. Significant mortality occurred even though grasshoppers had to locate dishes of bait in a large cage, and could feed on daylilies, or grass growing through the bottom of the cage, rather than on the bran flakes. Consumption of as little as a single carbaryl-treated bran flake could induce mortality, although individuals varied greatly in their susceptibility. The bait matrix developed in this study was readily consumed when in the presence of some plant species. We expect that wheat bran and corn oil bait would be most effective as protection for less preferred plants (tomato, pepper, eggplant, leek, parsley, fennel, daylily, lily of the Nile, and canna lily) because baits were readily consumed in the presence of these plants. Plants that are readily consumed in the presence of bait (preferred plants) included butter crunch lettuce, carrot, yellow squash, cauliflower, collards, green onion, chive, cucumber, cabbage, cantalope, endive, red leaf lettuce, society garlic, caladium, and amaryllis. Baits are likely to be less effective in the presence of such plants. On average, vegetables in Solanaceae (i.e., tomato, pepper, and eggplant) and Apiaceae (i.e., fennel and parsley) elicited high levels of bait-feeding activity, indicating that these vegetables were not highly preferred. The plants tested from Liliaceae, Cucurbitaceae, Asteraceae, and Brassicaceae elicited an intermediate-to-low level of bait feeding.