A model of the flight phenology of the beet armyworm (Lepidoptera: Noctuidae) in central California

Abstract

A model of the flight phenology of the beet annywonn (Spodoptera exigua Hubner) was constructed using a combination of laboratory and field experimentation. The model incorporates the following relationships: 1) developmental rates of immature stages as linear functions of temperature, 2) age-dependent immature mortality rates, 3) age-dependent oviposition rates, 4) age and temperature-dependent adult mortality rates, and 5) adult flight activity as a function of temperature.The model was used to examine beet armyworm flight phenology by simulating light trap catches. An extensive black light trapping program was conducted at five locations in three climatic regions within central California to provide a total of six data sets for these tests. Results of the simulations were generally favorable. When initialized with early season light trap data, the model was able to predict the patterns subsequently observed for the locations in the San Joaquin and Sacramento valleys, indicating that a good understanding of beet armyworm flight phenology in these regions was incorporated. The model did not reproduce observed patterns of flights in the cool Salinas Valley, however, indicating that one or more of the relationships in the model was not valid under the conditions of this region.

A new multistage dynamic model for biological control exemplified by the host–parasitoid system Spodoptera exigua–Chelonus oculator

“…The results obtained for the developmental stages of the host species, S. exigua (in days), are similar to those found by other authors (Butler 1966;Cayrol 1972;Fye and McAda 1972;Hogg and Gutierrez 1980;Sannino et al 1986;Tisdale and Sappington 2001;Elvira et al 2010). The slight differences might be attributable to the different food provided to larvae (Awmack and Leather 2002;Azidah and Sofian-Azirun 2006) or different origins of populations (Pashley 1986).…”

“…The values threshold temperatures found for eggs (13.9°C) are similar to those cited by El-Refai and Degheele (1988), but they are somewhat higher than those indicated by Cayrol (1972) andMcNally (1983). In turn, for small larvae, temperatures (12.5°C) are similar to those quoted by other authors (Cayrol 1972;Hogg and Gutierrez 1980;Ali and Gaylor 1992). The threshold temperature for the pupal stage (8.3°C) is quite different from those mentioned by El-Refai and Degheele (1988) and Ali and Gaylor (1992) for this species.…”

Antennal Resolution of Pulsed Pheromone Plumes in Three Moth Species

“…Attraction to synthetic pheromone occurs at temperatures from 12 to 30°C (Lingren et al, 1989), although catch is reduced below 18°C (Adams et al, 1995). For S. exigua, a minimum flight temperature of 15.6°C has been reported (Hogg and Gutierrez, 1980). The three ambient temperatures tested in our trials encompass a range that our test species would encounter in the field.…”

Impact of UV radiation on activity of linear furanocoumarins andBacillus thuringiensis var.Kurstaki againstSpodoptera exigua: Implications for tritrophic interactions

“…Nearly all larvae (95.5%) on control diets that were not exposed to UV light survived to pupate (Figure 2A). Because first to third instars of S. exigua prefer to feed on foliage rather than petioles in celery, and the larvae are positively phototactic in the first three stadia (Griswold and Trumble, 1985), the tow survival observed in the field (Hogg and Gutierrez, 1980) may be explained in part by the toxic effects triggered by UV light. However, in the aforementioned study all of the phototaxis experiments with early instar larvae were conducted at a single temperature, and larval movements associated with potential thermoregulating activities were not investigated.…”

“…This increase in developmental time during the larval stage could have substantial implications for the population dynamics of S. exigua in the celery system. Because the majority of the mortality observed in the field occurs in the larval stage (Hogg and Gutierrez, 1980), increased time in this susceptible stage, as opposed to the more protected egg and underground pupal stages (Oatman and Platner, 1972;Tingle et al, 1978), may allow additional opportunity for parasites and predators to reduce populations. Such increases (or decreases) in longevity of larvae previously have been implicated as critical factors in population regulation for other insects (Cardona and Oatman, 1971;Tremble et al, 1987).…”