German cockroaches spend most of the day in aggregations within shelters, which they leave in nocturnal foraging trips; cockroaches are rarely seen outside shelters during daylight hours. However, when population density exceeds shelter availability, diurnal aggregations form in exposed, unsheltered locations. To determine if shelter availability affects fitness of B. germanica, we reared cohorts of nymphs in laboratory arenas with or without shelters, and measured reproduction and longevity of tagged adults. When shelters were available in arenas, nymphs developed faster, adults gained more body mass, and females produced more fertile oothecae than when arenas lacked shelters. Therefore, shelter alone has a significant positive effect on growth and reproduction of B. germanica, and reducing or eliminating shelters should affect population growth of B. germanica in residential and industrial settings. and César Gemeno, Gregory M. Williams, Coby Schal.
The zoophytophagous mirid bug Macrolophus caliginosus is an important biocontrol agent of whiteflies in the Mediterranean region. Periods of low productivity in commercial breeding units and unsuccessful establishment in greenhouses prompted this study of mating behaviour. Here we describe copulation behaviour, the diel mating periodicity and post-copulatory refractory period. A natural plant substrate needs to be provided if one wants to observe the copulatory behaviour of M. caliginosus in the laboratory. There was no apparent directional orientation in the approach of the two sexes, instead males pursued females after "accidentally" contacting them. Males mounted females from above, very rapidly, and without any obvious courtship behaviour, and copulation duration was very consistent (286.33 ± 4.23 s, mean ± SE). Observations over a 24-h period showed that mating was most frequent in the 8-h scotophase and first half of the 16-h photophase than in the second half of the photophase. Mated females became strongly unreceptive to new male mounting attempts, shaking their abdomen and leaving the plant if harassed. To determine the duration of the post-mating refractory period mating receptivity of females that had mated 1 or 2 weeks earlier was compared with that of virgin females of similar age. Mated females remained unreceptive even 2 weeks after mating, whereas half of the virgin females of equivalent age mated. Mated females were more likely to abandon a plant than virgin females when harassed by a male. Most males remated a few minutes after mating for the first time. M. caliginosus is atypical among mirids in that females apparently mate only once.
Plant volatiles can synergize the response to moth pheromone. Synthetic pheromone analogs, in turn, have the opposite effect in reducing pheromone attractiveness. To determine how these two types of stimuli interact and influence male moth behaviour, we performed wind tunnel experiments on the grapevine moth, Lobesia botrana. We noticed that a blend of host plant volatiles [(E)-β-caryophyllene, 1-hexanol, (Z)-3-hexenyl acetate and 1-octen-3-ol in a 100:20:10:5 ratio] significantly increased the response of males to an optimized blend of sex pheromone [(7E,9Z)-dodeca-7,9-dienyl acetate (E7,Z9-12:Ac), (7E,9Z)- dodeca-7,9-dienol (E7,Z9-12:OH) and (Z)-9-dodecenyl acetate (Z9-12:Ac)] in a 100:10:2 ratio. However, the response of males to the natural attractant was significantly reduced by two analogs [(9E,11Z)-tetradeca-9,11-dien-2-one (MK 2) and [(9E,11Z)-1,1,1-trifluoro-tetradeca-9,11-dien-2-one (TFMK 3)], of the major component of the sex pheromone of the insect (E7,Z9-12:Ac). When both stimuli were tested on males at pheromone:analog:plant volatile blend 1:100:1000 ratio, the plant blend offset the inhibitory effect induced by TFMK 3 but not that of MK 2. Our results show for the first time that under laboratory conditions plant volatiles can prevent inhibition by a pheromone analog., Albert Sans, Miguel Morán, Magí Riba, Ángel Guerrero, Jaume Roig, César Gemeno., and Obsahuje bibliografii