52,463 research outputs found

    Aggregation Behavior of a Willow Flea Beetle, \u3ci\u3eAltica Subplicata\u3c/i\u3e (Coleoptera: Chrysomelidae)

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    This study examined the aggregation behavior of a specialist insect herbivore, Altica subplicata (Coleoptera: Chrysomelidae), on its host plant, Salix cordata. Mark-recapture experiments were conducted in patches of S. cordata growing along the shores of Lake Huron. Beetles aggregated on individual host plants, but did not aggregate in larger areas containing many host plants. Plants colonized by marked beetles had significantly higher abundances of unmarked beetles than did plants that were not colonized by marked beetles. Experimental manipulations of the number of beetles present on plants showed that colonization rates by marked beetles were higher on plants with conspecifics than on plants which had all beetles removed the previous day. The sex of beetles, however, did not influence colonization behavior; both male and female beetles colonized plants regardless of the sex of beetles already present on plants. These results are discussed with respect to possible explanations for aggregation, and the role of aggregation and movement in influencing insect distributions

    Notes on \u3ci\u3eChrysomelobia Labidomerae\u3c/i\u3e (Acari: Heterostigmata: Podapolipidae), Parasites of \u3ci\u3eLabidomera Clivicollis\u3c/i\u3e (Coleoptera: Chrysomelidae) in Michigan and Wisconsin

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    Chrysomelobia labidomerae Eickwort, ectoparasitic mite of chrysomelid beetles, is reported from 11 Wisconsin counties, from 16 of 82 adult Labidomera clivicollis (Kirby) beetles wild-caught in Wisconsin, and from 27 of 141 presumably wild-caught L. clivicollis beetles from 13 Michigan counties. Wisconsin beetles harboring C. labidomerae were found in dry to wet-mesic, open habitats. A distribution map and comments are presented

    Red Flour Beetle Response to Traps with Prior Captures

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    The red flour beetle (Tribolium castaneum) is a major pest of food facilities such as flour mills and is often monitored using pitfall type traps with a food oil and pheromone attractant. Previous research had indicated that prior captures of beetles could increase beetle behavior captures in a trap. Here we used a more realistic bioassay to evaluate how the number of beetles previously captured include beetle captures in traps. Results showed no significant impact of prior captures on the number of red flour beetles captured in a trap. There were some trends suggested in the results that warrant further study to investigate, perhaps by focusing on individual beetle behavior at traps rather then using groups of beetles

    Preferences of the Red Flour Beetle, Tribolium castaneum, for Nutritionally Different Dog Foods

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    Triboliumcastaneum, known as the red flour beetle (RFB)is a common pest of stored grain and milled grain products.Thisresearch studied how RFBs orient to and lay eggs in their standard flour diet and in two kinds of dog food.We tested whether RFBs have a preference toward two different dog foods, one with low protein, the “Light” food, and the other with high protein, the “Dark” food. We predicted the beetles would prefer the Light kibble with the lower protein.When given the choice between the two foods, 60% of beetlespreferredthe Light product, which had only 20% of the protein as the dark food, which was chosen by 40% of beetles. When the beetles were given the choice between either Light or Dark kibble, vs. their regular flour-based lab diet, flour was the preferred food. However, the two-choice test showed a higher proportion of beetles were in the Light compared to Dark food. These results are important because they will help the pet food industry further understand what the RFBs prefer, and thus help us take appropriate measures to prevent infestation

    Curculionidae and Chrysomelidae Found in Aquatic Habitats in Wisconsin

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    (excerpt) We became interested in aquatic weevils (Curculionidae) and leaf beetles (Chryso- melidae) during the Aquatic Entomology Course at the University of Wisconsin, in the spring of 1971. Many collections, taken from a variety of aquatic habitats in Wisconsin, contained weevils and leaf beetles. Most of the species were not fully treated in the keys found in aquatic entomology texts. We thought it would be useful to compile keys from the literature and present what is known of the distribution of these insects in Wisconsin. Nine species of weevils have been found in aquatic habitats in Wisconsin, representing seven genera, all belonging to the subtribe Hydronomi, and twenty-five species of leaf beetles, representing five genera in three subfamilies

    Regulation of the juvenile hormone titre in the Colorado potato beetle

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    Three main topics were investigated in regulation of the titre of juvenile hormone in haemolymph of the Colorado potato beetle ( Leptinotarsa decemlineata Say): enzymic breakdown of the hormone; binding and protection of the hormone by carrier proteins; the synthetic capacity of the corpora allata.Juvenile hormone was broken down by two major pathways: ester hydrolysis by esterases and hydration of the epoxide group by epoxide hydratases in tissue. In haemolymph of the beetle, juvenile hormone is solely broken down by juvenile hormone esterases. An in vitro method was developed to measure the catalytic activity of juvenile hormone esterase from haemolymph. High activities were observed in fourth-instar larvae and in beetles just before diapause. Lower activities were found in third- instar larvae and in beetles reared with long days, at diapause and after diapause. The juvenile hormone esterase was insensitive to diisopropylfluorophosphate (DFP), an inhibitor used to distinguish between carboxylesterases and esterases specific to juvenile hormone. Electrophoresis of the esterase from haemolymph showed one or more esterases specific to juvenile hormone.The short half-life of juvenile hormone measured in vivo and in vitro in the haemolymph and inhibition studies with Triton X-100 suggests that juvenile hormone esterases in haemolymph govern breakdown. Activities of juvenile hormone esterase correlate well with the juvenile hormone titre.The sharp changes in juvenile hormone esterase suggest that esterase activity is regulated. The mechanism was studied by supplying juvenile hormone and by microsurgery. Treatment of diapausing beetles with juvenile hormone itself or analogues caused an increase in activity of juvenile hormone esterase within 24 h. Ligation or removal of corpora allata suggested that this induction was an indirect effect of juvenile hormone. Transfer from short day to long day and treatment with hormone of beetles reared with short days prevented high activity of juvenile hormone esterase. Removal of corpora allata at emergence from beetles reared with short days resulted in the same. In beetles reared with short days the titre of hormone during the first days after adult emergence probably induces the rise in esterase. Esterase activity is thus most likely controlled indirectly by the hormone, via a centre in the brains (hormostate). The level of esterase activity is probably dependent on the sensitivity of this hormostate and on the titre of the juvenile hormone.In several insects juvenile hormone is transported bound to carrier proteins. In haemolymph of larval and adult Colorado potato beetles lipoproteins of high molecular weight (>100,00 daltons) were found, capable of binding juvenile hormone, its analogues, and palmitic acid. The lipoproteins were partially separated by gel permeation chromatography and electrophoresis on polyacrylamide gel. The binding characteristics of the lipoproteins indicate low affinity (K d ≈10 -5 M), low specificity and high binding capacity. The juvenile hormone complexed to lipoproteins was protected against esterases from haemolymph to some extent. Thus these carrier lipoproteins probably play little role in the regulation of the titre of juvenile hormone.In the last part of our investigations the activity of the corpora allata was measured in vitro. High activities were observed in beetles reared with long days and in beetles after emergence. In beetles reared with short days, amounts of hormone produced were intermediate until Day 6 after emergence, thereafter declining to a low value. During diapause, production remained low. The production by corpus allatum and the activity of juvenile hormone esterase were in good agreement with the titre of juvenile hormone. The corpora allata are probably the primary regulator of the hormone titre in the Colorado potato beetle.<p/