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Six compounds, representing the mono-tetrahydrofuran (THF) (gigantetrocin A, annomontacin), adjacent bis-THF (asimicin, parviflorin), and nonadjacent bis-THF (sylvaticin, bullatalicin) classes of annonaceous acetogenins, were compared with technical grades of synthetic amidinohydrazone (hydramethylnon), carbamate (propoxur, bendiocarb), organophosphate (chlorpyrifos), and pyrethroid (cypermethrin) insecticides to determine their dietary toxicities to insecticide-resistant and insecticide-susceptible strains of the German cockroach, Blattella germanica (L.). Differential susceptibility occurred among B. germanica nymphs of both strains to this variety of the acetogenins and the 5 conventional synthetic insecticides. The speed of kill (LT50) values against insecticide-susceptible and insecticide-resistant 2nd and 5th instars permitted ranking of all 11 compounds. The adjacent bis-THF acetogenins showed the highest potency among the 3 acetogenin classes. The acetogenins caused high percentages of mortality and delays in development of the 5th instars of both strains. Insecticide-susceptible nymphal development was mainly affected by gigantetrocin A and annomontacin, whereas insecticide-resistant nymphal development was mainly affected by gigantetrocin A and bullatalicin. Most tested acetogenins performed better than the conventional insecticides against both stages of both strains. No growth regulation effects were caused by any of the compounds tested. Low resistance ratios were obtained for most compounds (except chlorpyrifos). Low resistance ratios values for 2nd instars ranged from 0.9 to 2.2 with the natural acetogenins and from 1.0 to 3.8 with the synthetic compounds; the 5th instars ranged from 0.2 to 3.9 with the natural acetogenins and from 0.6 to 8.0 with the synthetic compounds. Insecticidal properties and characteristics of acetogenins and the possible use of acetogenins in baits for cockroach control are discussed.

Life parameters including pre-oviposition period, oviposition period, larval and pupal periods, adult male and female development times, and generation span, were obtained for the red palm weevil, Rhynchophorus ferrugineus Olivier, reared on artificial diets of oat, potato, pineapple, and palm fiber sheath, and on natural diets of sugarcane, palm heart, and palm leafbase. Significant differences in the duration of all life parameters were found when fed on various diets. The pre-ovipositional periods ranged from 3.15 to 3.61 d, while the oviposition periods ranged from 3.2 d to 3.8 d. The developmental times of larvae ranged from 70.8 d to 102.2 d, while the development time of pupae ranged from 16.1 d to 22.2 d. The developmental time of adults previously reared on natural diets were longer than those fed on artificial diets. Differences in the development time occurred between males and females reared on different diets, except on sugarcane and palm leafbase. The generation span ranged from 93.2 d to 131.3 d. Significant differences in the average number of eggs deposited per female, previously reared in their larval stages on various diets, ranged from 68.2 eggs to 185.2 eggs, while the average number of eggs deposited per female per day ranged from 1.28 eggs to 3.03 eggs. The percentage of hatchability (viability of eggs) ranged from 74.3% to 93.3%. The mean total number of eggs laid by females, eggs deposited 30 d after one full copulation with males of similar age, and rate of egg hatch decreased significantly with increasing weevil age, and ranged from 65.5 eggs (1-d-old female) to 43.5 eggs (45-d-old female). The rate of egg hatch, also decreased significantly with increasing weevil age, and ranged from 75.8% (1-d-old weevils) to 47.4% (45-d-old weevil). The short copulatory period was adequate for insemination of the female during copulation. Feeding of R. ferugineus on different diets resulted in different life parameters.

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 increasing the ratio of infected to unexposed cockroaches (i.e., 1:1 ratio >1:10 ratio), and by increasing the exposure time for the infected cockroaches (48 h versus 6 h) to both M. anisopliae and hydramethylnon. Cockroaches killed by M. anisopliae or hydramethylnon before being presented to healthy cockroaches were less effective in spreading the fungus or toxicant than were live infected cockroaches. When live infected nymphs were mixed with healthy cockroaches, M. anisopliae initially killed cockroaches slightly faster (LT50[95% CL] = 10.1 [9.2–11.0] d) than hydramethylnon (LT50[95% CL] = 12.5 [11.4 - 13.7] d). However, cumulative mortality reached 100% at day 26 for both M. anisopliae and hydramethylnon treatments. After mixing healthy nymphs with dead infected cockroaches, the rate of mortality was slower for M. anisopliae (LT50 = 20 [19.1 - 20.9] d) and hydramethylnon (LT50 = 14 [13.4 - 14.7] d) than those recorded in the previous test (that is, mixing live-infected nymphs with healthy cockroaches). However, the cumulative mortality 28 d after exposure to M. anisopliae and hydramethylnon reached 77 and 67%, respectively. Fungal growth was observed on all body parts of dead infected nymphs within 14 to 16 d of exposure to M. anisopliae. Dead infected nymphs were not cannibalized suggesting avoidance behavior by healthy nymphs. Consequently, the fungal conidia were not spread as effectively by dead nymphs as with live infected nymphs. Factors affecting performance in light of horizontal transmission of M. anisopliae are discussed.