Abstract
The wild plant Fagonia bruguieri was extracted by three organic solvents in the present study. Two concentration levels of methanol extract (7.5% and 3.7%), petroleum ether extract (30.0 % and 15.0%) or n-butanolic extract (30.0% and 15.0%) were applied against the newly moulted penultimate instar nymphs of the desert locust Schistocerca gregaria and their effects were assessed on the acid and alkaline phosphatases (ACP and ALP) in both the haemolymph and fat body of last instar nymphs and newly emerged adults. The haemolymph of both early- and late-aged nymphs contained remarkably reduced ACP activity while a strong enhancing effect of F. bruguieri was exhibited only in the early-aged nymphs after treatment with the lower concentration level of methanolic extract (Change %: +75.0). Haemolymph of the newly emerged adults appeared with pronouncedly induced ACP activity, irrespective of the solvent or the concentration level. A major inducing effect of F. bruguieri extracts on ACP activity in the fat body in last instar nymphs was significantly or insignificantly observed, with few exceptions. The strongest inducing effect on the enzyme activity in fat body of the newly emerged adults was exhibited by n-butanol extract (Change %: +40.9 at lower concentration level). The F. bruguieri, extracted by all organic solvents, exerted contradictory effects on the ALP activity in haemolymph of the nymphs depending on the age because the early- and mid-aged nymphs appeared with significantly decreased enzyme activity but induced activity in the late-aged ones. A considerable enhancing effect of F. bruguieri on ALP activity in haemolymph of the newly emerged adults was determined. In respect to the ALP activity in fat body, F. bruguieri extracts prohibited it in the early- and mid-aged nymphs but stimulated it in the late-aged ones. Also, an enhancing effect on the enzyme activity in fat body of the newly emerged adults was appreciated.
Highlights
Extensive use of the synthetic insecticides leads to the biological imbalance due to the destruction of beneficial species such as parasites and predators of pests beside the destruction of pollinating insects such as honey bees
1) Effects of F. bruguieri extracts on the acid phosphatase activity in haemolymph: The penultimate instar nymphs of S. gregaria were fed on clover leaves treated with each of two concentration levels of methanolic, petroleum ether or n-butanolic extracts of F. bruguieri
The acid phosphatase (ACP) activity was investigated in the haemolymph of last instar nymphs as well as in the newly emerged adults
Summary
Extensive use of the synthetic insecticides leads to the biological imbalance due to the destruction of beneficial species such as parasites and predators of pests beside the destruction of pollinating insects such as honey bees. Plants are known to contain a very diverse range of secondary metabolites such as terpenoids, alkaloids, polyacetylene, flavonoids and unusual amino acids and sugars. These compounds may protect the plants from the insect pest attacks (Benner, 1993), and act as insect repellents (Jacopson, 1975), or insect growth regulators (Rembold et al.1980). Identification of phytochemicals which mimic insect morphogenetic hormones or have growth regulating activity and synthesis of potent hormone agonists and antagonists in the recent past have led to their consideration as components of biorational approach to pest management (Josephrajkumar et al, 1999)
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