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Oviposition Strategy (oviposition + strategy)
Selected AbstractsOviposition strategies employed by the western spruce budworm: tests of predictions from the phylogenetic constraints hypothesisAGRICULTURAL AND FOREST ENTOMOLOGY, Issue 1 2003Kathryn J. Leyva Abstract 1,Predictions from the Phylogenetic Constraints Hypothesis were tested for the first time in an eruptive forest Lepidopteran species, the western spruce budworm. 2,In previous work, we established that western spruce budworm females exhibit oviposition preferences with regard to tree age, tree vigour and host species. However, there was no evidence to support a link between oviposition preference and larval performance, which supports the Phylogenetic Constraints Hypothesis. 3,Our preference data led us to test whether female budworms use oviposition strategies to select the sites where they lay their egg masses. Our experiments were designed to make direct comparisons between latent and eruptive insect herbivores with respect to two oviposition behaviours: egg retention and avoidance of conspecifics. This type of research has not previously been conducted on any eruptive forest Lepidopteran. 4,Female budworms retained eggs instead of laying them on less preferred hosts in two of three experiments, but the percentage of eggs they retained was significantly less compared to latent insect herbivores. 5,In addition, female budworms actively avoided oviposition in areas with the highest density of conspecific egg masses, but they laid egg masses in all the other locations provided. This contrasts with the pattern seen in latent insect herbivores, which consistently avoid laying their eggs near any sites already used by conspecifics. 6,Our research indicates that there are extreme differences between latent and eruptive insect herbivores with respect to egg retention and avoidance of conspecifics, thus supporting the Phylogenetic Constraints Hypothesis. [source] Avoidance responses of an aphidophagous ladybird, Adalia bipunctata, to aphid-tending antsECOLOGICAL ENTOMOLOGY, Issue 4 2008THOMAS H. OLIVER Abstract 1.,Insect predators often aggregrate to patches of high prey density and use prey chemicals as cues for oviposition. If prey have mutualistic guardians such as ants, however, then these patches may be less suitable for predators. 2.,Ants often tend aphids and defend them against predators such as ladybirds. Here, we show that ants can reduce ladybird performance by destroying eggs and physically attacking larvae and adults. 3.,Unless ladybirds are able to defend against ant attacks they are likely to have adaptations to avoid ants. We show that Adalia bipunctata ladybirds not only move away from patches with Lasius niger ants, but also avoid laying eggs in these patches. Furthermore, ladybirds not only respond to ant presence, but also detect ant semiochemicals and alter oviposition strategy accordingly. 4.,Ant semiochemicals may signal the extent of ant territories allowing aphid predators to effectively navigate a mosaic landscape of sub-optimal patches in search of less well-defended prey. Such avoidance probably benefits both ants and ladybirds, and the semiochemicals could be regarded as a means of cooperative communication between enemies. 5.,Overall, ladybirds respond to a wide range of positive and negative oviposition cues that may trade-off with each other and internal motivation to determine the overall oviposition strategy. [source] Inconsistent use of host plants by the Alaskan swallowtail butterfly: adult preference experiments suggest labile oviposition strategyECOLOGICAL ENTOMOLOGY, Issue 2 2007SHANNON M. MURPHY Abstract 1.,The Alaskan swallowtail butterfly (Papilio machaon aliaska) uses three unrelated plant species as hosts: Cnidium cnidiifolium (Apiaceae), Artemisia arctica (Asteraceae), and Petasites frigidus (Asteraceae). The research presented here investigated whether there are any consistent patterns in host choice by P. m. aliaska females. 2.,The first two experiments were designed to test if P. m. aliaska host preference is constant or if it changes from day to day. If host preference is labile, the experiments were designed to also test whether a female's diet breadth narrows or expands over time. 3.,The third experiment tested the host preferences of female offspring from several wild-caught P. m. aliaska females. If P. m. aliaska individuals are specialised in their host use, then all of the offspring from a single female would likely prefer the same host-plant species. This experiment was also designed to test the Hopkins' host selection principle; does the food plant on which a female is reared as a larva influence her future choices when she is searching for host plants for her own offspring? 4.,The results from all of these experiments indicate that P. m. aliaska females vary greatly in their oviposition behaviour and in their preferences for the three host plants. Most populations appear to consist of generalists with labile oviposition behaviour. There is no evidence to support the Hopkins' host selection principle. 5.,It is suggested that the generalised selection of host plants by P. m. aliaska females may be a ,bet-hedging' strategy and that this strategy may maximise reproductive fitness in an unpredictable environment. [source] Trade-off in oviposition strategy: choosing poor quality host plants reduces mortality from natural enemies for a salt marsh planthopperECOLOGICAL ENTOMOLOGY, Issue 3 2006DANIEL C. MOON Abstract 1.,Both host plant nutrition and mortality from natural enemies have been predicted to significantly impact host plant selection and oviposition behaviour of phytophagous insects. It is unclear, however, if oviposition decisions maximise fitness. 2.,This study examined whether the salt marsh planthopper Pissonotus quadripustulatus prefers higher quality host plants for oviposition, and if oviposition decisions are made so as to minimise mortality at the egg stage. 3.,A controlled laboratory experiment and 4 years of field data were used to assess the rates of planthopper oviposition on higher quality ,green' and lower quality ,woody' stems of the host plant Borrichia frutescens. The numbers and percentages of healthy eggs and eggs that were killed by parasitoids or the host plant were recorded. 4.,In all years, including the laboratory experiment, Pissonotus planthoppers laid more eggs on lower quality woody stems than on higher quality green stems. While host plant related egg mortality was higher in woody stems, the percentage of eggs parasitised was much greater in green stems. This resulted in a lower total mortality of eggs on woody stems. 5.,The results of this study demonstrate that, although Pissonotus prefers lower quality host plants for oviposition, this actually increases fitness. These data seem to support the enemy free space hypothesis, and suggest that for phytophagous insects that experience the majority of mortality in the egg stage, oviposition choices may be made such that mortality is minimised. [source] Egg performance on an egg-carrying bug.OIKOS, Issue 2 2001Experiments in the field Selection of oviposition sites has direct influence on female fitness. Differences in offspring survival among sites should favour females to select oviposition sites with the highest survival. Golden egg bug females (Phyllomorpha laciniata; Coreidae, Heteroptera) use conspecifics as oviposition substrates. Most eggs are laid on the back of the bug but they can be found on all body parts. Females never carry their own eggs, and males commonly carry eggs received without copulation with the donor. We examined differences in egg survival relative to paternity to the egg, host sex and body size and attachment of an egg on a host's body in the field. We also studied which bugs received eggs. Egg loss was surprisingly common: 30,80% of recaptured individuals lost eggs during a six-day period. Unexpectedly, host's paternity to the eggs did not affect egg survival. Also, egg loss did not differ among hosts in respect to other parameters studied. Males received more eggs than females, but survival of the eggs was not better on a male's back than on a female's back. Since egg loss is common in the golden egg bug, we suggest that female oviposition strategy to lay eggs on conspecifics is not perfect. This is due to active behaviour of potential hosts (for example, rejected oviposition attempts) or lack of suitable oviposition substrates (conspecifics) in the field. Since eggs do not survive unless carried, females may be acting opportunistically, doing the best job possible by laying eggs on available conspecifics. [source] | ||||||||||