ABSTRACT
Insects have been proposed as a rich alternative source of protein for the partial or total replacement of fishmeal in aquaculture. For maximum safety and effectiveness of insect meals, control of the quality composition of these products is considered mandatory. The aim of this study was the genetic analysis of the composition of commercially available insect meals at the species level. Commercially available Hermetia illucens, Tenebrio molitor and Musca domestica individuals, as well as nine insect meals produced from these species, were analyzed. The genetic identification of insects at the species level was based on a COI fragment, and analysis of the insect meals' composition was performed with the processes of cloning and colony PCR. Genetic analysis indicated that the commercially available larvae morphologically identified as Musca domestica belonged to the species Muscina stabulans. In the commercially available insect meals, no other animal species was identified beyond the expected one. However, in the insect meal produced for research purposes, fungal growth was detected. The used methodology, herein, allows for the qualitative genetic identification of insect meals and could be included in the methods of traceability of products containing insects and other animal species.
ABSTRACT
The effect of temperature on the development and survival of Cephalonomia tarsalis (Ashmead) (Hymenoptera: Bethylidae), larval ectoparasitoid of beetles of Oryzaephilus sp. (Coleoptera: Silvanidae) was studied in the laboratory. Durations of the development of the egg, larva and pupa were measured in eight constant temperatures (15, 17.5, 20, 25, 30, 32.5, 35 and 37.5°C) parasitizing larvae of the saw-toothed beetle Oryzaephilus surinamensis (L.) (Coleoptera: Silvanidae). The duration of development was decreased with temperature increase within the range 17.5-32.5°C. Survival was higher when immatures were exposed to medium temperatures (20-30°C) compared with those lived in a more extreme temperature regime (<20 and >30°C). Wasps failed to complete their development at 15 and 37.5°C. Thermal parameters (upper, lower and optimum developmental threshold, thermal constant) were estimated by fitting the linear and a non-linear (Logan I) model to our data. Upper and lower developmental thresholds ranged between 35.1-37.0°C and 13.2-13.8°C, respectively. The optimum temperature for development was estimated between 33.6°C and 34.6°C. Tests for developmental rate isomorphy (DRI) showed that change in the average proportion of time spent in each developmental stage was marginally significant, proving that development of C. tarsalis is probably incompatible with DRI. However, this conclusion is questionable given that lower developmental thresholds did not differ significantly among various developmental stages (bootstrap test). Thermal constant for total development was calculated 212.4 degree-days. Our results are discussed not only on the basis of thermal biology, but also of improving the efficiency of C. tarsalis as biocontrol agent.
Subject(s)
Coleoptera/parasitology , Temperature , Wasps/embryology , Animals , Larva/physiology , MortalityABSTRACT
Thermal requirements (lower temperature threshold and thermal constant) for the development of each developmental stage of the predator Harmonia axyridis (Pallas) were studied on Aphis fabae Scopoli and Dysaphis crataegi (Kaltenbach) under controlled laboratory conditions. The effect of temperature (15, 20, 25, and 30°C) and prey species was examined on pre-imaginal developmental duration and life cycle (pre-oviposition period included) of the predator. Our results suggest comparable thermal requirements for the development of H. axyridis on the particular prey and when compared with other aphid species. The total preimaginal development of H. axyridis, at 15, 20, and 30°C, and its life cycle, at 15 and 30°C, are shorter on D. crataegi than on A. fabae.
