Представлены результаты лабораторных и полевых экспериментов по определению выживаемости и численности гусениц капустной белянки (PierisbrassicaeL.) на разновидностях капусты как растения-хозяина. Полученные данные являются основой для дифференцированного применения биопрепаратов против фитофага.
In recent years, biological plant protection has been paying attention to the influence of plants upon a feeding phytophage. Therefore, we must study the effect of different plant species on phytophage before we consider it in the tritroph system. Today it is important to apply biological control on vegetable plants, especially on cabbage as the most common crop in field.
The purpose of the research is to study the survival and number of large cabbage butterfly (Pieris brassicae L.) larvae on different subspecies and cultivars of cabbage.
To study the problem under laboratory conditions, we took 10 hatched larvae and placed them on leaves of different subspecies and cultivars of cabbage located in Petri dishes. The early white cabbage, late white cabbage, red cabbage and cauliflower were used as host plants. We determined the number of survived larvae and their mass every day during the experiment. In field, the population dynamics was investigated in Toguchin and Novosibirsk districts in 2008-2009. The number of larvae was accounted once in 7-10 days. The data obtained was processed by the method of dispersion analysis.
We had no essential differences in mortality of larvae caterpillars on different subspecies and cultivars of cabbage in laboratory. However, the period of larvae development depended on subspecies and cultivars of cabbage. Faster development of larvae was observed on early white cabbage and cauliflower. Mass pupating lasted for 2-3 days. A more extended period of pupating was on red cabbage that lasted for 8 days (Table 1).
Table 1 – Effect of cabbage subspecies on development and mortality of P. brassicae larvae in laboratory
We had no essential differences in quantity of pupae in the variants. The mass of pupae was fluctuated from 0.23 to 0.31 grams (Table 2).
Table 2 – Quantity and mass of P. brassicae pupae after larvae feeding on different subspecies of cabbage in laboratory
(species of cabbage)
Quantity of pupae (mean per a variant)
Mass of pupae, gram. (mean per 1 pupa)
In 2008, number of larvae in both field plots was at low level. It should be noted that cauliflower was more attractive for insect oviposition. Amount of oviposition was 15-17 eggs per 100 plants. In 2009, in Toguchin plot most of larvae emerged in 3th part of August. Maximum of larvae number was on cauliflower – 529; less number of pests was on late white cabbage – 190 per 100 plants. Least of one was on red cabbage. As to the second plot (Novosibirsk), we could found only several caterpillars.. The population dynamics of insect was irregular in 2008 and 2009. However, late white cabbage and cauliflower were more damaged by the larvae.
Having analyzed the statistical data, we can come to conclusions that different subspecies and cultivars of cabbage influence the development and larvae mortality, and pupae mass of P. brassicae. The result of the research will be the basis for following experiments on biological pest larvae control.