Development and reproductive potential of diamondback moth Plutella xylostella (Lepidoptera: Plutellidae) on cultivated and wild crucifer species in Kenya

Abstract

The development, survival and reproductive potential of diamondback moth Plutella xylostella (Linnaeus) were studied at 25^1 8C in the laboratory in response to two cultivated Brassica oleracea cultivars (cabbage B. oleracea var. capitata and kale B. oleracea var. acephala) and four wild crucifer species Erucastrum arabicum, Raphanus raphanistrum, Rorippa nudiuscula and Rorippa micrantha. Rorippa micrantha was the most preferred species in oviposition choice tests, while cabbage and kale were least preferred. First instar larval mining period differed significantly between plant species with the longest period recorded on cabbage (3.0 days) and the shortest on R. micrantha (0.4 days). Pupal weight was significantly lower for larvae reared on R. nudiuscula, while those of the others were similar. The developmental period from first instar to adult was the shortest on R. micrantha (14.1 days) and the longest on R. raphanistrum (15.6 days). Survival to adult was not statistically affected by the host plant species. Adult longevity ranged between 18.2 days on R. raphanistrum and 24.7 days on R. nudiuscula. The females were significantly heavier than the males on all plant species. However, males lived longer than females. Moths reared on R. nudiuscula recorded the highest fecundity (326 eggs), while moths reared on cabbage had the lowest fecundity (262 eggs). Kale and R. nudiuscula recorded the longest generation time of 31.7 days, while E. arabicum had the highest net reproductive rate (126.4 eggs per day). The highest intrinsic rate of increase was calculated for R. micrantha (0.179) and the lowest for kale (0.147). This study shows the suitability of wild crucifers as hosts for P. xylostella and indicates that they may play a major role as reservoir for the pest during the absence of cultivated host plants.

Preference‒performance linkage in the diamondback moth,Plutella xylostella, and implications for its management

“…The results obtained in this study differ from those reported by Kahuthia-Gathu et al (2008) about the preference of P. xylostella for two cultivated and four wild brassicas in laboratory. These authors observed a significant oviposition preference for wild species.…”

“…In our study, we used excised leaves of the host plants in the preference tests; it is questionable whether this affected the ability of females to discriminate hosts and resulted in the observed lack of preference. Studies with P. xylostella and other lepidopteran species have shown that females are able to discriminate host plants using excised leaves and show a hierarchy of preference similar to the one obtained with the entire plant ( Greenberg et al 2002 , Kahuthia-Gathu et al 2008 ). On the other hand, female preference for some species of wild brassicas may be influenced by emission of volatiles when the host plant is attacked by herbivores or is otherwise injured ( Zhang et al 2008 ).…”

“…Nevertheless, P. xylostella completed development from egg to adult on wild radish and turnipweed, suggesting that these wild brassicas are adequate alternative hosts. Previous studies also recorded an extension in development time and lower survival rate and fecundity of P. xylostella that fed on wild compared with cultivated brassicas ( Ayalew et al 2006 , Kahuthia-Gathu et al 2008 , Saeed et al 2010 ), but the consequences of these results on host choice by females was not assessed.…”

Population genetic structure of two primary parasitoids of Spodoptera frugiperda (Lepidoptera), Chelonus insularis and Campoletis sonorensis (Hymenoptera): to what extent is the host plant important?

“…Although studies on the effects of specific plant chemicals on parasitoid fitness are limited, it is generally concluded that plant defence chemicals mostly have a negative impact on natural enemy traits such as development time, survivorship and body size (Thurston & Fox 1972;Campbell & Duffey 1979, 1981Barbosa et al 1986;El-Heneidy et al 1988;Barbosa et al 1991;Thaler 1999Thaler , 2002Dicke 2006). These effects can strongly vary among plant species (Smith 1957;Altahtawy et al 1976;Bhatt & Singh 1989;Senrayan & Annadurai 1991;Werren et al 1992;Fox et al 1996;Kruse & Raffa 1997;Eben et al 2000;Harvey et al 2003;Zvereva & Rank 2003;Lu et al 2004) and even among cultivars of a same plant species (Kauffman & Flanders 1985;Orr & Boethel 1985;Hare & Luck 1991;Reed et al 1991;Rogers & Sullivan 1991;Riggin et al 1992;Stark et al 1992;Dosdall & Ulmer 2004;Kahuthia-Gathu et al 2008).…”

Effect of Indian mustard on feeding, larval survival and development of Plutella xylostella at constant temperatures

“…(2005) have compared the larval development of P. xylostella on cabbage cultivars and reported that the larvae of P. xylostella develop more rapidly on Green Coronet cabbage than the Savoy King variety. Development period of larvae of P. xylostella is shorter on cabbage than the larvae reared on kale (Kahuthia et al . 2008).…”