Population dynamics and seasonal variation in the embryonic dormancy of Pilophorus gallicus (Hemiptera: Miridae): ‘don't put all your eggs in one basket'

Abstract

AbstractPilophorus gallicus Remane is a generalist predator in southern European pear orchards. Nymphs and adults are present in orchards from March to November; their winter absence suggests either migration to other hosts or embryonic dormancy on pear trees to overcome the adverse period. In addition, it has been hypothesized that aestivation takes place to cope with extreme summer conditions. The present study aimed to investigate the reproductive strategy of P. gallicus to overcome unfavourable periods. Accordingly, (i) its population dynamics were followed during several years and (ii) females were sampled in three different seasons to study the condition (diapausing or nondiapausing) of the laying. The results obtained show that nymphs were always the first mobile instar to show up in pear orchards and the presence of adults was delayed, indicating egg overwintering. Nondiapausing eggs prevailed in spring and summer, whereas the autumn eggs were mainly diapausing. Aestivation was rejected. Worthy of note are: (i) the presence of diapausing eggs under favourable conditions and (ii) the existence of females laying both diapausing and nondiapausing eggs; thus, ‘not laying all the eggs in one basket’. The reproductive strategy of P. gallicus is considered as bet‐hedging for the short‐ and long‐term survival of the species.