Effects of azadirachtin on Rhodnius prolixus: immunity and trypanosoma interaction

Abstract

The effects of azadirachtin, a tetranortriterpenoid from the neem tree Azadirachta indica J., on both immunity and Trypanosoma cruzi interaction within Rhodnius prolixus and other triatomines, were presented. Given through a blood meal, azadirachtin affected the immune reactivity as shown by a significant reduction in numbers of hemocytes and consequently nodule formation following challenge with Enterobacter cloacae beta 12, reduction in ability to produce antibacterial activities in the hemolymph when injected with bacteria, and decreased ability to destroy the infection caused by inoculation of E. cloacae cells. A single dose of azadirachtin was able to block the development of T. cruzi in R. prolixus if given through the meal at different intervals, together with, before or after parasite infection. Similarly, these results were observed with different triatomine species and different strains of T. cruzi. Azadirachtin induced a permanent resistance of the vector against reinfection with T. cruzi. The significance of these data is discussed in relation to the general mode of azadirachtin action in insects.

The effect of azadirachtin on fresh isolates of Trypanosoma cruzi in different species of triatomines

“…Since Azambuja and Garcia (1992) suggested that a high dose of azadirachtin aects all T. cruzi/vector systems, further studies should include high doses, to elucidate the mechanisms by which the development of T. cruzi is aected in some systems. Since azadirachtin has to be ingested by the bug together with the blood, the aim of such studies could never be a direct use of azadirachtin as a biological agent against T. cruzi.…”

Disturbing Effects of Botanicals on the Haemogram and Immune Parameters of Insects: Recent Progress of The Search for Effective Biopesticides

“…According to the currently available literature, Azt and some of its formulations considerably reduced the THC in many insect species, such as American cockroach Periplaneta americana (Qadri and Narsaiah, 1978), last instar female nymphs of the brown-spotted locust Cyrtacanthacris tatarica (John and Ananthackrishnan, 1995), S. litura (Sharma et al, 2003) and Dysdercus cingulatus (Pandey and Tiwari, 2011). Azambuja et al (1991) and Azambuja and Garcia (1992) reported that the administration of Azt via a blood meal to the last nymphal instar of the kissing bug Rhodnius prolixus led to a remarkable reduction in the THC. Drastic reduction of THC in the red cotton bug Dysdercus koenigii (Saxena and Tikku, 1990); the African monarch Danaus chrysippus (Pandey et al, 2008) and S. littoralis (Shaurub et al, 2014) had been recorded after treatment with Azt.…”

“…Azambuja et al (1991) reported an inhibited nodulation response after Azt treatment to the last instar nymphs of R. prolixus. A year later, Azambuja and Garcia (1992) administrated Azt, via a blood meal, to the last instar nymphs of R. prolixus and recorded a reduction of immune reactivity, as indicated by a remarkable reduction in the nodule formation following challenge with the bacterium Enterobacter cloacae E 12. Also, Azt induced permanent resistance to infection with the protozoan Trypanosoma cruzi in the vector of this parasite.…”

Immunomodulation in insects post-treatment with abiotic agents: A review

“…The decrease in the THC may be due to the formation of nodules comprised of groups of haemocytes or the inhibition of endocrine glands and their secretions (Tiwari et al, 2006). Azambuja & Garcia (1992) record that when azadirachtin is administered via a blood meal to last nymphal instars of R. prolixus, the immune reactivity of this insect is reduced, as shown by a significant reduction in the THC and consequently nodule formation following challenge with Enterobacter cloacae 12, a reduction in the antibacterial activity of its haemolymph and consequent decrease in its ability to destroy an infection when inoculated with E. cloacae. Azadirachtin induces permanent resistance to infection with Trypanosoma cruzi in the vector of this protozoan parasite.…”