Species ratio, spring emergence, population dynamics and damage of plum sawflies Hoplocampa minuta and H. flava in plum orchard

Abstract

An investigation of black plum sawfly (Hoplocampa minuta Christ, 1791) and yellow plum sawfly (Hoplocampa flava Linnaeus, 1761) populations using white sticky traps Rebell ® bianco was carried out in a plum orchard of Institute of Horticulture of Lithuanian Research Centre for Agriculture and Forestry from 2010 to 2012. A possibility to predict spring emergence of H. minuta and H. flava using temperature sum method, species ratio, main population parameters and relation between trap catches and infestation levels were investigated. H. minuta appeared to be more dominant in the complex of two plum sawfly species during the study overall, building up to 62% of individuals in comparison to H. flava and, considering various population parameters (emergence and flight dynamics, population density, sex ratio) being more significant contributor to fruit damage. Population density and flight dynamics were driving factors in determining potential damage to crop. Coincidence between mass flight and flowering periods was one of the major factors influencing fruit damage caused by plum sawflies. When mass flight coincided with flowering phase, vulnerable to sawfly attack of plum cv. 'Stanley', a high damage level of 27.8% was observed. When mass flight was strongly shifted towards the end of flowering, a relatively low damage of 7.0% was recorded. Based on the results of the correlation analysis, trap catch data could be reliably used to predict the magnitude of fruit damage level only when mass flight coincides with susceptible flowering phase. Further studies are needed to establish reliable damage thresholds for different plum cultivars. Temperature sum model to predict emergence of first plum sawfly adults was proposed. The model was based on soil temperature at 10 cm depth and two different starting dates to begin calculation. Temperature sums of 86 and 84 degree-days were calculated. Provisionary date at a temperature sum of 60 degree-days is proposed for trap placement in the orchards.

A review of West Palaearctic Hoplocampa species, focussing on Sweden (Hymenoptera, Tenthredinidae)

“…The fully-fed larvae spin parchment-like cocoons in the soil, in which they hibernate as quiescent larvae, until pupating shortly before emergence. Prolonged diapause, of up to three winters, has been reported by several authors for minuta and testudinea (Hadzistevic 1959, Tamosiunas et al 2014. This is presumed to be an adaptation against the risk to a population's survival in years when very few or no fruits develop, e.g.…”

“…the "pests", the sex-ratio has generally been observed to be close to 1:1, with a slight bias towards females (e.g. Tamosiunas et al 2014). Among the West Palaearctic species, brevis is clearly exceptional in being normally (or entirely?)…”

Biodiversity and population dynamics of litter-dwelling cockroaches inBelezma National Park (Algeria)

“…A good indicator of survival, the distribution of age classes, and the dynamics of insect populations (Sadoudi et al, 2011;Kraft and Vannouhuys, 2013), the sex ratio allows estimation and understanding of the effects of environmental conditions or the structure of the habitat during various stages of life history (Suarez-Coya, 2013). According to Tamošiūnas et al (2014), the determination of the sex ratio of an insect population is crucial to assess the conditions and status of this population, seasonal emergences, the number of generations, and population dynamics.…”

Monitoring of three Hoplocampa sawfly species in plum orchards

“…Paja c Zivkovi c et al ( 2020) reported that the first H. minuta and H. flava adults flew at end of March in Croatia, Zagreb in 2019. However, in Lithuania, the white sticky traps caught the first H. minuta and H. flava adults one month later presumably due to the lower annual temperatures between 2010-2012(Tamo si unas et al, 2014. In terms of the first adult catch in the same year (Pom az 2015, Fig.…”

“…The most important aim of integrated pest management (IPM) is to spatiotemporally predict the existence of pests to determine efficient insecticide delivery timing (Lefebvre et al, 2015). So far only the chromotropic white sticky trap is available to monitor the flight activity of these two sawfly species in plum orchards (Blaisinger, 1975;Tamo si unas et al, 2014). Although H. minuta and H. flava are present in Hungarian plum orchards, little is known about their populations' size, flight dynamics and distribution of the different species.…”