Abstract
Goal. To investigate the effect of low temperatures on coccinellides at different stages of growth with the aim to develop and improve methods of their storage and transportation before introduction into agrocenoses. Methods. Adults and larvae were kept in thermostats at different temperatures. Results. The survival of adult insects of Propylea quatuordecimpunctata and Harmonia axyridis increased with gradual decrease in temperature. The survival of the adult insects of Coccinella septempunctata in the laboratory and natural populations was the same. Keeping adult insects of this species at temperatures of 5 ± 0.5°C and 3 ± 0.5°C showed the same results. The best survival of adult insects, as well as larvae of P. Quatuordecimpunctata of the 2nd and 4th age groups was observed during storage at the temperature of 8 ± 0.5°C. Conclusions. During storage of adult insects of Harmonia axyridis and Propylea quatuordecimpunctata for 30 days, if the temperature was reduced gradually, survival was increased. Breeding insects of Coccinella septempunctata in the laboratory did not affect the survival of adult insects during storage. The comparison was made with the insects of the natural population. The results of storage of insects of the natural population at the temperature of 5 ± 0.5°C and 3 ± 0.5°C did not differ significantly. Insects of Propylea quatuordecimpunctata in the adult stage were more vulnerable to lower temperatures. The number of beetles that survived after being kept at 5 ± 0.5°C was lower than in the variant where the final storage temperature was 8 ± 0.5°C. It is recommended to store imago of Propylea quatuordecimpunctata at the temperature of 8 ± 0.5°C in the ventilated container. Also, the temperature of 8 ± 0.5°C was determined to be much better for storing Propylea quatuordecimpunctata larvae. Insects in the stage of larvae of the 4th age group can be kept at this temperature for 2 weeks without losses, larvae of the 2nd age group — for 1 week with insignificant losses (6–7%). The development of methods of storage of coccinellides can be a useful tool for reducing production costs and meeting the peak demand of farmers during the growing season.
Highlights
Materials and methodsThe studies were carried out with the following species common in Ukraine: Coccinella septempunctata (Linnaeus, 1758) 7th generation laboratory population; Propylea quatuordecimpunctata (Linnaeus 1758) of the 9th generation of the laboratory population and the Harmonia axyridis (Pallas, 1773) of the 7th generation of the laboratory population
Coccinellidae, or ladybeetles (Coleoptera) are an important part of the biotope in various climatic zones
There is a need to use the laws of development and formation of entomophagous and their effective use in modern crop management systems, as well as to determine the optimal timing of biological drugs depending on the biology of harmful and beneficial organisms of agrobiocenoses [7]
Summary
The studies were carried out with the following species common in Ukraine: Coccinella septempunctata (Linnaeus, 1758) 7th generation laboratory population; Propylea quatuordecimpunctata (Linnaeus 1758) of the 9th generation of the laboratory population and the Harmonia axyridis (Pallas, 1773) of the 7th generation of the laboratory population. Paper packages, Petri dishes, and food polyethylene bags were used (Fig. 1). The threshold of activity was determined, that is, the highest temperature at which the larvae and the imago enter the state of full evaluation. The temperature in the thermostat, where the predators were kept, gradually decreased from 15оС to 2-3оС every hour. To ensure the death of the larvae, insects without signs of life were kept in separate Petri dishes for two hours. It is determined that larvae of predators lose mobility, and imago fall into the state of physiological calm at an air temperature below 9оС. The research was carried out in cold-thermostats. When carrying out experiments imago was placed in packages of filter paper and in packages that were wrapped in food polyethylene. Schemes of research on imago are given in the tables (table 1-3)
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