Variation in the concentration of carminic acid produced by Dactylopius coccus (Hemiptera: Dactylopidae) at various maturation stages.

The concentration of carminic acid was found to vary based on the size and life cycle stage of the cochineal, Dactylopius coccus Costa. The concentration of carminic acid in cochineal eggs, nymph I, nymph II, fertilized adults, ovipositing adults, and sterile adults female was measured using capillary electrophoresis, and the total fluorescence of the carminic acid globules was measured using flow cytometry. The smallest sterile adult females had a greater percentage of carminic acid relative to their weight (26.27%; P < 0.001) than adult females in the remaining groups. In general, ovipositing females had a greater percentage of carminic acid than the remainder of the females. Nymph II was the phase that had the smallest percentage of carminic acid. Using flow cytometry, it was demonstrated that ovipositing females had a greater total fluorescence than the other sampled groups (P < 0.05). A positive correlation was found between the percentage of carminic acid and the total fluorescence of the carminic acid globules (r2 = 0.68; P < 0.05). The results of this study, together with others that involve industrial processes, shall allow an improvement of the current classification criteria of the commercial quality of dry cochineal.

Effect of new ethyl and methyl carbamates on biological parameters and reproduction of the cattle tick Rhipicephalus microplus.

The effect of carbamates on engorged female Rhipicephalus microplus ticks and larvae was evaluated using the adult immersion test (AIT) and the larval packet test (LPT), respectively. Seventeen synthetic carbamates different from current commercial acaricides were synthesised at the National Autonomous University of Mexico. None of the carbamates had an effect on the percentage of females laying eggs. Six of the compounds inhibited egg laying up to 65.4% and inhibited egg hatching by up to 100% (p<0.05). Compared to untreated females, eggs produced by treated females had a dark, dry, opaque appearance and were less adherent. Carbamates LQM 934 and LQM 938 had an effect on larval mortality (p<0.05). Carbamate LQM 934 showed lethal concentrations (LC) of LC90=0.76% and LC99=0.87%, while LQM 938 showed concentrations of LC90=0.267% and LC99=0.305%. The compounds were distributed into three classes of acaricidal activity using the AIT or the LPT. These three classes were as follows: (1) compounds having no apparent effect; (2) compounds that inhibit egg laying and embryo development or (3) compounds that exhibit acaricidal activity to larval ticks.