鲁北沿海蝗区蝗虫天敌蜘蛛类群发生规律初探

笔者于1992～2003 a对鲁北沿海蝗区的蝗虫天敌-蜘蛛类群,进行了大田调查与定点系统调查.鲁北沿海蝗区蜘蛛隶属6科9属14种.明确了蜘蛛类群的消长动态,并对优势种星豹蛛Pardosa astrigera 进行了系统观察,明确了其生活史和习性.并提出了保护利用措施.     

Macrolophus caliginosus: Functional response to whiteflies and preference and switching capacity between whiteflies and spider mites

Laboratory experiments were performed with adult female Macrolophus caliginosus Wagner (Heteroptera: Miridae) at 22ºC on bean plants to determine the functional response towards whiteflies, as well as the preference and switching capacity between the two prey species: whiteflies and spider mites. Predation of females presented with first instars of Trialeurodes vaporariorum Westwood (Homoptera: Aleyrodidae) was of a Type III functional response. The observed maximum predation was approximately 75 first instars at high prey densities within a 24-h period. The preference of M. caliginosus females between eggs of T. vaporariorum and Tetranychus urticaeKoch (Acarina: Tetranychidae) changed with the ratio of offered prey. The preference for T. vaporariorum eggs increased non-linearly with increasing proportions of this prey type. The average maximum predation of whitefly and spider mite eggs were approximately 166 and 111 eggs per day, respectively, at the highest ratio of the two preys. The proportion of M. caliginosus females found on the test plants at the end of the experiment increased with prey density suggesting that this mirid spends more time in areas with high prey density. Macrolophus caliginosus females are voracious predators of eggs and first instars of T. vaporariorum as well as of spider mite eggs and may thus be a valuable addition to existing methods of biological control of T. vaporariorum and T. urticae.     

Retention, capture and consumption of experimental prey by orb-web weaving spiders in coffee plantations of Southern Mexico

This study focuses on the predatory capacity of four sympatric species of web- building spiders that inhabit coffee plantations in Southern Mexico: Gasteracantha cancriformis, Cyclosa caroli, and the morphologically similar species pair Leucauge mariana and L. venusta which were considered as one species group. The retention capabilities of the webs of these species and the incidence of prey capture and consumption were measured using eight types of insect prey belonging to the orders Coleoptera (1 species), Hymenoptera (3), Diptera (2) Lepidoptera (1) and Homoptera (1). The different characteristics of each prey such as body weight, body size, defensive behaviour, etc., were recorded. The incidence of prey retention, capture and consumption were significantly higher in G. cancriformis than in any of the other species. The lowest rates of retention, capture and consumption were observed in C. caroli, while L. mariana/venusta were intermediate in their predatory capabilities. Significant negative correlations between prey size and percent consumption were detected in L. mariana/venusta and in G. cancriformis; in both cases, large prey were less likely to be immediately consumed than small prey items. The results can be interpreted in the light of the morphological characteristics of the spiders. G. cancriformis possesses long legs and a carapace and appeared to have few difficulties to manipulate all types of prey. In contrast, C. caroli showed lesser abilities to manipulate and subdue aggressive prey items, perhaps due to the short leg length and unprotected body of this species. The consumption of prey items may be related to the predatory strategy of each spider. G. cancriformis constructs a new web every morning and prey storage was never observed. The absence of prey storage behaviour could explain why this species consumes prey soon after capture. In contrast, C. caroli constructs a permanent web and stores captured prey on a stabilimentum that may explain the very low incidence of immediate consumption of prey observed in this species.     

Fitness costs and benefits of antipredator behavior mediated by chemotactile cues in the wolf spider Pardosa milvina (Araneae: Lycosidae)

Animals may exhibit a variety of defensive behaviors in thepresence of indirect predator cues. Such behavior offers immediatefitness benefits but may also incur substantial foraging andreproductive costs. We measured shifts in space use (verticalclimbing) by the wolf spider Pardosa milvina induced by chemotactilecues (silk and excreta) from a co-occurring predatory wolfspider Hogna helluo. We then measured foraging and reproductive costs, as well as survival benefits, of this behavior. For 2weeks, we maintained mated adult female Pardosa in plasticcontainers with one of three treated peat moss substrates:a container previously occupied by a conspecific for 3 days,a container previously occupied by an adult Hogna for 3 days,and a container devoid of either cue (control). We measuredprey capture efficiency, body condition, egg sac production,egg sac weight, and egg number for individuals in each treatment.We also counted the number of Pardosa that survived and exhibitedclimbing behavior in the presence of a live Hogna with andwithout silk and excreta cues. Pardosa climbed container wallssignificantly more often in the presence of Hogna silk andexcreta relative to other treatments. Pardosa exposed to Hognacues coupled with live Hogna survived significantly longerthan spiders that had no predator cues available. Pardosa placedin containers with Hogna cues, but no Hogna, lost weight morequickly, ate fewer prey, were in poorer body condition, producedlighter egg sacs, and produced fewer eggs than spiders in controlor conspecific treatments.     

The Effect of Predator Chemical Cue Age on Antipredator Behavior in the Wolf Spider Pardosa milvina (Araneae: Lycosidae)

The wolf spider, Pardosa milvina, exhibits reduced movement when detecting chemical cues (silk and excreta) from a larger wolf spider, Hogna helluo. We tested if cue age influenced Pardosa activity. Pardosa response was measured during 1-h trials using video-tracking equipment. Five treatments of predator cues were used: 5-day-old, 1-day-old, 1-h-old, and fresh cues and a control lacking predator cues. Pardosa moved significantly more slowly on substrates with fresh or 1-h-old cues compared to all other treatments and spent less time walking in all Hogna treatments relative to the control except with 5-day-old cues. Pardosa survived longer in the presence of Hogna with fresh compared to older cues. Prey may evaluate cue age as a measure of predation risk and grade antipredator behavior accordingly.     

Asymmetry of Leg Use During Prey Handling in the Spider Scytodes globula (Scytodidae)

In spitting spiders Scytodes globula collected in the field, anterior leg loss was more frequent on the left than on the right side, possibly as an outcome of predatory episodes. A laboratory study was performed in which intact adult females of S. globula were placed with individuals from three species of recluse spiders, Loxosceles intermedia, L. gaucho, and L. laeta. The frequency of probing touches by spitting spiders to their prey was significantly higher with left leg I than with right leg I. Left leg II and right leg II also differed in touching frequency, but in a less marked way. The results, which may represent the first evidence of behavioral laterality in a spider species, suggest that behavioral asymmetry may be an ancient evolutionary trait.     

Combined versus Single Species Release of Predaceous Mites: Predator–Predator Interactions and Pest Suppression

Interactions such as competition, intraguild predation (IGP), and cannibalism affect the development and coexistence of predator populations and can have significance for biological control of commonly exploited pest organisms. We studied the consequences of combined versus single release of two predaceous mite species (Phytoseiidae), with differing degrees of diet specialization, on their population dynamics and the suppression of the carmine spider mite, Tetranychus cinnabarinus Boisduval (Tetranychidae), on greenhouse-grown gerbera. Population growth of the specialist predator Phytoseiulus persimilis Athias-Henriot was greater and population decline steeper when released in combination with the generalist Neoseiulus californicus McGregor than when released alone. In contrast, the N. californicus population grew and declined more gradually when released in combination with P. persimilis, compared to the single species release. The differential impact on each other's population dynamics can be primarily attributed to contrasting properties in competition, IGP, and cannibalism. At the same overall predator density and as long as prey was abundant, the specialist P. persimilis was more strongly affected by intraspecific competition than by interspecific competition with the generalist N. californicus. In contrast, interspecific competition with P. persimilis had a greater impact on N. californicus than intraspecific competition. After prey depletion, the generalist predator N. californicus was more likely to engage in IGP than was the specialist predator P. persimilis. Overall, the study demonstrates that prey specificity has significance for the quality and intensity of predator–predator interactions and indicates potential implications for biological control of spider mites. All predator releases (i.e., either species alone and both species in combination) resulted in reduction of the spider mite population to zero density. Individual release of the specialist P. persimilis led to the most rapid spider mite suppression. Nonetheless, in perennial greenhouse-grown crops P. persimilis and N. californicus could have complementary effects and a combination of the two predators could enhance long-term biological control of spider mites. The potential risks and benefits associated with the release of both species are discussed.