210 Invasive Stink Bugs and Related Species (Pentatomoidea)
3.4 General Biology
3.4.1 Life History
Many aspects of the biology of B. hilaris have been described by researchers in the Old World (e.g.,
Howard 1906, Gunn 1918, Hutson 1935, Colazza et al. 2004, Deep et al. 2014a, b), particularly from India
(e.g., Rakshpal 1949, Mukerji 1958, Atwal 1959, Batra and Sarup 1962, Azim and Shafee 1986, Singh
and Malik, 1993, Rohilla et al. 2004, Ghosal et al. 2006). Its general life history is similar to most mem-
bers of the Pentatomidae but is rather unique with regard to oviposition and mating behavior (Guarino et
al. 2008, Taylor et al. 2014), particularly when compared with other stink bugs of North America. Both
nymphs and adults exhibit warning coloration and often aggregate on host plants throughout the grow-
ing season (Reed et al. 2013b) (Figure 3.1F). In general, B. hilaris thrives under warm, dry conditions
and may be active throughout the year. Life history parameters are linked closely to temperature and
food source (Manzar et al. 1999, Rohilla et al. 2004) and when optimal abiotic and biotic conditions are
present, this insect can reproduce extremely rapidly with populations often reaching outbreak propor-
tions. Field abundance generally increases with increasing seasonal temperatures (Atwal 1959, Verma
et al. 1993, Tiwari and Saravanan 2009, Abrol and Gupta 2010, Huang et al. 2013), but may be affected
negatively by rain, irrigation, and high relative humidity (Verma et al. 1993, Nagar et al. 2011, Huang
et al. 2013). Both reproduction and feeding injury inflicted upon plants diminishes during temperature
extremes. Deep et al. (2014b) reported the bugs could not survive at temperatures below 16°C, and popu-
lations decreased at temperatures greater than 40°C.
Bagrada hilaris is multivoltine (Batra 1958, Hill 1975, Taylor et al. 2015), although few studies have
evaluated all life stages in the field (see Taylor 2015). Batra and Sarup (1962) speculated from laboratory
rearing in India that the bugs could complete as many as 10–12 generations per year. However, this is not
supported by data collected from the field. In South Africa, Gunn (1918) reported four generations under
caged conditions (host not given) in the field. In India, Pruthi (1946) reported four generations (life stages
not given) on toria (field mustard) before the bugs moved to wild hosts. In New Mexico, Taylor et al.
(2015) reported two generations with evidence for a partial third on mesa pepperwort (Lepidium alyssoi-
des A. Gray), London rocket (Sisymbrium irio L.), and broccoli (Brassica oleracea L.) whose combined
phenologies overlapped and spanned the year. The differences in generations reported between the Old
FIGURE 3.4 New World Distribution of Bagrada hilaris. (Courtesy of Timothy R. Lewis).