Walid Kaakeh

Toxicity of fipronil to German and American cockroaches

Topical and oral toxicity of fipronil, compared to chlorpyrifos, was determined for the German cockroach, Blattella germanica (L.), and American cockroach, Periplaneta americana (L.). Fipronil and Combat bait matrices were evaluated for their attractancies to both species. In the topical toxicity tests, LD50s of fipronil, at 72 h after topical application, were 0.03 and 0.02 μg/g for adult B. germanica and P. americana, respectively. Fipronil was significantly more toxic than topically applied chlorpyrifos (LD50s were 0.06 and 0.16 μg/g for B. germanica and P. americana, respectively). The oral toxicity of fipronil and chlorpyrifos in Petri dish experiments, against both species, was affected by stage (for B. germanica), diet concentration, and feeding assay. Fipronil caused higher mortality of B. germanica than chlorpyrifos in two feeding assays (continuous and abbreviated). Both compounds were equally toxic to adult males of P. americana at all rates. Fipronil caused higher nymphal mortality than chlorpyrifos 48–72 h after exposure in both feeding assays. In large population chamber tests, fipronil bait was more effective and faster in killing P. americana than Raid and Combat. LT50s were 0.8, 2.4, and 7.6 d for fipronil, Raid (a.i. = chlorpyrifos), and Combat (a.i. = hydramethylnon) baits, respectively. Mortality reached 96.5, 93.4, and 84.6%, respectively, at the end of the 14 d test. In the bait attractancy tests, both strains of B. germanica were attracted similarly to fipronil and Combat bait matrices. P. americana were attracted more to fipronil than to Combat bait matrix or to other alternative foods.

Horizontal Transmission of the Entomopathogenic Fungus Metarhizium anisopliae (Imperfect Fungi: Hyphomycetes) and Hydramethylnon Among German Cockroaches (Dictyoptera: Blattellidae)

Horizontal transmission of the entomopathogenic fungus, Metarhizium anisopliae (Metchnikoff) Sorokin, and hydramethylnon toxicant among individuals of the German cockroach, Blattella germanica (L.), was evaluated in this study. Transmission of hydramethylnon occurred through the feces. Contaminated feces were toxic to other cockroaches when mixed with standard laboratory diet at different ratios. Lethal time (LT50) of the nymphs increased as the proportion of contaminated feces in the healthy laboratory diet was decreased. When cockroaches were fed a diet consisting of hydramethylnon-contaminated feces and a laboratory diet at ratios of 1:0, 1:1, and 1:5, the mortality reached 100% at days 9, 12, and 17, respectively. The mortality was reduced to approximately 80% at a ratio of 1:10. Fifth-stage nymphs exposed to the conidia of M. anisopliae or hydramethylnon toxicant for 6, 12, 24, or 48 h transferred the fungal conidia or the toxicant to healthy nymphs. Rate of mortality increased significantly by incre...

Topical toxicity of imidacloprid, fipronil, and seven conventional insecticides to the adult convergent lady beetle (Coleoptera: Coccinellidae)

The relative toxicities (comparing LD50 and LT50s) of two synthetic pyrethroids (cypermethrin and fenvalerate), two organophosphorus insecticides (chlorpyrifos, diazinon), three carbamates (propoxur, carbaryl, bendiocarb), a phenylpyrazole representative (fipronil), and a heterocyclic nitromethylene representative (imidacloprid or NTN 33893) were assessed with topical bioassays in the laboratory against the convergent lady beetle, Hippodamia convergens Guerin Meneville. LD50 values decreased (i.e., toxicity increased) with an increased time after application of a specific insecticide. The differences between the LD50 values caused by various insecticides were significant. Among tested insecticides, cypermethrin and bendiocarb were the most toxic; fipronil was the least toxic. H. convergens responded differently to different insecticides within the same class. Beetles exhibited similar responses to both organophosphorothionates chlorpyrifos and diazinon 24 to 72 h after application. Of the carbamates, prop...

Effect of Aphis spiraecola and A. pomi (Homoptera: Aphididae) on the growth of young apple trees

Abstract One-year-old ‘Redchief Delicious’ apple trees grown in pots in an unheated greenhouse with screened ends were inoculated during the summer with either spirea aphid, Aphis spiraecola Patch or apple aphid, A. pomi DeGeer. Photosynthesis and greenness (the extent of chlorophyll colour) of apple leaves were reduced by increasing accumulated aphid-days for both species. Accumulation of fresh and dry weights in leaves, lateral shoots, rootstock and roots during the first growing season were affected by both species. Differences in dry weight were still present when trees were harvested at the ten-leaf stage the following spring. The percentages of non-structural carbohydrates (NSC) in shoots, roots and leaves were reduced by both aphids; amounts of NSC were reduced in all tree partitions. At the ten-leaf stage of the second season, the percentage and amount of NSC were reduced in all tree partitions. Tree response to the two aphid species was generally similar.

Residual Activity and Population Effects of Noviflumuron for German Cockroach (Dictyoptera: Blattellidae) Control

Abstract A benzoylphenyl urea insect growth regulator with the common name noviflumuron was evaluated for efficacy and residual activity on the German cockroach, Blattella germanica (L.). In laboratory studies evaluating residual activity, 0.05% noviflumuron suspension concentrate produced 100% nymphal mortality 120 d after application to steel and masonite substrates. Residual activity of noviflumuron was more variable on painted plywood substrates compared with stainless steel and masonite. In bioassay arenas, population reductions caused by noviflumuron were significantly greater than Archer and the untreated populations. After 16 wk, populations exposed to 0.05, 0.1, and 0.2% noviflumuron were reduced by 51.9 ± 19.8, 62.2 ± 6.5, and 62.6 ± 18.4%, respectively. Control cockroach populations and populations exposed to 1.3% pyriproxyfen at labeled rate (Archer, 0.61 g/m2) increased by 1,286.3 ± 125.1 and 937.2 ± 137.1%, respectively, at the end of 16 wk. A field study in multifamily housing complexes showed noviflumuron (0.2 and 0.5%) to provide 73.3 ± 8.0 and 90.6 ± 3.6% trap catch reduction at 4 wk posttreatment, respectively. There were no significant differences in the performance of noviflumuron, Maxforce FC Roach Bait Stations (0.05% [AI] fipronil), and Avert dust bait (0.05% [AI] abamectin B1). Noviflumuron shows excellent potential for use in cockroach management programs.