Galendromus occidentalis (Acari: Phytoseiidae) life table parameters on Oligonychus yothersi (Acari: Tetranychidae) colonies and its behavior to odors of mites, avocado shoots and synthetic compounds

Ricardo Ceballos1, Cristóbal Campos1, and Tommy Rioja2*
The red mite, Oligonychus yothersi (McGregor) (Acari: Tetranychidae), is a serious pest of avocado (Persea americana Mill.) 'Hass' in Chile. Micro-coleopterans predators are observed in avocado orchards during outbreaks of O. yothersi, which are attracted by herbivore-induced plant volatiles (HIPVs). However, the damage to plants persists and new predators are needed. Due to its effectiveness and adaptability to dry climates, the western predatory mite Galendromus occidentalis (Nesbitt) (Acari: Phytoseiidae) has been adopted as a biological control agent on many crops. Ours objectives were to study the biological parameters of G. occidentalis preying on O. yothersi in controlled conditions and its attraction to volatile compounds from avocado shoots, live preys and four synthetic doses of methyl salicylate (MeSA) and ocimene using a Y-tube olfactometer. We found a net reproductive rate (R0) 34.41 offspring female-1, intrinsic rate of increase (rm) 0.19 females female-1 d-1, finite rate of increase (λ) 1.21 females female-1, mean generation time (T) 18.45 d, and doubling time (DT) of 3.61 d. Immature phytoseiids took 7.32 d to reach adulthood with 90% survival. Female longevity and fecundity were 36.27 d, and 59 eggs female-1, respectively. Phytoseiids show no attraction to O. yothersi volatiles or volatiles of O. yothersi-infested avocado shoots. Nevertheless, females showed a preference for synthetic MeSA and ocimene at 100 μg mL-1. Our findings indicate that O. yothersi is a potential diet to rear G. occidentalis, and MeSA and ocimene could be used in lures to manipulate its behavior in avocado orchards.
Keywords: Avocado shoot volatiles, behavioral response, life table parameters, red mite, western predatory mite.
1Instituto de Investigaciones Agropecuarias, INIA Quilamapu, Av. Vicente Méndez 515, Chillán, Chile.
2Universidad Arturo Prat, Facultad de Recursos Naturales Renovables, Campus Huayquique, Casilla 121, Iquique, Chile.
*Corresponding author (trioja@unap.cl).