Identification of the Key Weather Factors Affecting Overwintering Success of Apolygus lucorum Eggs in Dead Host Tree Branches

Abstract

Understanding the effects of weather on insect population dynamics is crucial to simulate and forecast pest outbreaks, which is becoming increasingly important with the effects of climate change. The mirid bug Apolygus lucorum is an important pest on cotton, fruit trees and other crops in China, and primarily lays its eggs on dead parts of tree branches in the fall for subsequent overwintering. As such, the eggs that hatch the following spring are most strongly affected by ambient weather factors, rather than by host plant biology. In this study, we investigated the effects of three major weather factors: temperature, relative humidity and rainfall, on the hatching rate of A. lucorum eggs overwintering on dead branches of Chinese date tree (Ziziphus jujuba). Under laboratory conditions, rainfall (simulated via soaking) was necessary for the hatching of overwintering A. lucorum eggs. In the absence of rainfall (unsoaked branches), very few nymphs successfully emerged under any of the tested combinations of temperature and relative humidity. In contrast, following simulated rainfall, the hatching rate of the overwintering eggs increased dramatically. Hatching rate and developmental rate were positively correlated with relative humidity and temperature, respectively. Under field conditions, the abundance of nymphs derived from overwintering eggs was positively correlated with rainfall amount during the spring seasons of 2009–2013, while the same was not true for temperature and relative humidity. Overall, our findings indicate that rainfall is the most important factor affecting the hatching rate of overwintering A. lucorum eggs on dead plant parts and nymph population levels during the spring season. It provides the basic information for precisely forecasting the emergence of A. lucorum and subsequently timely managing its population in spring, which will make it possible to regional control of this insect pest widely occurring in multiple crops in summer.

Occurrence and Distribution of Apolygus lucorum on Weed Hosts and Tea Plants in Tea Plantation Ecosystems

“…In April, the overwintering eggs of A. lucorum begin to hatch and the newly emerged nymphs feed on tender buds of tea plants. During the initial period of infestation, the highly mobile mirid bug nymphs can induce significant cryptic damage which is difficult to be detected [16]. Therefore, mirid bugs, mainly A. lucorum , can seriously damage tea plants in early spring, and cause estimated tea yield losses ranging from 30% to 40% of the total tea tender shoots [4].…”

“…Apolygus lucorum adults also prefer to deposit eggs for overwintering in the dead parts of branches of fruit trees such as the Chinese date Ziziphus jujuba Mill. and the grape Vitis vinifera L. where the eggs are less likely to be affected by plant growth, which makes weather conditions the most important factor evoking egg hatching [7,16]. Overwintering eggs of A. lucorum begin to hatch in April, and the newly emerged nymphs feed on the tender leaves, buds and flowers and cause serious damage.…”

“…Overwintering eggs of A. lucorum begin to hatch in April, and the newly emerged nymphs feed on the tender leaves, buds and flowers and cause serious damage. Weather conditions, especially rainfall, were the most important factor evoking overwintering eggs of A. lucorum hatching in the dead parts of tree hosts [3,16]. Therefore, during the spring season, rainfall can strongly affect the population densities of A. lucorum in agroecological systems which determine the degree of plant damage.…”

Maize fields are a potential sink for an outbreaking mirid bug pest in Chinese Bt-cotton agricultural landscapes

“…We likely missed the arrival and population build-up of A. lucorum in cotton fields from spring hosts (Pan et al, 2014;2015), due to a first sampling date in early July. However, we detected the first adults settling in, and we observed juveniles only later in maize fields.…”

Climate factors associated with the population dynamics of Sitodiplosis mosellana (Diptera: Cecidomyiidae) in central China

“…The geographical distribution and phenology of many major crop insect pest species have been affected by global climate change. For example, high temperatures increase the hatch rate and development of overwintering Apolygus lucorum (Meyer-Dür) eggs 2 . A temperature increase of 2 °C can add two generations of Plutella xylostella (L.) and five generations of Myzus persicae (Sulzer) per year in a large population 3,4 .…”