Susceptibility of Aedes aegypti larvae to parasitism by I Paragordius varizrs under laboratory conditions

CRISTINA DE VILLALOBOS; MARIA M. RONDEROS; NANCY GRECO; FERNANDA ZANCA; FLORENTINA DIAZ; CECILIA ACHIORNO

TRANSACTIONS OF THE AMERICAN ENTOMOLOGICAL SOCIETY

AMER ENTOMOL SOC

Año: 2006 vol. 132 p. 121 - 127

0002-8320

&amp;lt;!-- /* Font Definitions */ @font-face {font-family:"Cambria Math"; panose-1:2 4 5 3 5 4 6 3 2 4; mso-font-charset:0; mso-generic-font-family:roman; mso-font-pitch:variable; mso-font-signature:-1610611985 1107304683 0 0 159 0;} @font-face {font-family:Calibri; panose-1:2 15 5 2 2 2 4 3 2 4; mso-font-charset:0; mso-generic-font-family:swiss; mso-font-pitch:variable; mso-font-signature:-1610611985 1073750139 0 0 159 0;} /* Style Definitions */ p.MsoNormal, li.MsoNormal, div.MsoNormal {mso-style-unhide:no; mso-style-qformat:yes; mso-style-parent:""; margin-top:0cm; margin-right:0cm; margin-bottom:10.0pt; margin-left:0cm; line-height:115%; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-fareast-font-family:Calibri; mso-bidi-font-family:"Times New Roman"; mso-fareast-language:EN-US;} .MsoChpDefault {mso-style-type:export-only; mso-default-props:yes; font-size:10.0pt; mso-ansi-font-size:10.0pt; mso-bidi-font-size:10.0pt; mso-ascii-font-family:Calibri; mso-fareast-font-family:Calibri; mso-hansi-font-family:Calibri;} @page Section1 {size:595.3pt 841.9pt; margin:70.85pt 3.0cm 70.85pt 3.0cm; mso-header-margin:35.4pt; mso-footer-margin:35.4pt; mso-paper-source:0;} div.Section1 {page:Section1;} --&amp;gt; Six hundred larvae of all instar of Aedes aegypti Linnaeus, 1762 (Diptera: Culicidae) were experimentally infected with larvae of Paragordius varius (Leidy, 1851) (Gordiida: Nematomorpha). All A. oegypri larvae were examined under a light microscope in order to assess the percentage of parasitized larvae, the number of P. varius larvae per A. aegypti larva and their location (thorax and/or abdomen), ANOVA was used for statistical testing of treatment effects. Data of the number of P. varius larvae per A. aegypti larva were log transformed and analyzed by two-factors ANOVA (instars: Ist, 2nd, 33rd, 4th; position: thorax and abdomen). Means were compared by Tukey test and the significance level was set at P< 0.05. The results obtained showed that A. aegypti larval rnortality, at 2h 30min after infection, was higher in parasitized larvae (42.5 %) than in the control group (3 %). First and 2nd instar larvae were the most susceptible to parasitism (52.15% and 46.67 % respectively). More than 90% of each instar A. aegypti larvae were parasitized and the percentage parasitism did not differ between instars. More parasitic larvae were found in 1st and 2nd instar A. aegypti larvae than in 3rd; and 4th instars. Paragordius varius parasitize predominantly the abdomen. 9.1% 3rd instar and 68.4% 4th instar Aedes aegypti larvae induced an internal defense reaction (IDR). No infection was registered in the control group.