Scott H. Lecrone

Comparison of single and multiple releases of Heterorhabditis bacteriophora Poinar (Nematoda: Heterorhabditidae) for control of Cylas formicarius (Fabricius) (Coleoptera: Apionidae)

Abstract Single and multiple releases of the entomopathogenic nematode, Heterorhabditis bacteriophora Poinar (= H. heliothidis Khan, Brooks, and Hirschmann) (HP88 strain), were evaluated for controlling populations and damage of the sweetpotato weevil, Cylas formicarius (Fabricius), during two consecutive growing seasons in southern Florida. Sweet potato, Ipomoea batatas (L.) Lam., plants were treated with one, two, or three applications of H. bacteriophora in a Krome very gravelly loam soil. Weevil population reduction and damage in nematode-treated sweet potato plots were compared with that in plots treated with monthly applications of chemical insecticides and in nontreated plots. Persistence of nematodes in soil was assessed at various times after release by baiting soil samples with greater wax moth larvae, Galleria mellonella (L.). Applications of H. bacteriophora did not consistently reduce weevil abundance, but did consistently reduce damage to sweet potato storage roots compared with nontreated plants. Weevil densities and damage did not differ between plants treated with one, two, or three applications of H. bacteriophora , suggesting that a single, early season release of this nematode was adequate for managing this weevil. Weevil damage on plants treated with chemical insecticides was intermediate to that on nematodetreated and nontreated plants. H. bacteriophora persisted in soil for over 130 and 250 days after application in the first and second experiment, respectively.

Evaluation of food baits for pre-plant sampling of wireworms (Coleoptera: Elateridae) in potato fields in southern Florida

Experiments were conducted during two consecutive growing seasons to evaluate food baits for pre-plant sampling of wireworms that attack potato in southern Florida. Wireworm species studied were: Melanotus communis (Gyllenhal), southern potato wireworm, Conoderus falli Lane, C. amplicollis (Gyllenhal), and C. rudis (Brown). Baits evaluated were hybrid sweet corn seed, hybrid sorghum-sudangrass seed, a 1:1 mixture of corn and sorghum-sudangrass seed, a whole sweet corn ear, potato seed pieces, a 1:1 mixture of oatmeal and corn flake, rolled oats, and carrots. In the first year, numbers of wireworm larvae did not differ between food bait and soil samples for most food baits tested. Melanotus communis larvae were most numerous in the oatmeal-corn flake and sorghum-sudangrass seed baits. Conoderus spp. larvae were most numerous in the sorghum-sudangrass seed and corn ear baits. In the second year, M. communis larvae were more numerous in food baits than in soil samples, and more numerous in the oatmeal-corn flake and rolled oat baits than in other food baits. Numbers of Conoderus spp. larvae did not differ between food bait and soil samples nor among food baits. In addition to attracting more wireworms, oatmeal-corn flake and rolled oat baits had some of the shorter processing times. The use of one of these two baits is currently recommended for pre-plant sampling of wireworms in potato fields in southern Florida.

Monitoring sweetpotato weevil (Coleoptera: Curculionidae) with sex pheromone: effects of dosage and age of septa.

Abstract Studies were conducted to determine the potential of a synthetic sex pheromone that attracts only males for monitoring sweetpotato weevil, Cylas formicarius elegantulus (Summers), populations in southern Florida, the US Virgin Islands, and Puerto Rico. Trap counts consistently increased with an increase in pheromone dosage. Slope values from the regressions of log10weevil counts on log10 dosage and arcsine‐transformed percentages of weevils caught per dosage on log10 dosage did not differ among most trials despite large differences in weevil densities and time of year. In St Croix, US Virgin Islands, septa aged outdoors were as attractive as fresh septa (refrigerated septa) for up to 7 weeks (49 days). In southern Florida, trap counts decreased with an increase in septum age. From a practical perspective, however, aged septa were almost as attractive as fresh septa for at least 30 days. Results from these studies indicate that a dosage of 10 μg of pheromone formulated on methylene chloride‐extrac...

Scientific Notes: Euderus Purpureas (Hymenoptera: Eulophidae): a Parasitoid of Sweetpotato Weevil (Coleoptera: Apionidae) in Southern Florida

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Student Symposium: Alternatives to Chemical Control of Insects: Potential of Teflubenzuron for Diamondback Moth (Lepidoptera: Plutellidae) Management on Cabbage in Southern Florida

The potential of the chitin synthesis inhibitor, teflubenzuron (CME 13406), for managing populations of diamondback moth (DBM), Plutella xylostella L., on cabbage was assessed during two consecutive growing seasons in southern Florida. In the first year, the effectiveness of two rates of teflubenzuron at managing DBM populations was compared with those of three commonly used insecticides, fenvalerate, methamidophos, and methomyl in combination with Bacillus thuringiensis var. kurstaki, applied at recommended rates. In the second year, the effects of different treatment intervals (7, 14 or 21 days) of teflubenzuron on DBM management were assessed. Teflubenzuron was more effective than other insecticides at suppressing DBM populations and protecting plants. The percentages of marketable cabbage heads were 98, 98, 83, 80, and 50% on plants treated with teflubenzuron at 0.022 and 0.044 kg ai/ha, methomyl in combination with B. thuringiensis, fenvalerate, and methamidophos, respectively, and was 17% in nontreated plots. In the second year, teflubenzuron (0.033 kg ai/ha) was consistently more effective than other insecticides at suppressing DBM populations. DBM populations and the percentages of marketable heads did not differ among plants treated with teflubenzuron at 7-, 14-, and 21-day intervals, suggesting that the negative effects of teflubenzuron on DBM were persistent. The potential importance of teflubenzuron in DBM management programs in Florida is discussed.