Haemocytes and biochemical changes in Locusta migratoria (Orthoptera : Acrididae)‎ after treated with some essential oils

Abstract EN

The migratory locust, Locusta migratoria L.

(Orthoptera: Acrididae) is the most widespread species throughout different parts of the world.

It feeds on grass and often causes serious damage to agricultural crops.

The present study deals with the effect of essential oils of garlic, cumin and basil against the migratory locust, L.

migratoria in terms of percent mortality.

Total Haemocyte Count (THC) and Phenoloxidase (PO), Acid Phosphatase (ACP) and Alkaline Phosphatise (ALP) activity.

The effect of different concentrations (0.1, 0.5 and 1%) of essential oils were evaluated on last nymphal instar of L.

migratoria.

The results clearly demonstrated that the tested oils (garlic, cumin and basil) had stomach toxicity through the nymphal feeding on treated diet.

the mortality percentages were estimated that reached to 67.86, 48 and 37.93 % in one day old nymph treatment with basil, garlic and cumin oils respectively after ten days of treatment with concentration (1%), The LC50 of different oils varied from one to other, the best treatment among all the tested oils was Basil oil with LC50(0.45%), it was more toxic as stomach poison than garlic oil with LC50 (1.31%), finally cumin oil with LC50 (3.07%).

THC increased after 1 and 2 days while decreased after 3 and 4 days after treated with basil essential oil compared to control.

Garlic and cumin essential oils showed decreased the (THC) after 2, 3 and 4 days in the same time occurred increase in THC after 1 day compared to control.

The insect enzymes PO, ACP and ALP activities were affected fluctuated between increasing and decreasing 2, 4, 6 and 8 days after treatment with garlic, cumin and basil (at LC50 value).

ACP activity and PO activity were dramatically increased at 2nd and 4thin all treatments and decreased at 6 th and 8th days comparing with untreated nymphs.

Also, highly significant decline in ALP were recorded in them by garlic and cumin during the study.