Longevity and fecundity of Dichroplus maculipennis (Orthoptera, Acrididae) at non-outbreaking and outbreaking situations

• Published in: Revista brasileira de entomologia Vol. 55; no. 3; pp. 435 - 438
• Main Authors: Mariottini, Y, De Wysiecki, ML, Lange, CE
• Format: Journal Article
• Language: Portuguese
• Published: 01-09-2011
• Subjects: Acrididae; Orthoptera
• ISSN: 0085-5626

Dichroplus maculipennis is one of the most characteristic and damaging grasshopper species of Argentina, mainly in areas of the Pampas and Patagonia regions. We estimated and compared the longevity and fecundity of adult female D. maculipennis under controlled conditions (30 degree C, 14L:10D, 40% RH) from individuals collected as last instar nymphs (VI) in the field and with a known recent history of low and high density conditions. Densities of D. maculipennis at the collecting sites were 0.95 individuals per m super(2) in 2006 and 46 ind/m super(2) in 2009, representing non-outbreaking and outbreaking situations, respectively. Adult female longevity in 2006 (67.96 plus or minus 3.2 days) was significantly higher (p < 0.05) than in 2009 (37.44 plus or minus 1.98 days). The number of egg-pods per female was 3.32 plus or minus 0.44 for 2006 and 1.62 plus or minus 0.26 for 2009. The average fecundity in 2006 (89.29 plus or minus 11.9 eggs/female) was significantly greater (p < 0.05) than that in 2009 (36.27 plus or minus 5.82 eggs/female). While it was observed that the oviposition rate was higher in 2006, this difference was not significant (p > 0.05). The fecundity curves showed that the highest values were at weeks 11 and 13 for the 2006 females, and at week 6 for those of 2009. Since the daily oviposition rate at low and high densities was not significantly different, the diminished fecundity rate at high density is attributable to their reduced longevity.Original Abstract: de "non-outbreaking" e "outbreaking". O gafanhoto Dichroplus maculipennis e um dos mais caracteristicos e prejudiciales da Argentina, principalmente nas regioes das Pampas e da Patagonia. O objetivo deste estudo foi estimar e comparar a longevidade e fecundidade das femeas adultas do D. maculipennis sob condicoes controladas (30 degree C, 14 luz: 10 obscuridad, 40% RH) a partir do individuos coletados em campo como ultimo estadio ninfal (VI) e con historia recente conocida de baixas e altas densidades. As densidades de D. maculipennis nos locais de coleta foram de 0.95 individuos por m super(2) em 2006 e 46 individuos/m super(2) em 2009, representando situacoes de "non-outbreaking" e "outbreaking", respectivamente. A longevidade das femeas adultas em 2006 (67.96 plus or minus 3.2 dias) foi significamente maior (p < 0.05) do que as de 2009 (37.44 plus or minus 1.98 dias). O niimero de oviposic plus or minus aos por femea foi de 3.32 plus or minus 0.44 para 2006 e 1.62 plus or minus 0.26 para 2009. A fecundidade media em 2006 (89.29 plus or minus 11.9 ovos/femea) foi significativamente maior (p < 0.05) do que a das femeas de 2009 (36.27 plus or minus 5.82 ovos/femea). As curvas de fecundidade mostraram que os valores mais elevados ocorreram nas 11 super(a) e 13 super(a) semanas de 2006, e na 6 super(a) semana para aquelas de 2009. Comparando a taxa diaria de oviposicao para altas e baixas densidades, nao apresentaram diferencas significativas (p > 0.05). No entanto, as baixas taxas de fecundidade das femeas em densidades elevadas, se devem, provavelmente a longevidade reduzida.