Diamondback moth egg susceptibility to rainfall: effects of host plant and oviposition behavior

Abstract

Oviposition patterns of the diamondback moth (DBM), Plutella xylostella L. (Lepidoptera: Plutellidae), differ between common cabbage (Brassica oleracea L. var. capitata) and Chinese cabbage (Brassica rapa L. var. pekinensis) (Brassicaceae) host plants. This study shows that the moth prefers to oviposit on adaxial rather than abaxial leaf surfaces and petioles of both host plants. More eggs were laid in leaf veins than on leaf laminas of both host plants, especially in Chinese cabbage, where 94.6% of eggs were laid in veins. On Chinese cabbage, very few eggs were laid in clusters (≥2 eggs), whereas on common cabbage approximately 30% of eggs were laid in groups of 2 or more eggs. Removal of wax from common cabbage leaves dramatically increased the number of eggs laid singly on the leaf lamina of treated plants, suggesting that leaf waxes affect how eggs are distributed by ovipositing DBM. Eggs were most susceptible to removal by rainfall from the plant surface immediately (<1 h) after oviposition and when close to hatching (>72h old) whereas they were least susceptible 24 h after oviposition. Eggs laid on common cabbage plants were more susceptible to simulated rainfall than eggs laid on Chinese cabbage plants. On common cabbage plants, egg susceptibility to rainfall on different plant parts ranked adaxial leaf surfaces>petioles = abaxial leaf surfaces>stem, but there was no difference in egg susceptibility to rainfall on the various plant parts of Chinese cabbage. Furthermore, on common cabbage plants, eggs laid on both adaxial and abaxial leaf surfaces were afforded significant protection from the effects of rainfall by leaves higher in the plant canopy. On common cabbage plants, oviposition patterns reduce the potential impact of rainfall on eggs, possibly reducing the effect of this important abiotic mortality factor in the field.

Season and weather affect the mortality of immature stages ofAscia monusteorseis(Lepidoptera: Pieridae) caused by natural factors

“…Such an effect was already indicated under controlled conditions (Rahman et al . 2019), and we confirmed this in the field. In addition, the larva was indirectly affected by rainfall, since sand covers basal leaves after intense rain and may cause wear on larva mandibles (Lopresti et al .…”

Performance of Danaini larvae is affected by both exotic host plants and abiotic conditions

“…Wind intensity and precipitation, which differ in the localities where the experiments were conducted, were not recorded. Some studies point out that rainfall is one of the major factors causing mortality in eggs and newly hatched larvae (e.g., Caldas, 1992; Harcourt, 1966; Rahman et al., 2019). In this context, larval protection against natural enemies also prevents the larvae falling off the host plant.…”

“…Additionally, microclimate may be critical for the survival of early‐instar Lepidoptera that are small in size and limited in movement (Zalucki et al., 2002). Some studies have reported that wind and rainfall are among the major factors causing mortality in eggs (Kyi et al., 1991; Rahman et al., 2019) and newly hatched larvae (Caldas, 1992; Harcourt, 1966; Kyi et al., 1991), and light intensity can affect larval performance through its effects on the primary and secondary metabolism of host plants (Manuwoto & Scriber, 1985). Therefore, in field conditions a combination of factors may affect the interaction between herbivores and their host plants.…”

Effects of temperature, age and stage on testis development in diamondback moth, Plutella xylostella (L.) (Lepidoptera: Plutellidae)

“…The diamondback moth (DBM), Plutella xylostella (L.) (Lepidoptera: Plutellidae) is one of the most serious pests of cruciferous vegetables, and among the most widely distributed. of all lepidopterans worldwide (Odhiambo et al, 2010;Silva & Furlong, 2012;Wei et al, 2013;Fu et al, 2014;Ahmad et al, 2018;Rahman et al, 2019). High pest densities in crops result mainly from insecticide resistance (Liu et al, 1981(Liu et al, , 1982Hama, 1987;Adachi & Fujitomi, 1995;Odhiambo et al, 2010;Li et al, 2016) and pest resurgence due.…”