The study investigated interspecific agonistic behavior of Macrotermes gilvus Hagen (Isoptera: Termitidae: Macrotermitinae) against three economically important subterranean termites in the Philippines, viz., Coptotermes gestroi Wasmann, Nasutitermes luzonicus Oshima and Microcerotermes losbanosensis Oshima. Termite-termite interactions after a 1:1 pairing experiment showed that M. gilvus workers and soldiers were highly aggressive against C. gestroi, N. luzonicus and M. losbanosensis leading to severe injury or death of the opponent termite species in a short period of time. The levels of agonism were caste and species specific. Worker termites of M. gilvus showed an equally aggressive behavior as soldiers contributing to the high mortality of opponent species used in this study. It is likely that the highly aggressive behavior of M. gilvus limits foraging activity of C. gestroi, N. luzonicus and M. losbanosensis around in-ground bait stations contributing to the low success of termite baits containing chitin synthesis inhibitors in the Philippines.

Species in the Polysphincta genus group, as far as is known, are exclusively koinobiont ectoparasitoids of spiders. These wasps attack their hosts, inflicting a temporary paralysis, and then lay one egg on the host’s abdomen or prosoma. Parasitoid attack behavior is highly variable among species, including occasions where the wasp darts directly and holds the spider, as well as instances involving complex behavioral sequences. In the present study, we describe the attack behavior of Polysphincta sp. nr. purcelli and P. janzeni on Cyclosa fililineata and C. morretes, respectively. All attacks occurred at night. Initially, the female wasp landed on the web hub at the position occupied by the spider, with the spider always escaping from this initial attack. Subsequently, the wasp waited for up to 14 h at the web hub for the spider’s return. The wasp then inserted its ovipositor into the mouth of the spider, after which the spider became paralyzed and remained motionless for at least 30 min. The wasp laid one egg on the surface of the host’s abdomen and remained on the web for at least 1 h thereafter. The lie-in-wait and attack only after the return of the host to the web hub, as well as the permanence of the wasp on the web after the attack are not frequent behaviors described for polysphinctines. Behavioral idiosyncrasies, such as those observed here, are common among polysphinctines, suggesting a high level of specific adaptive matching of polysphinctine parasitoid behavior to their hosts’ biological characteristics.

The grape weevil, Naupactus xanthographus Germar (Coleoptera: Curculionidae), is a polyphagous insect which is a cause of important damage to several economically relevant crops, including grape (Vitis vinifera) and avocado (Persea americana), in several countries of Latin America. The larvae cause damage to the roots and rootlets of plants, and adults feed on leaves of their host plant. Despite its economic importance, there are few reports on the behavioral and nutritional ecology of this weevil. In this context, laboratory feeding and olfactometer bioassays with N. xanthographus were performed. The feeding performance was evaluated by measuring the weight variation of the insects after 1 and 6 h of feeding on grape or avocado leaves, respectively. After 1 h of feeding, insects showed no significant differences in weight increase. However, after a period of 6 h of feeding, males had continued feeding on grape leaves, but not on avocado leaves. Bioassays using a Y-tube olfactometer showed that males are attracted to volatiles of both host plants. Furthermore, starved males and females showed no preference to volatiles of grape or avocado. However, non-starved males and females preferred grape volatiles over avocado volatiles. Based on the combined results of the assays, we conclude that grape is preferred over avocado for N. xanthographus. Furthermore, this is the first report on the effect of starvation on the attraction to host plant volatiles in Curculionidae.

In South Africa, Thaumatotibia leucotreta is a key pest of citrus impacting its production and trade. Detection of newly infested fruit by visual inspection is challenging and poses a risk of packing infested with healthy fruit for export. Agathis bishopi is a larval endoparasitoid of T. leucotreta, attacking early larval instars. Understanding how A. bishopi parasitoids locate fruit infested with their host is of interest for developing an efficient detector for T. leucotreta infested fruit. The response of female adult A. bishopi parasitoids to olfactory and visual cues associated with T. leucotreta infested fruit were evaluated using a Y-tube olfactometer and flight tunnel. Agathis bishopi parasitoids were strongly attracted to infested fruit over healthy fruit, either when only olfactory or combinations of visual and olfactory cues were offered. Among the four synthetic compounds tested, D-limonene and ocimene elicited a strong attraction to parasitoids with response rates of 92 % and 72 % respectively. A blend of four synthetic compounds simulating T. leucotreta infested fruit odour equally elicited strong attraction to parasitoids (84 % response rate). Attraction of parasitoids to infested fruit cues was heightened by prior experience, suggesting the occurrence of associative learning. Results from this study indicate that A. bishopi parasitoids mainly rely on olfactory cues in host habitat location and that D-limonene and ocimene are the major attractants in infested fruit volatiles. These findings and the potential for manipulating A. bishopi for detection of infested fruit in the packhouse are discussed.

The Asian citrus psyllid (ACP) is an important pest because it transmits a bacterium putatively responsible for huanglongbing, a devastating citrus disease. Research on ACP chemical ecology is of interest with respect to identifying attractants and repellents for managing the psyllid. We report on an assay for investigating ACP attraction to the foliar odor of one of its host plants, orange jasmine (Murraya exotica L.). Flush shoots from this plant were placed into 25 dram vials covered with a paper wrapper, a lid with a small entrance hole was snapped onto each vial, the vials were placed into a small cage, adult ACP were released into the cage, and the location of the adults was determined 24 h later. A positive response required an adult to find and enter a vial. When single males or females were released, they were attracted into vials with flush 64 % of the time. At release rates of 25, 50 or 100 adults with 30 repetitions for each rate, relatively large mean percentages of adults (ca. 83 %) positively responded to flush shoots. ACP can escape from the assay vial and will do so if flush is not present. Working with ACP in empty vials, fluoropolymer resin applied to the inside of vials reduced escapes but did not eliminate them. An entrapment funnel for reducing escapes was tested, but it reduced ACP response rates. A good method of preventing escapes remains to be developed. When two vials of flush were placed in the assay cage and one was treated with a candidate repellent, only 8 % of adults settled in the vial with the repellent.

Alternative reproductive tactics (ARTs) evolve to maximise fitness by favouring alternative phenotypes when high variance in relative fitness occurs amongst individuals. In the damselfly Hetaerina vulnerata males occur as either territorial or nonterritorial, depending on whether males acquire and defend an area to which females are attracted for copulation. Territorial males are usually larger, more pigmented and more successful in obtaining copulations than nonterritorial males. Several studies further suggest that territorial males are in overall better condition than nonterritorial ones. Other studies have investigated whether wing pigmentation, a sexual trait in damselflies, scales hyperallometrically with body size, and asked whether this pattern is related to fitness—nonetheless, a clear answer to this question remains elusive. Here we investigate whether i) territorial and nonterritorial males differed in body size and wing pigmentation; ii) body size, wing pigmentation and/or male status (male ART) predicted male mating success; and iii) the allometry of wing pigmentation in territorial and nonterritorial males, and amongst mated and unmated males. We first found that territorial and nonterritorial males did not differ in body size. Second, contrary to what occurs in other damselflies, territorial and nonterritorial males exhibited similar amounts of wing pigmentation. Third, only territory tenure, but not body size or wing pigmentation, predicted male mating success. Finally, with the exception of the relationship exhibited by mated males, which exhibited isometry, wing pigmentation was hyperallometric in all groups of males tested. The latter result suggests that hyperallometry of the sexual trait in this damselfly may not be selectively advantageous.

Density dependent numerical response is considered advantageous for biocontrol agents. Although density dependent behaviors have been examined in aphidophagous ladybirds, they haven’t been studied for coccidophagous ladybirds. The relationship of prey density and prey oviposition stage on the aggregating behavior and oviposition of the coccidophagous predator Nephus includens (Coleoptera: Coccinellidae) was empirically investigated. In a semi-field experiment potted citrus trees were artificially infested with Planococcus citri (Hemiptera: Pseudococcidae) prey in order to obtain two densities, one mealybug and ten mealybugs per tree. Released N. includens adults were found to aggregate at citrus trees with high prey density. In a subsequent laboratory experiment four prey densities of P. citri were used ranging from 1 to 8 adult mealybugs at 3 ovipositional stages, a) at the young gravid female stage, b) at mid oviposition (half of egg load oviposited) and c) at the end of the ovipositional period (full egg load oviposited). Nephus includens females increased their oviposition rate as prey density increased and as prey oviposition progressed. It is hypothesized that this behavior of the predator might be advantageous for offspring survival and the efficacy of N. includens as a biological control agent against mealybugs.

Cannibalism is an important factor influencing both immature survival and adult reproductive success in aphidophagous lady beetles. This study employed three series of laboratory experiments to characterize life stage-specific cannibalism responses of Coccinella undecimpunctata L. and Cydonia vicina nilotica Mulsant to 1) different conspecific densities, with and without prey, 2) other life stages, and 3) various densities of prey, Myzus persicae Sulzer. All larval instars of both species cannibalized more in the absence of prey than in its presence at all conspecific densities, but in general, cannibalism increased with conspecific density only in the absence of prey, and more strongly for third and fourth instar C. undecimpunctata than for their C. vicina nilotica counterparts. Adults contributed the most cannibalism of any life stage, and eggs were the most vulnerable. In addition to cannibalizing their own and earlier instars, second and third instar C. undecimpunctata sometimes cannibalized third and fourth instars, respectively, and fourth instars occasionally ate pupae. Larvae of C. vicina nilotica were only preyed upon by the same or later stages and pupae, by adults, not fourth instars. A relative vulnerability index was calculated for each life stage based on its net vulnerability to cannibalism by all life stages and plotting these indices revealed species-specific patterns of diminishing vulnerability to cannibalism as a function of life stage. Relative species vulnerability to cannibalism, considering all life stages, was higher for C. undecimpunctata (0.55) than for C. vicina nilotica (0.45). Finally, linear regression was used to characterize the change in propensity for cannibalism between same-instar larval pairs as a function of prey density, which enabled determination of a theoretical upper prey threshold for each larval instar, i.e., the prey density beyond which no cannibalism would be expected. In both species, regressions for third and fourth instars did not intercept the X-axis, suggesting that some cannibalism by these stages was inevitable within the range of prey densities tested.

In this study, the relationship between physiological conditions, including oogenesis and gravidity, and attraction to carcass odors was examined in order to discover how the attractivity of volatile organic compounds (VOCs) varied in females of the necrophagous fly Lucilia caesar (Linnaeus, 1758) (Diptera: Calliphoridae). Thus we want to shed some light on settlement behavior of scavenger flies. In bioassays with a decomposed mouse (Mus musculus), mixtures of synthetic compounds and flies of several physiological states, we observed rates of attraction and found compound classes that attract the different physiological stages. We found that a protein-poor diet increased the attraction to a carcass, especially between the age of 3 and 7 days. 7-day old females were attracted to cyclic compounds when mated and after exposure to a protein-poor nutrition, whereas they responded to fatty acids when mated after exposure to a protein-enriched diet. Furthermore we found that only with a protein-rich diet did the gonadal development complete with mature eggs in the Xth stadium between seven and 10 days and an overlapping second cycle with eggs in the Vth stadium at day 10.

For any arthropod, molting is a risky endeavor; it leaves an organism vulnerable until its new cuticle hardens. In some social organisms, the safest place for an individual to molt may be within their group. Here I present preliminary observations of a potential signaling behavior associated with molting in the gregarious larvae of the Australian sawfly, Perga affinis. Observations of molting activity revealed that larvae were significantly more likely to molt during the day, while residing in tight clusters, than at night when they were dispersed. Additionally, on two occasions I witnessed a vibrational and tactile behavior given by a larva 30 min prior to ecdysis. In each case, this behavior affected the other group members by delaying dispersal for foraging until the molting individual finished ecdysis; this change in the group’s behavior suggests that the molting larva engaged in a form of communication. Potential benefits for a molting signal are discussed.