|
Abstract
|
Pesticide application is one of the effective control methods of pests. However, their
diverse effects on human health, beneficial and environment have provoked experts to seek
alternative measures. Botanical pesticides with relative safety to environment and non-target
organisms could be used in pest management programs. In this study, combination effects of
hexane extracts of Falcaria vulgaris and Apium graveolens with microbial pesticide Bt var
Krustaki were investigated on life span and adult emergence rate of potato tuber moth (PTM),
Phthorimea operculella. Extraction was carried out by standard maceration method using
hexane as non-polar solvent. PTM larvae were reared on potato tubers in controlled
condition. First larval instar of PTM were introduced on same shape and size potato tubers
treated with LC50 and LC30 values of both plant extracts and Bt. For co-toxicity evaluation,
combination of Bt and plant extracts were tested in above mentioned concentrations. Treated
tubers were kept in growth chamber at 25 ± 2 ºC, 50 ± 5 % RH and 16:8 (L:D) h. Larval
developmental time, number of pre-pupa, pupae and adult individuals were recorded in
control and treatments daily. Results revealed that larval life span of insects increased in
treatments with a dose dependent manner. LC50 values of plants extracts and Bt increased
larval duration by 8 ± 0.52 and 5 ± 0.45 days in comparison with control, respectively.
However, LC50 values of Bt combined with the same value of both plants extracts
significantly increased the larval developmental time by 45 ± 5.4 days compared with that in
control. LC50 values of Bt, F. vulgaris and A. graveolens decreased adults emergence by
47.66, 45.52 and 53.33 %, respectively. Moreover, adults emergence decreased by 66.6 and
70.5 % when they were treated by combined doses of LC50 of Bt and LC30 of F. vulgaris and
A. graveolens, respectively. No adult emergence was recorded after 60 days when they were
exposed to combination treatment of Bt
|