Chemical stability and aggregation activity of assembly pheromone of argasid ticks and its synthetic purine analogues were studied during long-lasting storage at room temperature as the potential components of attractant/acaricide mixtures. Guanine spherules from dry excreta of Omithodoros moubata Murray, 1877 were very stable in their chemical composition and did not suffer from purine degradation. However, an intensive purine conversion into uric acid occurred in samples of the fluid of the excreta of Argas persicus (Oken, 1818) and to a lesser extent also in an artificial mixture of synthetic guanine, xanthine and hypoxanthine in saline. The presence of bacteria Bacillus sp. and the moulds Talaromyces flavus (syn. Pénicillium dangeardii) and Aspergillus carbonarius, isolated from some samples, might explain the enzymic degradation of purines. The suspension of guanine hydrochloride in saline or in saline with ethanol (1 : 1 v/v) as a potential acaricide solvent, and with diatomaceous earth as the pheromone carrier, was very stable and no guanine degradation occurred. This proved to be suitable for potential use mixed with acaricides for tick control. The assembly of A. persicus males, on most of the substrates tested, was very high up to day 77 of experiment but decreased significantly on day 114-119 in samples of synthetic analogue of assembly pheromone variant 1 in which the absolute amount of guanine in solutions strongly decreased or disappeared completely.
The aim of this study was to show that the kind of AKH-mobilized energy substrates in insects can be predicted on the basis of the results obtained with the application of heterologous, i.e. inter-species, AKHs. Four different AKHs, the Locmi-AKH-I inducing hyperlipaemia and hyperglycaemia in Locusta migratoria, Tenmo-HrTH inducing hyperglycaemia in Tenebrio molitor, and Pyrap-AKH and Peram-CAH-II inducing hyperlipaemia in Pyrrhocoris apterus were used, firstly in conspecific tests, secondly in all possible species-AKH combinations, and finally in individual applications on the test species, the cotton bug Dysdercus cingulatus. Since each of the AKHs induced hyperlipaemia in D. cingulatus adults, we predicted that lipids are the only energy substrates which are mobilized in this species by its native AKH. The accuracy of this prediction was subsequently confirmed by the structural identification of the native D. cingulatus AKH and conspecific application tests. The proposed methodical approach can serve as a suitable monitoring system for determination of the kind of energy substrates mobilized by native insect AKHs until the structure of the hormone is identified.