تاثیر قارچ بیمارگر Beauveria bassiana روی ویژگیهای زیستی زنبور پارازیتوئید Habrobracon hebetor

نوع مقاله : مقاله پژوهشی

نویسندگان

• زهرا رحمتی حبیب آبادی
• نفیسه پورجواد

گروه گیاهپزشکی، دانشکده کشاورزی، دانشگاه صنعتی اصفهان، اصفهان، ایران

چکیده

کلیدواژه‌ها

• نرخ ذاتی افزایش جمعیت
• شب پره آرد
• کنترل بیولوژیک

موضوعات

• کنترل بیولوژیک آفات

Extended Abstract

Introduction

Since the interspecific interactions among natural enemies released for the biological control of different pests of a crop can affect the success of controlling each pest, knowing the relationships between natural enemy species in an agricultural system is very important. The fungus, Beauveria bassiana, is one of the most well-known entomopathogenic fungus that has broad host range and the low cost mass production and currently is widely used for pest management in greenhouses and outdoor crops.  This fungus is used to control the tomato leaf miner, Tuta absoluta, in tomato cultivation. The ectoparasitoid wasp, Habrobracon hebetor plays an important role in controlling many native and invasive pests, especially Pyralidae and Noctuidae moths, in agricultural products due to its high search ability, suitable adaptation and wide host range. In Iran, its mass production is done on Ephestia kuehniella, and adult wasps are released to parasitize Helicoverpa armigera larvae in cotton and tomato fields. The aim of this study is to evaluate the possible effects of B. bassiana on the biological characteristics of H. hebetor wasps.

Materials and Methods

The fertility-life table parameters of H. hebetor wasps were studied on the E. kuehniella larvae that were treated with the B. bassiana suspensions in three different concentrations (10³, 10⁶ and 10⁹ conidia/ml). In order to determine the effect of the duration of host infection with the fungus before parasitization on the fitness parameters of the H. hebetor, treated larvae at three times; one day, two days, and three days after the treatment with the fungus, were exposed to wasps. The experiment was carried out in laboratory conditions in an incubator at 25 ± 1°C, 65 ± 5% relative humidity, and 16L:8D photoperiod. Length of different life stages, number of eggs per female and population parameters including the net reproductive rate (R₀), the gross reproductive rate (GRR), the intrinsic rate of population increase (r), the finite rate of population increase (λ), the age-specific survival rate (l_X), the age-specific fecundity (m_X), and the mean generation time (T) were calculated by checking daily.

Results and Discussion

Our results showed that the embryonic period of wasps is not affected by the host infection with fungus, but the larval and pupal periods were significantly different in different treatments. Our results showed that the embryonic period of bees is not affected by the infection of the host with fungi, but the larval and pupal periods were significantly different in different treatments, so that with the increase of the infection time and the concentration of B. bassiana fungus, the length of the larval and pupal periods have increased. Also, the lifespan in female adult wasps that reared on infected host significantly decreased compared by others that reared on un-infected host. The amount of reduction in the adult lifespan was in line with the increase in the concentration of the fungus and the host infection duration. The amount of eggs per female decreased significantly with the increase in the host infection time and the concentration of the fungus. The fertility life table parameters of the parasitoid, H. hebetor, were significantly affected by different concentrations of B. bassiana in three different host infection times, so that with the increase in the concentration of the fungus and host infection time, amount of the intrinsic rate of population increase and the finite rate of population increase were decreased.

In conclusion, considering the negative effects of B. bassiana on the performance of H. hebetor, the time of using the entomopathogenic fungus and the release of parasitoid wasps should be chosen very carefully in order to minimize these negative effects in their combined application in biological control programs.