Effects of epilimonol and starvation on feeding and oviposition by Leptinotarsa decemlineata

Abstract

Epilimonol, a limonin derivative, was tested in short and long term feeding bioassays against Colorado potato beetles, Leptinotarsa decemlineata (Say), for feeding reduction and ovipositional suppression. At dosages of 10 to 30 #g/cm 2, epilimonol reduced feeding by 42 ~ to 65 ~o in short term no-choice assays. However, beetles did not strongly select untreated potato leaf discs over epilimonol-treated (10 #g/cm 2) ones in short term choice assays. In long term tests, epilimonol at 10/~g/cm 2 remained effective against feeding, caused mortality, and suppressed oviposition. Starvation (> 16 hours/day) also caused mortality and suppressed oviposition.

Citrus limonoid effects on Colorado potato beetle larval survival and development

“…Depressed rates of development and consumption among late instars and decreased consumption and oviposition among adult Colorado potato beetle have been shown to result from treatment with limonin and other citrus limonoids (Liu et al, 1989(Liu et al, , 1990Murray et al, 1995). Our findings of a negative log-linear response in survival and negative linear responses in larval body weight and development among early instar Colorado potato beetle associated with increasing con- centration are consistent with those earlier findings for late instars and adults.…”

“…One group of allelochemicals with good potential in this regard are the citrus limonoids. These compounds can be easily extracted in large quantities (Klocke & Kubo, 1982) and have been shown to be effective as insect antifeedants (Klocke & Kubo, 1982;Alford et al, 1987;Liu et al, 1989Liu et al, , 1990Mendel et al, 1991aMendel et al, , 1991bMendel et al, , 1993. They are also disruptants of insect growth (Liu et al, 1989), development (Alford & Bentley, 1986;Liu et al, 1990) and reproduction (Liu et al, 1989;Murray et al, 1995).…”

Temporary stay at various environmental humidities affects attachment ability of Colorado potato beetles Leptinotarsa decemlineata (Coleoptera, Chrysomelidae)

“…In green dock leaf beetles Gastrophysa viridula De Geer, males feed about 68 min per day taking up about 53 mm 2 of leaf area, whereas females feed on 419 mm 2 leaf area within 472 min per day. Thus, effects of hunger and thirst can be obviously neglected in our experiments, supported by previous studies, in which L. decemlineata showed starvation induced stress only after more than 24 h (Liu, Alford & Bentley, 1989; Furlong & Groden, 2003).…”

A study on mode of antifeedant effects of epilimonol against Leptinotarsa decemlineata

“…The 10 #g dosage injected was approximately the amount of epilimonol ingested by an adult beetle in about ten hours feeding on leaf discs coated with epilimonol at 30 #g/cm 2 (based on feeding rate of 3.27 mg/adult/12 h (Table 1) and an average weight of 8 mg of a 1 cm z potato leaf disc). Epilimonol at 30 #g/cm 2 reduced feeding 65 To by L. decemlineata adults in the short term feeding assays (Liu et al, 1989). In this respect, the sudden appearance of 10 #g epilimonol into the haemolymph by injection is a high dosage, and if feeding reductions demonstrated in feeding assays were caused by toxic effects of ingested epilimonol, we should have detected significant feeding reduction through injection 9 However, only a 21~o feeding reduction was achieved.…”

“…In S. exempta, S. littoralis and Heliothis virescens, the sensitivity of certain receptors increases over the last three instars (Blaney et al, 1986). In L. decemlineata, a considerable differences between 4th instars and adults was found in feeding reduction caused by epilimonol treatments (Bentley et aL, 1988;Liu et aL, 1989).…”