Population Dynamics and “Outbreaks” of Diamondback Moth (Lepidoptera: Plutellidae) in Guangdong Province, China: Climate or Failure of Management?

Abstract

Diamondback moth, Plutella xylostella (L.) (Lepidoptera: Plutellidae), became the major pest of Brassica vegetable production in Guangdong, a province in southeastern China, in the late 1980s and has continued to challenge growers, particularly during the spring and autumn. Control has relied on insecticides and, as has happened in other parts of the world, resistance to these has evolved and subsequent field control failures have occurred. We review and summarize the history of diamondback moth management in Guangdong. We show that the geographic distribution of the pest in China is well described by a simple climate niche model. Our model predicts the seasonal phenology and some of the variation in abundance among years in Guangdong. Discrepancies may reflect migration and insecticide use at a landscape level. The scale of the pest problem experienced varies with management practices. Local production breaks, and strict post harvest hygiene are associated with lower pest pressure on large-scale production units. As more and more insecticides become ineffective the need to implement an insecticide resistance management strategy, as well as basic integrated pest management practices, will become more pressing. The potential use and development of a better forecasting system for diamondback moth that will assist these developments is outlined.

Biology, Ecology, and Management of the Diamondback Moth in China

“…On Hainan Island, in the far south of China, the first DBM population peaks occur in February-March (94,135), in southern and southeastern mainland China the first DBM population peaks occur in MarchApril (53,93), in central China they occur in April-May (22), but in north China they occur in May-June (120,127), and they occur later still ( June-July) in northeast China (27,136). These dynamics reflect the local conditions and their suitability for DBM growth and development (51), but north of the region where overwintering is possible (Figure 3), these dynamics also likely reflect northern migrations and subsequent local population growth. As elsewhere in the world (26,84) (22)], crop type (9,47,104,123), the occurrence of natural enemies (25), and the presence of cruciferous weeds (22).…”

“…The first record of insecticide resistance in DBM in China dates back to 1986, when Wu & Gu (103) reported low levels of resistance to the pyrethroid fenvalerate in Shanghai. Since then, DBM resistance to products from all major classes of insecticides has been reported ( Table 1), and the rapid development of insecticide resistance has thwarted insecticide-based management programs (51,121). In a wide-ranging study conducted in 2007, You & Wei (121) ranked from highest to lowest the major insecticide groups in terms of DBM resistance: pyrethroids, carbamates, organophosphates, Bt, and insect growth regulators.…”

“…In recent years, genetic investigations have shown that PlxyGV contains the highly conserved gene pp31 (96) and that it is closely homologous to Autographa californica multicapsid nucleopolyhedrovirus (AcMNPV) (16). Formulations of Bt were introduced to control DBM from 1989 to 1994 and they have been widely used in DBM management since 1995 (17,20,51). The development of resistance to Bt in a field population of DBM in Hawaii, the first example of an insect developing field resistance to foliar applications of Bt, is well known and highly cited (83).…”

Identifying critical research gaps that limit control options for invertebrate pests in Australian grain production systems

“…These types of studies generally focus on factors that keep pest populations low or below a theoretical threshold of density, and they do not address what occurs after high densities have been reached. But we do not yet have a predictive model for outbreaks of P. xylostella that can be used by growers to predict risk across Australian grain crops; however, Australian researchers have collaborated in developing these tools in China (Li et al 2012;Li et al 2016). We have included ticks in Figure 1 to show parts of the pyramid the 59 articles found in our review relate to (also Zalucki et al 2015).…”

Determinants of parasitoid assemblages of the diamondback moth, Plutella xylostella, in cabbage farmer fields in Senegal

“…In addition, it dramatically impacts biodiversity and related ecosystem services such as pest regulation provided by natural enemies Bommarco et al, 2011;Ayalew, 2011). The need for more insecticides often leads to increases in production costs and field-evolved resistance in pest populations (Li et al, 2012;reviewed in Furlong et al, 2013).…”