03077nam a2200229 a 450000100080000000500110000800800410001910000160006024501530007626001240022930000140035352023190036765000130268665000160269965000240271565000200273965000170275965000090277670000240278570000170280970000210282614678732020-02-27       2003    bl uuuu     u00u1 u    #d1 aLEVY, S. M.  aIs the Nucleopolyhedrovirus of Anticarsia gemmatalis (AgMNPV) ineffective to infect AgMNPV resistant host larva midgut cells?h[electronic resource]  aIn: ANNUAL MEETING SOCIETY FOR INVERTEBRATE PATHOLOGY, 36., 2003, Burlington. Program and abstracts... Burlingtonc2003  ap. 81-82.  aAnticarsia gemmatalis, is a key pests of soybean in Brazil. It has been controlled by a nucleopolyhedrovirus (AgMNPV), which is widely used as a microbial insecticide in the country. The constant and increasing use of this biological insecticide in some regions have caused concerns about the possibility of selection of viral resistant populations. Although this phenomenon has not been detected in the field yet, a laboratory A. gemmatalis populations has been selected for high resistance to the AgMNPV. It is known that the midgut is considered one of the most important barriers against viral invasion, before systemic infections can be caused in various tissues if the virus succeeds in reaching the host larva hemocele. Our work aimed to verify whether or not the AgMNPV invades and infects the midgut cells of resistant larvae, comparing the ultrastructure of the midgut epithelial cells from the susceptible (SL) and resistant (RL) A. gemmatalis infected larvae. The susceptible and resistant strains of A. gemmatalis were reared on artificial diet, under laboratory-controlled conditions at Embrapa Soja, Londrina-PR, Brazil. The AgMNPV used as inoculum was incorporated into the insect diet at 60,000 occlusion bodies/ml of diet. The midguts were collected up to 120h post infection, processed and analyzed under transmission electron microscopy. The columnar cell were the most affected ones among the different midgut epithelial cells. In the SL, these cells showed many morphological signs of cellular damage from 24 hours after infection, mainly at the proximal midgut region. However, in RL these cells exhibited minor morphological damage up to 120 hours. Polyhedra were visualized in the midgut of both SL an RL from 96 hours of infection, but the amount of viral structures were always higher in SL, affecting the midgut epithelial and tracheal cells, as well as attached hemocytes (mainly plasmatocytes and granulocytes). Our results showed that the AgMNPV, in fact, invaded RL cells. However, the virus did not affect these insects as they did with the susceptible ones, allowing development and survival of resistant larvae. The mechanism interfering with the virus infection progress in midgut cells of RL it still unknown. This work has been supported by FAPESP and PRONEX (MCT/Finep/CNPq).  aSoybeans  aBaculovirus  aControle Biológico  aPraga de Planta  aResistência  aSoja1 aFALLEIROS, A. M. F.1 aMOSCARDI, F.1 aGREGÓRIO, E. A.